Monsters Part 3: Cretaceous Seas

Plesiosaurs were marine reptiles from which lived from around 220 million years ago, until about 65 million year ago. If you think of the normal depictions of the Loch Ness Monster, then you know what a classic plesiosaur looks like. They were large predators which live primarily on fish in the oceans whilst dinosaurs roamed the land and growing feathers. They ranged from having really long necks and small heads, to pretty much the opposite, small necks and big heads. They got about by having four rather large flippers, and essentially looked like a snake skeleton put inside a turtle shell, although they didn’t have a shell. They include things from the early 3m long beasties to possibly the largest predator to have existed, the aptly names “Predator X” (cue dramatic music).

This is Predator X, possibly 15m long, eating another plesiosaur

Plesiosaurs seem to have been coastal dwellers, as most fossils have been found in coastal and estuarine environments. They mainly fed on ammonites, hard-shelled molluscs similar in body-shape to the modern Nautilus, and Belemnites, creatures which were similar to squids. Larger varieties probably fed on smaller plesiosaurs, and some had teeth for crushing bony plates, like those on the armoured fish or turtles.

A classic image of a long-necked plesiosaur or elasmosaur

Possibly the most interesting thing about these creatures is not how they lived or anything about them at all. Some people want to think that plesiosaurs have lived on past their extinction in the K-T extinction, when the dinosaurs died. The strange thing is they have picked a hell of a spot to live. For some reason, these “modern plesiosaurs” have chosen a rather difficult environment to live in. You might think that living in salt water and fresh water are pretty much the same, but they aren’t. In salt water, you have the problem on keeping your water in and the salt out. This is basically because salt likes to disperse itself equally in a liquid. In Freshwater, you have the opposite problem, keeping your salt in and the water out. This might not be as much of a problem for large, skinned animals as it is for jellyfish (there aren’t many freshwater jellies), but it still does pose a big problem. Also, the majority of these lakes, like the quintessential Loch Ness, are in cold environments. Reptiles, especially marine reptiles, do not fare well in cold environments. Have a think of where the crocodiles live. They are pretty much an analogue of plesiosaurs, and they don’t live outside the tropics. This is basically because they don’t produce much heat in their bodies, and large bodies require lots of heat, so living in a lake that has an average temperature of 5.5°C! That and the fact that Loch Ness has only been there for about 12,000 years points to these cryptozoologists, as they are called, being wrong. These stories exist throughout the world, and they are all pretty much wrong. My favourite is the New Zealand lake monster in Lake Coleridge on the South Island. It’s called Lakey. Damn, New Zealand, that’s clever.

The most famous photo of the Loch Ness Monster, the Surgeon's Photo
 was probably an elephant.

Next is the terrifying Mosasaur.

Big, mean lizard-shark!

If you think back to Part 1 of this Monsters series, we met the Megalania. Well, good old mosasaur is pretty much a cross between that beast and a shark! They had mouths filled with long, pointy teeth, and had strong flippers and a powerful tail. They are relatives of snakes, which may surprise you, but they had very similar jaws, which allowed them to swallow their food whole. They hunted early birds, fish and sharks as well as eating smaller mosasaurs.

These things did get pretty big. Sure, the smallest were only about 3-3.5m long, but the biggest, one Tylosaurus, got to about 17.5m. They also seemed to have two sets of fangs, all the better to grab you with. These puppies lived pretty much worldwide, and seemed to prefer shallower waters. Generally, Mosasaurs were pretty successful as predators, as they seem to have had greater numbers than other predators in the sea. They outnumbered plesiosaurs and crocodiles, and seem to have filled the niche left over by the ichthyosaurs when they went extinct during the Cretaceous period. But, even being such great predators didn’t save these guys from the asteroid which did in the dinosaurs.

Mean, but at least they're all dead.

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Monsters Part 2: Giant Eagles and Mega Sharks

After our look at my favourite Australian monsters, I thought I’d have a look at my two favourite monsters from the time after the dinosaurs dies. These are namely the megalodon, a huge sharked that roamed the oceans, and the Haast’s Eagle, a massive predatory bird from New Zealand.

 

Firstly, let’s stay dry and have a look at this massive eagle. Haast’s Eagle would have been a truly terrifying sight to behold, especially since it only went extinct around 600 years ago. In fact, the Māori have a legend about this fearsome bird, known to them as the Pouakai, a bird-monster who ate humans. And, when you find out how big this thing was, and what it ate, it’s not hard to believe in that little myth.

