Efraasia — род вымерших ящеротазовых динозавров из группы зауроподоморфов (Sauropodomorpha), живших в позднем триасовом периоде (около 210 миллионов лет назад), на территории нынешней Европы. Окаменелости динозавра были найдены в Германии. Впервые описан палеонтологом F. von Huene d 1907–1908 под названием Teratosaurus minor. Представлен одним видом - E. minor.

 Efraasia was once thought to be a relatively small dinosaur, about 2 to 3 metres (6.6 to 9.8 ft) long, but this was because the most complete known fossils are from juvenile animals. Yates in 2003 has estimated the adult length at 6.5 metres (21 ft); the largest specimen is SMNS 12843 with a femur length of 627 millimetres (24.7 in). Efraasia was lightly built for its size, with gracile hands and feet. Like many "primitive" sauropodomorphs, Efraasia might have been partially bipedal and partly quadrupedal. It had long fingers and mobile thumbs, with which it would have been able to grasp food, but the shape of its wrists might have allowed it to walk easily on all fours. Some researchers however, contend that the lower arm did not allow pronation, a rotation of the radius around the ulna, so that the hand could not be directed downward, making the animal an obligate biped.

 The skull is small, pointed and triangular. There are four teeth in the premaxilla. The neck is only moderately elongated but thin. The neural spines of the tail are low. The second finger is longer than the third finger. The first toe is not strongly reduced. Von Huene identified a cluster of stomach stones (gastroliths) in association to specimen SMNS 12667.

 Yates identifies two unique derived traits (autapomorphies): the presence of a raised crescent-like ridge on the upper part of the inner side of the pubis shaft; and the presence of a vaulted bony web between two lower extensions of a braincase bone, the processus basipterygoidei, with a raised central bony platform on top of the vault.

 Von Huene continued interpreting these forms as predatory dinosaurs, in 1932 assigning them to a separate family Palaeosauridae as part of the Carnosauria. Only in 1965 Charig established they were plant-eating sauropodomorphs.

 In 1973 Galton assigned Efraasia to the Anchisauridae, but he used this name as a paraphyletic group encompassing all "prosauropods" that were not melanorosaurids. Modern phylogenetic analysis has indicated that Efraasia is a basal sauropodomorph, somewhat more derived than Thecodontosaurus, but less than either the Prosauropoda (including Plateosaurus) or the Sauropoda. The genus is sometimes recovered as the sister taxon to the last common ancestor of both larger groups.

 Репродукции (1, 2):

Tags: Вымершие рептилии, Триас, авеметатарзалии, архозавроморфы, архозавры, диапсиды, динозавроморфы, динозавры, завроподоморфы, ящеротазовые

(Leave a comment)