Sunday 11 June 2017

'King of the Beach'

This is a piece of art inspired by my recent post on Eustreptospondylus. It was created by Connor Ross, also known as RajaHarimau98, whose fine DeviantArt gallery can be seen here.
Here the theropod can be seen in the act of catching a fish in the shallows, its prey trapped between its jaws.

Thanks Connor! Everyone go take a look at his gallery, it's definitely worth a look.

Jacob

Tuesday 6 June 2017

Speculative Paleontology

When you're trying to imagine a prehistoric animal, your speculations and thoughts can be clouded by what has already been said. Something is repeated so often and seen so often, that it eventually just becomes the norm, and assumed to be the truth. Nothing is moved forward, and the concept stagnates, until you end up with a creature that went out of date centuries ago. Examples? Take your pick, there's plenty of them! Plesiosaurs being shrink wrapped snakes with necks as thin and flexible as a rubber hose. Baryonyx spending most of its life sitting beside a river waiting for a fish to skewer on its claw. Dromaeosaurids being exclusively pack hunters, when there's no reason that a fast-moving predator with a 9 cm long claw couldn't hunt for itself. I could go on. (I hasten to add here that I'm not picking on these in particular, I'm just using examples to make my point. Although I do have my problems with all three of these, but that's for another time.)
When trying to reconstruct an extinct animal, it makes perfect sense that you would look at other images, and then you would do the same, trying to be scientifically accurate - but accuracy isn't neccesarily being one of the crowd. In fact, I would say that being accurate in paleontology is very hard to do, but we can achieve a certain level of accuracy. But anyway, that's not my point. My point is creative stagnation, an inability to think out of the box, simply because it hasn't been done yet. If nobody stands up and complete rethinks something, nothing will ever move on. Plesiosaurs will remain shrink wrapped snakes. Baryonyx will be forever pretending to be a grizzly bear full time. Dromaeosaurids will be doomed to never hunt alone.
In some cases, this has been taken to the extreme. Allow me to use an example already stated: shrink wrapped plesiosaurs.


This is a well known piece of art first painted in 1830 - that's early Victorian times. You can see the plesiosaurs in his are shrink wrapped, with snake-like, disturbingly thin necks. Fast forward to the 21 Century, and you can still see these snake monsters depicted. Surely it would make sense to put some flesh on it's practically bare bones?

My point is, in palaeontology things quickly become unquestioned and fact, used again and again in paleoart. Out of the box thinking and speculation comes to a grinding halt, and we get conceptual stagnation.

To avoid this we sometimes need to completely rethink something. Create a new image, refresh the old concept that has been rotting for centuries. This sometimes means being a bit crazy with your ideas, experimenting . . .

What I'm getting at is, don't be afraid to try something crazy. Being conservative and doing what everybody else does isn't really going to get you anywhere - use your imagination, do some research, and come up with some new ideas, and suddenly a whole new world of paleontology is opened up. Really speculative reconstructions and thoughts on prehistoric creatures are things that I really encourage. I personally don't think sauropods were covered in some kind of fur-like integument. Does that make it a bad thing to think about this, speculate on it, reconstruct it as such? Paleontology is a guessing game, a fossil is a riddle - in a way, there are no right or wrong answers. There are so many possibilities, some of them undoubtedy a lot stranger than people might suspect, all of which are possible - it's part of what makes the subject so interesting to me.

What I aim to do is to start from scratch with different prehistoric creatures. Forget about the theories and the arguments, but focus on what I can find out, and what that tells me. Rethink an entire animal. Sometimes the results will not be so very different from the regular ideas, perhaps occaisonally I will create something quite strange and different. These exercises are fun to do, and the results are sometimes startling.

The creature that I've chosen to first take a look at is the notorious, infamous Tyrannosaurus rex. We'll have to wait and see what I come up with . . .

Bye for now.

