''Catonyx'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

ground sloth Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. The term is used to refer to all extinct sloths because of the large size of the earliest forms discovered, compared to existing tree sloths. The Caribbe ...

of the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Scelidotheriidae Scelidotheriidae is a family of extinct ground sloths within the order Pilosa, suborder Folivora and superfamily Mylodontoidea, related to the other extinct mylodontoid family, Mylodontidae, as well as to the living two-toed sloth family Choloe ...

, endemic to

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

during the Pliocene and

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

epochs. It lived from 2.5 Ma to about 10,000 years ago, existing for approximately . The most recent date obtained is about 9600 B.P.

Description

This animal, like many other terrestrial

sloths Sloths are a group of Neotropical xenarthran mammals constituting the suborder Folivora, including the extant arboreal tree sloths and extinct terrestrial ground sloths. Noted for their slowness of movement, tree sloths spend most of their li ...

, was of conspicuous size and mighty build. It had to reach and exceed 4 meters in length, and the skull alone was at least 50 centimeters long. Its weight has been estimated at over 1500 kg. The snout of ''Catonyx'' was elongated, although not as in some similar forms (e.g., ''

Scelidotherium ''Scelidotherium'' is an extinct genus of ground sloth of the family Scelidotheriidae, endemic to South America during the Late Pleistocene epoch. It lived from 780,000 to 11,000 years ago, existing for approximately . Description It is chara ...

''). Unlike the latter, ''Catonyx'' possessed shorter premaxillae that formed a triangular (and not rectangular like ''

'') snout tip, a pronounced rostrum bulge, a palate equipped with a median groove, and larger teeth. In addition, the mandibular

symphysis A symphysis (, pl. 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 ...

was elongated and elevated, and the posterior lobe of the lower fourth molar was more curved than that of ''Scelidotherium.'' Like all terrestrial sloths, ''Scelidotherium'' possessed strong-boned limbs and large

claws A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or tarsus ...

Taxonomy

At a cave in Lagoa Santa,

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

Peter Wilhelm Lund Peter Wilhelm Lund (14 June 1801 – 25 May 1880) was a Danish paleontologist, zoologist, and archeologist. He spent most of his life working and living in Brazil. He is considered the father of Brazilian paleontology as well as archaeology. He ...

and his crew members collected the fragmentary fossils of a fossil sloth that Wilhelm named ''Megalonyx cuvieri'' in 1838. ''Catonyx,'' the genus name, was made by Ameghino in 1891. It was assigned to Scelidotheriinae by Gaudin in 1995. Scelidotheriinae was elevated back to family status by Presslee ''et al.'' in 2019. The very first fossils of this animal were found in Upper Pleistocene strata of

and were described by

Lund Lund (, , ) is a city in the southern Swedish provinces of Sweden, province of Scania, across the Øresund, Öresund strait from Copenhagen. The town had 91,940 inhabitants out of a municipal total of 121,510 . It is the seat of Lund Municipali ...

in 1839, but for a long time there was considerable systematic confusion: the remains were gradually attributed to the genera ''

'' and ''

Scelidodon ''Scelidodon'' is an extinct genus of South American ground sloths. Its remains have been found in the Yupoí and Uspara Formations of Argentina, the Ulloma, Umala, Ñuapua and Tarija Formations of Bolivia, in Brazil, in Chile and in Peru.< ...

''. Only recently have revisions based on clear morphological anatomy been proposed, according to which the genera ''Scelidotherium'' and ''Catonyx'' are two valid

taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

, while ''Scelidodon'' may or may not be a valid genus. ''Catonyx,'' in any case, is a member of the Scelidotheriidae, a group of terrestrial sloths known from the Miocene, Pliocene, and Pleistocene and characterized by an elongated snout; scelidotheres themselves part are usually placed as a subfamily of the

Mylodontidae Mylodontidae is a family of extinct South American and North American ground sloths within the suborder Folivora of order Pilosa The order Pilosa is a clade of xenarthran placental mammals, native to the Americas. It includes the anteaters a ...

