Deinotherium - Hoe tusker
When: Mid-Miocene to Early Pleistocene (~10 million to 3 million years ago)
Where: Asia, Africa, and Europe
What: Deinotherium is a proboscidiean. The only two living species in Proboscidiea are the African and Indian elephants, but there are dozens of fossil species in this order. Unlike some other groups that not only have a much greater number of fossil species than living but a much wider variety of morphologies to go along with that, most fossil elephants well… look like elephants! That being large, graviportal, and trunked.
However, even though there is less extreme differences in morphology within proboscidieans, there are still a lot of variations on the basic elephant body plan. One great source of variation is in the tusks. The tusks of Deinotherium are enlarged incisors of its lower jaw whereas in modern elephants the tusks are enlarged upper incisors. The clade containing Deinotheirum spilt off from the rest of the order roughly 40 million years ago, and the last common ancestor had slightly enlarged upper and lower incisors - thus it appears that some elephant clades further enlarged one set over the other. Oh, one last note about Deinotheirum… it was over 3 times the size of the modern african elephant. It was the 3rd largest land mammal ever to lumber accross the Earth!
(via scientificillustration)
