Home-grown Shovel Tuskers?

Konobeladon

Elephants are unique and remarkable animals, looking quite unlike any other creature. They have no close living relatives among other mammals - you have to go back almost to the time of the dinosaurs to find any common ancestor with anything else. As a result, the elephant family is placed within its own order of mammals, a ranking equivalent to that given to such groups as "primates", "rodents", or "bats". With just one family, and only three living species, it isn't quite the smallest mammalian order, but it's very close.

This changes significantly if we choose to include the known extinct species. There are a great many of these, which tend to be large, heavily built creatures with elongated tusks, and, in most cases, features on their skulls that suggest they had a trunk. Indeed, this latter is the source of the official name of the order, the proboscideans. While only the elephant family survives today, at least six others are recognised to have existed in the past, and if we could see members of most of them today they'd be instantly recognisable as, if not actually elephants, at least "elephant-like".

Miocene (Pt 24): Of True Elephants and Three-toed Horses

Stegotetrabelodon

The first horses entered Africa towards the end of the Middle Miocene, about 10 million years ago. These have commonly been assigned to the same genera, Hipparion and Hippotherium, as were found in Eurasia at the time, although the fine details of the exact relationships are unclear. Although the latter in particular seems to have been reasonably successful on the continent, a more significant immigration from an African perspective took place later on, around 8 million years ago as the drier climate heralded the start of the Late Miocene.

Miocene (Pt 20): Unicorn-Pigs and the First Hippos

Prodeinotherium

Pigs seem to have been another example of animals crossing over from Asia when that continent collided with Africa around 17 million years ago. The oldest fossil pigs in Africa date from about that time and are represented by Kenyasus from Kenya and Nguruwe from Namibia and South Africa. These were relatively small, short-snouted pigs with a primitive appearance similar to that seen in their presumed Asian ancestors.

Because of these primitive features, determining exactly where they fit in the pig family tree isn't a simple matter, but they are often placed with a group called the kubanochoerines. Assuming this is correct (and it's far from settled) they must have evolved fairly rapidly into much larger and more distinctive animals. The best-known member of the group is the giant "unicorn-pig" Kubanochoerus, which lived in China during the Late Miocene. This was an exceptionally large, long-legged animal, perhaps standing 120 cm (4 feet) high at the shoulder and - even more dramatically - sporting a long pointed horn that projected from the centre of its forehead.

Miocene (Pt 7): Hornless Rhinos, Long-Tusked Elephants, and Three-toed Horses

Anancus arvernensis

As the climate cooled around 11 million years ago, the forests of Europe began to thin out once more, something that favoured fast-running animals such as horses. Until this time, the only kind of horse in Europe, however, was the small, three-toed, Anchitherium, which was likely adapted to dense woodland and not so suited to the new climate. Its own ancestors had reached the continent from the east, having crossed over during one of the periodic rises of the Bering Land Bridge, but now, not coincidentally, given the colder climate, the Land Bridge rose again, and a second kind of horse followed it out of the Americas.

Miocene (Pt 3): The Elephants Reach Europe

Gomphotherium angustidens

At the dawn of the Miocene, Europe was still relatively isolated from much of the rest of the world. The only other continent to which is was attached by land was Asia, and even with that, perhaps due to the higher sea levels and narrower land bridges of the day, there was less exchange of animals than one might expect. As a result, for a few million years at the dawn of the epoch, Europe remained a haven for animals that had died out elsewhere, or at least retreated. Tapirs, for example, were still common; today they are restricted to South East Asia and the Americas. The European rhinos of the day were also relatively small and primitive.

While the millions of years that they survived might actually have been quite notable, had we been talking about the much shorter, later epochs, in the grand sweep of the Miocene, we can say that they were quite rapidly replaced by immigrants from the east. The early tapirs were gone (although more modern forms did return for a while, much later), but the rhinos were instead replaced by larger and more sturdy, distinctly Miocene species.

Pliocene (Pt 8): Long-Tusked Elephants and Giant Camels

Cuvieronius

America today is not a place you associate with herds of wild elephants. Go back just a few tens of thousands of years, though, and it would have been quite a different story. The "elephants" of the time were, of course, mammoths, and they were accompanied by mastodons, animals that were not actually members of the elephant family, but which, from a modern perspective, have a pretty strong resemblance to them.

Mammoths first entered North America during the early Pleistocene, not long before the Ice Ages proper got going. They were, in their origin, Asian animals, but the mastodons were a different matter. Mastodons were already in North America when the mammoths arrived, and they had been there for a very long time indeed. For millions of years, America really was a place with herds of well... things that looked a lot like elephants, at any rate.

The creature that the American mammoths would have encountered was the American mastodon (Mammut americanum), an animal that first appeared close to the end of the Pliocene. But this was the last survivor of a much longer lineage, and there had been many more kinds of American proboscidean that lived before it, often alongside one another. In fact, only a minority of them were really mastodons, including the immediate predecessors of the American mastodon, such as Mammut raki, and the somewhat older Zygolophodon. The latter also lived in the Old World, and was likely the first mastodon to reach North America, shortly before the dawn of the Pliocene. Nonetheless, one of the best skulls we have of the animal was unearthed in California, and later mastodons of the continent are likely descended from something much like them.

Pliocene (Pt 4): Before the Mammoths

Anancus arvernensis

One of the markers for the end of the Pliocene is the "Mammoth-Horse Event" when the slide into autumnal temperatures that had defined the later part of the epoch reached the point that significant quantities of ice began to build up in the Northern Hemisphere - notably in Greenland, where it still remains today. In Europe, this cooler weather brought an end to many of the more northerly forests, replacing them with open tundra-like grassland. Many aspects of the local fauna didn't change all that much, although they likely edged a bit further south.

But the arrival of the grasslands did herald the appearance of single-toed horses, and of mammoths - albeit not the woolly ones that most people immediately think of. Mammoths are perhaps the poster-child for the Ice Ages, but Europe was, of course, not devoid of such large animals before their coming.