Last week, I promised you that I would find an animal that was tiny prehistorically and yet is large today, because that seems to be the exception and I thought that it would be interesting to discover an animal that doesn’t fit the norm. I anticipated that this would be difficult to find, and I was not wrong.
My tactic was to think of large modern-day animals and search “small prehistoric X”. It sounds like a good plan, right? “Small prehistoric whales” leads me to “gigantic prehistoric whale” articles. This is not exactly what I was looking for, because it was in fact the opposite of what I was looking for. The search for “small prehistoric giraffes” brought up no small prehistoric giraffes. “Small prehistoric elephants” brought up articles about the dwarf elephants. I expected this but they aren’t exactly what I’m looking for. The history of the dwarf elephants is one of an isolated species shrinking in order to require less food on an island environment. These elephants were in Sicily, and it’s the same thing that happened to lemurs on Madagascar.
And the search kept going on and on. Small ostriches, no results. Small sharks, no results. Small kangaroos brought up results about giant kangaroos and this article with the eye-catching headline “Kangaroos With Fangs” from, of all places, the International Business Times. In case you’d like to know, these kangaroos lived about 15-10 million years ago in rainforests in Australia where they used their short fangs (saber teeth like the saber-toothed tiger but smaller) to probably attract mates. Scientists think that they were still herbivores. They went extinct at the end of the last Ice Age, like many other animals.
All of this is interesting but does not get us closer to finding an animal which was small millions of years ago and is large today, and isn’t an ancestor to too many other species, like the earliest mammals. A complete non-success.
So why was that? How come so many prehistoric animals were gigantic, easily earning the name megafauna (mega meaning big and fauna meaning animal)? Partly, it could be due to their wide ranges and an abundance of resources. During Ice Ages, the ocean levels lower, meaning that more dry land is exposed. So the animals of millions of years ago had more room to move around and more plants to eat. Some scientists also think that there was a higher concentration of oxygen in the air which allowed for larger animals. Megafauna might not be able to survive in our atmosphere because of all the carbon dioxide in the air, but there was a lot of oxygen in the air millions and millions of years ago because of all the plants and the absence of us humans polluting.
Another theory could be that, because of those other factors, size was a factor in reproduction and so the largest animals’ genes were passed along, meaning that over time they grew to be massive. Many theories but very few absolute answers.
Do you have any theories? Or do you know of an animal that I didn’t come across? If so, please share in the comments down below. We publish a new blog every Tuesday and Friday so, until next time, thanks for reading and goodbye!
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