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''Trucidocynodon'' is an
extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
of ecteniniid
cynodont The cynodonts () (clade Cynodontia) are a clade of eutheriodont therapsids that first appeared in the Late Permian (approximately 260 mya), and extensively diversified after the Permian–Triassic extinction event. Cynodonts had a wide varie ...
s from
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. ...
of
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 ...
. It contains a single species, ''Trucidocynodon riograndensis''. Fossils of ''Trucidocynodon'' were discovered in
Santa Maria Formation The Santa Maria Formation is a sedimentary rock formation found in Rio Grande do Sul, Brazil. It is primarily Carnian in age (Late Triassic), and is notable for its fossils of cynodonts, "rauisuchian" pseudosuchians, and early dinosaurs and other ...
outcrops in Paleorrota
geopark A geopark is a protected area with internationally significant geology within which sustainable development is sought and which includes tourism, conservation, education and research concerning not just geology but other relevant sciences. In 20 ...
Agudo. ''T. riograndensis'' was similar to '' Ecteninion lunensis'' 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. ...
Ischigualasto formation The Ischigualasto Formation is a Late Triassic fossiliferous formation and Lagerstätte in the Ischigualasto-Villa Unión Basin of the southwestern La Rioja Province and northeastern San Juan Province in northwestern Argentina. The 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 List of South American countries by area, second-largest ...
, but differed in several respects, including its larger size. It is known from a nearly complete
holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...
skeleton as well as a referred skull. The holotype skeleton had an estimated length of 1.2 meters (4 feet), while the referred skull 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 m ...
ns in the entire
Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...
. 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 (metatarsals) touching the groun ...
forelimbs, being among the first
synapsids Synapsids + (, 'arch') > () "having a fused arch"; synonymous with ''theropsids'' (Greek, "beast-face") are one of the two major groups of animals that evolved from basal amniotes, the other being the sauropsids, the group that includes 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 us ...
. However, it was likely not a specialized runner, unlike
ungulate Ungulates ( ) are members of the diverse clade Ungulata which primarily consists of large mammals with hooves. These include odd-toed ungulates such as horses, rhinoceroses, and tapirs; and even-toed ungulates such as cattle, pigs, giraffes, ...
s and some other modern cursorial mammals.


See also

*
List of therapsids This list of therapsids is an attempt to create a comprehensive listing of all genera that have ever been included in the Therapsida excluding mammals and purely vernacular terms. The list includes all commonly accepted genera, but also genera tha ...


References


External links


Folha: Grupo acha fóssil de superpredador gaúcho com 220 milhões de anos
(in Portuguese)
Ciência Hoje:A nova fera do Rio Grande do Sul
in Portuguese) Prehistoric probainognathians Prehistoric cynodont genera 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 {{paleo-therapsid-stub