The Evolution of Pneumatic Foramina in Pterosaur Vertebrae

Area of Science:

• Paleontology
• Vertebrate Anatomy
• Evolutionary Biology

Background:

• Pterosaurs exhibit skeletal pneumatization, observable externally via pneumatic foramina.
• These foramina display significant variation in position, shape, and number across different pterosaur taxa.

Purpose of the Study:

• To introduce and test new characters for pterosaur phylogenetic analysis based on pneumatic foramina in cervical and dorsal vertebrae.
• To investigate the evolutionary history and homology of pneumatic foramina in pterosaurs.

Main Methods:

• First-hand examination of pterosaur fossil material in collections.
• Literature data compilation for phylogenetic analysis.
• Cladistic analysis using newly defined characters.
• Mapping of characters onto a strict consensus tree.

Main Results:

• The cladistic analysis yielded nine equally parsimonious trees, with the strict consensus tree showing minimal differences from previous studies.
• Mapping revealed that most pneumatic foramina evolved independently across various pterosaur lineages.
• Only two of the eight proposed characters for pneumatic foramina appeared to be evolutionarily conserved (occurred once).

Conclusions:

• Pneumatic foramina are generally more prevalent in Dsungaripteroidea.
• Preservation biases, particularly flattened specimens of non-pterodactyloids and Archaeopterodactyloidea, may obscure vertebral pneumatization.
• The true extent of vertebral pneumatization in pterosaurs might be underestimated and could be better understood with new fossil discoveries.