''Notiomastodon'' is an extinct genus of

gomphothere Gomphotheres are an extinct group of proboscideans related to modern elephants. First appearing in Africa during the Oligocene, they dispersed into Eurasia and North America during the Miocene and arrived in South America during the Pleistocene a ...

proboscidea Proboscidea (; , ) is a taxonomic order of afrotherian mammals containing one living family (Elephantidae) and several extinct families. First described by J. Illiger in 1811, it encompasses the elephants and their close relatives. Three l ...

n (related to modern elephants), endemic to

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

from the

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

to the early

Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...

. ''Notiomastodon'' specimens reached a size similar to that of the modern

Asian elephant The Asian elephant (''Elephas maximus''), also known as the Asiatic elephant, is the only living ''Elephas'' species. It is the largest living land animal in Asia and the second largest living Elephantidae, elephantid in the world. It is char ...

, with a body mass of 3-4 tonnes. Like other brevirostrine gomphotheres such as ''

Cuvieronius ''Cuvieronius'' is an extinct New World genus of gomphothere which ranged from southern North America to western South America during the Pleistocene epoch. Reaching a shoulder height of and a body mass of , it was on average shorter but compara ...

'' and ''

Stegomastodon ''Stegomastodon'' ('roof breast tooth') is an extinct genus of gomphotheres. It ranged throughout North America from the Pliocene (early Blancan ~4 Ma), to the Early Pleistocene (early Irvingtonian, ~1.2 Ma). The former South American species h ...

'', ''Notiomastodon'' had a shortened lower jaw and lacked lower tusks, unlike more primitive gomphotheres like ''

Gomphotherium ''Gomphotherium'' (; "nail beast" for its double set of straight tusks) is an extinct genus of gomphothere proboscidean from the Neogene of Eurasia, Africa and North America. It is the most diverse genus of gompothere, with over a dozen valid sp ...

''. The genus was originally named in 1929, and has been controversial in the course of taxonomic history as it has frequently been confused with or synonymized with forms called ''Haplomastodon'' and ''Stegomastodon''. Extensive anatomical studies since the 2010s have shown that ''Notiomastodon'' represents the only valid proboscidean in lowland South America, ''Haplomastodon'' is

synonymous A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

and ''Stegomastodon'' is limited to North America, with the only other gomphothere in South America ''Cuvieronius'' confined to the northwestern part of the continent. ''Notiomastodon'' arrived in South America along with many other animals of North American origin as part of the

Great American Interchange The Great American Biotic Interchange (commonly abbreviated as GABI), also known as the Great American Interchange and the Great American Faunal Interchange, was an important late Cenozoic paleozoogeographic biotic interchange event in which land ...

following the formation of the

Isthmus of Panama The Isthmus of Panama, historically known as the Isthmus of Darien, is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North America, North and South America. The country of Panama is located on the i ...

connecting the two continents during the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58ground sloths ''

Megatherium ''Megatherium'' ( ; from Greek () 'great' + () 'beast') is an extinct genus of ground sloths endemic to South America that lived from the Early Pliocene through the end of the Late Pleistocene. It is best known for the elephant-sized type spe ...

'' and ''

Eremotherium ''Eremotherium'' (from Greek for "steppe" or "desert" "beast": ἔρημος "steppe or desert" and θηρίον "beast") is an extinct genus of giant ground sloth in the family Megatheriidae. ''Eremotherium'' lived in southern North America, Cen ...

.'' ''Notiomastodon'' ranged widely over most of South America, from Colombia in the northwest to Northeast Brazil and southwards to the

Zona Sur Zona Sur (''Southern Zone'') is one of the five natural regions on which CORFO divided continental Chile in 1950. Its northern border is formed by the Bío-Bío River, which separates it from the Central Chile Zone. The Southern Zone borders the ...

in Chile in environments ranging from

scrubland Shrubland, scrubland, scrub, brush, or bush is a plant community characterized by vegetation dominance (ecology), dominated by shrubs, often also including grasses, herbaceous plant, herbs, and geophytes. Shrubland may either occur naturally o ...

rainforest Rainforests are forests characterized by a closed and continuous tree Canopy (biology), canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropi ...

. It is thought to have been a generalist mixed feeder that fed on a variety of plants including leaves, grasses and fruit, with its diet varying according to local conditions. Like living elephants, ''Notiomastodon'' is thought to have lived in family groups, with adult males suggested to have had

musth Musth or must (from Persian, ) is a periodic condition in bull (male) elephants characterized by aggressive behavior in animals, aggressive behavior and accompanied by a large rise in reproductive hormones. It has been known in Asian elephan ...

-like behaviour. ''Notiomastodon'' became extinct as part of the end-Pleistocene extinction event, simultaneously along with the majority of large (

megafauna In zoology, megafauna (from Ancient Greek, Greek μέγας ''megas'' "large" and Neo-Latin ''fauna'' "animal life") are large animals. The precise definition of the term varies widely, though a common threshold is approximately , this lower en ...

l) animals native to the Americas. During the last few thousand years of its existence, ''Notiomastodon'' lived alongside

Paleoindians Paleo-Indians were the first peoples who entered and subsequently inhabited the Americas towards the end of the Late Pleistocene period. The prefix ''paleo-'' comes from . The term ''Paleo-Indians'' applies specifically to the lithic period in ...

, the first human to inhabit the Americas. Specimens associated with artifacts suggest that humans hunted ''Notiomastodon'', which may have been a factor in its extinction.

Research history

Initial research

Gomphothere_Teeth_South_America_Cuvier_1806

Traditionally, several species of gomphotheres from the late

in South America were distinguished. These included, on the one hand, a highland form from the Andes, ''

'', whose classification has not been controversial, and, on the other hand, several forms present in the lowlands, such as ''Haplomastodon'' and ''Notiomastodon''. In addition to this is ''

'', which has a North American distribution. The relationships of the three genres with each other on their independence or synonymization have been the subject of continuous discussion. Research on South American proboscideans began with the expeditions of

Alexander von Humboldt Friedrich Wilhelm Heinrich Alexander von Humboldt (14 September 1769 – 6 May 1859) was a German polymath, geographer, natural history, naturalist, List of explorers, explorer, and proponent of Romanticism, Romantic philosophy and Romanticism ...

in the transition from the 18th to the 19th century. From his collection of finds,

Georges Cuvier Jean Léopold Nicolas Frédéric, baron Cuvier (23 August 1769 – 13 May 1832), known as Georges Cuvier (; ), was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuv ...

published two teeth in 1806, one of which came from the vicinity of the

Imbabura Volcano Imbabura is an inactive stratovolcano in northern Ecuador. Although it has not erupted for about 7,500 years, it is not thought to be extinct. Imbabura is intermittently capped with snow and has no permanent glaciers. Covered in volcanic ...

near Quito in Ecuador, and the other from Concepción in Chile. Cuvier did not give them scientific names that are valid today, but simply called the first in French "Mastodon des cordilléres" and the second "Mastodon humboldien". In 1814,

Gotthelf Fischer von Waldheim Gotthelf Fischer von Waldheim (; 13 October 1771 – 18 October 1853) was a Saxon anatomist, entomologist and paleontologist. Fischer was born as Gotthilf Fischer in Waldheim, Saxony, the son of a linen weaver. He studied medicine at Leipz ...

coined for first time scientific names for the South American proboscideans by renaming Cuvier's "Mastodon des cordilléres" as ''Mastotherium hyodon'' and "Mastodon humboldien" as ''Mastotherium humboldtii''. Cuvier himself would refer both species to the now-disused genus "Mastodon" in 1824, but created a new name of species for the Ecuadorian find which is ''"Mastodon" andium'' (he placed the Chilean find in ''"Mastodon" humboldtii''). From the present point of view, both teeth do not have specific diagnostic characteristics that allow them to be assigned to a species in particular. In the following years, the number of discovered fossils increased, which led

Florentino Ameghino Florentino Ameghino (born Giovanni Battista Fiorino Giuseppe Ameghino; September 19, 1853 – August 6, 1911) was an Argentine naturalist, paleontologist, anthropologist and zoologist, whose fossil discoveries on the Argentine Pampas, especial ...

in 1889 to give the first general review of the proboscideans in his extensive work on the extinct mammals of Argentina. In this he listed several species, all of which he considered analogous to Cuvier's "''Mastodon''". In addition to the species already created by Cuvier and Fischer, Ameghino named some new ones, including ''"Mastodon" platensis'', which he had already established a year earlier and whose description was based on a tusk fragment of an adult individual from

San Nicolás de los Arroyos San Nicolás de los Arroyos (usually shortened to ''San Nicolás'') is a city in the provinces of Argentina, province of Buenos Aires Province, Buenos Aires, Argentina, on the western shore of the Paraná River, from Rosario. It has about 133,000 ...

in the province of Buenos Aires, on the shores of the

Paraná River The Paraná River ( ; ; ) is a river in south-central South America, running through Brazil, Paraguay, and Argentina for some ."Parana River". Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2012. Web. ...

