Building a predator: macroevolutionary patterns in the skull of abelisaurid dinosaurs

Area of Science:

• Paleontology
• Macroevolution
• Comparative Anatomy

Background:

• Abelisauridae, a dominant Gondwanan theropod clade, exhibits distinctive skull morphology.
• Previous studies relied on anatomical and biomechanical analyses, lacking quantitative macroevolutionary insights into skull evolution.

Purpose of the Study:

• To quantitatively assess skull modularity, integration, and macroevolutionary trends in Abelisauridae.
• To identify cranial regions driving evolutionary changes and link them to ecological factors.

Main Methods:

• Utilized two-dimensional geometric morphometrics to quantify cranial regions and bones.
• Applied a macroevolutionary approach to analyze skull shape diversification.

Main Results:

• Revealed phylogenetic modularity and evolutionary integration between the neurocranium and rostral skull regions.
• Identified high evolutionary rates and disparity in the occipital region, squamosal, quadratojugal, lacrimal, and postorbital bones.
• The neurocranium emerged as the primary region influencing proportional cranial height increase.

Conclusions:

• Ecological pressures, particularly feeding strategies, significantly drove abelisaurid skull evolution.
• Cranial features may have been co-opted for socio-sexual display, alongside functional adaptations.
• Further research using evolutionary modeling is recommended to explore rate selection and constraints on skull shape diversification.