Fluid dynamics, scaling laws and plesiosaur locomotion

Area of Science:

• Paleontology
• Biomechanics
• Fluid Dynamics

Background:

• Plesiosaurs, successful marine reptiles, possessed unique tandem flippers, sparking debate about their locomotion and behavior.
• Previous studies suggested analogies to modern marine animals, but plesiosaur diversity complicates direct comparisons.

Purpose of the Study:

• To investigate plesiosaur locomotion dynamics using fluid dynamics scaling laws.
• To determine how flipper aspect ratio influenced plesiosaur agility and behavior.
• To explore diverse living animal analogies for plesiosaur movement.

Main Methods:

• Applied universal scaling laws from fluid dynamics to analyze plesiosaur flipper hydrodynamics.
• Estimated reduced frequency to characterize airfoil unsteadiness, a proxy for locomotive efficiency.
• Compared reduced frequency values across different plesiosaur morphotypes and living analogs.

Main Results:

• Plesiosaurs with high-aspect ratio flippers exhibited reduced frequencies similar to sea turtles.
• Plesiosaurs with lower aspect ratio flippers showed reduced frequencies comparable to penguins.
• Flipper aspect ratio significantly correlated with variations in plesiosaur agility.

Conclusions:

• Plesiosaur agility likely varied considerably, influenced by flipper morphology.
• The study supports broader and more diverse analogies to living animals than previously considered.
• Cruising reduced frequency can predict maneuvering behavior, not just cruising patterns.