Patterns of maximum body size evolution in Cenozoic land mammals: eco-evolutionary processes and abiotic forcing

Area of Science:

• Paleontology
• Macroevolution
• Climate Science

Background:

• Macroevolutionary trends in mammal evolution suggest similar trajectories across continents during the Cenozoic.
• These patterns may be driven by global abiotic factors like climate or eco-evolutionary processes such as niche specialization.

Purpose of the Study:

• To investigate the temporal distribution of maximum body size within individual mammal orders globally and continentally.
• To determine if macroevolutionary patterns of size evolution are congruent across different geographic regions.

Main Methods:

• Analysis of the temporal distribution of maximum body size for mammal orders.
• Comparison of size evolution patterns on different continents and globally.
• Correlation analysis between maximum size frequency and global temperature proxies.

Main Results:

• Maximum body size in mammal orders showed congruence in timing, peaking in the Middle Eocene, Oligocene, and Plio-Pleistocene.
• The Eocene peak coincided with high global temperatures and mammal diversity, suggesting niche expansion.
• A significant correlation between maximum size frequency and global temperature was observed since the Eocene.
• The Plio-Pleistocene peak, the most robust, occurred during low temperatures and is linked to global cooling.

Conclusions:

• Macroevolutionary patterns in mammal size are shaped by an interplay between eco-evolutionary processes and abiotic forcing.
• Global climate significantly influences mammal macroevolutionary trajectories, particularly since the Eocene.
• While niche dynamics play a role, abiotic factors like temperature are key drivers of size evolution in mammals.