Topic
Thecodontia
About: Thecodontia is a research topic. Over the lifetime, 6 publications have been published within this topic receiving 396 citations.
Papers
TL;DR: Although Postosuchus exhibits many carnosaurian traits, its ankle joint is of \`crocodile-normal' pattern, which suggests its pseudosuchian affinity, and Tyrannosaurs probably evolved from poposaurids, as indicated by the correlation between skull, pelvis and ankle structure.
Abstract: Postosuchus kirkpatricki (n.g., n.sp.) is a large, gracile, carnivorous thecodontian from the late Triassic Dockum Group of Texas. The species is characterized by its erect and facultative bipedal gait, highly advanced pelvis with slightly open acetabulum and footed pubis. The teeth are large, highly serrated, deeply set in sockets, and show a wave-like replacement pattern. Some flexibility in the palate and the lower jaw permitted the animal to swallow large chunks of flesh. Postosuchus was the arch predator of its time, and lived in the interfluves or upland regions along with aetosaurs, coelurosaurs, and ictidosaurs. The quarry's thanatocoenose probably reflects autochthonous burials of a Dockum community, perhaps in consequence of a catastrophic event such as a flash flood. Although Postosuchus exhibits many carnosaurian traits, its ankle joint is of \`crocodile-normal' pattern, which suggests its pseudosuchian affinity. All Triassic reptiles previously thought to be carnosaurs are considered herein as advanced thecodontians; true carnosaurs probably appeared in post-Triassic time. Postosuchus is grouped with Poposaurus, Teratosaurus, Arizonasaurus and the unnamed \`Warwick archosaur' in the family Poposauridae. The Poposauridae and Rauisuchidae are placed in the infraorder Rauisuchia. Tyrannosaurs probably evolved from poposaurids, as indicated by the correlation between skull, pelvis and ankle structure.
187 citations
TL;DR: This paper presents a reinterpretation of Tasmaniosaurus triassicus, a thecodontian reptile from the Knocklofty Formation (Early Triassic) of Tasmania, and new reconstructions of the skull are presented for Tasmaniosauri and Kalisuchus.
Abstract: This paper presents a reinterpretation of Tasmaniosaurus triassicus, a thecodontian reptile from the Knocklofty Formation (Early Triassic) of Tasmania. Tasmaniosaurus resembles the well-known thecodontian Chasmatosaurus and is included in the family Proterosuchidae (suborder Proterosuchia). Its skull is constructed on fairly standard proterosuchian lines, and there is no evidence to support the earlier suggestion that Tasmaniosaurus was an unusually long-snouted reptile showing resemblances to phytosaurs. A second Australian thecodontian, Kalisuchus rewanensis from the Arcadia Formation (Early Triassic) of Queensland, is also included in the family Proterosuchidae, but differs from Tasmaniosaurus in the structure of the snout and should be retained as a separate genus. The relationships of the Australian thecodontians are discussed, and new reconstructions of the skull are presented for Tasmaniosaurus and Kalisuchus.
18 citations
1 Jan 1985
TL;DR: Among the reptiles, the species belonging to the crocodilia order are the closest relatives of birds and probably arose directly from the primitive cotylosaurs during the Triassic period some 220 millions years ago.
Abstract: Among the reptiles, the species belonging to the crocodilia order are the closest relatives of birds (Romer, 1966). Indeed the thecodontia order probably arose directly from the primitive cotylosaurs during the Triassic period some 220 millions years ago. These thecodonts gave rise to crocodiles during the Jurassic period and birds during the Triassic about 150 millions years ago.
8 citations
TL;DR: In this article, a brief anatomical analysis of pedial adaptations of the archosaurs from Los Chanares is made based on new available data, and the authors show that each group has typical features that define "grades" or morphological sets that were present at the same time in the local fauna.
Abstract: A brief anatomical analysis of the pedial adaptations of the archosaurs from Los Chanares is made based on new available data. The archosaurs from the Los Chanares local fauna show four different patterns in the structure of their hind limbs: (1) crurotarsal asymmetrical (Chanaresuchus and Tropidosuchus) (2) crurotarsal symmetrical (Gracilisuchus) (3) mesotarsal asymmetrical (Lagerpeton) (4) mesotarsal symmetrical (Lagosuchus). Each group has typical features that define “grades”; or morphological sets that were present at the same time in the local fauna, showing more derived characters than previously expected from the Middle Triassic.
6 citations
TL;DR: Walker has restated the long-held belief that both birds and crocodiles evolved from thecodont ancestors, but he added the novel suggestion that these two groups arose from a common the codont ancestor and thus are much more closely related than has been previously realized.
Abstract: WALKER1 has restated the long-held belief that both birds and crocodiles evolved from thecodont ancestors, but he added the novel suggestion that these two groups arose from a common thecodont ancestor and thus are much more closely related than has been previously realized. Inasmuch as the Thecodontia include the most primitive as well as the most ancient archosaurs known, it is highly probable that all subsequent archosaurs (including birds) were derived from members of this order. Although Walker may be correct, I do not think that the evidence cited indicates such a close relationship between birds and crocodiles as he proposes.
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 1989 | 1 |
| 1986 | 1 |
| 1985 | 2 |
| 1982 | 1 |
| 1973 | 1 |