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Turtle evolution: Missing a missing link
1Department of Physiological Sciences, Biology Institute, Universidade de Brasília, Brasília, Brazil.
Current Biology : CB
|July 20, 2026
Summary
The study reappraises Eunotosaurus, a key fossil in turtle evolution. Results suggest Eunotosaurus is not a direct turtle ancestor, challenging its
Area of Science:
- Paleontology
- Evolutionary Biology
- Vertebrate Zoology
Background:
- Turtles possess a unique shell, a defining characteristic among vertebrates.
- The evolutionary origins of the turtle shell and its ancestors remain debated.
- Eunotosaurus has been considered a potential transitional fossil in turtle evolution.
Purpose of the Study:
- To re-evaluate the phylogenetic position of Eunotosaurus within vertebrate evolution.
- To clarify the relationship between Eunotosaurus and the origin of turtles.
- To resolve the controversy surrounding Eunotosaurus as a 'missing link'.
Main Methods:
- Comparative anatomical analysis of Eunotosaurus fossils.
- Phylogenetic analyses incorporating new data and taxa.
- Reassessment of key morphological features relevant to turtle ancestry.
Main Results:
- Eunotosaurus exhibits distinct anatomical features that differentiate it from early turtles.
- Phylogenetic analyses place Eunotosaurus outside the turtle crown group.
- The study provides evidence against Eunotosaurus being a direct ancestor or close relative of turtles.
Conclusions:
- Eunotosaurus is not the 'missing link' in turtle evolution as previously proposed.
- The evolutionary path to the turtle shell likely involved different lineages.
- Further research is needed to identify the true ancestors of turtles.
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