Thanks to a hundred years of Hollywood movies, many people are convinced that mammoths, mastodons and other prehistoric elephants lived alongside dinosaurs. The fact is, these huge, lumbering beasts evolved from the small, mouse-sized mammals that survived the K/T Extinction, and the first placental mammal even remotely recognizable as a primitive elephant didn't appear until five million years after the dinosaurs went kaput. (See a gallery of prehistoric elephant pictures.)
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That creature was Phosphatherium, a small, squat, pig-sized herbivore that appeared in Africa about 60 million years ago. Classified by paleontologists as the earliest known proboscid (an order of mammals distinguished by their long, flexible noses), Phosphatherium looked and behaved more like a pygmy hippo than an early elephant. The giveaway was this creature's tooth structure: we know that the tusks of elephants evolved from incisors rather than canines, and Phosphatherium's choppers fit the evolutionary bill.
The two most notable early proboscids after Phosphatherium were Phiomia and Moeritherium, which were also restricted to the northern African swamps and woodlands circa 37-30 million years ago. The better known of the two, Moeritherium, sported a flexible upper lip and snout, as well as extended canines that (in light of future elephant developments) could be considered rudimentary tusks. Like a small hippo, Moeritherium spent most of its time half-submerged in swamps; its contemporary Phiomia was more elephant-like, weighing about half a ton and dining on terrestrial (rather than aquatic) vegetation.
Yet another north African proboscid of this time was the confusingly named Palaeomastodon, which should not be confused with the famous mastodon (genus name Mammut) that ruled the North American plains 20 million years later. What's important about Palaeomastodon is that it was recognizably a primitive elephant, demonstrating that by 35 million years ago nature had pretty much settled on the pachyderm body plan (thick legs, long trunk, large size and tusks).
Toward True Elephants: Deinotheres and Gomphotheres
Twenty-five million years or so after the dinosaurs went extinct, the first proboscids appeared that could easily be discerned as primitive elephants. The most important of these, from an evolutionary perspective, were the gomphotheres ("bolted mammals"), but the most impressive were the deinotheres, typified by Deinotherium ("terrible mammal"). This 10-ton proboscid sported downward-curving lower tusks and was one of the largest mammals ever to roam the earth; it may well have inspired tales of "giants" in historical times, since it survived well into the Ice Age.
As terrifying as Deinotherium was, though, it represented a side branch in elephant evolution. The real action was among the gomphotheres, the odd name for which derives from the fact that the lower tusks of many genuses were "welded" together into shovel-like shapes, the better to dig for plants in soft, swampy ground. The signature genus, Gomphotherium, was especially widespread, stomping across the lowlands of North America, Africa and Eurasia from about 15 million to 5 million years ago.
Other gomphotheres of this era had an even more pronounced digging apparatus than Gomphotherium. The two prime examples were Amebelodon ("shovel tusk") and Platybelodon ("flat tusk"), the spoon-shaped lower tusks of which were so well adapted to their semi-aquatic lifestyles that they quickly went extinct when the lakebeds and riverbeds they depended on dried up.
However, not all gomphotheres had well-developed lower tusks. Anancus was distinguished by its unusually long upper tusks (13 feet long in adults), while Cuverionius' claim to fame was twofold: this early elephant's upper tusks were curved, like those of a modern narwhal, and it was also one of the few proboscids known to have settled in South America (the only other example being another gomphothere, Stegomastodon, which was notable for its ability to eat a wide variety of plants, possibly including grass).
Next Page: Mastodons, Mammoths, and Profiles of Early Elephant Genuses
