Evidence for modular evolution in a long-tailed pterosaur with a pterodactyloid skull

Area of Science:

• Paleontology
• Evolutionary Biology
• Vertebrate Zoology

Background:

• The fossil record offers crucial evidence for macroevolutionary events, yet detailed documentation of major clade transitions remains scarce.
• Understanding the mechanisms driving these transitions, characterized by rapid, large-scale changes, is hindered by the rarity of transitional fossils.

Purpose of the Study:

• To investigate the poorly understood evolutionary transition between basal long-tailed pterosaurs and derived short-tailed pterodactyloids.
• To analyze the skeletal morphology of a new pterosaur fossil from the Middle Jurassic of China.

Main Methods:

• Descriptive analysis of fossil morphology.
• Comparative skeletal analysis of Darwinopterus modularis with basal and derived pterosaurs.

Main Results:

• Discovery of Darwinopterus modularis, a new pterosaur genus and species from the Middle Jurassic of China.
• Darwinopterus exhibits a mosaic of traits: pterodactyloid-like skull and neck, and a plesiomorphic postcranial skeleton typical of basal pterosaurs.
• This modular combination of characters provides the first detailed evidence of the transition from long-tailed to short-tailed pterosaurs.

Conclusions:

• The discovery of Darwinopterus modularis supports the 'modular evolution' hypothesis.
• Evolutionary transitions may be driven by changes in 'modules'—integrated character complexes with independent evolutionary histories.
• Natural selection acting on these modules could facilitate rapid, large-scale evolutionary changes and major clade transitions.