Science Word of the Day: Mastodon

I have a soft spot for the American mastodon. The beast lived at the same time as the famous woolly mammoth, yet the mastodon is not nearly as popular as its tundra-living cousin. I can relate to that. But even worse, the shadow of the woolly mammoth stretches so far that the mastodon is often confused for its shaggy relative. This is not a new problem.

Back in the late 18th century, when paleontology was a nascent science, many naturalists thought that giant elephant bones found in Europe, northern Eurasia, and America were from modern species that used to live there. Elephantine bones found in England, for example, were attributed to behemoths the Romans must have used as pack animals during their occupation, and French naturalist Georges-Louis Leclerc, Comte de Buffon suggested that huge bones found in Siberia showed that the world was once much warmer and allowed modern elephants to range further afield.

Georges Cuvier disagreed. Remembered as one of the founders of paleontology, Cuvier was just 27 when he stood before France’s National Institute in 1796 and explained that the elephant bones from Eurasia and those from North America – then referred to the “American Incognitum” – actually belonged to extinct species unlike those alive today. “The first suspicions that there are more than one species [of elephant] came from a comparison of several molar teeth that were known to belong to elephants, and which showed considerable differences,” Cuvier explained to his audience, “some [teeth] having their crown sculpted in a lozenge form, the others in the form of festooned ribbons.” And from the fossil teeth, Cuvier concluded, “These [fossil] animals thus differ from elephants as much as, or more than, a dog differs from the jackal and the hyena.”

This wasn’t just anatomical hair-splitting. Cuvier had offered fossil proof that extinction is a reality – a fact some naturalists still questioned despite the fact that humanity had already wiped out the dodo and other species. More than that, Cuvier proposed that the fossil elephants preferred different habitats than their modern relatives. The conditions that had sustained them had been wiped away, perhaps in a terrible environmental catastrophe of the sort Cuvier was just beginning to entertain as he pondered the depths of the fossil record.

But what to call such beasts? The Siberian form – with the ribbon-like pattern on its teeth – was already known as the mammoth. The bumpy-toothed American form was still commonly called the Incognitum, and Cuvier did not offer a replacement in his initial paper on the subject. This oversight came back to bite him.

Despite their disparate teeth, the mammoth and Incognitum were often misconstrued as the same animal. Naturalists were not always careful to distinguish the two massive, extinct elephants from each other. Cuvier got fed-up enough with the confusion that in 1806 he wrote a paper that tried to sort out the mess.

Mammoth was still a fitting term for the Siberian animal, but, Cuvier decided, the North American animal should be called the mastodon. The name came from looking the animal in the mouth. Drawing from illustrations created by American artist and museum pioneer Rembrandt Peale, Cuvier noted that the bumps on the mammal’s molars looked like breasts. Since teeth were mainly what he and other naturalists were comparing, Cuvier took the Greek words for breast and tooth to coin mastodon – the “bubby-toothed elephant, as naturalist Thomas Jefferson would later put it.

How the American mastodon got its scientific name is a little more complicated. Scottish researcher Robert Kerr called the animal Elephas americanus in 1792, but, after Cuvier showed that the animal was distinct from all living elephants, German anatomist Johan Blumenbach replaced the genus name with Mammut in 1799. And even the common name can still cause a little confusion in the way it’s applied. By itself “mastodon” isn’t just the name for the American Ice Age species, but an entire group of breast-toothed elephants going back over 28 million years. The American mastodon just happened to be the last member of the group and the first that our species rediscovered as a fossil.

But the initial mammoth-mastodon division Cuvier zeroed-in on as a young scientist still holds true. You can immediately pick out a mastodon by its teeth. The next time you visit the bones of ancient proboscideans, look carefully at their massive molars. If the grinders remind you of toothy teats, you’re looking at the great American mastodon.

References:

Cuvier, G. 1806. Sur le grand mastodonte. Annales du Muséum d’Histoire Naturelle. 8: 270-312

Rudwick, M. 1997. Georges Cuvier, Fossil Bones, and Geological Catastrophes. Chicago: University of Chicago Press. pp. 18-24

Semonin, P. 2000. American Monster. New York: New York University Press. pp. 354-356