Ameghino's "Elephants"

I do not remember much from my elementary school education, but there are a few fragments that have stuck with me. One day in 6th grade geography, for example, Mr. McCutcheon asked the class what we thought the continents of South America and Africa looked like. Africa was easy, it looked like the head of an African elephant (northwestern Africa being the right ear and Madagascar the tip of the trunk), but there was a greater diversity of opinion about South America. The consensus was that South America either looked like a turkey leg or an ice cream cone (it was close to lunchtime, if I recall correctly), but I could not help but think that it looked a little bit like an elephant, too.

That Africa looked like an elephant's head at least made sense. That was where elephants lived, after all, but there were no elephants in South America outside of zoos.* Perhaps it was better to think of South America as being turkey leg-shaped since (as far as I knew then) elephants had nothing to do with the continent, but there was at least one naturalist who thought that South America was of extreme importance to the origin of elephants.

*[The existence of Asian elephants and the dispersal of extinct elephants during prehistory obviously negate any grade-school "rule" that elephants only live in Africa.]

By the beginning of the 20th century Africa had been positively identified as the center of elephant origins. Excavations in the Fayum region of Egypt, in particular, had turned up early proboscideans like Moeritherium and Palaeomastodon that appeared to represent the earliest elephant evolutionary stages. The Argentine naturalist Florentino Ameghino, however, disagreed.

Florentino is a paradoxical figure in paleontology. Where his brother, Carlos, was a tireless field worker, Florentino was more of a theorist who spent much of his time interpreting the fossils his brother found. Together they helped to establish the science of paleontology in South America, yet other naturalists were often left aghast by the hypotheses Florentino proposed.

Florentino's most controversial work often had a nationalistic bent. Ever since evolution became fully integrated into paleontology after 1859 many scientists wanted to trace the origins of living animals, especially humans. Identifying early transitional forms and the places of origin for major groups was thus an important task in understanding the history of life, and Florentino favored South America as a highly productive evolutionary cradle. Florentino traced every group of mammals back to South America, including elephants.

Florentino's hypothesis was primarily based upon fossils of strange mammals called astrapotheres and pyrotheres he had described in the late 19th century. Some members of both groups had trunks and enlarged canine tusks, and the genus Pyrotherium had enlarged procumbent incisor teeth that recalled the tusks of early proboscideans. Indeed, it was Pyrotherium in particular that seemed to be a good candidate for a South American elephant ancestor, at least as far as Florentino was concerned. While other naturalists were unsure of this hypothesis, the fragmentary fossils of Barytherium from the Fayum seemed similar enough to those of Pyrotherium that an evolutionary connection between them was at least plausible.

Yet Ameghino went a step further than his peers and suggested that the fossils from the Fayum really represented early "side branches" of proboscidean evolution that did not give rise to later elephants. Instead the wider diversity of later elephants had sprung from Pyrotherium, and Pyrotherium itself had evolved from earlier ancestors that Florentino thought could be traced all the way back into dinosaur-dominated Jurassic. Other naturalists were skeptical of this radical interpretation of the fossil record. In a 1903 communication to the Royal Society of London C.W. Andrews, the discoverer of many of the Fayum fossils, stated that even though it was "possible that some of the forms described by Ameghino are actually Proboscideans" Florentino's hypotheses about elephant evolution were hardly worth considering in detail;

Ameghino further considers that Moeritherium and Barytherium form side branches and are not on the main line of descent of the later elephants. The whole question of these South American forms [Pyrotherium, &c.] is at present so obscure that, for the purposes of the present paper, they may be ignored and attention directed to the Old-World genera only.

A review in a 1907 issue of Nature was not as restrained. Written by R.L. (Richard Swann Lull? Richard Lydekker?), the editorial opens with a devastating rhetorical salvo;

If eccentric originality stand for genius, and refusal to follow the beaten track, even when compass-bearings indicate that it is the right one, be deemed merit, then, unquestionably, the author of the work before us ["The Extinct Vertebrate Fauna of Patagonia" by Florentino Ameghino] is entitled to stand in the first rank of scientific men. If, on the other hand--but perhaps it will be better to leave our readers to complete this sentence as their own judgment dictates after the perusal of the following remarks and criticisms.

The body of the review was a roll-call of Florentino's scientific sins. R.L. was dumbfounded that Florentino proposed South America as the birthplace of all mammals, derived humans from marsupial ancestors, pushed Miocene mammals back into the Cretaceous, &c., &c. There were simply too many mistakes to correct, and the author of the review could only assure readers that Florentino's views were "not endorsed by even a respectable minority of expert opinion elsewhere."

Yet this was but the eye of the storm. After reiterating Florentino's incompetence the reviewer picked up where he had left off, this time considering the evolutionary trees Florentino had constructed. Florentino's scheme for the origin of elephants is singled out for special criticism;

Again, if there is one apparently well-established fact in palaeontology it is that the Egyptian Moeritherium is on the direct ancestral line of the modern Proboscidea. In this, according to our author, palaeontologists are, however, altogether wrong, and instead of Africa having been the birthplace of the elephants, we are to look for this in South America, whence, by some unexplained magic, various (shall we say imaginary?) genera with almost unpronounceable names blossomed on the one hand into Palaeomastodon and the elephants, and on the other into the forlorn and childless Moeritherium.

Florentino had worked hard to describe so many fossil mammals, but R.L. could not understand how his Argentine peer could have so hopelessly bungled their interpretation. Even if there was some disagreement about the ancestral status of Moeritherium, further studies of Pyrotherium, particularly those published by Albert Gaudry around the time of his death in 1908, supported the suspicion that the Florentino's early "elephant" was not really a proboscidean at all. Even so, Pyrotherium was so unlike other mammals and shared so many convergent features with early proboscideans that some authors continued to closely associate the two. In the 1914 monograph The Deseado Formation of Patagonia, for instance, Frederic Loomis suggested that the Pyrotheria be grouped within the Proboscidea. Other authorities disagreed, though, and even if they were not sure what Pyrotherium was Gaudry had left them fairly confident that it was irrelevant to the early evolution of elephants.

Florentino died a few years later, in 1911, and he left behind a mixed legacy. Florentino, along with his brother Carlos, did much to develop paleontology in South America, and together they brought many strange new fossils to the attention of their peers. Florentino's evolutionary and biogeographic hypotheses have not fared nearly as well, though, and South America was not the generative center of all mammal groups like he thought it was.

As for Florentino's early South American "proboscideans", they turned out to belong to unique groups of mammals that remain controversial to this day. The relationship of Moeritherium to later proboscideans is also still being debated, but the weight of the evidence points to Africa as the place in which the first proboscideans evolved. Still, I would be remiss if I did not acknowledge that extinct relatives of modern elephants inhabited in South America in the past. Around two million years ago at least two genera of gomphotheres walked into South America from the north, and they persisted there until a little less than 11,000 years ago.