We all know about woolly mammoths and saber-toothed cats, but such is evolution that all species have some pretty weird ancestors. Often they look nothing alike. From the least unexpected to the most, here are 10 of the weirdest of all.
10. The short-necked giraffe
The giraffe’s prehistoric forebear was roughly the size of a bull moose, complete with similarly large antlers. Sivatherium (along with Bramatherium and others) had a long neck to graze on treetops in Eurasia millions of years ago, but only about half as long as the present-day giraffe’s. Nevertheless, it’s thought to have been the largest ruminant (hoofed grazing animal) that has ever existed.
Interestingly, although the fossil evidence dates it to millions of years ago, it may have survived to much later. Not only do cave paintings depict the animal but a copper rein ring found by archeologists excavating the ancient Mesopotamian city of Kish also appears to feature a detailed image of Sivatherium.
9. The vested ant
Ants may be the most successful animal on Earth, comprising up to a quarter of the biomass in tropical regions and a fifth of the biomass in general. The ant family Formicidae has proliferated into more than 9,500 species known to science and an estimated 3,000-9,000 species yet to be described. They’ve also existed for millions of years, and continue to live in harmonious symbiosis with their planet.
However, little is known about how they originated. The earliest fossil evidence is from the mid-Cretaceous just 100 million years ago, when their planetary dominion was still in its fledgling stages. And there are few clues as to what came before. Instead, our best theories come from comparing ants to species living today. Their hive-like colonies, for example, bear similarities to those of wasps and bees — especially given that all generally center on a single mother, the queen.
But there’s one species of wasp to which researchers think the ant is most closely related: the mud dauber. Female mud daubers are known to house their eggs in carefully built mud cylinders. Then they find a victim, paralyze it, and seal it inside the nest with their eggs so that when they hatch the larvae have something to feed on. It’s thought the original proto-ants started out the same way, “building simple nests and delivering food to their offspring.” Then when the offspring grew up, it may have helped the mother raise more.
8. The four-legged fish
It might not be such a stretch to imagine that frogs evolved from fishes, but the intermediate creatures did look bizarre. Icthyostega was one of the first, living as long as 364 million years ago. It was, in many ways, a fish. It had scales, vestigial gill bones, and a dorsal fin along the length of its tail. But Icthyostega, which grew to three feet, also had four fleshy limbs, each with digits, as well as strong ribs for dwelling on land. Unlike fish, it also had lungs.
Obviously this traits emerged slowly. Most of them developed while Icthyostega’s forebears were still living fully aquatic lives. The limbs, for example, gradually evolved from ‘lobe-fins’, which looked like and served as fleshy paddles. The lungs also probably evolved underwater.
7. “Adam and Eve” the worm
Despite our differences, what all animals (except sponges and jellyfish) have in common is a bilaterally symmetrical body (mirrored left and right), along with a front side with a mouth and a back side with an anus. We are the ‘bilaterians’. And scientists think the earliest ancestor of us all was “a sluggish blob about the size of a grain of rice” called Ikaria wariootia.
Discovered in the Australian outback from fossilized burrowing traces, it’s dated to the Edicaran Period (560-551 million years ago). It differs from other possible candidates, such as Dickinsonia, by its possession of a mouth and gut.
This, then, is the ancestor of all other creatures on this list, as well as the creatures reading it.
6. The horned horse
The prehistoric Brontotheres had a special place in Sioux mythology. Known from its fossilized bones, it was called the Thunder Horse and was said to come down in storms and trample on the buffalo. True or not, the Brontotheres was indeed a fierce beast — the largest mammals in the whole of North America during the Eocene.
One species, for example, the 8-foot tall, 15-foot long Megacerops, had a pair of long horns which it probably used for headbutting. Emblotherium, meanwhile, had just one horn — long like a battering ram — containing its nasal bones. It’s thought it may have been used to make loud vocalizations across long distances.
