Transitional fossils and the origin of turtles

Tyler R. Lyson, Gabe S. Bever, Bhart Anjan S. Bhullar, Walter G. Joyce, Jacques A. Gauthier

Research output: Contribution to journalArticlepeer-review

105 Scopus citations


The origin of turtles is one of the most contentious issues in systematics with three currently viable hypotheses: turtles as the extant sister to (i) the crocodile-bird clade, (ii) the lizard- tuatara clade, or (iii) Diapsida (a clade composed of (i) and (ii)). We reanalysed a recent dataset that allied turtles with the lizard-tuatara clade and found that the inclusion of the stem turtle Proganochelys quenstedti and the 'parareptile' Eunotosaurus africanus results in a single overriding morphological signal, with turtles outside Diapsida. This result reflects the importance of transitional fossils when long branches separate crown clades, and highlights unexplored issues such as the role of topological congruence when using fossils to calibrate molecular clocks.

Original languageEnglish (US)
Pages (from-to)830-833
Number of pages4
JournalBiology Letters
Issue number6
StatePublished - Dec 23 2010
Externally publishedYes


  • Diapsida
  • Eunotosaurus africanus
  • Molecular clock
  • Odontochelys semitestacea
  • Transitional fossil
  • Turtle

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Agricultural and Biological Sciences(all)


Dive into the research topics of 'Transitional fossils and the origin of turtles'. Together they form a unique fingerprint.

Cite this