Friday 19 May 2017

The Spinosaurid Saga I: Aquatic Ancestors & Megalosaurid Musings

Spinosaurids are a weird bunch, a group of oddball dinosaurs that stand out. There's nothing really like them in the dinosaur world, they're unique anatomically and ecologically. And they're strange, really strange. Spinosaurus is a 14 metre long aquatic predator which between its locomotion and its sail, has caused a great deal of commotion and controversy in the world of paleontology. There's Baryonyx, with its 31 centimetre long claws on the first digits of its hands. There's Irritator from Brazil, its original skull modified to look more interesting, making classifying it a hard job for the paleontologists, so much so that they gave it it's name. I haven't really done much speculative work on spinosaurids before, so I decided that this weird bunch deserved a bit of scrutiny from my part, since despite my love of the weird, I've neglected this bizarre theropod family. So, it's time to unveil the spinosaurid saga!

I felt that I couldn't properly understand the spinosaurids and the ideas that I had circulating unless I understood where these animals came from. As I researched spinosaurid ancestry, I realised that this was too interesting not to talk about. So what started out as a short introduction at the beginning of my post on spinosaurids has become a post all of its own, and has left me with a new-found love of the close relative and possible ancestor of spinosaurids, Eustreptospondylus. So although this post isn't really focusing on spinosaurids but on megalosaurids and Eustreptospondylus, I hope that you find this interesting anyway, and I promise you, this will really help to back up my ideas in the next part of the spinosaurid saga!

Spinosauridae belongs to the superfamily Megalosauroidea, so megalosaurids seem like a good place to start. As regular readers of my blog may know, ecological niches and paleoecology are of particular interest to me - once you know that, you can work out how everything is interlinked and co-existed with each other, and also of course gives you lots of clues on other interesting stuff such as behaviour. So, my question here is -

Are aquatic habits ancestral to spinosaurids?

Let's look at megalosaurids, close relatives and possible ancestors of spinosaurids. I want to now look if there's any evidence for swimming abilities and aquatic habits in them. Turns out, yes, there is.

First of all, I'm going to talk about probably the most obvious factor here, and that's Eustreptospondylus. Not exactly a famous dinosaur, but it rose out of the mist of obscurity thanks to its appearance in episode 3 of Walking With Dinosaurs. In the BBC documentary, it was shown swimming from island to island, based on a hypothesis that it was a strong swimmer. The holotype specimen was found in southern England, a place which was at the time a scattered island sitting in a shallow, tropical sea. This specimen was estimated to be around 4.63 metres long and weighing 218 kg by Gregory S. Paul in 1988, and due to this size, it was assumed that this creature had undergone an evolutionary process known as insular dwarfism (when an island-dwelling creature becomes smaller, examples include the extinct pygmy mammoths). However, as Darren Naish and David Martill showed in 2000, the specimen was only a sub-adult, the adult creature would probably have been more like 6 metres long. So insular dwarfism wasn't at work here - more on insular dwarfism, or rather the lack of it, later.

Given that the location where Eustreptospondylus was discovered was at the time a group of islands, it has been suggested that the creature filled a beach comber niche - foraging on the shoreline, and moving from island to island like a Komodo dragon. Seems likely enough, but I would go so far as to suggest that Eustreptospondylus was participating in a little bit of fishing. Take a look at the skull.




The line of the upper jaw quite clearly shows a faint hook shape on the premaxilla, where the tip of the jaw bends down slightly.



This hook shape is something that can be seen in spinosaurids:


By AS - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=4743700

The premaxilla has that bend, albeit a lot more developed, but that's only to be expected. But this is interesting, that this feature is shared in spinosaurids and Eustreptospondylus. This suggests that they were doing something similar, probably in their diet, and of course shows their kinship with each other. Since it's basically an accepted fact that spinosaurids were piscivores, at least in part (it could be argued that some species definitely varied their diet a bit more, but undoubtedly they were focusing quite heavily on aquatic life), this to me suggests that Eustreptospondylus was snacking on sea food. Why? Well, let's take a look at crocodilians . . .

