An abelisauroid dinosaur with a non-atrophied manus from the Late Cretaceous Pari Aike Formation of southern Patagonia

被引:0
作者
Ezcurra, Martin D. [1 ]
Agnolin, Federico L. [1 ,2 ]
Novas, Fernando E. [1 ,3 ]
机构
[1] Museo Argentino Ciencias Nat Bernardino Rivadavia, Lab Anat Comparada & Evoluc Vertebrados, Buenos Aires, DF, Argentina
[2] Univ Maimonides, Fdn Historia Nat Felix Azara, RA-1405 Buenos Aires, DF, Argentina
[3] Consejo Nacl Invest Cient & Tecn, RA-1033 Buenos Aires, DF, Argentina
关键词
Dinosauria; Theropoda; Abelisauroidea; Late Cretaceous; Pari Aike Formation; Argentina; CARNIVOROUS DINOSAUR; PREDATORY DINOSAUR; GROWTH-PATTERNS; THEROPODA; EVOLUTION; REMAINS; ORNITHISCHIA; CERATOSAUR; HISTOLOGY; SKELETON;
D O I
暂无
中图分类号
Q95 [动物学];
学科分类号
071002 ;
摘要
We describe the new basal abelisauroid dinosaur Austrocheirus isasii gen. et sp. nov. from the Late Cretaceous Pari Aike Formation of southwestern Patagonia, Argentina. The preserved remains include manual bones, a distal tibia, and some pedal and axial elements. Austrocheirus is differentiated from other basal theropods by the presence of metacarpal III with a dorsoventrally compressed shaft and posteriorly displaced collateral tendon fossae located at the same level of the proximal end of distal condyles, and pedal phalanges with a conspicuous longitudinal crest delimitating the dorsal margin of the distal collateral tendon fossae. A cladistic analysis recovered the new species as more derived than Ceratosaurus and Berberosaurus, but within a polytomy at the base of Abelisauroidea, an assignment supported by two abelisauroid synapomorphies: distal end of tibia with a planar vertical scar for the reception of the ascending process of the astragalus that occupies most of its anterior surface and is medially bounded by the longitudinally oriented facet; and scar for the reception of the ascending process with a median vertical ridge, which imbeds into a crescentic vertical groove on the posterior surface of the ascending process of the astragalus forming an interlocking tibiotarsal articulation. Furthermore, Austrocheirus represents the first known medium-sized Late Cretaceous abelisauroid bearing non-atrophied hands. The evidence provided here suggests that the strong reduction of the forelimb recorded in derived abelisaurids is not directly correlated with their increased body-size, but it seems to be an evolutionary event exclusive to this lineage within Ceratosauria.
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页码:1 / 25
页数:25
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