Coryphodon (Greek for "peaked tooth"); pronounced core-IFF-oh-don
Swamps of the northern hemisphere
Early Eocene (55-50 million years ago)
Size and Weight:
Up to seven feet long and half a ton, depending on species
Squat body; quadrupedal posture; semiaquatic lifestyle; exceptionally small brain
A mere 10 million years after the dinosaurs went extinct, the first giant mammals, the pantodonts, appeared on the planet--and among the biggest pantodonts was Coryphodon, the largest species of which only measured about seven feet long from head to tail and weighed half a ton, but still counted as the largest land animals of their day. (It's important to remember that mammals didn't suddenly spring into existence after the K/T Extinction; they existed alongside bigger dinosaurs for most of the Mesozoic Era, but in small, shrew-like form, cowering in the tops of trees or burrowing underground for shelter.) Coryphodon wasn't the first identified pantodont of North America, however; that honor belongs to the slightly smaller Barylambda.
Coryphodon and its fellow pantodonts seem to have lived like modern hippopotami, spending a large part of their day in weed-choked swamps and uprooting plants with their powerful necks and heads. Possibly because efficient predators were in short supply during the early Eocene epoch, Coryphodon was a relatively slow, lumbering beast, equipped with an unusually small brain (only a handful of ounces compared to its 1,000-pound bulk) that beckons comparison with those of its sauropod and stegosaur predecessors. Still, this megafauna mammal managed to populate most of North America and Eurasia during its five million years on earth, making it a true success story of the early Cenozoic Era.
Because it was so widespread, and left so many fossil specimens, Coryphodon is known by a bewildering array of species and outmoded genus names. Within the last century, it has been "synonymized" with the would-be pantodonts Bathmodon, Ectacodon, Manteodon, Letalophodon, Loxolophodon and Metalophodon, and various species were described by the famous 19th-century American paleontologists Edward Drinker Cope and Othniel C. Marsh. Even after decades of pruning, there are over a dozen named Coryphodon species; there used to be as many as fifty!