Megafauna are what they sound like: large animals. Elephants, hippopotami, rhinoceroses and giraffes are pretty much the only examples still alive. However, until the end of the Pleistocene epoch (from around two million to ten thousand years ago), megafauna abounded across the world, to a much greater extent than they do today, and they were prevalent in a variety of locales. Africa is the last bastion of megafauna today, along with parts of Asia, but in their heyday, they were found across the world, even (and especially) in the Americas.
There exist a few theories as to why these creatures are no longer with us for the most part. As described in The World Without Us (the book that spurred me into writing this post), they are:
1. Over-kill. Early humans destroyed the species as they hunted them for food and other materials.
2. Over-chill. Climatic variations destroyed them.
3. Over-ill. Disease wrought their destruction. Of course, these diseases could have been ones we brought with us.
The book makes a very good case for over-kill. However, I’m not writing to debate the reason for their demise. I was fascinated by this period of prehistory almost as much as I was by dinosaurs when I was younger, and I am simply going to point out a few outlandish species that captivated me when I was younger, and still do so today.
First, I should give you a little background in the geological classifications of prehistory, for a little context. Everyone knows the Jurassic, Triassic and Cretaceous periods, which comprise the Mesozoic era. This is when the dinosaurs lived; it ended around 65 million years ago. The Cenozoic era, which follows, is divided into the Paleogene, Neogene, and Quaternary periods (The Paleogene and Neogene used to be classified as the Tertiary period—in this context, the name “Quaternary” makes sense). These periods are further subdivided into epochs, which run: Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocene, the most recent epoch which began around ten thousand years ago. Tangentially, some geologists think that we should delineate a new epoch, the Anthropocene, to indicate that humans have become the dominant environmental force on the planet, coinciding with the invention of the steam engine in 1784. Anyway, these epochs have differences in climate, geology, and different predominant flora and fauna. After the extinction of dinosaurs, pterosaurs, and their marine and terrestrial brethren, mammals increased in number and size. However, after the end of the Paleocene, climatic variations forced evolution to favor smaller creatures. The largest land mammal ever lived during the Oligocene, and until the end of the Pleistocene the world brimmed with a huge variety of huge and strange creatures. And on to the creatures we proceed:
Saber-toothed cats
One of the most iconic prehistoric mammals, everyone usually calls these guys “saber-toothed tigers.” They aren’t tigers, though. Most of them are a distinct scions of felines, but there were some marsupials which, in a showcase of convergent evolution, developed similar saber-teeth and bodily characteristics
Smilodon fatalis, the most commonly known saber-tooth.
Smilodon is probably what everyone thinks of when they think of saber-toothed cats. It’s prototypical: somewhat more solidly built than modern big cats (they ambushed their prey), with the two iconic canine teeth. The species pictured to the right weighed around 160-200 kg; the largest, Smilodon populator, weighed around 200-300 kg (some may have weighed as much as 400!) Since saber-tooths’ teeth were fairly brittle, scientists think that, instead of strangling their prey by biting down on their trachea, like modern big cats, they used their teeth to pierce jugular veins, killing without the need for a prolonged struggle.
I mentioned above that some marsupials had similar characteristics. Thylacosmilus was one of them. Despite looking very similar to the saber-toothed cats, it was not a cat. Convergent evolution can lead to similar appearances between completely unrelated creatures; this is an excellent example of the phenomenon. Thylacosmilus’s Wikipedia page has some good images which show off its characteristic bone scabbards that jutted from its lower jaw, protecting the teeth when its mouth was closed (a characteristic that visually differentiates it from saber-toothed felines), and also a link to the convergent evolution article, if you’re interested to learn more about that.
Gomphotheres
Weird name, huh? Weirder creatures. Gomphotheres were a family of elephant-like animals common during the Miocene and Pliocene. Examples include the group’s namesake, Gomphotherium, and my personal favorite, Platybelodon. They were similar in bodily structure to elephants, but their faces were quite different. We think most species had trunks, but they also had four tusks, two on the bottom jaw and two on the upper. Gomphotherium’s lower jaw was elongated and its bottom tusks, while still thin and pointy, may have helped it shovel food into its mouth. Here’s a picture of one with a sexy lady (not to scale, unless she’s six or seven feet tall):
Sexy ladies were also common in the Miocene and Pliocene. If you search Google Images for Gomphotherium, you'll find a website which has more images of scantily clad women with prehistoric pachyderms
Platybelodon was odder. Its bottom tusks were literally shaped like shovels (it and similar creatures are colloquially known as shovel-tuskers). We think it lived in swampy areas and used its shovel-shaped jaws to trawl marshy goop for sustenance. It probably died because of climatic variations drying out the swamps it made its home. Without further ado:
Platybelodon: weird and awesome.
Terror birds (Phorusrhacidae)
Return of the dinosaurs! These dominant predators lived up to the standard set by their ancestors, the dromeosaurids, by being apex predators for millions of years. Imagine an ostrich. Now beef it up significantly. Give it a neck that can’t be snapped, powerful legs with claws that rend flesh, and replace its bill with an eagle’s beak three times the size of the ostrich’s. They range from a few feet tall to the largest, like Brontornis, which stood around nine feet.
Paraphysornis is a typical terror bird
There were other huge birds that were part of prehistory. Dromornithidae had longer necks and smaller heads than Phorusrhacidae, and we aren’t sure if they were predatory or herbivorous. Haast’s Eagle had a wingspan of eight to ten feet. The eagle’s prey, the Moa (think of a twelve foot ostrich/kiwi bird cross) was hunted to extinction by Māori tribesmen, and this drove the great raptor to extinction. But imagine: if these eagles could take down such a huge bird as a Moa, they surely would have not thought twice about attacking grown men, just half the size of their ordinary quarry.
I’m going to draw this post to a close now. I could go on for pages and pages. I’ve been opening tabs of the Wikipedia entries for animals I find interesting, with the intention of adding them to this post, but there are currently fourteen open that I haven’t even mentioned. But if you’re ever in need of a megafauna fix, here are some Wikipedia articles to get you started:
