Saturday, February 21, 2009

Mastodon nightmares

Brian Switek has a couple of good posts up on things relating to mastodons. The first is about one of the many nineteenth century frauds committed in order to to prove either that Native Americans still retained some memory of ancient mammoths and mastodons or that the two proboscideans had still roamed the land until very recently. Both ideas still have adherents, but these days they are less likely to use out and out fraud to make their cases.

Brian's second post is about various attempts to reconstruct the mastodon into something more exotic than just another variety of elephant. Most of his post is about the idea that mastodons could use their front limbs to feed themselves. Picture a mastodon sitting on its butt like a panda, using its front "paws" to tear apart pine trees and shove them into its mouth. The trunk would be kind of pointless in that scenario, but that didn't bother nineteenth century naturalists.

The earlier of these misconception was that the mastodon had been a carnivore. This idea wasn't completely ridiculous according to the state of knowledge in the eighteenth century. Comparative anatomy was still a relatively new discipline and detailed information about non-European animals was scarce. Their evidence for the carnivorous mastodon lay in its teeth. Living elephants and mammoths have giant molars made up of hard enamel plates held together with softer cement. Botanists call the teeth "grinders" for reasons that are obvious when you look at them.

Mammoth grinder. The surface of the tooth has many parallel ridges like an old fashioned washboard. This allows the mammoth to pulp hard to digest grass cellulose. Modern elephants eat many other types of plants besides grasses, but with this type of grinder, they can live on just grass if they need to.

Mastodons have pointed molars. At the time, naturalists believed only carnivores had pointed teeth. Georges Cuvier thought the points looked like breasts and coined the name "mastodon" (or mastodont) for the animal using the Greek words "mastos" (breast) and "odont" (tooth). Thomas Jefferson endorsed the new name, but had a slightly more earthy take on it:
I have no doubt that the marked differences between the elephant & our colossal animal entitle him to a distinct appellation. One of these differences & a striking one, is in the protuberances on the grinding surface of the teeth, somewhat in the shape of the mamma, mastos, or breast of a woman, which has induced Cuvier to call it the Mastodonte, or bubby-toothed.

Mastodon molar. The points make it easier them to tear apart tree branches, which probably made up the majority of their diet.

The idea that the mastodon was carnivorous came from the brother of William Hunter. In a paper read before the Royal Society in 1767, Hunter explained that he heard of a shipment of bones arriving from the Ohio valley that appeared to be of some kind of elephant. He asked the curators at the Tower if he might examine them and they sent him a tusk and a molar.

Let's pause for a moment and think about that. Imagine reading about the fossil of a new type of glyptodont arriving at the Smithsonian. You're curious, so you call them up and ask if you can look at it. They say, "of course you can" and send the glyptodont's skull and one leg to your house so you can examine them at your leisure.

Back to Hunter. The good doctor and his brother looked over the tusk and agreed that is came from an elephant. When they got to the molar, Hunter's brother "being particularly conversant with comparative anatomy, at the first sight told [Hunter] that the grinder certainly was not an elephant's. From the form of the knobs on the body of the grinder, and from the disposition of the enamel, which makes a crust only on the outside of the tooth, as in a human grinder, he was convinced that the animal was either carnivorous or of a mixed kind."

The Americans enthusiastically adopted the idea of the killer mastodon. Almost every Indian legend about giants or monsters was called forth as proof that the beasts had once prowled the same land where rustic frontiersmen were setting down roots. In his Notes on Virginia Thomas Jefferson, citing those legends, argued that the monster must still exist in the far north or west of the continent. The only reason for its current absence in the East, he went on, was that the Indians had exterminated its food supply when they were given guns and incorporated into the fur trade.

The image of a carnivorous elephant lurking in the forests of America inspired some wonderfully purple prose. George Turner, who along with Jefferson and Franklin, was a prominent member of the American Philosophical Society, wrote:
Now, may we riot infer from these facts that nature had allotted to the mammoth the beasts of the forest for his food? How can we otherwise account for the numerous fractures which every where mark these strata of bones? May it not be inferred, too, that as the largest and swiftest quadrupeds were appointed for his food, he necessarily was endowed with great strength and activity? That as the immense volume of the creature would unfit him for coursing after his prey through thickets and woods, nature had furnished him with the power of taking it by a mighty leap? That this power of springing to a great distance was requisite to the more effectual concealment of his great bulk, while lying in wait for his prey? The Author of existence is wise and just in all his works; he never confers an appetite without the power to gratify it.

Turner pictured the mastodon as an ambush hunter similar to a great cat. However, if the mastodon took its prey "by a mighty leap" it would need sharp molars. After being jumped on by a pouncing mastodon, the prey would have had the consistency of runny pate and the mastodon could have slurped it up with a straw. As to his conclusion that the "Author of existence ... never confers an appetite without the power to gratify it," I refer you to this documentary of an animal with just that problem.

A few years after writing this, Turner was caught misappropriating the Society's funds for land speculation and ejected from the Society, thus depriving us of his further insights.

At about the same time a Turner's scientific career was coming to its abrupt end, Thomas Ashe, an Irish adventurer, arrived in America and traveled down the Ohio River. On his way down the river he took possession of a mastodon skeleton belonging to William Goforth. Goforth expected Ashe to find a buyer for the bones in New Orleans and send him the proceeds minus Ashe's commission. Instead, Ashe took the bones to England, exhibited them for a while, sold them, and absconded with the funds. Ashe's travels resulted in two books. The first took the form of a series of letters describing the new country, not always in flattering terms. A long section rather imaginatively describing him exploring a crypt beneath a Hopewell mound may be the source for parts of the Book of Mormon. In the second book, he gave his conclusions about the mastodon.
With the agility and ferocity of the tiger, with a body of unequalled magnitude and strength, this monster must have been the terror of the forest and of man. ... In fine, huge as the frowning precipice, cruel as the bloody panther, swift as the descending eagle, and terrible as the angel of night must have been this tremendous animal when clothed with flesh and animated with principles of life. ... From this rapid review of these majestic remains it must appear that the creature to whom they belonged was nearly sixty feet long and twenty-five feet high.

The enormous size that Ashe gave for the mastodon may have been a product of his own overactive imagination, but he wasn't alone in this exaggeration. It's a curious fact about elephants that they always seem to inspire over-estimation. Early travelers, on first seeing an elephant, regularly described them as eighteen or twenty feet tall (Asian elephants rarely surpass ten feet and Africans twelve). Medieval European illustrations of war elephants revealed a beast large enough to carry a multi-storied stone tower full of armored soldiers on its back. A broadsheet for PT Barnum's elephant Jumbo, shows the elephant with bleachers on his sides carrying dozens of happy circus goers. Other illustrations of the nineteenth century routinely showed grown men standing under the belly of an elephant.

When they finally discovered that there were herbivores with pointed molars, European naturalists began to give up on the killer mastodon and recognize that it was more like a mundane elephant than like a giant cheetah. Only a shrinking minority held on to the old vision. Hunter, whose study led to the idea of a pouncing, carnivorous mastodon, also gave us the last word on the topic:
[I]f this animal was indeed carnivorous, which I believe cannot be doubted, though we as philosophers regret it, as men we cannot but thank Heaven that its whole generation is probably extinct.

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