The above photograph is of the forelimb claws of the giant ground sloth Megalonyx wheatleyi, first named by E.D. Cope in 1871. The genus name for this animal was assigned to a similar animal at the close of the previous century, however, Megalonyx first being assigned to fossils that first found their way into the possession of Thomas Jefferson around 1797. Jefferson first inferred the giant claws to be from some gigantic, ancient big cat,* but shortly after he formally described the find it was compared with the giant sloth Megatherium that Cuvier had described earlier. The similarities between the fossils were too close to miss. Jefferson only ascribed a genus name to the fossils, though, and it was not until 1822 that zoologist Anselme Gaëtan Desmarest named it Megatherium jeffersonii. This caused a bit of a problem because Megalonyx was distinct from Megatherium, so ultimately the species name became Megalonyx jeffersonii when a taxonomic revision was made a few years after Desmarest named the giant sloth in Jefferson's honor.
*Partial remains of herbivores were often confused with those of carnivores during the early days of paleontology, the rough & pointed molars of mastodons often being attributed to gigantic meat-eaters rather than relatives of modern-day elephants. This was seemingly in violation of Cuvier's hypothesis that if you could find one part of a creature (the classic example being the claw of a carnivore) you could therefore infer what the rest of the animal was probably like.
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