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Prozostrodontia
Prozostrodontia is a clade of cynodonts including mammaliaforms and their closest relatives such as Tritheledontidae and Tritylodontidae. It was erected as a node-based taxon by Liu and Olsen (2010) and defined as the least inclusive clade containing ''Prozostrodon brasiliensis'', ''Tritylodon langaevus'', ''Pachygenelus monus'', and ''Mus musculus'' (the house mouse). Prozostrodontia is diagnosed by several characters, including: * Reduced prefrontal bone, prefrontal and postorbital bones, with the disappearance of a strut of bone called the postorbital bar separating the Orbit (anatomy), eye socket from the Temporal fenestra, temporal region * Unfused Mandibular symphysis, symphysis between the dentary bones in the lower jaw * The presence of a small hole within the eye socket called the sphenopalatine foramen * A long sagittal crest extending to the rearmost part of the lambdoid suture, lambdoidal crest at the back of the skull * Neural spines of the dorsal vertebrae angled back ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prozostrodon
''Prozostrodon'' is an extinct genus of probainognathian cynodonts that was closely related to mammals. The remains were found in Brazil and are dated to the Carnian age of the Late Triassic. The holotype has an estimated skull length of , indicating that the whole animal may have been the size of a cat. The teeth were typical of advanced cynodonts, and the animal was probably a carnivore hunting reptiles and other small prey. Discovery and naming ''Prozostrodon brasiliensis'' was originally described as a species of ''Thrinaxodon'' in a 1987 paper by Mário Costa Barberena, Mário C. Barberena, José F. Bonaparte and A. M. Sá Teixeira. The holotype (UFRGS-PV-0248-T) includes a well-preserved skull preserving the front half of the cranium, a mostly complete lower jaw and all of the teeth, but missing most of the braincase, sagittal crest and zygomatic arches. It also preserves multiple postcranial elements, including parts of the vertebral column, ribs, interclavicle, humeri, r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prozostrodon Brasiliensis
''Prozostrodon'' is an extinct genus of probainognathian cynodonts that was closely related to mammals. The remains were found in Brazil and are dated to the Carnian age of the Late Triassic. The holotype has an estimated skull length of , indicating that the whole animal may have been the size of a cat. The teeth were typical of advanced cynodonts, and the animal was probably a carnivore hunting reptiles and other small prey. Discovery and naming ''Prozostrodon brasiliensis'' was originally described as a species of '' Thrinaxodon'' in a 1987 paper by Mário C. Barberena, José F. Bonaparte and A. M. Sá Teixeira. The holotype (UFRGS-PV-0248-T) includes a well-preserved skull preserving the front half of the cranium, a mostly complete lower jaw and all of the teeth, but missing most of the braincase, sagittal crest and zygomatic arches. It also preserves multiple postcranial elements, including parts of the vertebral column, ribs, interclavicle, humeri, right ilium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alemoatherium
''Alemoatherium'' is an extinct genus of prozostrodontian cynodont which lived in the Late Triassic of Brazil. It contains a single species, ''A. huebneri'', named in 2017 by Agustín Martinelli and colleagues. The genus is based on UFSM 11579b, a left lower jaw ( dentary) found in the Alemoa Member of the Santa Maria Formation, preserving the late Carnian-age ''Hyperodapedon'' Assemblage Zone. ''Alemoatherium'' was among the smallest species of cynodonts found in the rich synapsid fauna of the Santa Maria Formation. Its blade-like four-cusped postcanine teeth show many similarities with those of dromatheriids, an obscure group of early prozostrodontians. Description The dentary is similar in shape to that of many other prozostrodontians, with an overall slender form that abruptly changes angle near the front of the jaw. This distinct change in angle separates the dentary into two main regions, the horizontal ramus behind the level of the first postcanine tooth, and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Santacruzgnathus
''Santacruzgnathus'' is an extinct genus of small cynodonts from the Late Triassic (Carnian) ''Santacruzodon'' Assemblage Zone of Brazil. It contains one species, ''S. abdalai''. ''Santacruzgnathus'' is known from a single partial lower jaw with four postcanine teeth, only one of which is well-preserved. Some features of the specimen, including the slender shape of the jaw and the incipiently double-rooted teeth, indicate that the animal was an early member of Prozostrodontia, a group that includes mammals and their close relatives. Discovery and naming The holotype and only known specimen of ''Santacruzgnathus'' (UFRGS-PV-1121-T) consists of a partial right dentary bone with a well-preserved final postcanine tooth and fragments of three other postcanines. The specimen was discovered at the Schoenstatt site near the town of Santa Cruz do Sul within the state of Rio Grande do Sul. The outcrop in which the specimen was found belongs to the Santa Cruz Sequence of the Sant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudotherium
''Pseudotherium'' ("false beast") is an extinct genus of prozostrodontian cynodonts from the Late Triassic of Argentina. It contains one species, ''P. argentinus'', which was first described in 2019 from remains found in the La Peña Member of the Ischigualasto Formation in the Ischigualasto-Villa Unión Basin. Discovery and naming The holotype and only known specimen, PVSJ 882, was discovered in 2006 by Argentine palaeontologist Ricardo N. Martínez during an expedition to the Ischigualasto Formation. It consists of a partial skull lacking the lower jaw, quadrate bones and most of the zygomatic arches and premaxillae. The generic name ''Pseudotherium'' is derived from the Greek words , meaning "false", and , meaning "beast". The specific name ''argentinus'' references the country of Argentina where it was found. Description ''Pseudotherium'' would have been a relatively large cynodont; excluding its missing premaxillae, the holotype skull is in length. Running along the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dromatheriidae