, (catalog number MLP 8-63). Henry Fairfield Osborn used ''"Mastodon" humboldtii'' in 1923 to include it in the new genus ''Cuvieronius'' (another genus name he created in 1926, ''Cordillerion'' based on ''"Mastodon" andium'', is now considered a synonym of ''Cuvieronius''). Forty years after Ameghino, Ángel Cabrera reviewed the proboscidean finds. He named the genus ''Notiomastodon'', "southern mastodon" and assigned to it the new species ''Notiomastodon ornatus'', of which he had found a mandible and another tusk fragment at Playa del Barco near Monte Hermoso also in Buenos Aires province (catalog number MACN 2157). For his part, he assigned Ameghino's ''"Mastodon" platensis'' to ''Stegomastodon'' and synonymized this species with some of the names previously proposed by Ameghino. The genus ''Stegomastodon'' itself dates back to Hans Pohlig in 1912, who referred it to some findings of North American mandible. Stegomastodon waringi

In the northernmost part of South America, Juan Félix Proaño discovered in 1894 an almost complete skeleton near Quebrada Chalán, in the vicinity of Punín in the Ecuadorian province of Chimborazo. The skeleton he named as the new species ''"Masthodon" chimborazi'' in 1922. However, in 1929 it was almost completely lost in a fire at the University of Quito, along with another skeleton recovered at Quebrada Callihuaico near Quito a year earlier. In 1950, Robert Hoffstetter used the right and left humeri of the Quebrada Chalán skeleton to name ''Haplomastodon'', which he considered to be a

subgenus In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...

of ''Stegomastodon''. As type species he assigned ''Haplomastodon chimborazi'' (catalog numbers MICN-UCE-1981 and 1982); in 1995 Giovanni Ficcarelli ''et al''. identified a

neotype In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to anchor or centralizes ...

with catalog number MECN 82 to 84 from Quebrada Pistud in the Ecuadorian province of Carchi, which also included a complete skeleton. Only two years later Hoffstetter raised ''Haplomastodon'' to the level of the genus, and the main criterion for distinguishing it from ''Stegomastodon'' being the absence of a transverse opening in the

atlas An atlas is a collection of maps; it is typically a bundle of world map, maps of Earth or of a continent or region of Earth. Advances in astronomy have also resulted in atlases of the celestial sphere or of other planets. Atlases have traditio ...

(first cervical vertebra). Simultaneously, he distinguished two more subgenera, ''Haplomastodon'' and ''Aleamastodon'', which he differentiated from each other by the absence and presence of said openings in the

axis An axis (: axes) may refer to: Mathematics *A specific line (often a directed line) that plays an important role in some contexts. In particular: ** Coordinate axis of a coordinate system *** ''x''-axis, ''y''-axis, ''z''-axis, common names ...

, respectively.

''Stegomastodon'', ''Notiomastodon'' and ''Haplomastodon''

Since the establishment of ''Stegomastodon'' by Pohlig in 1912, ''Notiomastodon'' by Cabrera in 1929, and ''Haplomastodon'' as an independent genus by Hoffstetter in 1952, there have been multiple discussions about the validity of these three taxa. As early as 1952, Hoffstetter had limited ''Haplomastodon'' to northwestern South America, while for the remaining finds such as those from Brazil, he preferred to place them within ''Stegomastodon''. This was reviewed by

George Gaylord Simpson George Gaylord Simpson (June 16, 1902 – October 6, 1984) was an American paleontologist. Simpson was perhaps the most influential paleontologist of the twentieth century, and a major participant in the modern synthesis, contributing '' Tempo ...

and Carlos de Paula Couto in 1957 in their extensive work ''Mastodonts of Brazil''. In this, both authors referred all the Brazilian finds to ''Haplomastodon''. They determined that the other two genera, ''Notiomastodon'' and ''Stegomastodon'', were found further to the southeast in the Pampas region. The features of the transverse foramina of the first cervical vertebra, which Hoffstetter applied to distinguish ''Haplomastodon'' from ''Stegomastodon'', turned out to be highly variable, even in the same individual, according to the investigations of Simpson and Paula Couto. Therefore, both highlighted as a diagnostic feature of ''Haplomastodon'' compared to ''Notiomastodon'' and ''Stegomastodon'' the much more upwardly curved upper tusks, which do not present any layer of enamel. Simpson and Paula Couto established ''Haplomastodon waringi'' as the type species of the genus. The designation of this species refers to ''"Mastodon" waringi'', a taxon coined by William Jacob Holland in 1920. This was based on a highly fragmented remains of a jaw found in Pedra Vermelha in the Brazilian state of Bahia, and because it was named much earlier, Simpson and Paula Couto argued and in accordance with

ICZN The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its formal author, t ...

nomenclature rules, this name has priority over ''Haplomastodon chimborazi''. However, the validity of the designation of this species was frequently criticized, including by Hoffstetter himself, given that the material from Brazil is of little significance due to its poor preservation status. Other authors followed this idea and considered ''Haplomastodon chimborazi'' as the valid name (although in 2009 the taxon ''"Mastodon" waringi'' was preserved by the ICZN due to its multiple mentions in the scientific literature). In 1995, Maria Teresa Alberdi and José Luis Prado synonymized ''Notiomastodon'' with ''Stegomastodon'', leaving ''Stegomastodon platensis'' as the valid species. In the same study they also synonymized ''Haplomastodon'' with ''Stegomastodon'' creating the combination ''Stegomastodon waringi''. According to his vision, in his time ''Stegomastodon'' was the only gomphotherid genus present in the South American lowlands. However, in 2008 Marco P. Ferretti defended the independent classification of ''Haplomastodon'', but at the same time questioned the separation of ''Notiomastodon'' respect to ''Stegomastodon''. Only two years later, he published an exhaustive work focused on the anatomy of the skeleton of ''Haplomastodon'', in which he clearly separated it from ''Stegomastodon'' and gave it an intermediate position between it and ''Cuvieronius'' in the Andes. Around the same period, Spencer George Lucas and collaborators reached a similar conclusion, especially after examining an almost complete skeleton of ''Stegomastodon'' from the Mexican state of Jalisco and determined that this genus should be separated from the South American gomphotheres due to its different musculoskeletal characteristics. They differentiated ''Notiomastodon'' from ''Haplomastodon'' due to the much more complex chewing surface of their molariforms. According to this, there would be at least two species of gomphotheres living in the lowlands of South America. Analysis by a team of researchers led by Dimila E. Mothé in the early 2010s gave a different result. After examining abundant material from South American proboscideans, they determined that apart from ''Cuvieronius'', there was only one other genus of proboscidean in South America during the Pleistocene. In their opinion, this animal showed great variability in relation to the morphology of the teeth and skull, mainly in the shape of the tusks and molariform teeth. By following the ICZN priority rules, the first genus name given to this gomphothere, which would be ''Notiomastodon'', remains valid, and with only one species which must be called ''Notiomastodon platensis''. This is the classification that has been adopted at various times in the following years, and Mothé and colleagues through extensive morphological analysis of the teeth and skeletons, found that ''Stegomastodon'' differed significantly from ''Notiomastodon'' and was confined to North America. Later, Spencer George Lucas also supported this idea. However, some authors as Alberdi & Prado considered this is inconclusive, as they think the North American ''Stegomastodon'' material is too scarce and fragmentary to make a definitive statement. However, in a review about the fossil record of gomphotherids in South America published in 2022, both authors agreed to call it ''Notiomastodon''.

''Amahuacatherium''

Especially problematic is the genus ''Amahuacatherium'', which was described in 1996 by Lidia Romero-Pittman based on a fragmented mandible and two isolated molars found in the Madre de Dios region of southeastern Peru. The findings come from the Ipururo Formation, which outcrops along the Madre de Dios River. However, a partial skeleton that had been discovered along with these fossils was lost during a violent flood. As a special feature of ''Amahuacatherium'', the authors highlighted the short mandible with sockets for rudimentary incisors and molars with moderately complex molar masticatory surface pattern. The age of the sedimentary layers of these fossil remains is estimated at 9.5 million years, which corresponds to the late Miocene. This would make ''Amahuacatherium'' one of the first mammals to reach South America from the north before the Great American Biotic Interchange, which would only begin about six million years later. Additionally, this find is much older than the gomphotherid evidence considered as the oldest in both Central and South America, dating back to 7 and 2.5 million years, respectively. Only a few years later, several authors expressed doubts about the identity of this genus and its age. For example, their molars were considered to be barely distinguishable from other South American gomphotheres and the presence of alveoli for the lower tusks would be a misinterpretation of the mandibular cavities. Geologic age is also difficult to determine due to the complex stratigraphic conditions at the site. Other scientists agreed with this, and further dental analysis revealed no significant differences with ''Notiomastodon'', relative to the other South American finds.

Classification

Phylogeny

The following

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

shows the placement of the ''Notiomastodon'' among Late Pleistocene and modern proboscideans, based on genetic data:''Notiomastodon'' is a genus of

n in the family

Gomphotheriidae Gomphotheres are an extinct group of proboscideans related to modern elephants. First appearing in Africa during the Oligocene, they dispersed into Eurasia and North America during the Miocene and arrived in South America during the Pleistocene ...

. The proboscideans are a relatively successful mammalian order with a long history, which began at the end of the

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

. Originally from Africa, they reached a great diversity and expansion in both the Old and the New World in the course of their evolutionary history. Different phases of evolutionary radiation can be distinguished. The gomphotheres belong to the second phase, which began in the lower Miocene. The main characteristic of true gomphotheres is the formation is the formation of three transverse ridges on first and second molars (trilophodont gomphotheres; later forms with four tusks are sometimes known as tetralophodont gomphotheres, but are no longer included in the family). As in extant elephants, gomphotheres had a horizontal tooth replacement pattern which includes them in the modern group

Elephantimorpha Elephantimorpha is a clade of proboscideans that contains the Mammutidae (mastodons), as well as Elephantida ( amebelodonts, choerolophodonts, gomphotheres, stegodontids and elephantids). All members of Elephantimorpha have the horizontal toot ...

, compared to their ancestors which lacked this trait. In contrast to vertical tooth replacement which is used for most mammals, in which all permanent teeth are available at the same time, in horizontal replacement the individual molariform teeth erupt one after another in a row. This originated from jaw shortening in the course of proboscidean evolution and is first detectable in '' Eritreum'' in the late Oligocene, about 28 million years ago. Still, unlike modern elephants, gomphotheres possess a number of primitive and advanced traits. These include, for example, a generally flatter skull, the formation of upper and lower fenders as well as molariform teeth with fewer ridges and a mamelonated masticatory surface pattern. For this reason, gomphotheres are often placed in their own superfamily, the Gomphotherioidea, which is sister to the modern

Elephantoidea Elephantimorpha is a clade of proboscideans that contains the Mammutidae (mastodons), as well as Elephantida ( amebelodonts, choerolophodonts, gomphotheres, stegodontids and elephantids). All members of Elephantimorpha have the horizontal tooth r ...

