My first introduction to gomphotheres was a research critique of a seminal Quaternary paper by Janzen in ‘Science’ journal. Something about these peculiar and ungainly looking distant cousins of today’s noble elephant fascinated me! Everyone has of course heard of woolly mammoths, but gomphotheres are perhaps less well known by the public, and more of a connoisseurs Pleistocene creature by their very strangeness, and I think their very endearing faces!
Gomphotheridiiae were members of the Proboscidea order, which also includes the more swish woolly mammoth (Mammuthus primigenius) and the mastodon (Mammut americanum). Where the mammoth became the byword for something colossal, the Gomphotheriidae became a little forgotten. Not anymore.
Imagine a smallish elephant with a shorter snout and four tusks – two at the top and two at the bottom. Then imagine that the tusks at the bottom pan out to create a shovel which could sweep food up in a flash. Nature being nature, gomphotheres evolved: one group had short lower jaw of todays elephant, and the other kept the long shovel jaw we associate with the entire family. The structure of their blunt shovel or wedge shaped lower tusks meant they were the ultimate fruit eating opportunists, and their success as a group spans millions of years, from the Miocene to the very age of humans.
These amazing prototype tuskers evolved first on the savannahs of Miocene Africa, some 22 million years ago. Nelly the sort-of-elephant packed her trunk and said goodbye to that continent. In an occurrence which is now known by palaeo sorts as the ‘Proboscidean Datum Event’ early gomphotheres headed for Asia and Europe where they spread even further, making this group one of the most cosmopolitan of Pleistocene creatures. Specimens found as far as China and the Americas showing that these animals lolloped all over the planet.
Land bridges were a key factor in these wonderful animals’ migrations. Looking for new lands brimming with juicy fruits and tasty seeds, they made their way eventually into North America via Beringia, the ‘bridge’ which once existed between Alaska and Siberia connecting the two land masses allowing animals to move freely.
North and South America had been separate land masses until the formation of the Isthmus of Panama during the late Pliocene, around 3 million years ago. This corridor allowed the exchange of plants and animals between what were previously isolated continents, resulting in many species making their way to the warmer climates of South America. This period is known as the Great American Biotic Interchange (GABI) and it is during this time that two genera of Gomphotheriidae, Cuvieronius and Stegomastodon crossed from North to South America looking for new and tasty vegetation.
The South American genera of Stegomastodon and Cuvieronius evolved to have different feeding patterns; Stegomastodon adapted to a warmer savannah-like ecosystem along the Atlantic coastline of South America, while Cuvieronius was more suited to the cooler temperatures of the Andes corridor. They do appear to have been fussy eaters (maybe why I like them!), as they only liked certain fruits, with which they developed a symbiotic relationship: gomphotheres liked to wander, and they spread the pollen and seeds of their favourite fruits wherever they went via their skin and poo!
So how did such a spectacular and successful herbivore become extinct? The answer may lie in a combination of factors. Their heyday came as the Ice Age was marching slowly but steadily into the pages of history and palaeoecology. Gomphotheres were specialists, and specialists are the animals that are hit worst when the environment around them changes. When climate change decreased the diversity of plant taxa, the gomphothere was faced with imminent extinction because of their dietary preference, shown by studies of the isotope δC13 taken from teeth and tusks found in South America. As the gomphothere declined in South America, dependent vegetation could no longer disperse or germinate without the megafaunal dispersers creating – at least in some parts of South America – a rather sad mutual demise.
Nothing is ever that simple, of course. Some sites have shown that gomphotheres were hunted by early human settlers. It is possible the South American extinctions are a combination of environmental change and humans doing what they sadly do: overhunting. Recent excavations of El Fin del Mundo, Mexico have produced evidence of Clovis-era hunting of North American gomphotheres. The site has produced assemblages of bones belonging to juveniles, combined with finely worked chert and quartz spear-heads. Calibrated radiocarbon dating has suggested a date of 13,390 BP. These are the youngest gomphothere fossils so far discovered. What’s even more incredible, is there is direct evidence at this site of humans, the Clovis hunters, were hunting these magnificent animals.
As to the rest of the world? We really don’t know what was happening at the end of the Pleistocene in places like China, but it’s likely that climate change and humans affected the habitat of these unique critters. They are one of the many incredible Twilight Beasts our ancestors most likely saw with their own eyes lolloping across the plains. Our own Pleistoicene Beastmaster here, Jan, has a thing for the Auel books, and it’s a bit sad that the gomphothere was not mentioned in those books! So, spread a little gomphothere love for these amazing Twilight Beasts; seek them out in your local museum, and think how wonderful they must have been in the flesh!
Written by Rena Maguire (@justrena)
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