Inferring the physiological regimes of extinct vertebrates: methods, limits and framework

Area of Science:

• Paleophysiology
• Vertebrate Physiology
• Bone Histology

Background:

• Current understanding of ancient vertebrate physiology relies on outdated, binary classifications ('cold-blooded' vs. 'warm-blooded').
• Palaeobiologists need advanced tools to interpret physiological regimes of extinct vertebrates.
• Existing frameworks are limited by the relatively depauperate nature of extant vertebrate fauna.

Purpose of the Study:

• To re-imagine vertebrate palaeophysiology and general vertebrate physiology.
• To explore how bone tissue signals can inform our understanding of ancient physiology.
• To move beyond simplistic dichotomous classifications of vertebrate physiology.

Main Methods:

• Integration of histoanatomical data with patterns of size, growth, and phylogeny.
• Analysis of four key influences on bone tissues: phylogeny, ontogeny, mechanics, and environment.
• Utilizing a phylogenetic framework for interpreting fossilized animal tissues.

Main Results:

• Identified four key 'signals' or 'influences' on bone tissues: phylogeny, ontogeny, mechanics, and environment.
• Demonstrated the utility of these signals in addressing questions about ancient vertebrate physiology.
• Provided a more nuanced approach to understanding physiological variation beyond binary categories.

Conclusions:

• Bone tissue analysis offers a powerful method for reconstructing ancient vertebrate physiology.
• A multi-faceted approach considering phylogeny, ontogeny, mechanics, and environment is crucial.
• This integrated approach allows for a more comprehensive understanding of vertebrate physiology across evolutionary time.