''Astraponotus'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of astrapotheriids. It lived during the Middle-Late Eocene (in the

Mustersan The Mustersan age is a period of geologic time (48.0–42.0 Mya (unit), Ma) within the Eocene epoch of the Paleogene, used more specifically within the South American land mammal age (SALMA) classification. It follows the Casamayoran and precedes th ...

and

Tinguirirican The Tinguirirican () age is a period of geologic time (36.0–29.0 Mya (unit), Ma) within the Eocene, Late Eocene and Oligocene, Early Oligocene epochs of the Paleogene, used more specifically within the South American land mammal age, SALMA classi ...

of the

South American land mammal age The South American land mammal ages (SALMA) establish a geologic timescale for prehistoric South American fauna beginning 64.5 Ma during the Paleocene and continuing through to the Late Pleistocene (0.011 Ma). These periods are referred to as age ...

s (SALMA), 48-33.9 million years ago) and its fossil remains have been found in the

Sarmiento Formation The Sarmiento Formation (Spanish language, Spanish: ''Formación Sarmiento''), in older literature described as the Casamayor Formation, is a geological formation in Chubut Province, Argentina, in central Patagonia, which spans around 30 million y ...

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

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 ...

.''Astraponotus''
at

Fossilworks Fossilworks was a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cr ...

.org

Description

Unlike most astrapotheres, ''Astraponotus'' was equipped with an unusually high, short, narrow skull. The nasal bones were quite withdrawn, which suggests the presence of a short proboscis. Other unusual features of ''Astraponotus'' includes the extreme reduction of the

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammals h ...

ry and

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 ...

s, the absence of an antorbital circle, and the reduction of the frontal region. The canines were long and strong, as in all astrapotheres.Kramarz, A. G., Bond M. and Forasiepi, A. M., 2010. New remains of ''Astraponotus'' (Mammalia, Astrapotheria) and considerations on Astrapothere cranial evolution. ''Paläontol Z''. DOI 10.1007/s12542-010-0087-4.

Classification

''Astraponotus'' was first described in 1901 by

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 ...

, based on teeth fossils.F. Ameghino. 1901. Notices préliminaires sur des ongulés nouveaux des terrains crétacés de Patagonie reliminary notes on new ungulates from the Cretaceous terrains of Patagonia ''Boletin de la Academia Nacional de Ciencias de Córdoba'' 16:349-429 The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

, ''Astraponotus assymetrum'', comes from Eocene terrains known as Gran Barranca, in

Patagonia Patagonia () is a geographical region that includes parts of Argentina and Chile at the southern end of South America. The region includes the southern section of the Andes mountain chain with lakes, fjords, temperate rainforests, and glaciers ...

(

). The area was later nicknamed ''capas Astraponotenses'' ("''Astraponotus layers" in

Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many countries in the Americas **Spanish cuisine **Spanish history **Spanish culture ...

) due to the abundance of the peculiar fossils of this animal. Other species were described later (for example, ''A. dicksoni'' and ''A. holdichi''), but always based just on the remains of the teeth and jaws. A nearly complete skull was not described until 2010, which has allowed hypothesis of the

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

relationships of this animal more precisely. The features observed in the teeth of ''Astraponotus'' are intermediate between the

Middle Eocene The Eocene ( ) is a geological epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''Ēṓs'', ' Dawn') a ...

astrapotheres and those of the

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

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 ...

in the degree of hypsodonty, the reduced

dental formula Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology ...

, and the development of accessory occlusal elements. Moreover, the skull retains

plesiomorphic In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, an ...

features also observed in the archaic genus '' Trigonostylops'', while the auditory region and the skull base are much closer to those of ''

Parastrapotherium ''Parastrapotherium'' is an extinct genus of South American land mammal that existed from the Late Oligocene (Deseadan SALMA) to the Early Miocene (Colhuehuapian SALMA). The genus includes some of the largest and smallest known astrapotherians, ...

'', ''

Astrapotherium ''Astrapotherium'' ("lightning beast") is an extinct genus of large Astrapotheria, astrapotherian ungulate native to South America during the early-middle Miocene. It is the best known member of the group. The type species. ''A. magnus'' have bee ...

'', and '' Granastrapotherium''. Furthermore, the ''Astraponotus'' skull differs from all astrapotheres known in its disproportionate height, the narrowness of the skull, and other numerous cranial specializations that are opposite to ''Astrapotherium''. These features seem surprisingly derived for an Eocene astrapothere, and suggest that these extreme cranial specializations were developed independently during the evolution of this order; ''Astraponotus'' could represent a lineage distinct from ''Astrapotherium'' and other Miocene forms.

Phylogeny

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 ...

based in the

phylogenetic analysis In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...

by Vallejo-Pareja ''et al''., 2015, showing the position of ''Astraponotus'':

References

External links

* {{Taxonbar, from=Q18416301 Astrapotheriidae Eocene mammals of South America Tinguirirican Divisaderan Mustersan Paleogene Argentina Fossils of Argentina Fossil taxa described in 1901 Taxa named by Florentino Ameghino Prehistoric placental genera Golfo San Jorge Basin Sarmiento Formation