Diictodon: Burrowing Therapsid

Diictodon was a small genus of therapsid that lived during the Late Permian Period. Therapsids are also known as mammal-like reptiles due to their "missing link" status between mammalian characteristics and reptilian ones. It is one of the most commonly found therapsid in the fossil record and remains have been unearthed in Africa and Asia.

Diictodon was a burrowing therapsid that lived in the deserts of the supercontinent, Pangaea. It presumably burrowed in order to avoid the intense heat and inhospitable conditions taking place on the desert surface. The burrow would have afforded relief both from the elements and from predators stalking about above. It wasn't a very big animal, only measuring about half a meter long with a barrel-shapped body, stubby tail and a short head with two small tusks. Instead of teeth, diictodon had a hard beak at the end of its skull which would have aided in snipping off bits of tough desert vegetation or grinding up root tubers. These plant tubers would have provided sufficient water for such a small and efficient mammal. Being able to live on very small amounts of water would be an indispensable adaptation for an animal living in a hot, arid environment where standing pools of water are scarce.

Diictodon bears a number of mammalian characteristics and it was creatures like it that would form the basis for the true mammals that would emerge in later eons. Very few true reptiles burrow, so its gopher-like lifestyle made it much more akin to modern burrowing mammals. Furthermore, small bones in its skull were probably used for hearing, much like our inner ear bones vibrate and allow us to detect sounds. Reptiles lacked this adaptation and lacked a strong sense of hearing. Also, due to the fact that some remains of diictodon have been found in pairs, it has been suggested that these small desert animals mated for life. This trait has been observed in many modern mammals such as beavers. Also, the difference in size of tusks between sexes of diictodon suggest that they might have had a complex social organization in which males would fight for dominance over the females with the size and display of their tusks.

Diictodon succeeded where most other animals failed at the end of the Permian. During this period when all continents were fused into one giant land mass, conditions for life were becoming less and less favorable. When larger herbivores and predators died out as a result of the expanding deserts, diictodon was able to bear it out and evolve into many new groups of therapsids that lived during the Triassic.