Diacodexis

A little Diacodexis trotting through the forest.  Diacodexis is one of the the oldest known artiodactyls, or even-hoofed mammals (though not all ungulates had an even number of toes per foot).  It lived from about 55 to 46 million years ago and fossils of it were found in Europe, America and Asia.  Some fossils may be misattributed to it, since palaeontologists tend to lump early artiodactyl fossils in the genus.  Its remains are patchy and it's difficult to be certain about the species that existed.  It was at any rate a small critter, 60 cm/2' long in total of which the long tail made up a good part.  It had fairly long legs and was probably a good runner, although the artiodactyls that came later became much better adapted at running and leaping.  Charcoal, coloured with Photoshop.