. However, they are sometimes considered to be members of the Elephantoidea. In general, the gomphotheres are one of the most successful groups among the proboscideans, which underwent numerous changes in their long existence. These include a substantial increase in their overall size, their tusks and their molar teeth, as well as an increase in their complexity. ''Notiomastodon'' is a genus of

n in the family

. The proboscideans are a relatively successful mammalian order with a long history, which began at the end of the

. Originally from Africa, they reached a great diversity and expansion in both the Old and the New World in the course of their evolutionary history. Different phases of evolutionary radiation can be distinguished. The gomphotheres belong to the second phase, which began in the lower Miocene. The main characteristic of true gomphotheres is the formation of three transverse ridges on first and second molars (trilophodont gomphotheres; later forms with four tusks are sometimes known as tetralophodont gomphotheres, but are no longer included in the family). As in extant elephants, gomphotheres had a horizontal tooth replacement pattern which includes them in the modern group

Tethys Ocean The Tethys Ocean ( ; ), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean during much of the Mesozoic Era and early-mid Cenozoic Era. It was the predecessor to the modern Indian Ocean, the Mediterranean Sea, and the Eurasia ...

and the appearance of the land bridge to Eurasia during the transition to the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

. Among others, ''Gomphotherium'' reached North America about 16 million years ago through the

Bering Strait The Bering Strait ( , ; ) is a strait between the Pacific and Arctic oceans, separating the Chukchi Peninsula of the Russian Far East from the Seward Peninsula of Alaska. The present Russia–United States maritime boundary is at 168° 58' ...

, while in Central America they are recorded as early as the end of the Miocene about 7 million years ago. Gomphotherids reached South America during the

between 3.5 and 2.5 million years ago. South American gomphotheres differ from their relatives in other parts of the world by their relatively short snouts (brevirostral gomphotheres) and high-domed skulls. Additionally, they only had upper tusks. The two known South American genera (''Notiomastodon'' and ''Cuvieronius'') together with their North American relative (''Stegomastodon'') form a monophyletic group known as the subfamily Cuvieroniinae, which in turn are grouped with ''Rhynchotherium'' in a larger group called Rhynchotheriinae. Some researchers have proposed the idea that ''Cuvieronius'' is a direct descendant of ''Rhynchotherium'', as evidenced by its highly specialized upper tusks, which feature a spiral enamel band. ''Notiomastodon'' could have descended directly from ''Cuvieronius''. The idea is supported by the recognition that unlike adult specimens, juvenile ''Cuvieronius'' still had lower tusks, while in ''Rhynchotherium'' the mandible has lower tusks at all ages. This idea does not take into account relationships with other short-faced gomphotherids which are mostly unclear. The situation of ''

Sinomastodon ''Sinomastodon'' ("Chinese mastodont") is an extinct gomphothere genus (of order Proboscidea) known from the Late Miocene to Early Pleistocene of Asia, including China, Japan, Thailand, Myanmar, Indonesia and probably Kashmir. Extinct animals o ...

'', an East Asian form with skeletal characteristics very similar to South American gomphotheres, is problematic. In several phylogenetic studies, ''Sinomastodon'' forms a group with ''Stegomastodon'', ''Cuvieronius'' and ''Notiomastodon'', for which its presence in Asia is interpreted as a migration from America. Due to its geographic isolation from the American genera, the Chinese scientists usually place it in the independent subfamily Sinomastodontinae. Taking into account the lack of intermediate forms, some authors consider the similarities between ''Sinomastodon'' and the South American gomphotheres to be the result of

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...

. As with many mammals known only from fossils, phylogenetic relationships are inferred from skeletal anatomical features. It is only since the 2000s that methods based on

molecular genetics Molecular genetics is a branch of biology that addresses how differences in the structures or expression of DNA molecules manifests as variation among organisms. Molecular genetics often applies an "investigative approach" to determine the st ...

and

biochemical Biochemistry, or biological chemistry, is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology, ...

analyzes have gradually acquired a greater role. In addition to the

woolly mammoth The woolly mammoth (''Mammuthus primigenius'') is an extinct species of mammoth that lived from the Middle Pleistocene until its extinction in the Holocene epoch. It was one of the last in a line of mammoth species, beginning with the African ...

(''Mammuthus primigenius''), the Columbian mammoth (''Mammuthus columbi'') and the

straight-tusked elephant The straight-tusked elephant (''Palaeoloxodon antiquus'') is an extinct species of elephant that inhabited Europe and Western Asia during the Middle Pleistocene, Middle and Late Pleistocene. One of the largest known elephant species, mature full ...

(''Palaeoloxodon antiquus'') which are members of the modern family Elephantidae, the

American mastodon American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, p ...

(''Mammut americanum'') of the family

Mammutidae Mammutidae is an extinct family of proboscideans belonging to Elephantimorpha. It is best known for the mastodons (genus ''Mammut''), which inhabited North America from the Late Miocene (around 8 million years ago) until their extinction at the ...

is the only non elephantid proboscidean whose molecular data has been sequenced. ''Notiomastodon'' is the only representative of the gomphotheres for which biochemical data are available for comparison. In stark contrast to what was suspected of its close anatomical resemblance to elephantids, a study published in 2019 indicated a closer relationship to mastodonts. It is unclear whether this result can be extrapolated to the rest of the entire group of gomphotherids. On the other hand, a 2021 study based on

mitochondrial DNA Mitochondrial DNA (mtDNA and mDNA) is the DNA located in the mitochondrion, mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the D ...

determined that ''Notiomastodon'' is more closely related to modern elephants than to ''Mammut''. Within this genus, only one species is recognized: *''N. platensis'' (Ameghino, 1888) Various other forms have been described throughout history, some of them associated with ''Notiomastodon'' (''N. ornatus''), some also with ''Haplomastodon'' (''H. waringi'', ''H. chimborazi''), but are now considered more recent synonyms of ''N. platensis''.

Evolutionary history

The appearance of gomphotherids in South America originates with the Great American Interchange. This began in the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Isthmus of Panama The Isthmus of Panama, historically known as the Isthmus of Darien, is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North America, North and South America. The country of Panama is located on the i ...

closed and a mainland connection between North and South America was established. This exchange occurred in both directions, so that for example

ground sloth Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. They varied widely in size with the largest, belonging to genera '' Lestodon'', ''Eremotherium'' and ''Megatherium'', being around the size of elephants. ...

s and

glyptodont Glyptodonts are an extinct clade of large, heavily armoured armadillos, reaching up to in height, and maximum body masses of around 2 tonnes. They had short, deep skulls, a fused vertebral column, and a large bony carapace made up of hundreds o ...

s arrived in the north, while carnivorous mammals and

artiodactyls Artiodactyls are placental mammals belonging to the order Artiodactyla ( , ). Typically, they are ungulates which bear weight equally on two (an even number) of their five toes (the third and fourth, often in the form of a hoof). The other thre ...

, as well as proboscideans, among others, mixed with the endemic fauna of the south. The oldest record of proboscideans from South America comes from the middle section of the Uquia Formation in northwestern Argentina. It dates from about 2.5 million years ago, and the findings, which correspond to fragmentary remains of vertebrae, are not attributable to a particular genus. It is unknown when ''Notiomastodon'' originated. There are no clear documented finds of this genus in Central America. On another hand, ''Cuvieronius'' appeared in the region about 7 million years ago. It has been generally assumed that the gomphotherids invaded South America in two independent waves. ''Cuvieronius'' used a corridor west of the Andes, while ''Notiomastodon'' used an eastern one along the Atlantic coast and lowlands. It is possible that the emigration to South America was much more complex, since ''Cuvieronius'' does not show a restriction to the highlands in Central America, but can also be found there in lowlands. The oldest unambiguous evidence of ''Notiomastodon'' in South America is an individual tooth found on the continental shelf off the Brazilian coast in the state of

Rio Grande do Sul Rio Grande do Sul (, ; ; "Great River of the South") is a Federative units of Brazil, state in the South Region, Brazil, southern region of Brazil. It is the Federative units of Brazil#List, fifth-most populous state and the List of Brazilian s ...

, which was radiometrically dated to 464,000 years ago and therefore corresponds to the Middle Pleistocene. The vast majority of ''Notiomastodon'' finds belong to the late Middle Pleistocene and Late Pleistocene. Its distribution areas in central Chile may have been reached relatively late, either by a route from the Pampas to the low inter-Andean valleys or from the north through the Amazonian lowlands. This may have occurred during the warm periods of the last glacial period, when the Patagonian ice cap was less extensive.

Description

Size

''Notiomastodon'' was a medium to large proboscidean. A complete skeleton was reconstructed a height at the

withers Withers are the ridge between the shoulder blades of an animal, typically a quadruped. In many species, this ridge is the tallest point of the body. In horses and dogs, it is the standard place to measure the animal's height. In contrast, catt ...

of about 2.5 meters and a body weight of 3.15 tons, while other analyzes put the weight of the same individual at more than 4.4 tons. For another individual, the weight calculations vary between 4.1 and 7.6 tons. Since these estimates are based on the dimensions of the limb bones, but these differ proportionally from those of extant elephants, these values can only be considered as an approximation. In general, this genus reached approximately the dimensions of current

Asian elephants The Asian elephant (''Elephas maximus''), also known as the Asiatic elephant, is the only living ''Elephas'' species. It is the largest living land animal in Asia and the second largest living elephantid in the world. It is characterised by ...

(''Elephas maximus''). A partial femur head from

Yumbo Yumbo is a small, industrial city and municipality in western Colombia. It is located in the Valle del Cauca Department, just north of Cali. In 2020, the municipality had a population of approximately 110,000. History Modern Yumbo was founded ...

in Colombia, with a circumference of 51.2 cm, suggests that this specimen could have exceeded 7.9 tons in weight; some specimens could reach 3 meters in height.

Skull and teeth

''Notiomastodons skull was short and tall, and compared to that of its relative ''

'', it was narrower and shorter. In side view, this was pronounced in a dome, comparable to that of the skulls of today's elephants. However, in the case of modern elephants, the skull has an even more upright orientation and the snout is much shorter. The skulls found have total lengths of 75 to 113 cm, and the height of these, measured from the upper edge to the dental alveoli, is 41 to 76 cm. The upper part of the skull was characterized in frontal view by having two domes, between which is a slight suture along the center of the skull. Both domes were formed by the air-filled chambers of the

neurocranium In human anatomy, the neurocranium, also known as the braincase, brainpan, brain-pan, or brainbox, is the upper and back part of the skull, which forms a protective case around the brain. In the human skull, the neurocranium includes the cal ...

