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Sphenosuchia
Sphenosuchia is a suborder of basal crocodylomorphs that first appeared in the Triassic and occurred into the Middle Jurassic. Most were small, gracile animals with an erect limb posture. They are now thought to be ancestral to crocodyliforms, a group which includes all living crocodilians. Stratigraphic range The earliest known members of the group (i.e. '' Hesperosuchus'') are early Norian in age, found in the Blue Mesa Member of the Chinle Formation. Only one sphenosuchian is currently known from the Middle Jurassic, '' Junggarsuchus'', from the Junggar Basin (Shishugou Formation) of China during either the Bathonian or the Callovian (~165 Ma) age,Clark, J.M., ''et al.'' (2004A Middle Jurassic 'sphenosuchian' from China and the origin of the crocodylian skull''Nature'' 430:1021-1024. and the Hallopodidae are known from the Late Jurassic of North America. Phylogeny The monophyly of the group is debated, although several synapomorphies characterize the clade, including extr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Litargosuchus
''Litargosuchus'' is a sphenosuchian crocodylomorph, a basal member of the crocodylomorph clade from the Early Jurassic of South Africa. Its genus name ''Litargosuchus'' is derived from Greek meaning "fast running crocodile" and its species name ''leptorhynchus'' refers to its gracile snout. ''Litargosuchus'', along with all of South Africa's crocodylomorph taxa, are confined to the upper Elliot Formation (UEF) in South Africa. History of discovery In 1988 James Kitching found the holotype fossil of ''Litargosuchus'' in a field expedition in Eagles Crag, a farm near Barkly East in the Eastern Cape. The material recovered consisted of a near-complete skull with its mandible and several bones belonging to the postcranial skeleton. At the time, Kitching was the director of the Evolutionary Studies Institute (previously the Bernard Price Institute) of the University of the Witwatersrand in Johannesburg. Kitching brought the holotype fossil back to the institute where he describ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terrestrisuchus
''Terrestrisuchus'' is an extinct genus of very small early crocodylomorph that was about long. Fossils have been found in Wales and Southern England and date from near the very end of the Late Triassic during the Rhaetian, and it is known by type and only known species ''T. gracilis''. ''Terrestrisuchus'' was a long-legged, active predator that lived entirely on land, unlike modern crocodilians. It inhabited a chain of tropical, low-lying islands that made up southern Britain, along with similarly small-sized dinosaurs and abundant rhynchocephalians. Numerous fossils of ''Terrestrisuchus'' are known from fissures in limestone karst which made up the islands it lived on, which formed caverns and sinkholes that preserved the remains of ''Terrestrisuchus'' and other island-living reptiles. Description ''Terrestrisuchus'' was a small, slender crocodylomorph with very long legs, quite unlike modern crocodilians. It was initially estimated to have been between long, although this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Junggarsuchus
''Junggarsuchus'' is an extinct genus of sphenosuchian crocodylomorph from the Middle Jurassic of China. The type species is ''J. sloani''. Discovery ''Junggarsuchus'' was discovered in the Shishugou Formation in Xinjiang, China. Description Although the skull of ''Junggarsuchus'' shares many characteristics with those of modern crocodilians, it is morphologically intermediate between sphenosuchians and mesoeucrocodylia Mesoeucrocodylia is the clade that includes Eusuchia and crocodyliforms formerly placed in the paraphyletic group Mesosuchia. The group appeared during the Early Jurassic, and continues to the present day. Diagnosis It was long known that M ...ns. As in other sphenosuchians, the limbs of ''Junggarsuchus'' were adapted to terrestrial locomotion (movement on land), rather than semi-aquatic locomotion seen in living crocodilians. These adaptations include: a vertically orientated upper arm bone, ball-and-socket shoulder joint, and a functionally tridact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudhesperosuchus
''Pseudhesperosuchus'' (meaning "false '' Hesperosuchus''") is a genus of sphenosuchian, a type of basal crocodylomorph, the clade that comprises the crocodilians and their closest kin. It is known from a partial skeleton and skull found in rocks of the Late Triassic (Norian-age) Los Colorados Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina. History and description ''Pseudhesperosuchus'' is based on PVL 3830. This specimen consists of a skull and lower jaws, most of the vertebral column, the shoulder girdle, and parts of the arms and legs. The genus was named by José Bonaparte in 1969. The type species is ''P. jachaleri''. The skull, though nearly complete, is poorly preserved, and some of its bones and sutures have been misidentified over the years. A 2002 phylogenetic analysis In biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saltoposuchus
''Saltoposuchus'' is an extinct genus of small (1-1.5 m and 10-15 kg), long-tailed crocodylomorph reptile ( Sphenosuchia), from the Norian (Late Triassic) of Europe. The name translated means "leaping foot crocodile". It has been proposed that '' Terrestrisuchus gracilis'' and ''Saltoposuchus connectens'' represent different ontogenetic stages of the same genus. ''Saltoposuchus'' was commonly (and incorrectly) referred to in popular literature as the ancestor (or close ancestors) to dinosaurs, however, recent scientific research show that this is not the case. Description and Paleobiology Fossil evidence of Sphenosuchia and early crocodylomorphs lead paleontologists to conclude that ''Saltoposuchus'' is a terrestrial animal. As a monophyletic group of crocodylomorphs, Saltoposuchidae have many key morphological traits shared with most crocodylomorphs. Skull Much like other crocodylomorphs, ''Saltoposuchus'' skulls had a (reduced) antorbital fenestra, an overhanging ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kayentasuchus
