What’s it about?
In mammals, each vertebra is a single bone. However, these apparently singular bones are actually composed of several bones that are sutured together. This paper explores the individual bones that get fused together, and their origins in the transitional forms between fish and terrestrial tetrapods (four legged animals, e.g. amphibians, reptiles, birds, and mammals).
Why does it matter?
The authors utilize X-ray synchrotron microtomography (kinda like a CT scan or an MRI, but different) to be able to look inside of fossils and distinguish the different parts of the vertebrae. In hand sample, the different parts are difficult to tell apart, and this paper shows that what paleontologists have been thinking was the way that modern tetrapod vertebrae form is actually incorrect.
Why did I read this?
I am about to begin a section in my class about the transition from water to land in vertebrates. This paper was relevant in its discussion of the vertebrae of fishes closely related to the earliest tetrapods.