. These were larger than in ''

''. The forehead was broad and flattened for the most part. As in all advanced proboscideans, the

nasal bone The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose. Eac ...

was short and lay on top of the very wide but flat nasal opening where the trunk connected to the skull. Seen from the side, a groove bounded the nasal bone, which served as an anchor point for the maxillolabial muscle, which acted as a load-bearing arm for the tube. The remaining edges of the nasal opening were formed by the premaxillary bone and individual extensions of it. This bone also formed the alveoli of the upper incisors. These were very long, sometimes up to 59 cm, and they were very wide and their diameter increased towards the front. These only diverged slightly and in side view aligned with the profile of his forehead. This created a wide angle between the orientation of the tusks sockets and the plane of the chewing surface of the molars. Upwards, the alveoli of the incisors were slightly indented. In general, the premaxilla was much more massive than in ''Gomphotherium'', for example. Due to the shortening of the skull at the snout, the eye orbit of ''Notiomastodon'' was above the front end of the molar tooth row, which is markedly more forward than in long-snouted gomphotheres such as ''Gomphotherium'' or ''Rhynchotherium''. The

zygomatic arch In anatomy, the zygomatic arch (colloquially known as the cheek bone), is a part of the skull formed by the zygomatic process of temporal bone, zygomatic process of the temporal bone (a bone extending forward from the side of the skull, over the ...

was robust and high. Its upper border was rather straight, while the lower one had a slight notch in which the

masseter muscle In anatomy, the masseter is one of the muscles of mastication. Found only in mammals, it is particularly powerful in herbivores to facilitate chewing of plant matter. The most obvious muscle of mastication is the masseter muscle, since it is the ...

began.

The jaw reached 77 cm in length, and the area where the teeth were inserted was quite wide and noticeably arched at its lower edge. The height under the molars was more than 15 cm. In contrast, ''Stegomastodon'' had a mostly straight lower border. The

symphysis A symphysis (, : symphyses) is a fibrocartilaginous fusion between two bones. It is a type of cartilaginous joint, specifically a secondary cartilaginous joint. # A symphysis is an amphiarthrosis, a slightly movable joint. # A growing together o ...

was typical of South American gomphotheres as it was relatively short (brevirostral), and in some individuals it pointed downwards and sometimes formed a small prominence, as is the case in ''Cuvieronius''. Downward directed symphysis is considered a diagnostic feature. On the other hand, in ''Stegomastodon'', this prominence was significantly reduced. In some cases, there were as many as three holes known as mental foramina. The ascending ramus of the mandible was massive and rose up to 47 cm. The leading and trailing edges showed a parallel orientation. The frontal process was significantly lower than that of the joint, which was not the case in ''Stegomastodon''. The joint ended transverse to the longitudinal axis of the mandible and was very robust, with a distance between its tips from side to side of 57 cm. Also unlike ''Stegomastodon'', the angular process was less prominent. The teeth consisted of its large tusks and the molariform teeth. In contrast to Eurasian gomphotheres, incisors were only formed in the upper dentition, although small sockets were sometimes formed in the lower jaw. As in all proboscideans, the upper tusks were actually hypertrophied second incisor teeth. These tusks could vary in shape in each individual, so that the tusks could be short and with the tips clearly curved upwards or relatively straight. The enamel layer disappears in adult individuals. This differentiates it from ''Cuvieronius'', whose upper tusks were spiraled with an enamel band that wrapped around them. Additionally, in the latter, lower tusk appear in juveniles. In general, the tusks of ''Notiomastodon'' were very robust. Their lengths could reach more than 88 cm outside the alveoli, and in particularly long specimens it could reach 128 cm measured on the external curvature. The cross section was oval in shape and varied from 11.5 to 16.4 cm in diameter. The remaining dentition was composed of the

premolar The premolars, also called premolar Tooth (human), teeth, or bicuspids, are transitional teeth located between the Canine tooth, canine and Molar (tooth), molar teeth. In humans, there are two premolars per dental terminology#Quadrant, quadrant in ...

s and

molars The molars or molar teeth are large, flat tooth, teeth at the back of the mouth. They are more developed in mammal, mammals. They are used primarily to comminution, grind food during mastication, chewing. The name ''molar'' derives from Latin, '' ...

as in modern elephants, which erupted one after the other due to the horizontal replacement of the teeth. The chewing surface was generally composed of seven pairs of ridges or lophs, which gave the teeth a

bunodont The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone tooth ...

pattern. The first two molars had three pairs of ridges (trilophodonts) that were oriented along the longitudinal axis. The upper three, meanwhile, had four and the lower one more than five pairs of ridges (tetra- and pentalophodont), so these additional ridges were less pronounced. ''Stegomastodon'', on the other hand, had five ridges on the upper teeth and more than eight on the lower ones. The upper and lower third molars (M3/m3) were tetralophodont or pentalophodont; and their wear morphology in the occlusal phase varies from simple to complicated due to the presence of central conules and accessory conules between the main cusps of pre- and postrites, which makes it look like a double trefoil. It is characteristic of this species is a greater proportion of teeth with these very complex trefoil figures and marked ptychodonty in their enamel. Additionally, two morphotypes can be identified in ''Notiomastodon'' in relation to molars, one with two additional central ridges on each half side of the tooth longitudinally and one without. Also very characteristic is the cloverleaf structure on the individual ridges in the weathered state. In general, the dental structure of ''Notiomastodon'' was characterized by a basal pattern, which was more similar to that of ''Cuvieronius''. However, due to the different morphotypes, it more closely approximated the complex pattern of the chewing surface of ''Stegomastodon'', which was formed mainly by the formation of additional lateral ridges. The last chewing molar would have had between 35 and 82 ridges in ''Notiomastodon'', 33 and 60 in ''Cuvieronius'', and 57 and 104 in ''Stegomastodon''. In total, the chewing surface of the last molar in ''Notiomastodon'' was 57 to 160 cm² (12 to 32 cm² per lophid) and in ''Stegomastodon'' 72 to 205 cm² (12 to 34 cm² per lophid). Thus the teeth were typical for a relatively large proboscidean. The lower last molar was 21.6 cm long, and the upper last molar was over 19.3 cm.

Postcranial skeleton

In terms of the shape of its postcranial skeleton, ''Notiomastodon'' was for the most part similar to living elephants, but generally stockier. The

humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

was massive and 78 to 87 cm long. This widened towards the ends of the joints, the joint head was wide and clearly rounded. However, only some prominences showed rough areas on the axis. The ulna was rather gracile, with a total length of 75 to 80 cm but almost as large as the humerus. Due to the large

olecranon The olecranon (, ), is a large, thick, curved bony process on the proximal, posterior end of the ulna. It forms the protruding part of the elbow and is opposite to the cubital fossa or elbow pit (trochlear notch). The olecranon serves as a lever ...

, the superior joint extension, the length of the bone was only 57 to 64 cm. As a result, the ulna was functionally much shorter than the humerus, which is characteristic of South American gomphotheres compared to their Eurasian relatives. The physiological length of the ulna also corresponded to the approximate total length of the radius. The femur was 96 to 100 cm long and consisted of a nearly cylindrical shaft, slightly flattened only at the front and back. The spherically shaped femoral head towered over the other prominence, but sat on a shorter neck than that of ''Cuvieronius''. At the lower end, the prominence internal was greater than the external. The fibula, which was up to 70 cm long, was characterized by a prismatic axis and a higher end at the lower joint. The hands and feet had five fingers, as in modern elephants. The limbs of ''Notiomastodon'', like those of other short-jawed gomphotheres, were generally more massive and robust than in extant elephants. It is also very curious that the length of the upper and lower sections of the legs of ''Notiomastodon'' were more balanced with each other than those of modern elephants and ''Stegomastodon''. In the case of the latter, the length of the femur exceeded that of the tibia by almost twice. Another important difference can be seen in the ratio of the front legs compared to the hind legs. These have an average of 82% for ''Notiomastodon'' and 93% for ''Stegomastodon'', which means that the hind legs of the latter were significantly shorter than the front ones. In ''Stegomastodon'', the ratio of the upper and lower sections of its legs as well as the fore and hind legs to each other gave it a better adaptation for open environments and long strides and a greater degree of graviportality, than in the case of ''Notiomastodon''. This is also reflected in the build of the feet, which were slimmer and taller than in ''Stegomastodon''.

