Soft tissues influence nasal airflow in diapsids: Implications for dinosaurs

Area of Science:

• Paleontology
• Comparative Anatomy
• Biomechanics

Background:

• The nasal passage is crucial for olfaction and thermoregulation in amniotes.
• Fossilization results in low-resolution nasal passage models due to soft-tissue loss.
• Interpreting extinct animal physiology from fossil nasal passages is challenging.

Purpose of the Study:

• To assess the impact of fossilization on nasal passage airflow interpretations.
• To compare airflow in extant animals with soft tissues versus fossil-based bony reconstructions.
• To infer the presence of specific nasal structures in extinct taxa like dinosaurs.

Main Methods:

• Comparative analysis of nasal passages in extant diapsids (alligator, turkey, ostrich, iguana, monitor lizard).
• 3D reconstruction of nasal passages.
• Computational fluid dynamics (CFD) simulations of airflow.
• Comparison of soft-tissue-bounded and fossil-limited (bony-bounded) airway models.

Main Results:

• Airflow in bony-bounded airways was more homogeneous and slower than in soft-tissue-bounded airways.
• Fossil-based reconstructions impose overly restrictive physiological limitations.
• Consistent nasal passage constrictions were observed across diverse extant species.

Conclusions:

• Bony-bounded airway reconstructions are too conservative for accurately modeling extinct animal nasal physiology.
• Nasal constrictions at the olfactory region junction are likely ancestral traits present in extinct taxa.
• This study refines our understanding of respiratory function in extinct animals.