, although they are sometimes considered a separate family,

. The

type species In 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 species that contains the biological type specimen ...

of ''Catonyx'' is ''Catonyx cuvieri'', named in 1839 by

. ''C. cuvieri'' has been found in Brazil and

Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...

, and dates to the Late Pleistocene and likely the Early Holocene. Other species attributed to this genus but are sometimes considered to belong to a separate genus, ''Scelidodon'', are ''C. tarijensis'' and ''C. chiliense,'' found in

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

, Argentina, Uruguay, Bolivia, and Ecuador. Below is a phylogenetic tree of the

Scelidotheriinae Scelidotheriidae is a family of extinct ground sloths within the order Pilosa, suborder Folivora and superfamily Mylodontoidea, related to the other extinct mylodontoid family, Mylodontidae, as well as to the living two-toed sloth family Choloe ...

, based on the work of Nieto and colleagues (2020), showing the position of ''Catonyx''.

Palaeobiology

The cranial anatomy of the species ''C. tarijensis'' indicates it may have been a browser which used its strong lips to grab vegetation, and Santos Pereira et al. (2013) tentatively suggested browsing habits for ''C. cuvieri''. Isotopic analysis of ''

Smilodon ''Smilodon'' is a genus of the extinct machairodont subfamily of the felids. It is one of the most famous prehistoric mammals and the best known saber-toothed cat. Although commonly known as the saber-toothed tiger, it was not closely related ...

populator'' remains from

indicates that ''Catonyx'' was one of its main prey items.

Fossil distribution

Fossils of ''Catonyx'' have been uncovered in

, the San José Formation of

, the Tezanos Pinto Formation of

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

, and the Tarija Valley of Bolivia.

Paleoecology

In the Brazilian Intertropical Region in eastern Brazil, ''Catonyx'' was a browser in arboreal savannahs and forested grasslands. Large, mesoherbivorous mammals in the BIR were widespread and diverse, including the cow-like toxodontids ''

Toxodon platensis ''Toxodon'' (meaning "bow tooth" in reference to the curvature of the teeth) is an extinct genus of South American mammals from the Late Miocene to early Holocene epochs (Mayoan to Lujanian in the SALMA classification) (about 11.6 million to 11 ...

'' and ''

Piauhytherium ''Piauhytherium'' is an extinct genus of herbivorous notoungulate mammal of the family Toxodontidae. It lived during the Late Pleistocene, about 10,000 years ago; fossils have been found in Brazil. The only known species is ''Piauhytherium capiva ...

'', the macraucheniid

litoptern Litopterna (from grc, λῑτή πτέρνα "smooth heel") is an extinct order of fossil hoofed mammals from the Cenozoic era. The order is one of the five great orders of South American ungulates that were endemic to the continent, until th ...

Xenorhinotherium ''Xenorhinotherium'' is an extinct genus of macraucheniine macraucheniids, closely related to '' Macrauchenia'' of Patagonia. The type species is ''X. bahiense''.Hippidion principale'' and '' Equus neogaeus.'' Toxodontids were large mixed feeders as well and lived in forested areas, while the equids were nearly entirely grazers. Other xenarthran fossils are present in the area as well from several different families, like the giant

megatheriid Megatheriidae is a family of extinct ground sloths that lived from approximately 23 mya—11,000 years ago. Megatheriids appeared during the Late Oligocene (Deseadan in the SALMA classification), some 29 million years ago, in South America. ...

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, the largest and most heavily built family of sloths. ...

,'' the fellow scelidotheriid ''

Valgipes ''Valgipes'' is an extinct genus of scelidotheriid ground sloth, endemic to intertropical Brazil and Uruguay during the Late Pleistocene. Thought to have been a forest-dwelling browser, ''Valgipes'' is a monotypic genus with a complex and lon ...

'', the mylodontids ''

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

'', '' Ocnotherium'', and '' Mylodonopsis''. Smaller ground sloths such as the megalonychids ''

Ahytherium ''Ahytherium'' is an extinct genus of megalonychid sloth that lived during the Pleistocene of what is now Brazil. It contains a single species, ''A. aureum''. Discovery and taxonomy The almost-complete skeleton of ''Ahytherium'' alongside rema ...