Paleobiology

Diet

The

chewing pattern of gomphotheres is usually associated with a generalist diet, which suggests a preference for mixed feeding on both grass and foliage. This has also been delineated in studies on traces of wear and scratches on ''Notiomastodon'' molars from the Upper Pleistocene site of Aguas de Araxin Island in the Brazilian state of Minas Gerais. The teeth exhibit a high number of nicks and scratches, which is consistent with similar abrasion marks on the teeth of extant ungulates that consume both hard and soft plants. Through some plant residues from the teeth, it was possible to identify that the basis of their diet were

conifer Conifers () are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a sin ...

s, knotweed plants and polypodiacean ferns. In contrast, isotope analyzes of other areas of South America paint a more complex picture. This results in a predominance of C₄ plants in the dietary spectrum of Upper Pleistocene specimens from northern and central South America such as Ecuador or the Gran Chaco, while those from southern regions such as the Pampas fed mostly on C₃ plants. ''N. platensis'' fossils from Minas Gerais suggest a diet based primarily on C₄ plants. In the intermediate areas, a mixed diet could be reconstructed based on the isotopes. Specimens from

Mato Grosso Mato Grosso ( – ) is one of the states of Brazil, the List of Brazilian states by area, third largest by area, located in the Central-West Region, Brazil, Central-West region. The state has 1.66% of the Brazilian population and is responsible ...

indicate ''N. platensis'' had a generalised browsing diet in that region, with ''N. platensis'' from

Paraíba Paraíba ( , ; ) is a states of Brazil, state of Brazil. It is located in the Brazilian Northeast, and it is bordered by Rio Grande do Norte to the north, Ceará to the west, Pernambuco to the south and the Atlantic Ocean to the east. Paraíba i ...

similarly being identified as mixed feeders during isotopic analysis. The dietary flexibility of ''N. platensis'' was particularly apparent in the fossil finds from the Quequen Grande site in the Argentine province of Buenos Aires. Isotope studies of finds there from the Middle Pleistocene indicate a relatively mixed diet, while others from the Late Pleistocene suggest that it specialized in consuming grasses. Remains near Santiago del Estero in Argentina from the Last Glacial Maximum show a diet exclusively composed of C4 plants. ''Notiomastodon'' may have been an opportunistic herbivore adapting its habits food to local conditions, similar to what has been documented in living elephants. Especially during the course of the Late Pleistocene, when climatic changes from the last glacial period in the

Southern Cone The Southern Cone (, ) is a geographical and cultural subregion composed of the southernmost areas of South America, mostly south of the Tropic of Capricorn. Traditionally, it covers Argentina, Chile, and Uruguay, bounded on the west by the Pac ...

caused forests to shrink and be replaced by grassland environments, this was an important adaptive phenomenon. A 2025 study found that in central Chile, its diet varied depending on location (which ranged from

xerophytic A xerophyte () is a species of plant that has adaptations to survive in an environment with little liquid water. Examples of xerophytes include cactus, cacti, pineapple and some gymnosperm plants. The morphology (biology), morphology and physiology ...

temperate rainforest Temperate rainforests are rainforests with coniferous or Broad-leaved tree, broadleaf forests that occur in the temperate zone and receive heavy rain. Temperate rainforests occur in oceanic moist regions around the world: the Pacific temperate ...

) but was predominantly leaf browsing, with its diet notably including fruit and seeds, including seeds of ''

Chusquea ''Chusquea'' is a genus of evergreen bamboos in the grass family. Most of them are native to mountain habitats in Latin America, from Mexico to southern Chile and Argentina. They are sometimes referred to as South American mountain bamboos. Unl ...

'' bamboo, as well as the fruit of the

Chilean wine palm ''Jubaea'' is a genus of palms with one species, ''Jubaea chilensis'', commonly known in English as the Chilean wine palm or Chile cocopalm, and palma chilena in Spanish. It is native to southwestern South America and is endemic to a small area ...

(''Jubaea chilensis),'' thus providing evidence for the contention by Daniel H. Janzen and Paul S. Martin in a 1982 paper that gomphotheres were likely important seed dispersers in Pleistocene neotropical ecosystems including " evolutionary anarchronisms" with large fruit that lack effective living seed dispersers.

Palaeopathology

Pathological vertebrae belonging to ''N. platensis'' have been found in Late Pleistocene deposits at Anolaima, Cundinamarca, Colombia. Specifically, they consist of deep bone lesions on the spinous process, osteoarthritic lesions, and asymmetrical articulations of the zygaphophyses, which were caused by nutrient deficiencies caused by environmental perturbations and likely exacerbated by excessive biomechanical stress on the bones as the proboscidean moved through the uneven, upland terrain of the region. Late Pleistocene ''N. platensis'' fossils from Águas de Araxá in Brazil have been shown to exhibit Schmorl's node, osteoarthritis, and osteomyelitis. The teeth of ''N. platensis'' reveal the species was relatively susceptible to the development of

dental tartar In dentistry, calculus or tartar is a form of hardened dental plaque. It is caused by precipitation of minerals from saliva and gingival crevicular fluid (GCF) in plaque on the teeth. This process of precipitation kills the bacterial cells wit ...

Population structure and reproduction

Like modern elephants, ''Notiomastodon'' is suggested to have lived in social family groups. The Águas de Araxá site is significant as it has one of the largest collections of ''Notiomastodon'' fossils. These are interpreted as the remains of a local population that was wiped out by a catastrophic event. According to dental studies, the group consisted of 14.9% juveniles (0 to 12 years of age), 23.0% near-adult individuals (13 to 24 years of age), and 62.1% of adult individuals (25 years of age and older). This last group can be broken down into 27.7% of middle-aged animals (25 to 36 years) and 17.2% of old (37 to 48 years) and senile (49 to 60 years) specimens. The large proportion of individuals over 37 years of age is notable, suggesting that there was a high survival rate in this group. Some of the adult animals suffered from pathological changes in their bones from Schmorl's nodes,

osteomyelitis Osteomyelitis (OM) is the infectious inflammation of bone marrow. Symptoms may include pain in a specific bone with overlying redness, fever, and weakness. The feet, spine, and hips are the most commonly involved bones in adults. The cause is ...

and

osteoarthritis Osteoarthritis is a type of degenerative joint disease that results from breakdown of articular cartilage, joint cartilage and underlying bone. A form of arthritis, it is believed to be the fourth leading cause of disability in the world, affect ...

. These are evident in the vertebrae and long bones among others, and may be due to individual diseases. Osteomyelitis has also been diagnosed in ''Notiomastodon'' finds from other sites. The remains found at Águas de Araxá must have been exposed for a long time after their deposit. Not only did this allow dermestid beetles to bore into the bones, but there is also evidence of bite marks from large canids such as '' Protocyon''. The gnawed bone marks are the result of carrion consumption, possibly caused by a period of food scarcity. Due to its size, ''Notiomastodon'' would hardly have natural enemies in life. Traces left by a large predator were also found on a skeleton from the Pilauco site in southern Chile. A study of the tusk of a male animal from the Santiago de Chile basin allowed the analysis of the last four years of its life by means of isotope and thin-section analyses. During this period, tusk appositional thickness increased by about 10 mm per year. This growth rate was found to be cyclical, slowing briefly in early summer with reduced tooth growth. The reduced growth is interpreted to correspond to the

stage, a hormone-controlled phase that occurs annually in modern elephants and is characterized by a huge increase in testosterone. During the musth, males become extremely aggressive and battles for mating rights can ensue, sometimes with fatal consequences. An external feature is the increased flow of a secretion from the temporal gland. In the case of the animal from Santiago de Chile, growth abnormalities were partially linked to a change in diet. The individual's death took place relatively abruptly in early autumn.

Ichnofossils

Proboscidean footprint fossils documented in South America are relatively rare. One of the most important sites is Pehuen Có near Bahía Blanca in the Argentine province of Buenos Aires. The site was discovered in 1986 and covers an area of 1.5 km². The numerous footprints were printed on a substrate that was originally soft. It has been possible to identify several ichnogenera produced by mammals, such as ''Megalamaichnum'' (corresponding to the camelid '' Hemiauchenia''), ''Eumacrauchenichnus'' (from the native ungulate ''

Macrauchenia ''Macrauchenia'' ("long llama", based on the now-invalid llama genus, ''Auchenia'', from Greek "big neck") is an extinct genus of large ungulate native to South America from the Pliocene or Middle Pleistocene to the end of the Late Pleistocene. I ...

''), ''Glyptodontichnus'' (produced by the armadillo relative ''

Glyptodon ''Glyptodon'' (; ) is a genus of glyptodont, an extinct group of large, herbivorous armadillos, that lived from the Pliocene, around 3.2 million years ago, to the early Holocene, around 11,000 years ago, in South America. It is one of, if not th ...

'') or ''Neomegatherichnum'' (the giant sloth ''

''), and additionally, footprints of birds such as ''Aramayoichnus'', which would represent a rhea, have also been found. Due to the diversity of footprints, Pehuen Có is one of the most important sites with ichnofossils in the world. It has been dated to about 12,000 years before present. Proboscidean tracks, however, are not common there. The main trail comprises seven footprints over a length of 4.4 meters. The individual prints have an oval shape with lengths from 23 to 27 cm and widths from 23 to 30 cm. In general, these have a depth of 8 cm below the surface. In some cases, small prominences are found on the front edge, which are interpreted as markings of three to five fingers, comparable to the nail-shaped structures of living elephants. The largest frontal footprints have five, and those of the smallest in some cases only have three of those prominences. In the same way they have a flattened shape that was generated by the fat pads of the legs as it happens in modern elephants. The footprints of Pehuen Có are assigned to the ichnogenus ''Proboscipeda'', whose

synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

is ''Stegomastodonichnum''. The size of these footprints suggests that they were made by animals the size of the Asian elephant, roughly matching ''Notiomastodon''.

Distribution

The geographic range of ''Notiomastodon'' extended through northern, eastern, and southern South America, with its southernmost distribution limit between the latitudes of 37 and 38 south. The specimens of this proboscidean are found mostly in the lowlands, while in the mountainous areas of the Andes it was largely absent, with ''Cuvieronius'' present in these regions instead. It is possible that both proboscideans avoided direct competition due to the strict definition of habitat, since both had a similar ecological spectrum. Modern elephants also generally avoiding higher elevation areas due to the associated energy cost of traversing them. In Colombia, it is suggested that ''Notiomastodon'' migrated through inter-Andean valleys. Many fossils of ''Notiomastodon'' have been found in the Pampas region and the Gran Chaco in Argentina. These include deposits such as Santa Clara del Mar in the province of Buenos Aires and the Río Dulce in the province of

Santiago del Estero Santiago del Estero (, Spanish for ''Saint-James-Upon-The-Lagoon'') is the capital of Santiago del Estero Province in northern Argentina. It has a population of 252,192 inhabitants, () making it the twelfth largest city in the country, with a sur ...

. Remains have also been documented from southern Bolivia, which are still found in the Gran Chaco area. Otherwise, most of the finds from that area correspond to ''Cuvieronius''. The southernmost evidence of this proboscidean comes from isolated remains from Chile, with the southernmost remains in the country being from

Chiloé Island Chiloé Island (, , ), also known as Greater Island of Chiloé (''Isla Grande de Chiloé''), is the largest island of the Chiloé Archipelago off the west coast of Chile, in the Pacific Ocean. The island is located in southern Chile, in the Los L ...

