Powered flight in hatchling pterosaurs: evidence from wing form and bone strength

Area of Science:

• Paleontology
• Vertebrate Zoology
• Functional Morphology

Background:

• Debate exists regarding the flight capabilities of juvenile pterosaurs, with models including 'flap-early', 'fly-late', and 'glide-early'.
• Understanding early life stages is crucial for reconstructing pterosaur behavior and ecology.

Purpose of the Study:

• To test competing models of pterosaur juvenile flight capabilities.
• To analyze the biomechanics and morphology of early-stage pterosaurs.

Main Methods:

• Analysis of wing bone strength, wing loading, wingspan, and wing aspect ratios.
• Examination of embryonic and hatchling specimens, including Pterodaustro guinazui and Sinopterus dongi.
• Re-evaluation of specimen classifications, such as a young Sinopterus specimen.

Main Results:

• Juvenile pterosaur humeri possess sufficient bending strength for flight.
• Wing size and aspect ratios of young juveniles support powered flight capabilities.
• Young juveniles were capable gliders, though not specialized for it.
• Wing morphology varied significantly with ontogeny, indicating developmental changes in flight characteristics.

Conclusions:

• The 'fly-late' and 'glide-early' models for pterosaur juveniles are rejected.
• Pterosaur juveniles were capable of powered flight from a very early age.
• Ontogenetic niche partitioning likely occurred, with juveniles adapted for different environments than adults.