Dromatheriidae is an extinct family of prozostrodontian cynodonts, closely related to mammals. Members of the family are known from the Late Triassic ( Carnian to Rhaetian) of India, Europe and North America. Apart from a few jaw fragments, dromatheriids are mainly known from their sectorial (flesh-slicing) postcanine teeth. The teeth were fairly typical among early prozostrodontians, as they were labiolingually compressed (flattened sideways), with a single root and crown hosting a longitudinal row of sharp cusps. Dromatheriids in particular have a very narrow and symmetrical crown (when seen from above) without a prominent cingulum (a ridge or array of cuspules adjacent to the main cusps). Dromatheriid teeth on average have four main cusps, though some have as few as two ('' Dromatherium'') or three ('' Tricuspes''), or as many as six ('' Inditherium'', '' Pseudotriconodon''). Although the teeth have a single root, a vertical furrow on each side of the root appears to be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pachygenelus Monus
''Pachygenelus'' is a genus of extinct cynodont. Fossils have been found from the Karoo basin in South Africa and date back to the Early Jurassic. The genus was named in 1913 on the basis of a partial lower jaw found from South Africa, with the type species being named ''P. monus''. A new species, ''P. milleri'', was named in 1983 and distinguished from the type species in possessing an accessory posterior cusp on the lower postcanines. Description ''Pachygenelus'' had both an articular- quadrate and dentary- squamosal jaw joint characteristic of ictidosaurs. Only mammals possess the dentary-squamosal articulation, while all other tetrapods possess the typical arcticular-quadrate articulation. Thus the jaw of ''Pachygenelus'' can be seen as transitional between non-mammalian synapsids and true mammals. Another feature of ''Pachygenelus'' that is shared with mammals is plesiomorphic prismatic enamel, or enamel arranged into strengthened prisms. The upper and lower tooth rows ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 extinct ancestors and close relatives (Mammaliaformes), having evolved from advanced probainognathian cynodonts during the Late Triassic. Non-mammalian cynodonts occupied a variety of ecological niches, both as carnivores and as herbivores. Following the emergence of mammals, most other cynodont lines went extinct, with the last known non-mammaliaform cynodont group, the Tritylodontidae, having its youngest records in the Early Cretaceous. Description Early cynodonts have many of the skeletal characteristics of mammals. The teeth were fully differentiated and the braincase bulged at the back of the head. Outside of some Crown group, crown-group mammals (notably the therians), all cynodonts probably laid eggs. The temporal fenestrae#Fenestra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mus Musculus
The house mouse (''Mus musculus'') is a small mammal of the rodent family Muridae, characteristically having a pointed snout, large rounded ears, and a long and almost hairless tail. It is one of the most abundant species of the genus ''Mus (genus), Mus''. Although a wild animal, the house mouse has benefited significantly from associating with human habitation to the point that truly wild populations are significantly less common than the synanthropic populations near human activity. The house mouse has been domestication, domesticated as the pet or fancy mouse, and as the laboratory mouse, which is one of the most important model organisms in biology and medicine. The complete mouse reference genome was Whole genome sequencing, sequenced in 2002. Characteristics House mice have an adult body length (nose to base of tail) of and a tail length of . The weight is typically . In the wild they vary in color from grey and light brown to black (individual hairs are actually Agouti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prefrontal Bone
The prefrontal bone is a bone separating the lacrimal and frontal bones in many tetrapod skulls. It first evolved in the sarcopterygian clade Rhipidistia, which includes lungfish and the Tetrapodomorpha. The prefrontal is found in most modern and extinct lungfish, amphibians and reptiles. The prefrontal is lost in early mammaliaforms and so is not present in modern mammals either. In dinosaurs The prefrontal bone is a very small bone near the top of the skull, which is lost in many groups of coelurosaurian theropod dinosaurs and is completely absent in their modern descendants, the bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...s. Conversely, a well developed prefrontal is considered to be a primitive feature in dinosaurs. The prefrontal makes contact with several other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Postorbital Bone
The ''postorbital'' is one of the bones in vertebrate skulls which forms a portion of the dermal skull roof and, sometimes, a ring about the orbit. Generally, it is located behind the postfrontal and posteriorly to the orbital fenestra. In some vertebrates, the postorbital is fused with the postfrontal to create a postorbitofrontal. Birds have a separate postorbital as an embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ..., but the bone fuses with the frontal before it hatches. References * Roemer, A. S. 1956. ''Osteology of the Reptiles''. University of Chicago Press. 772 pp. Skull bones {{Vertebrate anatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Triassic
The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch. The corresponding series (stratigraphy), series of rock beds is known as the Upper Triassic. The Late Triassic is divided into the Carnian, Norian and Rhaetian Geologic time scale, ages. Many of the first dinosaurs evolved during the Late Triassic, including ''Plateosaurus'', ''Coelophysis'', ''Herrerasaurus'', and ''Eoraptor''. The Triassic–Jurassic extinction event began during this epoch and is one of the five major mass extinction events of the Earth. Etymology The Triassic was named in 1834 by Friedrich August von Namoh, Friedrich von Alberti, after a succession of three distinct rock layers (Greek meaning 'triad') that are widespread in southern Germany: the lower Buntsandstein (colourful ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
