|
Eucynodonts
Eucynodontia ("true dog teeth") is a clade of cynodont therapsids including mammals and most non-mammalian cynodonts. The oldest eucynodonts are known from the Early Triassic and possibly Late Permian. Eucynodontia includes two major subgroups, Cynognathia and Probainognathia. The clade was named in 1982 by Thomas Kemp, who defined it as all cynodonts more derived than '' Thrinaxodon''. In 2001, Hopson and Kitching redefined the clade Eucynodontia as the least inclusive group containing Mammalia and ''Exaeretodon''.James A. Hopson and James W. Kitching, 2001, "A Probainognathian Cynodont from South Africa and the Phylogeny of Nonmammalian Cynodonts" pp 5-35 in: PARISH A. JENKINS, JR., MICHAEL D. SHAPIRO, AND TOMASZ OWERKOWICZ, EDITORS, ''STUDIES IN ORGANISMIC AND EVOLUTIONARY BIOLOGY IN HONOR OF A. W. CROMPTON'' Bullettin of the Museum of Comparative Zoology. Harvard University 156(1) Phylogeny Cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kataigidodon
''Kataigidodon'' ("thunderstorm tooth") is an extinct genus of eucynodont cynodont therapsid that was discovered in the Chinle Formation of Arizona.Kligman, B.T.; Marsh, A.D.; Sues, H.D.; Sidor, C.A.; 2020 "A new non-mammalian eucynodont from the Chinle Formation (Triassic: Norian), and implications for the early Mesozoic equatorial cynodont record": Biological Letters. https://doi.org/10.1098/rsbl.2020.0631 It is a monotypic genus, with only type species ''Kataigidodon venetus'' known. Description The large mental foramen The mental foramen is one of two foramina (openings) located on the anterior surface of the mandible. It is part of the mandibular canal. It transmits the terminal branches of the inferior alveolar nerve and the mental vessels. Structure Th ... of ''Kataigidodon venetus'' is anteroposteriorly longer than it is tall. It opens on the lateral side of the dentary below the first and second postcanine teeth. The mental foramen is at the anterior end of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brasilitherium Riograndensis
''Brasilodon'' ("tooth from Brazil") is an extinct genus of small, mammal-like cynodonts that lived in what is now Brazil during the Norian age of the Late Triassic epoch, about 225.42 million years ago. While no complete skeletons have been found, the length of ''Brasilodon'' has been estimated at . Its dentition shows that it was most likely an insectivore. The genus is monotypic, containing only the species ''B. quadrangularis''. ''Brasilodon'' belongs to the family Brasilodontidae, whose members were some of the closest relatives of mammals, the only cynodonts alive today. Two other brasilodontid genera, ''Brasilitherium'' and ''Minicynodon'', are now considered to be junior synonyms of ''Brasilodon''. Discovery and naming The first three specimens referred to ''Brasilodon quadrangularis'' were found at the Linha São Luiz site, a quarry near the town of Faxinal do Soturno in the state of Rio Grande do Sul. The rocks where ''Brasilodon'' was found belong to the upper part ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Triassic
The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between 251.9 Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a unit in chronostratigraphy. The Early Triassic is the oldest epoch of the Mesozoic Era. It is preceded by the Lopingian Epoch (late Permian, Paleozoic Era) and followed by the Middle Triassic Epoch. The Early Triassic is divided into the Induan and Olenekian ages. The Induan is subdivided into the Griesbachian and Dienerian subages and the Olenekian is subdivided into the Smithian and Spathian subages. The Lower Triassic series is coeval with the Scythian Stage, which is today not included in the official timescales but can be found in older literature. In Europe, most of the Lower Triassic is composed of Buntsandstein, a lithostratigraphic unit of continental red beds. The Early Triassic and partly also the Middle Trias ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Hopson