Original image: By Matt from Melbourne, Australia - Saltwater Crocodile (Crocodylus porosus)Uploaded by SunOfErat, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=27543014

Seeing something familiar there? That's right, that notch, hook, or whatever you want to call  is there again. It doesn't seem to have a technical term, so I'm just using premaxillary suture.
Looking at nile crocodiles, in young individuals its just the notch, a slight dip in the flesh, where the tooth from the lower jaw fits into. But in adults, it clearly develops into a more pronounced hook. Compare the skull of this juvenile . . .

 By H. Krisp - Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=13665385

. . . to the head of this adult.

 By Gianfranco Gori - File:Etiopia - omo river valley DSC 2835 (4).jpg, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=41557894

In the above image you can clearly see that a notch for the tooth to fit into, so as not to slice into the gum, has developed into a more distinct shape, similar to what is seen in spinosaurids and Eustreptospondylus.

But there's more . . .

 This feature is present in the extinct, aquatic phytosaurs:

By Ryan Somma - originally posted to Flickr as Phytosaur skull, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=5076886

And in pike eels:


There are other animals too, such as gars. In some of these the feature creates a hook shape at the tip of the snout. And what do all of these creatures have in common? They all either eat fish or are thought to have eaten fish. Clearly there is something about this particular jaw structure that helps in snatching up and keeping hold of slippery prey. Spinosaurus has a well developed one, and our Eustreptospondylus has what looks like the beginnings of a premaxillary suture. It's underdeveloped, but it's still there. But remember how underdeveloped it is in a young croc skull, see one of the images above in this post. And remember that the specimen of Eustreptospondylus isn't fully grown! I would suggest that this feature could develop, just as with crocodiles, as it matures - or maybe it didn't, who knows. But either way, I would say this is evidence for a partially piscivorous diet.

Now, let's move onto other megalosaurids to see if we can uncover any further evidence.

Magnosaurus: lived on a chain of islands, so as with Eustreptospondylus it seems entirely plausible that would have been capable of swimming from island to island.
Streptospondylus: as above.
Duriavenator: as above.
Dubreuillosaurus: as above

That's 5 megalosaurids, all of them living on small islands in a shallow, tropical ocean, all of them close relatives of spinosaurids, at least one of them a possible piscivore. I would say that these island-dwellers were likely all fairly good swimmers, allowing them to swim from island to island. My reasoning behind that is centered around insular dwarfism.
It has been proven that, despite previous misconceptions, non of these megalosaurids are insular dwarfs. Thing is, I've been thinking, that's actually a bit weird. They were living on small islands - insular dwarfism is known as an island rule for a reason. How come they haven't become insular dwarfs? One of the reasons this process occurs is because if you're a smaller animal, you need smaller territories and less food, which helps when you're living on a small island with the rest of your population.

 By Nils Knötschke - Nils Knötschke, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=1228462

Above: an example of insular dwarfism in a dinosaur. This shows Europasaurus compared to its continental relative, Giraffatitan.

You would think that the pressures of living on an island would lead these megalosaurids to become small. But they haven't. Why? The best reason I can think of is that they weren't stuck on a single island. Think about it - it's already been suggested that some of these species were good swimmers, and I've suggested that
Eustreptospondylus was a partial piscivore. It makes sense that these creatures could, and frequently would, move from island to island. In other words, they didn't have a restricted population, so the rule of insular dwarfism didn't neccesarily effect them, because they could move wherever they wished. They might have been moving around a lot, never using up all of the resources in any one place, instead island hopping, swimming through the shallow, tropical sea.
This seems the most plausible way of explaining how these island dwelling theropods hadn't been influenced by insular dwarfism: they weren't constrained. They could move where they wished, perhaps not having set territories, or maybe defending islands from rival island-hoppers, until resources began to dwindle, and the creature was forced to move on. I don't know. But I feel like this is a good and plausible explanation.

Let's return, for a moment, to Eustreptospondylus, probably the most important dinosaur in this post. It has been argued that it was the closest relative to the spinosaurids, and some have even said that it may be the ancestor of spinosaurids. I agree with that. All of what I've found researching this post really backs up that idea in my head, and I find it entirely likely that Eustreptospondylus was in fact the ancestor of all spinosaurids.