 

Haast's Eagle about to catch dinner

This flying monster stood about 90cm tall and weighed between 9 and 15kg. Now, that may not sound like much, but this thing would fly at 80km/h! Anything travelling at those speeds demands respect. Also, they hunted moa, New Zealand’s version of the emu or ostrich. The only thing is moas were much larger than their Australian or African equivalents, reaching some 230kg themselves, some 15 times the weight of the Haast’s Eagle. The fact that this predator would take something like that down is really cool.

 

Haast’s Eagle had a wingspan of about 3m, on par with the largest of the Golden Eagles or Stellar’s Sea Eagles, but even the biggest of these don’t get much more than half the weight of the Haast’s Eagle. It also had rather powerful legs, able to get into flight from a single jump, quite a feat for such a large bird (think of how a pelican gets into flight, and they max out at bout 13kg). The Haast’s short, strong wings were probably a benefit when hunting through the dense scrub and woodland of New Zealand. So, not only was its size amazing, but it probably was also a very agile bird. Running into a forest wouldn’t save you from this giant.

 

When hunting moa, the eagle would sit on a perch and stay motionless for a while until a suitable moa came along. It would then rapidly soar down and grip the moa near the pelvis with one taloned foot, whilst the other would kill the animal with a swift strike to the head or neck. This strike would have been equivalent to that from a brick which has fallen some 8 stories, quite a punch. Obviously, this 15kg bird can’t eat a whole 230kg moa in a single sitting, so it would use the same carcass for several days, and stay nearby.

 

Haast's Eagle and two Moa

One of the most amazing things about this bird is how recently it went extinct. The Māori didn’t reach New Zealand until about 700 years ago, and they rapidly wiped out the moa, the Haast’s main food source. It is completely likely that the Haast’s did kill and eat people, especially since we are a lot smaller than the big moas, so the legend of the Pouakai would suggest that the Māori did have contact with this eagle. But, if humans didn’t get to New Zealand until recently, it is more than likely that we would still be able to see this great, majestic beast in all its glory. Because the Māori hunted the Moa into extinction, the Haast’s Eagle could not find food, so went extinct itself.

 

If you’re scared of sharks, you might want to skip this bit, or you might be kept up at night.

 

Put your hand up if you’ve seen Megashark vs. Giant Octopus. I can’t see your hands... probably because I’m not exactly looking at you, but hey. If you haven’t, I suggest you get a couple of like minded friends, a bottle of your chosen beverage (mine’s wine) and watch the pants off this movie. It has the absolutely most terrible depiction of my next monster, megalodon.

 

So, you think Great Whites can get pretty big, huh? 6m is a rather large fish, hey? Well, between 25 and 1.5 million years ago there was a shark which made the Great White look like the fish you catch off the pier. Megalodon (Greek for big tooth) topped the scales at about 105 tons and a length in excess of 20m. This fish could literally swallow you in a single gulp.

 

Megalodon tends to make you feel small and insignificant

This fish, like many sharks, had 5 rows of teeth, but these teeth were over 18cm long. They are shaped much like great white teeth, but are more robust. This, coupled with the great size of the shark, allowed it to bite down with a maximum force of over 18 tons! That’s like having a rather large truck drive into you, and all focused along those teeth. It probably wouldn’t hurt; there wouldn’t be time for that.

 

So, we have a really big shark, so what would it eat? Well, whales are pretty big, aren’t they, so it could have eaten them. And true to form, there have been many different whale fossils found with tooth marks which match those of megalodon. There have also been several teeth found near fossils, so that adds to the idea that this giant shark ate whales. But, it didn’t stop there. It was probably a pretty opportunistic hunter, taking what it came across, such as seals, dugongs and manatees and even large sea turtles. It would also have eaten other fish, and possibly ate other megalodons. They could swim at high speeds, so chasing prey wasn’t a problem, and they are thought to have been rather smart predators too.

 

From evidence of whale fossils, megalodon probably tried to immobilise its prey by biting its fins and tail, or crushing its vital organs. It could also have acted similar to great whites when hunting seals, and attacked by ramming smaller prey from below at great speed. It kind of adds something to those images of great whites flinging seals into the air. Imagine an airborne whale!

