Developmental origin underlies evolutionary rate variation across the placental skull

Area of Science:

• Evolutionary biology
• Comparative anatomy
• Paleontology

Background:

• The mammalian skull exhibits extreme morphological diversity.
• Previous studies focused on the skull as a whole, neglecting individual element evolution.
• Cranial elements have diverse developmental origins and functions.

Purpose of the Study:

• To analyze the macroevolution of individual mammalian skull elements.
• To investigate how developmental origin and function influence evolutionary trajectories.
• To compare evolutionary rates and ecological signals across cranial regions.

Main Methods:

• High-dimensional morphometrics applied to a dataset of 322 eutherians (living and extinct placental mammals and relatives).
• Quantification of variation, phylogenetic, allometric, and ecological signals.
• Comparison of evolutionary rates across ecological categories and clades, with lineage and temporal reconstructions.

Main Results:

• Distinct macroevolutionary patterns were observed across different cranial elements.
• Elements derived from neural crest exhibited the fastest rates of evolution.
• Ecological signal was significant in both neural crest and paraxial mesoderm-derived bones, indicating functional adaptation potential.

Conclusions:

• Developmental origin influences the tempo of skull element evolution.
• Functional specialization capacity is not solely determined by developmental origin.
• Cranial element evolution is shaped by both developmental constraints and ecological pressures.