'' and ''

Australonyx ''Australonyx'' is an extinct genus of ground sloths, endemic to South America during the Late Pleistocene. It was found in Brazil. Discovery The holotype A holotype is a single physical example (or illustration) of an organism, known to ...

'' and the

nothrotheriid Nothrotheriidae is a family of extinct ground sloths that lived from approximately 17.5 mya—10,000 years ago, existing for approximately . Previously placed within the tribe Nothrotheriini or subfamily Nothrotheriinae within Megatheriidae, they ...

Nothrotherium ''Nothrotherium'' is an extinct genus of medium-sized ground sloth from South America (Bolivia, Brazil and the Ware Formation, La Guajira, Colombia).Amson et al., 2016, p.12 It differs from ''Nothrotheriops'' in smaller size and differences in sku ...

'' 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. Other glyptodonts and cingulates like the grazing glyptodonts ''

Glyptotherium ''Glyptotherium'' (from Greek for 'grooved or carved beast') is a genus of glyptodont (an extinct group of large, herbivorous armadillos) that lived from the Early Pliocene, about 4.9 million years ago, to the Early Holocene, around 7,000 years ...

'' and ''

Panochthus ''Panochthus'' is an extinct genus of glyptodont, which lived in the Gran Chaco- Pampean region of Argentina ( Lujan, Yupoí and Agua Blanca Formations), Brazil (Jandaíra Formation), Bolivia (Tarija and Ñuapua Formations), Paraguay and Urugua ...

'' and the omnivorous

pampatheres Pampatheriidae ("Pampas beasts") is an extinct family of large plantigrade armored armadillos related to extant armadillos in the order Cingulata. However, pampatheriids have existed as a separate lineage since at least the middle Eocene Musters ...

Pampatherium ''Pampatherium'' is an extinct genus of xenarthran that lived in the Americas during the Pleistocene. Some species went extinct right at the Pleistocene-Holocene border. Distribution ''Pampatherium humboldtii'' and ''P. typum'' lived in South Ame ...

'' and ''

Holmesina ''Holmesina'' is a genus of pampathere, an extinct group of armadillo-like creatures that were distantly related to extant armadillos. Like armadillos, and unlike the other extinct branch of megafaunal cingulates, the glyptodonts, the shell was ...

'' were present in the open grasslands. A

proboscidean The Proboscidea (; , ) are 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. From ...

species has also been found in the BIR, '' Notiomastodon platensis,'' which was also present and was a mixed grazer on the open grasslands. Carnivores included some of the largest known mammalian land carnivores, like the giant felid ''

Smilodon populator ''Smilodon'' is a genus of the extinct machairodont subfamily of the felids. It is one of the most famous prehistoric mammals and the best known saber-toothed cat. Although commonly known as the saber-toothed tiger, it was not closely related ...

'' 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

guanacos 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 being the vicuña, which lives at higher elevations. Etymology The guanaco g ...

giant anteaters The giant anteater (''Myrmecophaga tridactyla'') is an Insectivore, insectivorous mammal native to Central America, Central and South America. It is one of four living species of anteaters, of which it is the largest member. The only extant memb ...

collared peccaries The collared peccary (''Dicotyles tajacu'') is 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 referred to as ...

, 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 fox, wood fox, bushdog (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 Caipora is an entity of the Tupi- Guarani mythology in Brazil. The word "Caipora" comes from tupi and means "inhabitant of the forest". It is represented as a dark-skinned, small Native American, naked with a very long red mane, smoking a cigar ...

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

was thought to have been covered in open tropical

cerrado The ''Cerrado'' (, ) is a vast ecoregion of tropical savanna in eastern Brazil, particularly in the states of Goiás, Mato Grosso do Sul, Mato Grosso, Tocantins, Minas Gerais, and the Federal District. The core areas of the Cerrado biome are t ...

vegetation during the Late Pleistocene, but if ''Protopithecus'' and ''Caipora'' 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.Halenar, Lauren B. (December 2011). "Reconstructing the Locomotor Repertoire of Protopithecus brasiliensis". The Anatomical Record. 294 (12): 2048–2063.

Description

Taxonomy

Palaeobiology

Fossil distribution

Paleoecology

References

Further reading