The phylogenetic relationships of early dinosaurs: a comparative report

  title={The phylogenetic relationships of early dinosaurs: a comparative report},
  author={Paul C. Sereno},
  journal={Historical Biology},
  pages={145 - 155}
  • P. Sereno
  • Published 1 January 2007
  • Environmental Science
  • Historical Biology
Surprising new anatomical information has come to light for the early dinosaurs Eoraptor lunensis and Herrerasaurus ischigualastensis. Eoraptor has a mid mandibular jaw joint, and Herrerasaurus has a promaxillary fenestra at the anterior end of the antorbital fossa. Initial cladistic interpretation placed Herrerasaurus outside Dinosauria. Since then, Eoraptor and Herrerasaurus have been placed at the base of Saurischia or within Theropoda in two large-scale quantitative analyses. A comparative… 

The higher-level phylogeny of Archosauria (Tetrapoda: Diapsida)

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.

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

A time-calibrated phylogeny of Archosauriformes indicates that the origin and initial diversification of archosauria occurred during the Early Triassic following the Permian-Triassic extinction.

The phylogeny of Tetanurae (Dinosauria: Theropoda)

An exhaustive examination of all basal tetanurans and all existing character data, taking advantage of recent discoveries and adding new morphological, temporal and geographic data achieved significantly improved phylogenetic resolution.

The origin and early evolution of dinosaurs

The oldest unequivocal records of Dinosauria were unearthed from Late Triassic rocks accumulated over extensional rift basins in southwestern Pangea, and the group achieved a nearly global distribution by the latest Triassic, especially with the radiation of saurischian groups such as “prosauropods” and coelophysoids.


  • M. Langer
  • Geography, Environmental Science
  • 2014
Research this century has greatly improved our knowledge of the origin and early radiation of dinosaurs. The unearthing of several new dinosaurs and close out- groups from Triassic rocks from various

The origins of Dinosauria: much ado about nothing

  • M. Langer
  • Geography, Environmental Science
  • 2014
Research this century has greatly improved our knowledge of the origin and early radiation of dinosaurs. The unearthing of several new dinosaurs and close outgroups from Triassic rocks from various

A late-surviving basal theropod dinosaur from the latest Triassic of North America

Various features of the skull of Daemonosaurus, including the procumbent dentary and premaxillary teeth and greatly enlarged premaxilla and anterior maxillary teeth, clearly set this taxon apart from coeval neotheropods and demonstrate unexpected disparity in cranial shape among theropod dinosaurs just prior to the end of the Triassic.

A new herrerasaurid (Dinosauria, Saurischia) from the Upper Triassic Ischigualasto Formation of northwestern Argentina

The presence of Sanjuansaurus at the base of the Ischigualasto Formation, along with other dinosaurs such as Herrerasaurus, Eoraptor, Panphagia, and Chromogisaurus suggests that saurischian dinosaurs in southwestern Pangea were already widely diversified by the late Carnian rather than increasing in diversity across the Carnian-Norian boundary.

Taxonomic, palaeobiological and evolutionary implications of a phylogenetic hypothesis for Ornithischia (Archosauria: Dinosauria)

The results find further support for the hypothesis that silesaurs comprise a paraphyletic grouping of taxa on the stem of Ornithischia and that successive silesaur taxa acquire anatomical characters anagenetically in a process that culminates in the assembly of what may be described as a ‘traditional’ ornithischian.

Revision of the early crocodylomorph Trialestes romeri (Archosauria, Suchia) from the lower Upper Triassic Ischigualasto Formation of Argentina: one of the oldest‐known crocodylomorphs

Trialestes romeri represents the most completely known of the earliest non‐crocodyliform crocodylomorph taxa known to date and its phylogenetic relationships are tested using a comprehensive data matrix focused on early archosaurs.



Early dinosaurs: A phylogenetic study

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.

Primitive dinosaur skeleton from Argentina and the early evolution of Dinosauria

The discovery of Eoraptor supports the hypothesis that dinosaurs diverged rapidly at small body size from a common ancestor, with the principal herbivorous and carnivorous lineages present by the middle Carnian.

Dinosaurian precursors from the Middle Triassic of Argentina: Marasuchus lilloensis, gen. nov.

Several synapomorphies unite Marasuchus and dinosaurs (as Dinosauriformes) to the exclusion of the contemporary dinosauromorph Lagerpeton and pterosaurs.

Basal Dinosauriform Remains from Britain and the Diagnosis of the Dinosauria

The definition and diagnosis of the Dinosauria are restated and the positions of the new form, herrerasaurs and Eoraptor relative to true dinosaurs are discussed.

New information on the systematics and postcranial skeleton of Herrerasaurus ischigualastensis (Ther

New evidence supports this group as saurischian dinosaurs: the posterior process of the jugal is forked, a hyposphene-hypantrum articulation is present in dorsal vertebrae, the distal shaft of the ischium is rod-like, and six other saurishian synapomorphies are present.

The Complete Skull and Skeleton of an Early Dinosaur

Fossils of Herrerasaurus and younger dinosaurs from Upper Triassic beds in Argentina suggest that the dinosaurian radiation was well under way before dinosaurs dominated terrestrial vertebrate communities in taxonomic diversity and abundance.


  • P. Sereno
  • Geography, Environmental Science
  • 1997
The phylogenetic history of ornithischian and saurischian dinosaurs reveals evolutionary trends such as increasing body size and Adaptations to herbivory in dinosaurs were not tightly correlated with marked floral replacements.

The evolution of dinosaurs.

  • P. Sereno
  • Environmental Science, Geography
  • 1999
The ascendancy of dinosaurs on land near the close of the Triassic now appears to have been as accidental and opportunistic as their demise and replacement by therian mammals at the end of the

The skull and neck of the basal theropod Herrerasaurus ischigualastensis

The skull of Herrerasaurus ischigualastensis has a rectangular profile and a transversely narrow snout and other features of the skull constitute dinosaurian synapomorphies, such as the loss of the postfrontal and small post-temporal opening.

Faunal replacement in the Triassic of South America

Improvements in the locomotor apparatus are discernible in seven groups of archosaurs and indicate that a great adaptive radiation took place before the oldest recorded fauna dominated by archosaurs appeared.