Pisanosaurus mertii and the Triassic ornithischian crisis: could phylogeny offer a solution?

@article{Baron2019PisanosaurusMA,
  title={Pisanosaurus mertii and the Triassic ornithischian crisis: could phylogeny offer a solution?},
  author={Matthew G. Baron},
  journal={Historical Biology},
  year={2019},
  volume={31},
  pages={967 - 981}
}
  • M. Baron
  • Published 14 September 2019
  • Geography, Environmental Science
  • Historical Biology
Abstract Two recent studies have independently recovered Pisanosaurus mertii – long thought to represent the oldest known member of Ornithischia – within Silesauridae. These finds are expanded upon here, as are the implications of this hypothesis. Based upon these finds, it now appears that Ornithischia was absent in the Triassic Period entirely, which constitutes a major incongruence between the fossil record and current phylogenetic hypotheses, particularly the traditional model of dinosaur… 

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References

SHOWING 1-10 OF 77 REFERENCES

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, we

Ecologically distinct dinosaurian sister group shows early diversification of Ornithodira

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.

Early ornithischian dinosaurs: the Triassic record

Abstract Ornithischian dinosaurs are one of the most taxonomically diverse dinosaur clades during the Mesozoic, yet their origin and early diversification remain virtually unknown. In recent years,

Postcranial anatomy of Lesothosaurus diagnosticus (Dinosauria: Ornithischia) from the Lower Jurassic of southern Africa: implications for basal ornithischian taxonomy and systematics

This study has found that the material of L. diagnosticus and S. dangershoeki almost certainly represents the same taxon and that the apparent differences between these genera is probably a product of ontogentic (rather than taxonomic) differences.

A dinosaur missing-link? Chilesaurus and the early evolution of ornithischian dinosaurs

The authors' analyses recover Chilesaurus in a novel position, as the earliest diverging member of Ornithischia, rather than a tetanuran theropod, thereby offering potential insights into the earliest stages of ornithischian evolution, which were previously obscure.

Phylogenetic reassessment of Pisanosaurus mertii Casamiquela, 1967, a basal dinosauriform from the Late Triassic of Argentina

The present analysis indicates that Pisanosaurus should be removed from the base of the Ornithischia and should no longer be considered the oldest representative of this dinosaurian clade.

The systematic relationships and biogeographic history of ornithischian dinosaurs

The resulting strict consensus tree is the most well-resolved, stratigraphically consistent hypothesis of basal ornithischian relationships yet hypothesized and provides a comprehensive framework for testing further hypotheses regarding evolutionary patterns and processes within Ornithischia.

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.

A palaeoequatorial ornithischian and new constraints on early dinosaur diversification

A new dinosaur from the earliest Jurassic of the Venezuelan Andes is the first basal ornithischian recovered from terrestrial deposits directly associated with a precise radioisotopic date and the first-named dinosaur from northern South America, helping to underscore the importance of the ornithische record in broad-scale discussions of early dinosaur history.

The phylogeny of the ornithischian dinosaurs

Surprisingly, Heterodontosauridae is placed as the most basal group of all well‐known ornithischians, phylogenetically distant from a stem‐defined Ornithopoda, creating a topology that is more congruent with the known Ornithischian stratigraphical record.
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