All Brontotheres were extinct by the end of the Eocene, but their relatives today include rhinos, tapirs, and… horses! In fact, aside from the horns and their common depiction as rhino-like, they may have looked quite similar to horses — at least in the head, on account of their elongated skulls.
5. The meat-eating ground sloth
The so-called “great beast from America,” Megatherium americanum, looked similar to the sloths of today — except ten times the size. Weighing roughly the same as a bull elephant, it stood up to 12 feet tall on its hind legs. Needless to say, it lived on the ground and not in the trees.
Unlike present-day sloths, ground sloths ate meat in addition to plants to support this great size. But they probably scavenged from kills made by big cats, wolves, and so on, rather than hunting for themselves.
They were still roaming the pampas of Argentina and elsewhere in South America as late as the Holocene 8,000 years ago, living with early humans. In fact, humans are thought to have hunted ground sloths to extinction. Although some think they survive to this day.
4. The towering hornless rhino
You may have heard of the woolly rhinoceros, which went extinct around 12,000 years ago. They were a common subject of cave paintings. As the name suggests, they all had woolly coats. And, curiously, one species of woolly rhino had two horns instead of one.
But they were nothing compared to the mighty Paraceratherium. Over 26 feet long, the rhino’s ancestor from 35-20 million years ago was tall with a long, brontosaurus-like neck. It weighed as much as five adult elephants (15-30 tons). And, weirdest of all perhaps, for the rhino’s distant forebear, it had no horns at all.
It’s thought that elephants (not humans for a change) destroyed Paraceratherium’s habitat by stripping and felling trees, driving the giant to extinction. But there’s still much we don’t know about this dino-like mammal. For example, we still haven’t even pieced together a full Paraceratherium skeleton.
3. The giant beaver
Imagine a beaver taller than a human, weighing 200 pounds with six-inch incisors, and you’ve imagined the genus Castoroides. This shaggy-haired giant beavered away in North American woodlands from 3 million to 10,000 years ago, when it’s thought to have been hunted to extinction by humans. It’s likely that both their meat and their fur was in demand.
Like the present-day beaver, Castoroides had large gnawing teeth and lived on plants. It was also partially aquatic, probably because it was an easy mark on land for predators like the saber-toothed tiger.
As to whether it built giant dams, though, it’s not entirely clear. No evidence remains except, possibly, a four-foot high one in Ohio.
2. The ferocious pangolin
The dominant carnivorous mammals 55-35 million years ago were the Creodonts, relatives of the present-day pangolin. What makes this all the more interesting for such a timid-seeming creature is that Creodonta means “meat teeth,” and the pangolin doesn’t have any. Instead, they gather up insects with their tongues, earning the nickname “scaly anteater” despite not being related at all.
So what were the phylogenetic ancestors of the pangolin like? Of the roughly 30 species, perhaps the most impressive are the Hyaenodontids. Named for their hyena-like teeth adapted for shearing flesh as opposed to clamping down, these species hunted in packs like wolves — usually at night. Some of the larger Hyaenodontids, like the 4.5-foot tall, 10-foot long, 1100-pound Hyaenodon gigas, may have hunted alone in the day.
1. The land-based whale
How do mammals end up in the sea? Whales, dolphins, seals, walruses, and so on all descend from species that once roamed the land. The pinnipeds, for example (seals, walruses, and sea lions), are thought to have evolved from primitive bears, just like their land-lubber cousins the weasels, otters, and skunks. The sirenians or sea cows, meanwhile, appear to be related to elephants, as well as that most unlikely of elephant relatives the hyrax.
The most iconic group of ocean-dwelling mammals, however, the cetaceans (whales, dolphins, porpoises, narhwals), descend from something unrecognizable — a creature that “ran like a wolf … waded like a hippopotamus … put its ear to the ground to hear distant rumbles … [and] had the ankles of a cow.” Pakicetus had the body of a land mammal but the distinctive long skull of a whale. Preying on animals both on land and in water, it lived around the edges of the shallow Tethys Sea 50 million years ago.