''Trucidocynodon'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

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 ...

ecteniniid Ecteniniidae is an extinct family (biology), family of probainognathian cynodonts from the Triassic of South America. They are notable for their large size, as well as for being among the first synapsids with specializations towards cursoriality. ...

cynodont Cynodontia () is a clade of eutheriodont therapsids that first appeared in the Late Permian (approximately 260 Megaannum, mya), and extensively diversified after the Permian–Triassic extinction event. Mammals are cynodonts, as are their extin ...

s from the

Upper Triassic The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch. T ...

(

Carnian The Carnian (less commonly, Karnian) is the lowermost stage (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227.3 ...

) 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 ...

. It contains a single species, ''Trucidocynodon riograndensis''. Fossils of ''Trucidocynodon'' were discovered in outcrops of the Upper Santa Maria Formation in Paleorrota Geopark, Agudo. ''Trucidocynodon'' is one of the most completely known Triassic cynodonts, as its

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

is a nearly complete and fully articulated skeleton.

Description

''T. riograndensis'' was a carnivorous cynodont closely related to '' Ecteninion lunensis'' and '' Diegocanis eleganus'', from the Upper Triassic Ischigualasto Formation of

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 ...

. It differed from other ecteniniids in several respects, including its larger size. The holotype skeleton has a skull around in length and a total body length of around . The holotype, UFRGS PV-1051-T, is accessioned at the Federal University of Rio Grande do Sul (UFRGS) alongside four paratypes based on postcranial fossils. A second skull was described in 2018 from the same site. This referred skull
CAPPA
UFSM 0029, was 17% larger than that of the holotype. ''Trucidocynodon'' is considered one of the largest known carnivorous cynodonts from the Triassic, as well as one of the largest

probainognathia Probainognathia is one of the two major subgroups of the clade Eucynodontia, the other being Cynognathia. The earliest forms were carnivorous and insectivorous, though some groups eventually also evolved herbivorous diets. The earliest and most b ...

ns in the entire

Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...

Paleobiology

A biomechanical study has argued that ''Trucidocynodon'' not only had erect limbs, but that it also possibly had

digitigrade In terrestrial vertebrates, digitigrade ( ) locomotion is walking or running on the toes (from the Latin ''digitus'', 'finger', and ''gradior'', 'walk'). A digitigrade animal is one that stands or walks with its toes (phalanges) on the ground, and ...

forelimbs, being among the first

synapsids Synapsida is a diverse group of tetrapod vertebrates that includes all mammals and their extinct relatives. It is one of the two major clades of the group Amniota, the other being the more diverse group Sauropsida (which includes all extant rept ...

to show adaptations for

cursoriality A cursorial organism is one that is adapted specifically to run. An animal can be considered cursorial if it has the ability to run fast (e.g. cheetah) or if it can keep a constant speed for a long distance (high endurance). "Cursorial" is often ...

. However, it was likely not a specialized runner, unlike

ungulate Ungulates ( ) are members of the diverse clade Euungulata ("true ungulates"), which primarily consists of large mammals with Hoof, hooves. Once part of the clade "Ungulata" along with the clade Paenungulata, "Ungulata" has since been determined ...

s and some other modern cursorial mammals.

References

External links

* * {{Taxonbar, from=Q20673567 Ecteniniidae Monotypic prehistoric animal genera Late Triassic synapsids of South America Fossils of Brazil Triassic Brazil Paleontology in Rio Grande do Sul Santa Maria Formation Fossil taxa described in 2010

Description

Paleobiology

See also

References

External links