James Allen Hopson (born 1935) is an American paleontologist and professor (now retired) at the University of Chicago. His work has focused on the evolution of the synapsids (a group of amniotes that includes the mammals), and has been focused on the transition from basal synapsids to mammals, from the late Paleozoic through the Mesozoic Eras. He received his doctorate at Chicago in 1965, and worked at Yale before returning to Chicago in 1967 as a faculty member in Anatomy, and has also been a research associate at the Field Museum of Natural History since 1971. He has also worked on the paleobiology of dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...s, and his work, along with that of Peter Dodson, has become a foundation piece for the modern understanding of duckbi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trirachodon
''Trirachodon'' (Greek: "three ridge tooth") is an extinct genus of cynodonts. Fossils have been found in the ''Cynognathus'' Assemblage Zone of the Beaufort Group in South Africa and the Omingonde Formation of Namibia, dating back to the Early and Middle Triassic. Description The skull of ''Trirachodon'' had a short, narrow snout with a wide orbital region. The zygomatic arches were relatively slender. ''Trirachodon'' was quite small for a cynodont, growing no larger than 50 cm in length. It had noticeably less molariform teeth than its closely related contemporary '' Diademodon''. These teeth tended to be transversely broader than ''Diademodon'' as well. A bony secondary palate and precise postcanine tooth occlusion are seen as derived characteristics in ''Trirachodon'' that are similar to those of mammals. Species The type species is ''T. berryi'', named in 1895 on the basis of a single cranial skeleton. Three other specimens were later referred to ''T. kannemeyeri'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Langbergia
''Langbergia'' is an extinct genus of Trirachodontidae, trirachodontid cynodont from the Early Triassic of South Africa. The type species, type and only species ''L. modisei'' was named in 2006 after the farm where the holotype was found, Langberg 566. ''Langbergia'' was found in the Burgersdorp Formation in the Beaufort Group, a part of the Cynognathus Assemblage Zone. The closely related trirachodontids ''Trirachodon'' and ''Cricodon'' were found in the same area. History of discovery ''Langbergia'' was discovered in the Cynognathus Assemblage Zone of the Beaufort Group of South Africa in 2006. It was named after the farm where the holotype was found (Langberg 566). Description and paleobiology Trirachodontidae, Trirachodontids are distinguishable due to the shape of their Cheek teeth, postcanines; the postcanines, distal to the canines, are transversely widened teeth with three main cusps disposed in a transverse row across the center of the tooth. ''Langbergia'' are small ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diademodon
''Diademodon'' is an extinct genus of cynodonts. It was about long. Discovery Harry Seeley had found his fossil in the Burgersdorp Formation of the Beaufort Group in the Karoo Basin of South Africa. As late as 1988, ''Diademodon'' had been considered a Gomphodont due to its transversely expanded cheek teeth, however, it has since been placed in the Cynodont order due to significant differences in skull morphology. Additional species were named by paleontologist A. S. Brink in 1979, although they are now considered synonyms of the type species ''Diademodon tetragonus''. Fossils of the ''Diademodon tetragonus'' have more recently been found in the Omingonde Formation of Namibia, the Fremouw Formation of Antarctica, the Ntawere Formation of Zambia and the Río Seco de la Quebrada Formation in Mendoza Province, Argentina. Although ''Diademodon'' is the most well accepted name for the genera to date, it was originally named ''Cynochampsa laniarius'' by Owen in 1860. The p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gomphodontia
Gomphodontia is a clade of cynognathian cynodonts that includes the families Diademodontidae, Trirachodontidae, and Traversodontidae. Gomphodonts are distinguished by wide and closely spaced molar-like postcanine teeth, which are convergent with those of mammals. Other distinguishing characteristics of gomphodonts include deep zygomatic arches, upper postcanines with three or more cusps spanning their widths and lower postcanines with two cusps spanning their widths. They are thought to have been herbivorous or omnivorous. Gomphodonts first appeared in the Early Triassic and became extinct at the end of the Late Triassic. Fossils are known from southern Africa, Argentina and southern Brazil (Paleorrota geopark), eastern North America, Europe, China, and Antarctica. Gomphodontia was first named by paleontologist Harry Seeley in 1895. He considered it an order of wide-toothed therapsids (then called anomodonts) from South Africa, distinct from Cynodontia. By the 1930s Gomphodont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cynognathus