 

I love it when these guys play with their food

Try this on for size. Megalodon could inhabit pretty much any marine environment. It’s thought that they had their nurseries in shallow coastal waters, and moved out into more open water as adults. Whilst it probably wouldn’t have gone up to the Polar Regions, it would have inhabited most temperate and tropical oceans, much like the great white today. This is possibly one reason it began to go extinct. As the globe cooled over the last few million years, water temperature dropped too, forcing megalodon to more equatorial latitudes. A cooling globe would also reduce the available nurseries for this beast, limiting its ability to repopulate. It also could have lost out like the Haast’s Eagle and lost its food supply, or may have been out competed by the emerging Orca. Anyways, I’m kind of glad it’s extinct, it was a true monster.

 

A truly terrifying beast

Next week, I’ll take a look at Nessie’s cousins and a similar predator from the time of the dinosaurs. As always, if you have comments questions or suggestions, please email me!

Monsters Part 1: Ancient Aussie Beasties

Monsters are interesting. Now, I don’t mean yetis, Loch Ness Monsters or any of that ilk, I’m talking about the real thing. So I’m going to take a wander through some of the coolest of these bad boys (and girls) who were about in the past. This will make up a couple of posts, but let’s start with my favourite two Australian prehistoric monsters.

Our first beast is something which might be responsible for the Yowie and Bunyip myths in Oz. About 46 000 years ago, there was a rather large predator stalking the bushland of Australia. This thing rivalled the lion for shear carnivorous terror, so much so it’s called the marsupial lion. Its Latin name is Thylacoleo and there have been 3 species, the largest, Thylacoleo carnifex, was about the size of a small lion. The most striking thing about this animal is its jaws. A glance at a skull makes you double take, because it is basically filled with tooth, and I mean tooth, here have a look!

Those teeth which stretch for the majority of the jaw effectively make up a knife blade in this monster’s mouth. That knife blade is made up of two teeth on the bottom jaw, and one on the top. Those teeth are like the fourth and fifth teeth in your mouth, but have become rather specialised. Thylacoleo was a relatively small predator; maxing out at around 160kg compared to the average 250kg for a lion, but had a hell of a bite. It holds the record for the strongest bite of any animal past or present, which is kind of cool.

This puppy had really strong forelimbs and large retractable claws, all the better to grab you with. It also had cool little bones in its tail which let it use it as a tripod so it had free use of its arms for mauling. Since its claws were retractable, it was able to keep them sharp, and enabled it to climb trees. It also had a semi-opposable thumb with which to grab its prey, so once it had you, you weren’t getting away.

What really gets me about these nasty monsters is what they took on. It’s thought that they hunted, killed and ate prey that was 20 times its weight. They probably hunted Diprotodons, monsters in their own right. These were basically giant wombats which weighed over 2000kg (4400lb in the old money). Interestingly, these herbivores might be responsible for the Bunyip myth as well. But Thylacoleo probably also ate a whole bunch of different kangaroos, some of which were over 200kg in their own right. Here’s a reconstruction of the marsupial lion.

So, why the Yowie myth?

Well, these beasts were around until about 46 000 years ago. That puts then here around when people started to arrive in Australia. Well, who’d have thunk it, but there are actually aboriginal rock art depicting Thylacoleo. Also, there have been several linguistic misinterpretations by Europeans of aboriginal language. That coupled with the 46 000 years removal from the actual animal and 20^th century popular culture probably come to make the Yowie something like a bigfoot myth, but this one is loosely based on an actual animal.

We go from giant, man-eating possums, to giant man-eating lizards. Megalania was a giant, 5.5 metre long monitor lizard which used Australia as a stomping ground around 40 000 years ago. There is a reconstructed skeleton of this monster in the Melbourne Museum, and it is kind of terrifying. They would have essentially have been like giant komodo dragons, and are known to be the largest known monitor lizard ever to walk the Earth. Here’s one chasing an Emu.

It’s a bit of a terrifying image to think of a goanna the size of a car running at you, especially since it has a mouth full of sharp, pointy teeth huge claws and possibly a big forked tongue. But, it had venom glands, if that didn’t make you day. So not only was it big enough to eat you in a couple of bites, but it also would have poisoned you to boot. They were thought to be ambush predators, and possibly partially aquatic, so you probably wouldn’t have seen it coming. It’s a good thing they died out around the time of the last ice age. This might not have the cool jaws of Thylacoleo, but it was the largest predator to live in Australia in the last few million years, so it’s cool for that reason, shear terrifying size. The best thing about them is that they actually existed!

As a last point, I’ve had the opportunity to hold and play with a Thylacoleo skull, and that was just cool. Here’s an amazing picture of some Australian mega fauna by the best palaeo-wildlife artist around, Peter Trusler.

Questions, suggestions and comments? Please do so. Correction or requests? Email me!