. There are several findings in Uruguay and Paraguay. Other finds are known from Brazil, where ''Notiomastodon'' was widely distributed from the open areas of the southern Chaco to the current Amazon basin, and fossil remains have been found on the continental shelf of the Atlantic coast. One of the sites most important, however, is the state of Minas Gerais. At least 47 ''Notiomastodon'' individuals were found there. These were preserved in a sinkhole with coarse-grained sediments. The genus has also been reported from Peru, Ecuador, Colombia, and Venezuela. Is interesting to note that some of the localities with ''Notiomastodon'' remains in these countries, as

Nemocón Nemocón is a municipality and town of Colombia in the Central Savanna Province, part of the department of Cundinamarca. Nemocón, famous for its salt mine, was an important village in the Muisca Confederation, the country in the central Colombi ...

in Colombia, Punín, in Ecuador and Leclishpampa, Lima in Peru, are located in high mountain deposits, meanwhile that in La Huaca in Peru, a lowland environment, has been found remains of ''Cuvieronius'', in contrast with the traditional division between lowland/mountain habitats for these animals. In Ecuador, the Quebrada Pistud site near Bolívar in the province of

Carchi Carchi () is a Provinces of Ecuador, province in Ecuador. The capital is Tulcán. The Carchi River rises on the slopes of Chiles (volcano), Chiles volcano and forms the boundary between Colombia and Ecuador near Tulcan. Rumichaca Bridge is the m ...

is noteworthy. This contained about 160 ''Notiomastodon'' fossil remains housed over several dozen square meters in flood deposits. These represented at least seven specimens, and a single skeleton consisted of 68 bone elements scattered over an area of 5 m². Another important site there is the natural asphalt pit of Tanque Loma on the Santa Elena peninsula, which had over 1000 individual bones. About 660 of them were examined in detail, and about 11% can be placed in ''Notiomastodon''. These correspond to 3 individuals, including two juveniles.

Paleoecology

Large, mesoherbivorous mammals in the Brazilian Intertropical Region were widespread and diverse, including the rhinoceros-like toxodontids ''

Toxodon platensis ''Toxodon'' (meaning "bow tooth" in reference to the curvature of the teeth) is an extinct genus of large ungulate native to South America from the Pliocene to the end of the Late Pleistocene. ''Toxodon'' is a member of Notoungulata, an order of ...

'' and '' Piauhytherium'', the macraucheniid

litoptern Litopterna (from "smooth heel") is an extinct order of South American native ungulates that lived from the Paleocene to the Pleistocene-Holocene around 62.5 million to 12,000 years ago (or possibly as late as 3,500 years ago), and were also pres ...

Xenorhinotherium ''Xenorhinotherium'' is an extinct genus of macraucheniine macraucheniids, native to northern South America during the Pleistocene and Holocene epoch, closely related to ''Macrauchenia'' of Patagonia. The type species is ''X. bahiense''.

'' and equines such as '' Hippidion principale'' and '' Equus neogeus.'' Toxodontids were large mixed feeders as well and lived in forested areas, while the equids were nearly entirely grazers.

Xenarthra Xenarthra (; from Ancient Greek ξένος, xénos, "foreign, alien" + ἄρθρον, árthron, "joint") is a superorder and major clade of placental mammals native to the Americas. There are 31 living species: the anteaters, tree sloths, and ...

n fossils are present in the area as well from several different families, like the giant megatheriid

,'' the fellow scelidotheriid '' Valgipes'', the mylodontids ''

Glossotherium ''Glossotherium'' is an extinct genus of large mylodontid ground sloths of the subfamily Mylodontinae. It represents one of the best-known members of the family, along with ''Mylodon'' and '' Paramylodon''. Reconstructed animals were between ...

'', '' Ocnotherium'', and '' Mylodonopsis''. Smaller ground sloths such as the megalonychids '' Ahytherium'' and '' Australonyx'' and the nothrotheriid '' Nothrotherium'' have also been found in the area. ''Eremotherium'' was a generalist, while ''Nothrotherium'' was a specialist for trees in low density forests, and ''Valgipes'' was an intermediate of the two that lived in arboreal savannahs. Glyptodonts and cingulates like the grazing glyptodonts ''

Glyptotherium ''Glyptotherium'' (from Ancient Greek for 'grooved or carved beast') is a genus of glyptodont (an extinct group of large, herbivorous armadillos) in the family Chlamyphoridae that lived from the Early Pliocene, about 5 million years ago, to th ...

'' and '' Panochthus'' and the omnivorous pampatheres '' Pampatherium'' and '' Holmesina'' were present in the open grasslands. Carnivores included some of the largest known mammalian land carnivores, like the giant felid '' Smilodon populator'' and the bear '' Arctotherium wingei.''Keeley, J. E., & Rundel, P. W. (2003). Evolution of CAM and C4 carbon-concentrating mechanisms. ''International journal of plant sciences'', ''164''(S3), S55-S77. Several extant taxa are also known from the BIR, like

guanaco The guanaco ( ; ''Lama guanicoe'') is a camelid native to South America, closely related to the llama. Guanacos are one of two wild South American camelids; the other species is the vicuña, which lives at higher elevations. Etymology The gua ...

giant anteater The giant anteater (''Myrmecophaga tridactyla'') is an Insectivore, insectivorous mammal native to Central America, Central and South America. It is the largest of the four living species of anteaters, which are classified with sloths in the or ...

collared peccaries The collared peccary (''Dicotyles tajacu'') is a peccary, a species of artiodactyl (even-toed) mammal in the family Tayassuidae found in North, Central, and South America. It is the only member of the genus ''Dicotyles''. They are commonly ref ...

, and striped hog-nosed skunks.Cartelle, Castor; Hartwig, W. C. (1996). "A new extinct primate among the Pleistocene megafauna of Bahia, Brazil". Proceedings of the National Academy of Sciences. 93 (13): 6405–6409. Two crab-eating types of extant mammals are also known from the BIR, the crab-eating raccoon and the

crab-eating fox The crab-eating fox (''Cerdocyon thous''), also known as the forest dog, wood fox, bushfox (not to be confused with the bush dog) or maikong, is an extant species of medium-sized canid endemic to the central part of South America since at least ...

, indicating that crabs were also present in the region. The environment of the BIR is unclear, as there were both several species that were grazers, but the precede of the arboreal fossil monkeys ''

Protopithecus ''Protopithecus'' is an extinct genus of large New World monkey that lived during the Pleistocene. Fossils have been found in the Toca da Boa Vista cave of Brazil, as well as other locales in the country. Fossils of another large, but less robu ...

'' and ''

Caipora bambuiorum ''Caipora'' is an extinct genus of large New World monkey that lived during the Pleistocene. It contains a single species, ''Caipora bambuiorum''. Fossils have been found only in Brazil's Toca da Boa Vista cave, alongside the larger '' Protopith ...

'' in the area causes confusion over the area’s paleoenvironment. Most of

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

was thought to have been covered in open tropical

cerrado The Cerrado () is a vast ecoregion of Tropics, tropical savanna in central Brazil, being present in the states of Goiás, Mato Grosso do Sul, Mato Grosso, Tocantins, Maranhão, Piauí, Bahia, Minas Gerais, São Paulo (state), São Paulo, Paraná ...

vegetation during the Late Pleistocene, but if ''Protopithecus'' and ''C. bambuiorum'' were arboreal, their presence suggests that the region may have supported a dense closed forest during the Late Pleistocene. It is possible that the region alternated between dry open savannah and closed wet forest throughout the climate change of the Late Pleistocene.

Relationship with humans and extinction

During the last few thousand years of its existence, ''Notiomastodon'' was contemporary with

, first human groups of hunter-gatherers that arrived in South America. ''Notiomastodon'' disappeared simultaneously with most other

(large animals) in the Americas around the Pleistocene-Holocene transition as part of the

Late Pleistocene megafauna extinctions The Late Pleistocene to the beginning of the Holocene saw the extinction of the majority of the world's megafauna, typically defined as animal species having body masses over , which resulted in a collapse in faunal density and diversity acro ...

, the exact causes of which are the subject of long-standing controversy in the scientific literature, with scholars suggesting climate change, human hunting or a combination of both as the likely cause of the extinctions. Several sites have been reported in South America where ''Notiomastodon/''gomphothere remains display cut marks and/or are associated with human artifacts, these span from Venezuela and Colombia and eastern Brazil to Chile, though the association between humans and gomphotheres has been questioned at some of these sites. At Muaco, Venezuela, an El-Jobo style projectile point has been found associated with burned ''Notiomastodon'' bones, suggested to date to around 17,000–15,000 years ago, but the mixed nature of the site including much more recent pottery makes the association questionable. At Taima-taima also in Venezuela, suggested to date to around 16,000–14,500 years ago, bones of a juvenile ''Notiomastodon'' individual have been found alongside those of glyptodonts, bears, equines and

felids Felidae ( ) is the family of mammals in the order Carnivora colloquially referred to as cats. A member of this family is also called a felid ( ). The 41 extant Felidae species exhibit the greatest diversity in fur patterns of all terrestria ...

, have been suggested by some authors to display scratch marks made during use as anvil tools. Some authors have considered the site a natural trap were stuck animals were killed and butchered. A lithic artefact was found "within the cavity of the right pubis" of the juvenile gomphothere. Cruxent 1979 suggested that this may have been the result of a spear having been thrust up the gomphothere's anus. The gomphothere's humerus and rib bones display marks that Cruxent 1979 and Bryan et al. 1978, considered consistent with butchery, while Lynch 1990 attributed these marks to natural processes involving the changing of water levels and trampling. At the controversial Monte Verde II site in Chile, suggested to represent a campsite dating to around 14,500 years ago, remains of at least 7 ''Notiomastodon'' individuals were found, suggested to display cut marks indicating butchery, with some displaying evidence of preserved flesh still attached to the bones. Taguatagua 3 in central Chile, suggested to date to around 12,440–12,550 cal yr Before Present, has been suggested to have functioned as a "logistic and temporary camp associated mainly with gomphothere hunting and butchering". Other localities in the Taguatagua area are also suggested to display evidence of gomphothere butchery, but the evidence for this has been questioned. In 2019, a description of a young ''Notiomastodon'' specimen from Brazil was published which had an artifact lodged into its skull, suggested to provide clear evidence that this individual was hunted. Finds of ''Notiomastodon'' suggested to be around 11,740 to 11,100 years old were obtained from Quereo in Chile, from Itaituba on the Tapajós River in central Brazil, and from Tibitó in Colombia, the latter being associated with three dozen tools of stone. Even more recent is a skull from Taguatagua in Chile, estimated to be 10,300 years before present. On the other hand, some scientists suggest a review of individual sites with finds dated to the early Holocene, as in Quebrada Ñuagapua in Bolivia. A specimen of ''Notiomastodon'' from the Jirau Paleontological Site has been dated to 7,836–10,159 years cal.

