A progressive “march” of elephant evolution as portrayed in Ingersoll’s The Life of Animals. From left to right Moeritherium, Palaeomastodon, Gomphotherium (“Trilophodon“), Mammut americanum (American mastodon), Elephas maximus (Asian elephant).
Every now and then I like to browse through old popular-audience books about evolution. Given that I am writing such a popular book myself I enjoy looking back to see how other authors have approached the same task. In some cases I have come away quite impressed, but other times it seems that some authors of old used such platforms to give their personal flights of fancy a more authoritative gloss.
An example that falls into the latter category can be found in Robert Knipe’s 1912 book Evolution in the Past. The book is organized by time period, and in the Eocene section Knipe stops to consider the strange, semi–aquatic proboscidean Moeritherium. At the time of its discovery the stout-bodied Moeritherium was considered by many naturalists to represent, if not actually embody, the earliest phase of elephant evolution. It just barely fit into the proboscidea (though much earlier proboscideans have since been found), but with so many later fossil proboscideans known it easily slid into place at the base of the elephant family tree.
A herd of Moeritherium as envisioned in Knipe’s Evolution in the Past.
Yet Knipe’s view of Moeritherium was obviously colored by his understanding of modern elephants. He considered Moeritherium to be “elephants in the making” , and as such he thought that these proboscideans from the Fayum were already on the road to the increased brain size seen in modern elephants. Furthermore, he thought that Moeritherium traveled in herds and included a restoration of such a pachyderm party in his book.
I do not know of any evidence, like a Moeritherium mass death assemblage or trackway, that would throw support to Knipe’s hypothesis. (If I am wrong, though, I would love to be corrected!) To the contrary, most Moeritherium restorations I have seen have depicted the creature as a solitary, hippo-like animal. Just how social Moeritherium was in life is difficult to say (depicting it as entirely solitary is also a hypothesis, not a fact), but there does not appear to be any reason to think that it traveled in large herds. It seems more likely that Knipe knew the modern “end point” of elephant evolution and wanted to imbue the earliest-known proboscidean with the glimmerings of traits seen in living elephants.