The Early Evolution of Archosaurs: Relationships and the Origin of Major Clades

@inproceedings{Nesbitt2011TheEE,
  title={The Early Evolution of Archosaurs: Relationships and the Origin of Major Clades},
  author={Sterling J. Nesbitt},
  year={2011}
}
Abstract Archosaurs have a nearly 250 million year record that originated shortly after the Permian-Triassic extinction event and is continued today by two extant clades, the crocodylians and the avians. The two extant lineages exemplify two bauplan extremes among a diverse and complex evolutionary history, but little is known about the common ancestor of these lineages. Renewed interest in early archosaurs has led to nearly a doubling of the known taxa in the last 20 years. This study presents… Expand
Macroevolutionary patterns in the evolutionary radiation of archosaurs (Tetrapoda: Diapsida)
TLDR
New data is provided on archosaur lineage origination, diversity and lineage evolution, morphological disparity, rates of morphological character change, and faunal abundance during the Triassic–Early Jurassic. Expand
New clade of enigmatic early archosaurs yields insights into early pseudosuchian phylogeny and the biogeography of the archosaur radiation
TLDR
The recognition of Gracilisuchidae provides further support for a rapid phylogenetic diversification of crown archosaurs by the Middle Triassic, and falsify previous hypotheses suggesting that T. dabanensis and Y. sangbiensis are not members of the archosaur crown group. Expand
Systematics and evolutionary history of proterosuchian archosauriforms
TLDR
The results obtained here suggest that the evolutionary history of the archosauriforms during the Early Triassic can be subdivided into a first phase characterized by the short-lived “disaster-clade” Proterosuchidae and a second phase that witnessed the initial morphological and probably palaeoecological diversification of the group. Expand
The phylogenetic relationships of basal archosauromorphs, with an emphasis on the systematics of proterosuchian archosauriforms
TLDR
A new data matrix composed of 96 separate taxa and 600 osteological characters was assembled and analysed to generate a comprehensive higher-level phylogenetic hypothesis of basal Archosauromorphs and shed light on the species-level interrelationships of taxa historically identified as proterosuchian archosauriforms. Expand
Anatomy, phylogeny and palaeobiology of early archosaurs and their kin
TLDR
A state-of-the-art examination of early archosaur groups and their close relatives including historical, anatomical, biogeographical, evolutionary and palaeobiological data is presented. Expand
The stem-archosaur evolutionary radiation in South America
Abstract The oldest archosauromorphs (dinosaurs, birds, crocodiles, and their stem-taxa) are recorded in middle−upper Permian rocks, but it was not after the Permo−Triassic mass extinction that theExpand
A sail-backed suchian from the Heshanggou Formation (Early Triassic: Olenekian) of China
  • S. Nesbitt, J. Liu, Chun Li
  • Geology
  • Earth and Environmental Science Transactions of the Royal Society of Edinburgh
  • 2010
ABSTRACT The two major lineages of extant archosaurs, crocodylians and avians, diverged in the Triassic, but the details and timing of this event are incompletely understood. Fragmentary andExpand
Revised phylogenetic analysis of the Aetosauria (Archosauria: Pseudosuchia); assessing the effects of incongruent morphological character sets
TLDR
A new phylogenetic analysis of the Aetosauria includes more than 40 new characters that focus on better sampling the cranial and endoskeletal regions, and represents the most comprenhensive phylogeny of the clade to date. Expand
A new archosauromorph from South America provides insights on the early diversification of tanystropheids
TLDR
The morphology of the new specimen is consistent with a terrestrial lifestyle, suggesting that this condition was plesiomorphic for Tanystropheidae, and represents further evidence for a premature wide geographical distribution of this clade. Expand
The Origin and Early Evolution of Sauria: Reassessing the Permian Saurian Fossil Record and the Timing of the Crocodile-Lizard Divergence
TLDR
A revision suggests a minimum fossil calibration date for the crocodile-lizard split of 254.7 Ma, and early archosauromorph growth strategies appear to be more diverse than previously suggested based on new data on the osteohistology of Aenigmastropheus. Expand
...
1
2
3
4
5
...

References

SHOWING 1-10 OF 278 REFERENCES
PROGRESS AND FUTURE DIRECTIONS IN ARCHOSAUR PHYLOGENETICS
TLDR
The basic structure of archosaurian phylogeny is understood to include two primary crown-group lineages—one leading to living crocodiles and including a broad diversity of Triassic animals and another leading to dinosaurs. Expand
The higher-level phylogeny of Archosauria (Tetrapoda: Diapsida)
TLDR
This analysis produces a well-resolved phylogeny, which recovers mostly traditional relationships within Avemetatarsalia, places Phytosauria as a basal crurotarsan clade, finds a close relationship between Aetosaurian and Crocodylomorpha, and recovers a monophyletic Rauisuchia comprised of two major subclades. Expand
Ecologically distinct dinosaurian sister group shows early diversification of Ornithodira
TLDR
The analysis suggests that the dentition and diet of silesaurids, ornithischians and sauropodomorphs evolved independently from a plesiomorphic carnivorous form, and Asilisaurus demonstrates the antiquity of both Ornithodira and the dinosaurian lineage. Expand
Arizonasaurus and its implications for archosaur divergence
  • S. Nesbitt
  • Biology, Medicine
  • Proceedings of the Royal Society of London. Series B: Biological Sciences
  • 2003
TLDR
Characteristics of the skeleton of Arizonasaurus show that it belongs to a poorly known group of Middle Triassic archosaurs called the ctenosauriscids, and that cteno-poposaurs are or are closely related to poposaurs, which suggests that the divergence of birds and crocodiles occurred earlier than previously thought. Expand
Basal Archosaurs: Phylogenetic Relationships and Functional Implications
TLDR
Erect posture has been identified as the key adaptation (possibly associated with locomotor stamina) that resulted in the archosaurian radiation. Expand
Early dinosaurs: A phylogenetic study
TLDR
A new cladistic analysis of the early dinosaur radiation was performed to assess the relationships among the three major clades (Ornithischia, Sauropodomorpha and Theropoda) and to define the phylogenetic position of the basal members of the group. Expand
Sarmatosuchus and the early history of the Archosauria
TLDR
Evidence suggesting that proterosuchids may have existed with erythrosuchids and early crown-group archosaurs in the Middle Triassic requires a revision of the understanding of the earl... Expand
A primitive ornithischian dinosaur from the Late Triassic of South Africa, and the early evolution and diversification of Ornithischia
Although the group played an important role in the evolution of Late Mesozoic terrestrial ecosystems, the early evolutionary history of the ornithischian dinosaurs remains poorly understood. Here, weExpand
The phylogenetic relationships of early dinosaurs: a comparative report
TLDR
A comparative approach is taken here to show, first, that character choice is a major factor behind differing results; only half of the character data critical for each interpretation is incorporated into the opposing analysis. Expand
A new species of Azendohsaurus (Diapsida: Archosauromorpha) from the Triassic Isalo Group of southwestern Madagascar: cranium and mandible
TLDR
A new species of Azendohsaurus is described from the Middle–Late Triassic of Madagascar, extending the geographical range of a taxon known otherwise only by a single species from Morocco and indicating a complex evolution and distribution of features traditionally thought to be derived within archosaurs. Expand
...
1
2
3
4
5
...