Сообщество, посвящённое ра Below are the 3 most recent journal entries recorded in the "Сообщество, посвящённое ра" journal:
December 11th, 2011
04:16 pm
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Millerosaurus

 Millerosaurus is an extinct genus of small reptile from South Africa, dated to the Permian age. Unlike many other Anapsidan reptiles, it had holes (Fenestrae) behind the eyesockets in the skull. It had a slabsided body, long tail, and a narrow but triangular skull (about 2 inch long) with large eyes. Likely It had a lifestyle similar to the modern lizards, and scientists believe it was an insectivore.

 

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04:10 pm
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Milleretta

 Milleretta was a fast-moving reptile that lived in the late Permian period of South Africa, 250 million years ago. Fossils have been found at the Oberperm site.

 Milleretta was a moderately sized, lizard-like animal, about 60 centimetres (24 in) in length. It was probably insectivorous and had acute hearing. Although once thought to have been ancestral to the diapsids, the group that includes lizards, the discovery of much older diapsid fossils has since ruled this possibility out.

 There is only one representative of this genus.

 Это маленькое существо, похожее на ящерицу, быстро бегало и, вероятно, питалось насекомыми. До сих пор ископаемые останки миллеретты находили только в Южной Африке. Их датируют концом пермского периода. В черепе миллеретты имеются дополнительные отверстия, однако она все же принадлежит к числу примитивных рептилий-анапсид.

 

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02:54 pm
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Eunotosaurus

 Eunotosaurus is a genus of parareptile from the Middle Permian Karoo Supergroup of South Africa. It was once widely accepted as the missing link between turtles and their prehistoric ancestors. Many fossils have been found showing a semi-rigid, turtle-like rib cage, one which presumably necessitated a tortoise-like fashion of walking. The ribs are very wide and flat, touching each other to form broad plates analogous to the carapace of a turtle. Moreover, the number of vertebrae, the size of the vertebrae, and their structure are nearly identical to those of some turtles. Despite the many similarities to turtles, Eunotosaurus has a skull that shares many characteristics with the skulls of more primitive anapsids. Because of these features, Eunotosaurus is now placed within the Parareptilia and is not widely considered an immediate ancestor of turtles. According to this view, the expanded ribs and similar vertebral column are a case of evolutionary convergence.

 Eunotosaurus was considered the ancestor of turtles up until the late 1940s. In his 1956 book Osteology of the Reptiles, American paleontologist Alfred Sherwood Romer claimed that Eunotosaurus could not be included within Chelonia based on the available evidence. He placed it within Anapsida in its own order incertae sedis.

 Eunotosaurus was assigned to its own family, Eunotosauridae, in 1954. However, this name has fallen into disuse. In 1969, it was placed in the anapsid suborder Captorhinomorpha, which is now considered to be within the clade Eureptilia. In 2000, Eunotosaurus was placed in the clade Parareptilia, separate from turtles and cotylosaurs. A 2008 phylogenetic analysis of parareptiles found Eunotosaurus to be the sister taxon of Milleretta and thus within the family Millerettidae.

 Eunotosaurus was incorporated in a recent 2010 phylogenetic analysis that sought to determine the origin of turtles. Turtles have recently been considered diapsids on the basis of genetic and phylogenetic evidence, and thus more closely related to modern lizards, snakes, crocodiles, and birds than parareptiles or any other anapsid. However, with the inclusion of Eunotosaurus and the Late Triassic stem turtle Proganochelys, the resulting phylogenetic tree placed turtles outside Diapsida in a position similar to turtle's original placement as anapsids. This study claimed that Eunotosaurus shared derived features of its ribs and vertebrae with the earliest turtles, thus making it a transitional form. The study identified several features that united Eunotosaurus with turtles in a true clade. These include broad T-shaped ribs, ten elongated trunk vertebrae, cranial tubercles (small projections on the surface of the skull), and a wide trunk. The clade consisting of Eunotosaurus and turtles was called "Pan-Testudines." More derived testudines, such as the earliest turtle Odontochelys, have a plastron.

 

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