''Cynognathus'' is an extinct genus of large-bodied cynodontian therapsids that lived in the Middle Triassic. It is known from a single species, ''Cynognathus crateronotus''. ''Cynognathus'' was a predator closely related to mammals and had a southern hemispheric distribution. Fossils have so far been recovered from South Africa, Argentina, Antarctica, and Namibia. Description ''Cynognathus'' was a heavily built animal, and measured around in snout-to-vent body length and up to in total length. It had a particularly large head, up to in length, with wide jaws and sharp teeth. Its hindlimbs were placed directly beneath the body. There has been controversy about whether the forelimbs were also held upright or sprawled outwards in a reptilian fashion, but recent studies suggest cynodonts typically held their front legs in a posture between these two extremes. A study of living mammals concluded that "upright posture" in mammals is a myth based on the posture of mammal species ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platycraniellus
''Platycraniellus'' is an extinct genus of carnivorous cynodonts from the Early Triassic. It is known from the ''Lystrosaurus'' Assemblage Zone of the Normandien Formation in South Africa. ''P. elegans'' is the only species in this genus based on the holotype specimen from the Ditsong National Museum of Natural History in Pretoria, South Africa (formerly known as the Transvaal Museum). Due to limited fossil records for study, ''Platycraniellus'' has only been briefly described a handful of times. ''Platycraniellus'' has been recognized as basal cynodonts, characterized by the broad temporal region of the skull and a short snout. Based on its phylogenetic position, ''Platycraniellus'' has a variety of morphologies similar to the sister taxon of '' Thrinaxodon'', a relatively well-studied taxon. History of discovery ''Platycraniellus elegans'' was discovered in the ''Lystrosaurus'' Assemblage Zone in the Free State Province of South Africa. The holotype (TM25) was first de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galesaurus
''Galesaurus'' (from the Greek roots for 'weasel' and 'lizard') is an extinct genus of carnivorous cynodont therapsid that lived between the Induan and the Olenekian stages of the Early Triassic in what is now South Africa. It was incorrectly classified as a dinosaur by Sir Richard Owen in 1859. Notably, ''Galesaurus'' was mentioned in the first issue of Nature (journal), Nature in 1869, where T. H. Huxley erroneously expressed confidence that it would eventually be shown to be a dinosaur. Description The largest ''Galesaurus'' skull discovered is roughly long. Larger remains indicate that an adult ''Galesaurus'' is roughly long. Cynodonts, including ''Galesaurus,'' are believed to have had sprawling postures. Examination of ''Galesaurus'' reveals two distinct morphs, a gracile and a robust morph. The main differences between the two morphs lie in the pectoral and pelvic girdles, as well as subtle differences in the fore and hind limbs. The morphological differences may be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Procynosuchus
''Procynosuchus'' (Greek: "Before dog crocodile") is an extinct genus of cynodonts from the Late Permian. It is considered to be one of the earliest and most basal (phylogenetics), basal cynodonts. It was 60 cm (2 ft) long. Remains of ''Procynosuchus'' have been found in Russia, Germany, Zambia and South Africa.T. S. Kemp: ''The Origin and Evolution of Mammals'' Oxford University Press, 2005. Paleobiology As one of the earliest cynodonts, ''Procynosuchus'' has many primitive features, but it also has features that distinguish it from all other early therapsids. Some of these features were interpreted by Kemp (1980) as adaptations for a semi-aquatic lifestyle. For example, the wide zygapophyses of the vertebrae allow for a high degree of lateral flexibility, and ''Procynosuchus'' may have used anguilliform locomotion, or eel-like undulation, to swim through the water. The tail of ''Procynosuchus'' is also unusually long for a cynodont. The long haemal arches would have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
