The evolutionary position of turtles revised.

Area of Science:

• Evolutionary biology
• Comparative genomics
• Paleontology

Background:

• The evolutionary position of turtles within amniote phylogeny remains a long-standing debate.
• Turtles possess unique morphology, complicating their phylogenetic placement.
• Historically, turtles were considered anapsids, lacking skull temporal fenestrae.

Purpose of the Study:

• To resolve the phylogenetic position of turtles within the amniote lineage.
• To reconcile conflicting evidence from morphological and molecular studies.
• To re-evaluate the primitive or derived nature of turtle skull morphology.

Main Methods:

• Analysis of molecular data from various amniote groups.
• Comparative morphological studies of skeletal structures.
• Phylogenetic analyses integrating both molecular and morphological datasets.

Main Results:

• Molecular data suggest turtles are closely related to archosaurs (crocodiles, birds).
• Morphological data indicate turtles are most closely related to lepidosaurs (tuatara, lizards, snakes).
• Evidence supports turtles as diapsids that secondarily lost temporal fenestrae.

Conclusions:

• Turtles are not primitive reptiles but possess derived skull characteristics.
• The phylogenetic placement of turtles is complex, with differing support from molecular and morphological data.
• Further research is needed to fully elucidate turtle evolutionary history and relationships.