Ancient Seas: Megalodon

I got a request from someone I work with to do a post about Megalodon. So me being me, I thought, why not make a segment about it? There is so much more to our oceans than what inhabits it right now. There are literally billions of years to cover. I am only one mermaid, but I can do my bit.

So welcome to the Ancient Seas segment!

Ancient Seas

MEGALODON

Class: Chondrichthyes

Status: Extinct (EX)

Size: 60ft*

Weight: 77 tons*

Era: Early Miocene to end of Pliocene aka 23-2.6 million years ago

Diet: Large prey; whales, seals, giant turtles

Habitat: Warm waters; juveniles: coastal

*Estimates as, without time travel, it is impossible to acutally measure and weigh a Megalodon. And who would want to, right?

Me inside Megalodon jaws, South Africa Museum

What exactly was Megalodon? Well, it was huge. And I mean huuuggggeeeee! (Yes, that many extra letters huge.) If you are a fan at all of the creature feature B-movie genre, then I'm sure you've seen a number of Megalodon films where it is pitted against equally big critters and is usually very hungry. I think the only truth in those films is its size. Don't get me started on the trailer for the new film The Meg. (Actually, I quite like the over lay of Beyond the Sea, but that is my media nerd talking.)

Megalodon was a prehistoric shark, simple. It shares common ancestors with modern sharks, such as the Great White. It has been over 2 million years since they last roamed our seas, which I'm sure is a sigh of relief for many.  There are a number of reasons which could potentially have lead to their extinction. I say "potentially" as it was, you know, 2 million years ago. There is also so little to go on as, like modern sharks, Megalodon were cartilaginous. This means their skeleton was made of cartilage rather than bone. All that remains of them are their teeth. Everything known about this incredible creature has been extrapolated from its teeth. That's why there is such a debate over its size.

And it's not just its size up for debate. It was originally believed that they shared a genus with Great Whites, due to the similarity in their teeth. Because of this, most recreations look a lot like Great Whites - just bulkier and bigger. It is now believed that these similarities occured because of convergent evolution, which is the independent evolution of similar features across species, and that they actually belong to the genus carcharoles and the otodontidae family. This basically means not the Great White genus.

With this new perspective, current theories on its appearance is that it would have looked more like Whale and Basking sharks. These are the modern gargantuans of the sea. While they are filter feeders and probably don't share facial features, they have crescent tail fins and smaller anal and second dorsal fins which are features to reduce drag. Many big fish have them, which is why it believed Megalodon would have had them too. Imagine being 60ft long, you'd need to reduce all the drag you could!

So why did they go extinct?

They lived in a competitive food chain. Ancient Killer Whales hunted the same prey as them - Baleen whales, which are filter feeding whales like the Humpback. While Megaolodon were at the top of their food chain and opportunistic feeders to boot, their very existence influenced diversity. The competiton evolved defensive adaptations, such as becoming pack predators, just so they could keep up. This would have led to there being less food.

Much like today, there were evironmental factors as well. While they didn't have to deal with plastic clogging their oceans, climate change was a thing back then as much as it is now. Megalodon liked warm waters and their nurseries were in coastal areas. Lowered sea levels and temperatures decreased the spaces where they could live, hunt and breed. Their food sources also shifted to be more polar and into cooler seas, once again depleting what they could eat.

Between all that, there really wasn't much left to support their bulk. Maybe with sea temperatures and levels rising, we'll see something more Megalodon-like once again. Probably best not though. With the sensational media and the insane vendetta against sharks, they'd probably become the ultimate hunting sport. And wouldn't that just be tragic.

From: https://www.fossilera.com/pages/megalodon-size

Fun Facts!

• Megalodon were bigger than Tyrannosarus Rex. Let that sink in.
• They had a bit force of up to 108,500-182,200N. (Very forceful in non-Newton speak.)
• Their teeth were thick and robust, designed to bite through bone.
• From fossil evidence, it is believed they attacked from the side, either ramming or biting their prey.
• Megalodon literally translates to "Big Tooth".
• Their fossilised teeth were once believed to be petrified dragon tongues. Gross.
• Their extinction impacted animal size - everything got bigger after they were no longer being eaten by Megalodon. This was most notable in Baleen whales.
• Cartliage skeletons are much more flexible than bone skeletons - making it easier to swim.