Tuesday, 26 July 2016

Ancient monsters: The largest extinct aquatic creatures

The largest animal ever to have lived is in our oceans today – the blue whale – and most of our seafaring legends almost certainly stemmed from chance encounters with giant squid, oarfish and other marine giants, but aquatic life used to exist on a much larger scale. Many water animals have barely changed their appearance in millions of years, spare one minor detail – they’ve gotten smaller.

For all we don’t know about the modern day oceans, we know even less about the prehistoric oceans, but we’ve already found fossilised evidence of some utterly terrifying megafauna.


Jaekelopterus – 2.5 metres 

Img source: pinterest
The largest scorpion you’re ever likely to encounter in this day and age could still fit neatly on your hand, and probably wouldn’t be too happy with you if you submerged it in water, but 350 million years ago, they were happily hunting in estuaries and rivers. There’s a sea-faring equivalent, the largest of which is the Pterygotus, but at a maximum size of 1.6 metres, it’s not even a patch on its larger freshwater cousin.


Nautiloid Endoceras Giganteum – 9 metres

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Both the giant squid and the colossal squid are larger than the Endoceras, reaching 13 and 14 metres long, respectively, but this estimated size is conservative, given that we have only the most basic fossilised evidence of this monster. The shell stored in Harvard University is 3 metres long, but it’s incomplete, and it’s estimated that a complete shell would be nearer to 5.7-5.8 metres. The length of the giant and colossal squid comes from the tentacles, but this older genus was all shell, which is even more terrifying, in a way.


Sarcosuchus Imperator – 12 metres

Img source: carnivoraforum.com
Crocodiles and alligators aren’t exactly small now, especially the ones that like to wander around on golf courses, but try and imagine one the size of a whale shark. The Sarcosuchus, the largest saltwater amphibian ever discovered, was indeed this big, the largest of a family which averaged at about 10.5 metres from head to tail. Averaged. Evidence of them has been found almost the world over, and it is thought that their diet largely consisted of dinosaurs.


Elasmosaurus – 14 metres

Img source: dkfindout.com
Plesiosaurs are one of three main groups of large marine reptiles which share d the earth with the dinosaurs. They are characterised by their extremely long necks and set of four flippers.  Since they predominantly ate small fish, they didn’t get particularly big, save for Elasmosaurus. This bruiser was originally mistakenly thought to have a short neck and an exceptionally long tail, such was the guess work nature of early palaeontology. Once it was rearranged, it was found that the creature was capable of amazing ‘swan like’ ventral and lateral movement, which leads experts to think that it probably approached schools of fish slowly, and then whipped its head around at speed to catch them.


The Monster of Aramberri – 15 metres

Img source: carnivoraforum / Dan Varner
There is a lot of debate about the largest pilosaur. It’s a subspecies of marine reptile we still have a lot to learn about, and the 2 largest specimens discovered have yet to be placed in any defined taxon. The first, ‘Predator X’, was discovered in Norway in 2008, and is also about 15 metres long, but The Monster of Aramberri is thought to be a juvenile, and there’s also evidence that was attacked by another, larger member of its own species. There are some claims that it’s a Liopleuradon, as seen in Walking with Dinosaurs, but since all previous specimens of those have been around half that length, it seems highly unlikely.


Leedsichthys – 16.5 metres


Boned fish are some of the greatest survivors in natural history, and some of them have remained largely unchanged for millennia, such as the coelacanth, which was thought to have been extinct until one was spotted off the coast of South Africa in 1938. The leedsichthys is very much extinct, which is comforting, given that it’s bigger than any fish living today, shark or otherwise. They lived during the Jurassic period, and fed on plankton. It may have been preyed on by the pilosaurs which it shared the ocean with, but there has been no evidence found to confirm this yet.


Mosasaurus Hoffmanni – 17.6 metres

Img source: worldofprehistory.com
Not to be confused with pilosaurs (or ichthyosaurs, but we’ll get to that), mosasaurs were actually marine lizards. They existed during the cretaceous period, and their nearest modern cousins are monitor lizards. There are 40 known species, but Hoffmanni is by far the largest. Interestingly/terrifyingly, they also sported a loose lower jaw with a moveable joint, similarly to a snake, which meant that they could consume very large prey. Their teeth, meanwhile, were built to crack shells as much as to pierce flesh, and it’s thought that they would have gone after larger species of ammonites.


C. Megalodon – 18 metres

Img source: nationalgeographic.com
Megalodon has become the stuff of legend. It inspired half of a terrible movie and in a recent spate of weirdness; the half-eaten carcass of a great white led certain people to suggest that they were still out there somewhere. They aren’t, but you can certainly see their lineage in many modern sharks, especially bulls and great whites. As you can imagine, Megalodon is thought to have had a ridiculously strong bite, some 6-10 times as powerful as the great white. That’s between 11 and 18 tons of force. Combine that with 18cm long teeth and you’ve got something which would have been able to break through bone almost effortlessly.


Shastasaurus – 21 metres

Img source: listverse.com
Given that ichthyosaurs were the largest form of predatory marine reptile, it stands to reason that the biggest one yet found is also the largest extinct marine animal ever discovered, bigger than any prehistoric whale. In fact, the Shastasaurus was bigger than all but 2 of the largest animals ever to exist in the ocean, or anywhere else – the fin whale and the blue whale. Some of the links between whales and marine reptiles can be traced through examination of this huge beast, particularly the tail, which featured something which was almost a midpoint between a fluke and a dorsal fin. Since they lived in the Triassic, it could be suggested that later marine reptiles and predatory whales never got that big again because it was almost too big for its own good. 



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