evidence of cannibalism

Amphibian August #07 – Trimerorhachis

Known from the Early Permian of the south central United States (~290-272 mya), Trimerorhachis reached about 1m in length (3′3″) and was an early member of a highly aquatic group of temnospondyls called dvinosaurs. It probably spent its entire life in water, having gills even as an adult – although unlike modern amphibians these were internal gills, developed during metamorphosis before the loss of the larval external gills.

Its long body was covered in multiple overlapping layers of small fish-like bony scales, which made up 10-15% of its total body weight. While they may have served a defensive function, they might also have acted as a sort of ballast, weighing it down to help it stay underwater.

One specimen preserves a cluster of tiny bones around its gills which seem to belong to several Trimerorhachis larvae. These are either evidence of cannibalism, or something even more interesting – it’s possible that these animals were protecting their eggs and young by mouth-brooding.