15 March 2015

Frederic Loomis Discovers Everything, Episode 1: Raiders of the Lost Continent

Around three million years ago, South America became connected to North America via the Isthmus of Panama, and an event called the Great American Biotic Interchange took place, where wildlife from South America moved north and vice versa. Prior to this, South America had been isolated from most of the rest of the world since the Cretaceous Period, and connected only to Antarctica until they separated about 30 million years ago, allowing little exchange of wildlife from other places in world. As such, South America was a 'lost continent,' a strange land cut off almost completely from the rest of the world, with its own array of unique organisms, the characters in their own isolated evolutionary story. It was into this strange world that the North American emigrants came some three million years ago, and it was into the fossil echoes of this world that a very different group of North Americans came in the early 20th century.

Some Patagonian fossils from the Cenozoic Era. They include notoungulates (top row
and left middle row) such as the sheep-sized digger 
Mesotherium (top centre), superficially
elephantine astrapotheres (lower jaw of
Parastrapotherium, middle right), and the extant
xenarthrans (bottom row), including the flattened armour of an armadillo.
[photograph by the author]

Frederic Brewster Loomis (1873-1937) received his undergraduate degree in Amherst College's Class of 1896. After going off for graduate school in Munich, he returned to Amherst College, where he remained for the rest of his life. In 1908, he became Amherst's professor of comparative anatomy, and in 1917, he became a professor of geology. Since he was a schoolboy, Loomis exhibited a strong interest in fossils and spent most of his career acting as a vertebrate palaeontologist. Over his career, as you may have guessed from this article's title, he recovered a colossal number of fossils over the course of numerous expeditions that remain in the Beneski Museum's collections. It was during his days as a comparative anatomy professor, in 1911, that he made one such expedition to South America to search for fossils in Patagonia.

The world of prehistoric South America was certainly a strange one. Since the animals that lived there were unique, they had to fill niches occupied elsewhere by other groups. Through convergent evolution (the evolution of similar appearances and habits between organisms of different evolutionary backgrounds due to living in similar environments), strange groups of animals with no living relatives filled ecological roles such as antelope-like grazers, cat-like ambush predators, and large, powerful browsers.

Exemplifying the 'large, powerful herbivores' category of animals and representing the jewel of the 1911 expedition's collections was a creature called Pyrotherium. When Loomis and his team travelled to Patagonia, this animal was only known from fossil teeth clearly belonging to a large herbivorous animal, variously thought to be allied to the diprotodontid marsupials of Australia, the native South American toxodonts (part of South America's large radiation of unique extinct 'ungulates'), and the elephant group Proboscidea. The Amherst expedition, however, turned up the first-ever complete Pyrotherium skull.

The complete skull of Pyrotherium sorondoi, collected on the
Amherst College expedition to Patagonia in 1911.
[photograph by the author]

Pyrotherium was like no creature alive today. Its skull was huge, about 95 centimetres (37.4 inches) long, and equipped with impressive teeth. The six protrusive front teeth would have been used for cropping food, while the large molars were so wide they nearly covered the whole roof of the mouth in a powerful chewing pavement. The body would have been bulky and short-limbed, like a hippo or rhino; in fact, Loomis rather unflatteringly describes it in his book Hunting Extinct Animals In the Patagonian Pampas as having 'such a form as the rhinoceros except that it would have been considerably more clumsy.' Loomis also noted in his book that this animal, contrary to the ideas of his contemporaries, did not coexist with the non-avian dinosaurs; Loomis was correct, as Pyrotherium can now be dated to the Early Oligocene, around 30 million years ago. The discovery of a complete skull also revealed that it possessed the adaptations that correspond with having a trunk in life, though a short and broad one, more akin to the trunk of a tapir than of an elephant.

As to its identity, Pyrotherium does not appear to be member of any of the groups it was imagined to belong to in the early 20th century. Despite its trunk, it is no elephant, and it's certainly not a marsupial. While related to the toxodonts more closely than either elephants or diprotodonts, they are not close allies. Instead, it is a member of its own group of animals, Pyrotheria, that does not seem to be much like the other bizarre South American ungulates. Through convergent evolution, these animals diverged from their relatives to take on an appearance and ecological role similar to that of giant herbivores like elephants, rhinos, and hippos on the lost continent of South America.

A Pyrotherium wallowing in the mud. It has a short trunk like
 a tapir and a bulky, short-legged body like a rhino.
[illustration by the author]

-- M


Loomis, Frederic B. Hunting Extinct Animals In the Patagonian Pampas. New York: Dodd, Mead and Company, 1913. Print.

Loomis, Frederic B. The Deseado Formation of Patagonia. The Trustees of Amherst College, 1914. Print.

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