Origin of the Mammal Backbone

Katrina Jones

The rich fossil record of non-mammalian synapsids provides a window into mammalian evolution.

This NSF-funded project strives to understand the role of the vertebral column in the origin of mammalian locomotor modes.


Our team is using biomechanical experiments, comparative anatomy and digital imaging of exceptionally-preserved fossils to understand the evolution of mobility and regionalization in the synapsid backbone. 

Vertebral Regionalization

Vertebral regions are patterned during development by a series of highly conserved genes, known as the hox genes. Mammals are unusual as they have a trunk which is subdivided into two or three subregions, allowing specialization of locomotor and respiratory function. We are investigating the origin of the differentiated mammal back by measuring vertebral regions in fossil synapsids.

We are also examining the functional implications of increasing regionalization by measuring the biomechanical properties of vertebral joints in several model taxa. By linking regionalization of vertebral function and anatomy of extinct fossil synapsids, we can begin to understand the role of hox genes and changing locomotor behavior in the evolution of mammals. 

Katrina Jones

Vertebral Biomechanics

The highly specialized anatomical regions of mammals are thought to have distinct functions during locomotion, however the link between form and function in the vertebral column is poorly understood. We are testing the influence of anatomical regions on vertebral function using ex vivo bending experiments on cadaveric spines of a range of mammals with different locomotor types. This data will help us understand how changing vertebral regions in non-mammalian synapsids may have contributed to the evolution of mammal-type locomotor patterns.

Collaborators: Stephanie Pierce, Ken Angielczyk, Dave Polly, Jason Head, Vincent Fernandez