''Kayentasuchus'' (meaning "Kayenta Formation crocodile") is a genus of sphenosuchian, a type of basal crocodylomorph, the clade that comprises the crocodilians and their closest kin. It is known from a single skeleton found in rocks of the Sinemurian-Pliensbachian-age Lower Jurassic Kayenta Formation, northeastern Arizona. History and description ''Kayentasuchus'' is based on UCMP 131830, a fragmentary skeleton. UCMP 131830 was known for many years before its description as the "Kayenta Form". It was found in 1983 by James M. Clark. The location was at Willow Springs, northeast of Flagstaff. The specimen was found in a channel sandstone about halfway up the formation, in the "silty facies". Specimens of the turtle ''Kayentachelys'', the dinosaur ''Scutellosaurus'', and tritylodonts were found in the immediate vicinity a few meters below it. ''Kayentasuchus'' was named in 2002 by Clark and Hans-Dieter Sues. The type species is ''K. walkeri'' in memory of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crocodylomorph
Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. During Mesozoic and early Cenozoic times, crocodylomorphs were far more diverse than they are now. Triassic forms were small, lightly built, active terrestrial animals. The earliest and most primitive crocodylomorphs are represented by " sphenosuchians", a paraphyletic assemblage containing small-bodied forms with elongated limbs that walked upright, which represents the ancestral morphology of Crocodylomorpha. These forms persisted until the end of the Jurassic. During the Jurassic, Crocodylomorphs morphologically diversified into numerous niches, including into the aquatic and marine realms. Evolutionary history When their extinct species and stem group are examined, the crocodylian lineage (clade Pseudosuchia, formerly Crurotarsi) proves to have been a very diverse and adaptive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dibothrosuchus
''Dibothrosuchus'' is a genus of sphenosuchian, a type of basal crocodylomorph, the clade that comprises the crocodilians and their closest kin. It is known from several partial skeletons and skulls. These fossils were found in Lower Jurassic (Lower Pliensbachian, circa 186 million years old) rocks of Yunnan, China. ''Dibothrosuchus'' was a small terrestrial crocodylomorph that probably had a keen sense of hearing, and thus was probably a vocal animal like modern crocodilians. History and description ''Dibothrosuchus'' was named in 1965 by D.J. Simmons based on a partial skull and skeleton collected by Father Oehler of Fu Jen Catholic University from mudstones near Huangchiatien. The type species is ''D. elaphros''. Additional remains of this genus were recovered in 1985 by a joint Chinese-US expedition. Fossils of ''Dibothrosuchus'' come from the Zhangjiawa Formation, being originally assigned to the Reds Beds of the Lufeng Formation, thus being geologically you ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period of the Mesozoic Era. Both the start and end of the period are marked by major extinction events. The Triassic Period is subdivided into three epochs: Early Triassic, Middle Triassic and Late Triassic. The Triassic began in the wake of the Permian–Triassic extinction event, which left the Earth's biosphere impoverished; it was well into the middle of the Triassic before life recovered its former diversity. Three categories of organisms can be distinguished in the Triassic record: survivors from the extinction event, new groups that flourished briefly, and other new groups that went on to dominate the Mesozoic Era. Reptiles, especially archosaurs, were the chief terrestrial vertebrates during this time. A specialized subgroup of arch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carpal Bones
The carpal bones are the eight small bones that make up the wrist (or carpus) that connects the hand to the forearm. The term "carpus" is derived from the Latin carpus and the Greek καρπός (karpós), meaning "wrist". In human anatomy, the main role of the wrist is to facilitate effective positioning of the hand and powerful use of the extensors and flexors of the forearm, and the mobility of individual carpal bones increase the freedom of movements at the wrist.Kingston 2000, pp 126-127 In tetrapods, the carpus is the sole cluster of bones in the wrist between the radius and ulna and the metacarpus. The bones of the carpus do not belong to individual fingers (or toes in quadrupeds), whereas those of the metacarpus do. The corresponding part of the foot is the tarsus. The carpal bones allow the wrist to move and rotate vertically. Structure Bones The eight carpal bones may be conceptually organized as either two transverse rows, or three longitudinal columns. Wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synapomorphies
In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have evolved in their most recent common ancestor. ) In cladistics, synapomorphy implies homology. Examples of apomorphy are the presence of erect gait, fur, the evolution of three middle ear bones, and mammary glands in mammals but not in other vertebrate animals such as amphibians or reptiles, which have retained their ancestral traits of a sprawling gait and lack of fur. Thus, these derived traits are also synapomorphies of mammals in general as they are not shared by other vertebrate animals. Etymology The word —coined by German entomologist Willi Hennig—is derived from the Ancient Greek words (''sún''), meaning "with, together"; (''apó''), meaning "away from"; and (''morphḗ''), meaning "shape, form". Clade ana ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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