Fossils reveal the complex evolutionary history of the mammalian regionalized spine

Early shifts lead to big changesMammals represent one of the most morphologically diverse taxonomic groups. One of the unique features underlying this diversity is variability of the spine, which facilitates everything from flexibility for speedy running and support for upright walking. Joneset al.studied a group ancestral to modern mammals—nonmammalian synapsids, or mammal-like reptiles. As forelimb function diversified, the spine developed distinct regions. These regions then differentiated further, leading to the highly varied mammalian forms we see today.Science, this issue p.1249