Docodont

For much of their history of study, docodontan fossils were represented by isolated teeth and jaws. The first docodontan known from decent remains was Haldanodon, from the Late JurassicGuimarota site of Portugal. Recently, exceptionally preserved skeletons have been discovered in the Jurassic Tiaojishan Formation of China. Chinese docodontans include otter-like, mole-like, and squirrel-like species, hinting at impressive ecological diversity within the group. Many docodontans have muscular limbs and broad tail vertebrae, adaptations for burrowing or swimming. Like true mammals, docodontans have hair, a saddle-shaped hyoid apparatus, and reduced postdentary jaw bones which are beginning to develop into middle ear ossicles. On the other hand, the postdentary bones are still attached to the jaw and skull, the nares (bony nostril rims) have yet to fuse, and in most species the spine'sthoracic-lumbar transition is rather subdued.