Before Present Before Present (BP) or "years before present (YBP)" is a time scale used mainly in archaeology, geology, and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Because ...

(BP). A find of a gomphothere, probably ''Notiomastodon'' in Totumo, Colombia was dated as recently as 6,060 ± 60 years before present, however, given how much later this date is than other finds of ''Notiomastodon'', this date should be considered with caution without other corroboration. The climatic models projected for South America during the latter Pleistocene and the early Holocene suggests that the habitats were more humid and with more presence of forests, which could reduce the suitable habitat for ''Notiomastodon'' and '' Equus neogeus'', another species commonly found in open habitats, along with the subsequent changes in the vegetation could affect to these large mammals.

Notes

References

Per Christiansen: Body size in proboscideans, with notes on elephant metabolism. ''Zoological Journal of the Linnean Society'', 140, 2004, S. 523–549 Richard A. Fariña, Sergio F. Vizcaíno & María S. Bargo. Body mass estimations in Lujanian (Late Pleistocene-Early Holocene of South America) mammal megafauna. ''Mastozoología Neotropical'' 5 (2), 1998, S. 87–108 José Luis Prado, María Teresa Alberdi, B. Azanza, Begoña Sánchez & D. Frassinetti. The Pleistocene Gomphotheres (Proboscidea) from South America: diversity, habitats and feeding ecology. In: G. Cavarretta, P. Gioia, M. Mussi & M. R. Palombo (Hrsg.): ''The World of Elephants – International Congress.'' Consiglio Nazionale delle Ricerche Rom, 2001, S. 337–340 Begoña Sánchez, José Luis Prado & María Teresa Alberdi: Feeding ecology, dispersal, and extinction of South American Pleistocene gomphotheres (Gomphotheriidae, Proboscidea). ''Paleobiology'' 30 (1), 2004, S. 146–161 José Luis Prado, Maria Teresa Alberdi, Beatriz Azanza, Begonia Sánchez & Daniel Frassinetti: The Pleistocene Gomphotheriidae (Proboscidea) from South America. ''Quaternary International'' 126–128, 2005, S. 21–30 Alberdi, M.T.; Cerdeño, E.; Prado, J.L. (2008) ''Stegomastodon platensis'' (Proboscidea, Gomphotheriidae) from Pleistocene levels of Santiago Del Estero, Argentina. Ameghiniana, v.45, p.257-272. 2008. María Teresa Alberdi & José Luis Prado. Presencia de ''Stegomastodon'' (Gomphotheriidae, Proboscidea) en el Pleistoceno Superior de la zona costera de Santa Clara del Mar (Argentina). ''Estudios Geológicos'' 64 (2), 2008, S. 175–185 Silvia A. Aramayo, Teresa Manera de Bianco, Nerea V. Bastianelli & Ricardo N. Melchor: ''Pehuen Co: Updated taxonomic review of a late Pleistocene ichnological site in Argentina.'' Palaeogeography, Palaeoclimatology, Palaeoecology 439, 2015, S. 144–165 José Luis Prado, María Teresa Alberdi, Begoña Sánchez & Beatriz Azanza: ''Diversity of the Pleistocene Gomphotheres (Gomphotheriidae, Proboscidea) from South America.'' Deinsea 9, 2003, S. 347–363 Dimila Mothé, Willer Flores Aguanta, Sabrina Larissa Belatto & Leonardo Avilla: ''First record of Notiomastodon platensis (Mammalia, Proboscidea) from Bolivia.'' Revista brasileira de Paleontologia 20 (1), 2017, S. 149–152 Fernando Henrique de Souza Barbosa, Kleberson de Oliveira Porpino, Ana Bernadete Lima Fragoso & Maria de Fátima Cavalcante Ferreira dos Santos: ''Osteomyelitis in Quaternary mammal from the Rio Grande do Norte State, Brazil.'' Quaternary International 299, 2013, S. 90–93 Fernando Henrique de Souza Barbosa, Hermínio Ismael de Araújo-Júnior, Dimila Mothé & Leonardo dos Santos Avilla: ''Osteological diseases in an extinct ''Notiomastodon (''Mammalia, Proboscidea) population from the Late Pleistocene of Brazil.'' Quaternary International 443, 2017, S. 228–232, doi:10.1016/j.quaint.2016.08.019 Victor Hugo Dominato, Dimila Mothé, Leonardo dos Santos Avilla & Cristina Bertoni-Machado: ''Ação de insetos em vértebras cervicais ''Stegomastodon waringi'' (Gomphotheriidae: Mammalia) do Pleistoceno de Águas de Araxá, Minas Gerais, Brasil.'' Revista Brasileira de Paleontologia 12 (1), 2009, S. 77–82 Victor Hugo Dominato, Dimila Mothé, Rafael Costa da Silva & Leonardo dos Santos Avilla: ''Evidence of scavenging on remains of the gomphothere ''Haplomastodon waringi'' (Proboscidea: Mammalia) from the Pleistocene of Brazil: Taphonomic and paleoecological remarks.'' Journal of South American Earth Sciences 31, 2011, S. 171–177 Joseph J. El Adli, Daniel C. Fisher, Michael D. Cherney, Rafael Labarca & Frédéric Lacombat: ''First analysis of life history and season of death of a South American gomphothere.'' Quaternary International 443, 2017, S. 180–188 Jeheskel Shoshani, Robert C. Walter, Michael Abraha, Seife Berhe, Pascal Tassy, William J. Sander, Gary H. Marchant, Yosief Libsekal, Tesfalidet Ghirmai & Dietmar Zinner: '' A proboscidean from the late Oligocene of Eritrea, a ‘‘missing link’’ between early Elephantiformes and Elephantimorpha, and biogeographic implications.'' PNAS 103 (46), 2006, S. 17296–17301 Giovanni Ficcarelli, Vittorio Borselli, Gonzalo Herrera, Miguel Moreno Espinosa & Danilo Torre: Taxonomic remarks on the South American mastodonts referred to ''Haplomastodon'' and ''Cuvieronius''. Geobios 28 (6), 1995, S. 745–756 W. J. Holland: ''Fossil mammal collected at Pedra Vernelha, Bahia, Brazil, by G. A. Waring.'' Annals of the Carnegie Museum 13, 1920, S. 224–232 George Gaylord Simpson & Carlos de Paula Couto: ''The mastodons of Brazil.'' Bulletin of the American Museum of Natural History 112, 1957, S. 131–189 Giovanni Ficcarelli, Vittorio Borselli, Miguel Moreno Espinosa & Danilo Torre: New ''Haplomastodon'' finds from the Late Pleistocene of Northern Ecuador.'' Geobios 26 (2), 1993, S. 231–240'' María Teresa Alberdi & José Luis Prado: ''Los mastodontes de América del Sur.'' In: M. T Alberdi, G. Leone & E. P. Tonni (Hrsg.): ''Evolución biológica y climática de la Región Pampeana durante los últimos 5 millones de años. Un ensayo de correlación con el Mediterráneo occidental.'' Monografías Museo Nacional de Ciencias Naturales, CSIC, Spanien, 1995, S. 277–292 María Teresa Alberdi, Madrid, José Luis Prado & Rodolfo Salas: ''The Pleistocene Gomphotheriidae (Proboscidea) from Peru.'' Neues Jahrbuch für Geologie & Paläontologie Abhandlungen 231 (3), 2004, S. 423–452 José Luis Prado & María Teresa Alberdi: ''A cladistic analysis among trilophodont gomphotheres (Mammalia, Proboscidea) with special attention to the South American genera.'' Palaeontology 51 (4), 2008, S. 903–915 María Teresa Alberdi & José Luis Prado: ''Fossil Gomphotheriidae from Argentina.'' In: F. L. Agnolin, G. L. Lio, F. Brisson Egli, N. R. Chimento & F. E. Novas (Hrsg.): ''Historia Evolutiva y Paleobiogeogr afica de los Vertebrados de America del Sur.'' Contribuciones del MACN 6, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Buenos AiSpenceres, Argentina, 2016, S. 275–283 Marco P. Ferretti: ''A review of South American gomphotheres.'' New Mexico Natural History and Science Museum Bulletin 44, 2008, S. 381–391 Spencer George Lucas: Taxonomic nomenclature of ''Cuvieronius'' and ''Haplomastodon'', proboscideans from the Plio-Pleistocene of the New World. New Mexico Museum of Natural History and Science Bulletin 44, 2008, S. 409–415 Spencer George Lucas. ''Mastodon waringi'' Holland, 1920 (currently ''Haplomastodon waringi''; Mammalia, Proboscidea): proposed conservation of usage by designation of a neotype. Bulletin of Zoological Nomenclature 66 (2), 2009, S. 164–167

