Detecting Mismatch in Functional Narratives of Animal Morphology: a Test Case With Fossils

Area of Science:

• Paleontology
• Functional Morphology
• Biomechanics

Background:

• Recent technological advancements have increased the diversity and power of analytical tools in biomechanical and functional morphology research.
• Investigating complex datasets often requires focusing on single functional narratives, potentially overlooking other crucial form-function relationships.
• Ammonoid shells underwent significant morphological changes from the Middle Triassic to the Early Jurassic, with hydrodynamics proposed as a primary driver.

Purpose of the Study:

• To present a framework for synthesizing multiple functional hypotheses using joint performance landscapes.
• To apply this framework to the ammonoid morphological transition and assess the role of hydrodynamics.
• To highlight the need for exploring alternative functional explanations beyond hydrodynamics.

Main Methods:

• Utilized maximum likelihood to determine joint performance landscapes.
• Analyzed the shift in morphospace occupation of ammonoids from the Middle Triassic to the Early Jurassic.
• Evaluated the explanatory power of hydrodynamic measures for the observed morphological transition.

Main Results:

• The study found that hydrodynamic performance measures poorly explain the observed shift in ammonoid morphospace occupation.
• Morphospace occupation shifted from broad to a dense region emphasizing an exposed umbilicus and modest frontal profile.
• Conflicting interpretations of hydrodynamic performance persist, with limited alternative explanations offered in previous research.

Conclusions:

• Hydrodynamics alone is insufficient to explain the ammonoid morphological transition.
• A more robust investigation of alternative functional hypotheses is necessary.
• The proposed framework aids in consolidating understanding of form-function relationships and identifying when current characterizations are inadequate.