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Related Experiment Video

Updated: Feb 18, 2026

Probing the Limits of Egg Recognition Using Egg Rejection Experiments Along Phenotypic Gradients

Probing the Limits of Egg Recognition Using Egg Rejection Experiments Along Phenotypic Gradients

Published on: August 22, 2018

Multiple optimality criteria support Ornithoscelida.

Luke A Parry^1,2, Matthew G Baron^2,3, Jakob Vinther¹

¹Bristol Life Sciences Building, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TH, UK.

Royal Society Open Science

|November 15, 2017

Summary

This summary is machine-generated.

A new study on early dinosaur evolution suggests Ornithischia and Theropoda form a clade called Ornithoscelida, challenging historical classifications. This finding is supported by Bayesian inference and parsimony analyses, reinforcing the novel hypothesis of dinosaur interrelationships.

Keywords:

Avemetatarsalia Bayesian Dinosauria cladistics likelihood phylogenetics

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Area of Science:

Paleontology
Evolutionary Biology
Systematics

Background:

Historical dinosaur classification recognized Ornithischia and Saurischia as sister taxa.
Recent phylogenetic analyses using equal-weights parsimony proposed a novel clade, Ornithoscelida, comprising Ornithischia and Theropoda.
Concerns exist regarding the accuracy of equal-weights parsimony in phylogenetic reconstruction.

Purpose of the Study:

To provide additional support for the Ornithoscelida hypothesis using alternative phylogenetic methods.
To investigate the robustness of the Ornithoscelida clade across different analytical approaches.
To assess the influence of novel versus existing characters on phylogenetic resolution.

Main Methods:

Bayesian inference using the Mkv model.
Parsimony analyses, including implied weighting.
Systematic exclusion of character sets to test hypothesis robustness.

Main Results:

Bayesian inference and implied weighting consistently recovered a monophyletic Ornithoscelida, supporting the novel hypothesis.
The Ornithoscelida topology was robust across multiple phylogenetic methods.
Novel characters were crucial for resolving relationships within Dinosauromorpha.

Conclusions:

The Ornithoscelida clade is supported by multiple phylogenetic methods, challenging the traditional Ornithischia-Saurischia dichotomy.
Phylogenetic analyses of early dinosaur evolution are sensitive to methodological choices and character selection.
Further research is needed to fully elucidate early dinosaur evolutionary relationships.