Spencer George Lucas & Guillermo E. Alvarado: ''Fossil Proboscidea from the Upper Cenozoic of Central America: Taxonomy, evolutionary and paleobiogeographic significance.'' Revista Geológica de América Central 42, 2010, S. 9–42 Spencer George Lucas, Ricardo H. Aguilar & Justina Spillmann: ''Stegomastodon'' (Mammalia, Proboscidea) from the Pliocene of Jalisco, Mexico and the species-level taxonomy of ''Stegomastodon''. New Mexico Museum of Natural History and Science Bulletin 53, 2011, S. 517–553 Renato Pereira Lopes, Luiz Carlos Oliveira, Ana Maria Graciano Figueiredo, Angela Kinoshita, Oswaldo Baffa & Francisco Sekiguchi Buchmann: ''ESR dating of pleistocene mammal teeth and its implications for the biostratigraphy and geological evolution of the coastal plain, Rio Grande do Sul, southern Brazil.'' Quaternary International 212, 2010, S. 213–222 Alexsandro Schiller Aires & Renato Pereira Lopes: ''Represantivity of Quaternary mammals from the Southern Brazilian continental shelf.'' Revista brasileira de Paleontologia 15 (1), 2012, S. 57–66 Alan J. Bryan, Rodolfo M. Casamiquela, José M. Cruxent, Ruth Gruhn & Claudio Ochsenius: ''An El Jobo Mastodon Kill at Taima-Taima, Venezuela.'' Science 200, 1978, S. 1275–1277 D. Frassinetti & María Teresa Alberdi: Presencia del género ''Stegomastodon'' entre los restos fósiles de mastodontes de Chile (Gomphotheriidae), Pleistoceno Superior. Estudios Geológicos 61 (1–2), 2005, S. 101–107 Rafael Labarca Encina & María Teresa Alberdi: ''An updated taxonomic view on the family Gomphotheriidae (Proboscidea) in the final Pleistocene of south-central Chile.'' Neues Jahrbuch für Geologie & Paläontologie Abhandlungen 262 (1), 2011, S. 43–57 José Luis Prado, Joaquín Arroyo-Cabrales, Eileen Johnson, María Teresa Alberdi & Oscar J. Polaco: ''New World proboscidean extinctions: comparisons between North and South America.'' Archaeological and Anthropological Sciences 7, 2015, S. 277–288, doi:10.1007/s12520-012-0094-3 Mauro Coltorti, Jacopo Della Fazia, Freddy Paredes Rios & Giuseppe Tito: ''Ñuagapua (Chaco, Bolivia): Evidence for the latest occurrence of megafauna in association with human remains in South America.'' Journal of South American Earth Sciences 33, 2012, S. 56–67 Jorge B. Carrillo, Edwin A. Chávez & Imerú H. Alfonzo: ''Notas preliminares sobre los Mastodontes Gonfoterios (Mammalia: Proboscidea) del cuaternario venezolano.'' Boletín Antropológico 26 (7), 2008, S. 233–263 Webb, S.D. (1991). Ecogeography and the Great American Interchange. Paleobiology, 17: 266-280. M. A. Reguero, A. M. Candela & R. N. Alonso: ''Biochronology and biostratigraphy of the Uquı´a Formation (Pliocene–early Pleistocene, NW Argentina) and its significance in the Great American Biotic Interchange.'' Journal of South American Earth Sciences 23, 2007, S. 1–16 Dimila Mothé, Leonardo S. Avilla & Mario A. Cozzuol: ''The South American Gomphotheres (Mammalia, Proboscidea, Gomphotheriidae): Taxonomy, Phylogeny, and Biogeography.'' Journal of Mammalian Evolution 20, 2013, S. 23–32 Dimila Mothé & Leonardo Avilla: ''Mythbusting evolutionary issues on South American Gomphotheriidae (Mammalia: Proboscidea).'' Quaternary Science Reviews 110, 2015, S. 23–35 Henry Fairfield Osborn: ''New subfamily, generic, and specific stages in the evolution of the Proboscidea.'' American Museum Novitates 99, 1923, S. 1–4 Henry Fairfield Osborn: ''Additional new genera and species of the mastodontoid Proboscidea.'' American Museum Novitates 238, 1926, S. 1–16 Ángel Cabrera: ''Una revisión de los Mastodontes Argentinos.'' Revista del Museo de La Plata 32, 1929, S. 61–144

Ameghino, F. 1888. Rápidas diagnosis de algunos mamíferos fósiles nuevos de la República Argentina. ''Obras Completas'', Buenos Aires V: 469-480. Florentino Ameghino: ''Contribución al conocimiento de los mamíferos fósiles de la República Argentina.'' Academia Nacional Ciencias (Córdoba) 6, 1889, S. 1–1027 (S. 633–650)

Hans Pohlig: Sur une vieille mandibule de ''Tetracaulodon ohioticum'' Blum, avec defense in situ. Bulletin de la Société belge de géologie, de paléontologie et d'hydrologie 26, 1912, S. 187–193

Nadin Rohland, Anna-Sapfo Malaspinas, Joshua L. Pollack, Montgomery Slatkin, Paul Matheus & Michael Hofreiter: ''Proboscidean Mitogenomics: Chronology and Mode of Elephant Evolution Using Mastodon as Outgroup.'' PLoS Biology 5 (8), 2007, S. 1663–1671, doi:10.1371/journal.pbio.0050207 M. Buckley, N. Larkin & M. Collins: ''Mammoth and Mastodon collagen sequences; survival and utility.'' Geochimica et Cosmochimica Acta 75, 2011, S. 2007–2016 Matthias Meyer, Eleftheria Palkopoulou, Sina Baleka, Mathias Stiller, Kirsty E. H. Penkman, Kurt W. Alt, Yasuko Ishida, Dietrich Mania, Swapan Mallick, Tom Meijer, Harald Meller, Sarah Nagel, Birgit Nickel, Sven Ostritz, Nadin Rohland, Karol Schauer, Tim Schüler, Alfred L Roca, David Reich, Beth Shapiro, Michael Hofreiter: ''Palaeogenomes of Eurasian straight-tusked elephants challenge the current view of elephant evolution.'' eLife Sciences 6, 2017, S. e25413, doi:10.7554/eLife.25413 Kenneth E. Campbell, Jr., Carl D. Frailey & Lidia Romero-Pittman: In defense of ''Amahuacatherium'' (Proboscidea: Gomphotheriidae).'' Neues Jahrbuch für Geologie & Paläontologie Abhandlungen 252 (1), 2009, S. 113–128'' Jeheskel Shoshani & Pascal Tassy. ''Advances in proboscidean taxonomy & classification, anatomy & physiology, and ecology & behavior.'' Quaternary International 126–128, 2005, S. 5–20 Malcolm C. McKenna & Susan K. Bell: ''Classification of mammals above the species level.'' Columbia University Press, New York, 1997, S. 1–631 (S. 497–504) Jan van der Made: ''The evolution of the elephants and their relatives in the context of a changing climate and geography.'' In: Harald Meller (Hrsg.): ''Elefantenreich – Eine Fossilwelt in Europa.'' Halle/Saale 2010, S. 340–360 Wang Yuan, Jin Chang-Zhu, Deng Cheng-Long, Wei Guang-Biao & Yan Ya-Ling: The first ''Sinomastodon'' (Gomphotheriidae, Proboscidea) skull from the Quaternary in China. Chinese Science Bulletin 57 (36), 2012, S. 4726–4734 William J. Sanders, Emmanuel Gheerbrant, John M. Harris, Haruo Saegusa & Cyrille Delmer: ''Proboscidea.'' In: Lars Werdelin & William Joseph Sanders (Hrsg.): ''Cenozoic Mammals of Africa.'' University of California Press, Berkeley, London, New York, 2010, S. 161–251 Brunella Muttillo, Giuseppe Lembo, Ettore Rufo, Carlo Peretto & Roberto Lleras Pérez: ''Revisiting the oldest known lithic assemblages of Colombia: A review of data from El Abra and Tibitó (C&iboyacense Plateau, Eastern Cordillera, Colombia).'' Journal of Archaeological Science: Reports 13, 2017, S. 455–465 Francisco Javier Aceituno & Sneider Rojas-Mora: ''Lithic technology studies in Colombia during th Late Pleistocene and Early Holocene.'' Chungara, Revista de Antropología Chilena 47 (1), 2015, S. 13–23 Emily L. Lindsay & Eric X. Lopez R.: ''Tanque Loma, a new Late Pleistocene megafaunal tar seep locality from southwest Ecuador.'' Journal of South American Earth Sciences 57, 2015, S. 61–82 Emily L. Lindsay & Kevin L. Seymour: ''“Tar pits” of the Western Neotropics: Paleoecology, Taphonomy, and Mammalian Biogeography.'' Natural History Museum of Los Angeles County, Science Series 42, 2015, S. 111–123 Rafael Labarca, Omar Patricio Recabarren, Patricia Canales-Brellenthin & Mario Pino: ''The gomphotheres (proboscidea: Gomphotheriidae) from Pilauco site:Scavenging evidence in the Late Pleistocene of the Chilean Patagonia.'' Quaternary International 352, 2014, S. 75–84 Araújo, T., Machado, H., Mothé, D., & dos Santos Avilla, L. (2021). Species distribution modeling reveals the ecological niche of extinct megafauna from South America. ''Quaternary Research'', 104, 151-158. Cione, A.L., Gasparini, G.M., Soibelzon, E., Soibelzon, L.H., Tonni, E.P., 2015. The Great American Biotic Interchange in Southern South America: Land Mammal Biostratigraphy, Climatic Evolution and Faunal Integration. Springer Briefs in Earth System Sciences. Springer, New York-London Gadens-Marcon, Gabrielli Teresa (2007) ''Contribuição ao estudo dos Proboscidea (Mammalia, Gomphotheriidae) do Quaternário do Estado do Rio Grande do Sul, Brasil''. 2007. 115p. cita pág.:p.14. Dissertação (Mestrado em Geociências) Programa de Pósgraduação em Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre. María T. Alberdi & José L. Prado (2022)
Diversity of the fossil gomphotheres from South America
''Historical Biology'', DOI: 10.1080/08912963.2022.2067754 Mones, A. y Francis, J.C. 1973. Lista de los Vertebrados fósiles del Uruguay, II. ''Comunicaciones Paleontológicas del Museo de Historia Natural de Montevideo'' 1: 39-97 {{Taxonbar, from=Q2002264 Gomphotheres Pliocene proboscideans Pleistocene proboscideans Pleistocene mammals of South America Prehistoric placental genera Pleistocene first appearances Holocene extinctions Fossil taxa described in 1929 Fossils of Argentina Fossils of Bolivia Fossils of Brazil Fossils of Chile Fossils of Colombia Fossils of Ecuador Fossils of Peru Fossils of Uruguay Fossils of Venezuela