Challenging the lateral-to-sagittal shift in mammalian locomotion

Very recommendable! Just a reminder that science is rarely ever settled! Karl Popper Falsifiability!

"... Nonmammalian synapsids, the extinct forerunners to mammals, like living reptiles, had limbs splayed out to the side instead of beneath like today’s mammals. So scientists believed that they must have also moved in similar ways, with spines more suited to the side-to-side flexing of a sashaying lizard instead of the up-and-down bending typical of a mammal in motion. The transition is known as the lateral-to-sagittal paradigm. It’s an explanation that’s been taught in college textbooks on anatomy and evolution for decades....
The analysis demonstrates that the three lineages differ from one another other when it comes to the morphology, function, and characteristics of their spines, and suggests that mammal backbones didn’t evolve from a reptile-like ancestor. There had to have been a completely different type of backbone function not observed in today’s living vertebrates. ..."

"Highlights

• “Lateral-to-sagittal” paradigm is too simple to explain mammal vertebral evolution

• Extant reptiles are a poor functional model for extinct non-mammalian synapsids

• Non-mammalian synapsid vertebral joints are characterized by high stiffness

• Mammal backbone evolution involved acquisition of multiple vertebral functions"

Challenging the lateral-to-sagittal shift in mammalian locomotion – Harvard Gazette Findings point to the importance of checking the fossil record

Here is the link to the underlying research paper:

Adaptive landscapes challenge the “lateral-to-sagittal” paradigm for mammalian vertebral evolution (open access)