Here's a section of a drawing that I did for this post, depicting Eustreptospondylus. As I was drawing it, I realised that compared to some other megalosaurids, this particular genus has an unusually slender, spinosaurid-like snout. Its nostrils are already quite far back on its skull. It has the beginnings of a hook-like shape on in its maxilla (and as I've already argued, as the specimen is a young one, it could have developed more as the animal reached maturity). I'll talk more later on what speculative features I've added in this drawing.
But looking at this, I can very much support the idea of Eustreptospondylus being the ancestor of spinosaurids. And if that was the case, could it be that all spinosaurids came from island-hopping theropods, which habitually travelled through the shallow, tropical sea, moving from island to island, and feasting upon sealife? I think it's plausible, and it would mean that spinosaurids evolved in and around the sea. And if all that I've talked about was true, and Eustreptospondylus was a good swimmer, a possible partial piscivore, and regularly paddled from island to island, that would mean that spinosaurids were ancestrally at home in and around the water. Which neatly backs up the ideas I'm going to be explaining in part II of the spinosaurid saga.

Before we move on, I would like to briefly describe a few things about the drawing I made, in particular the features on Eustreptospondylus here. One thing that I always try and include in my reconstructions is soft tissue. By that I don't mean religiously sticking to the skeleton. I use skeletal references of course, they are an invaluable resource, but I choose to always try and put a thick layer of flesh between where the bone lies and the skin. In particular here it's obvious on the outline of the skull - some people seem to only put skin over the skull, with the antorbital fenestrae painfully obvious, skin sunken in as if the creature has been shrink-wrapped. So, as always, I added more soft tissue, particularly on its nose, and on its lacrimal bone (the jutting-out bone above its eye). The lacrimal bone is obvious in quite a lot of theropods, genera such as Allosaurus, etc - but I often find that as usual, the lacrimal bone isn't much more than just that - bone. Skin draped over the top of it, and that's it. I tend to think that the lacrimal bone would have been extended by soft tissue, as shown here in this
Eustreptospondylus. Also bear in mind that I illustrated a sub-adult here, as the specimens we have are a similar age, so the lacrimal bone itself could have grown as it reached maturity - regardless, I made it more of a display structure, the bone itself supporting a fleshy comb. I also tend to think that spinosaurids would have had a pouch similar to pelicans, so to illustrate that I support the theory of Eustreptospondylus being a spinosaurid ancestor, I gave it an extendable throat pouch. The only thing that I'm displeased with here is its nostril, I think that I may have placed it too far back in the external naris.

Now, to conclude, I've created a small, speculative piece of paleo fiction featuring ideas I've put across today. Enjoy!

163 million years ago, and we are in what will one day become southern England - although it is not recognisable as such, looking completley different from the land it will, millions of years in the future, become. It is covered in the shallow, sparkling azure sea, dotted with small islands, shaggy with vegetation, rimmed with golden sand. The climate is warm and tropical, the whole place has a paradisical air to it. But just last night, this primordial paradise was wracked by a storm that turned the aquamarine ocean into a steely grey, whipping up waves, and tugging at the plant-covered scalps of the islands. Now, the dark, stormy rind of night has peeled away, leaving the day fresh and blue. But the storm has left its mark . . .
On the shore of an island shaped like the head of a plesiosaur, there is chaos. Marine life has been tugged unmercifully from the depths, before being thrown onto the beach, where it now lies strewn across the golden sand. Driftwood encrusted with the thick, banded stalks of Pentacrinites crinoids, some of them several metres long; ammonites with glossy shells and spotted tentacles; an empty Hybodus eggcase. All of it, lying there for the taking. The occaisonal tropical storms may be brutal, but for the survivors, it's a feast.
A Eustreptospondylus emerges from the woodland that covers the center of the island. It's a sub-adult, soon to enter sexual maturity, the twin red combs on its head, one above each eye, signalling that he's a male. He spent the storm curled up in a hollow, but now he can stretch his legs and search for food. As he leaves the vegetation behind, his whole body comes into view - he is nearly 5 metres long (fully grown, he'll be 6 metres), and is covered in dark chocolate brown skin, almost black, cream on his underside. His left hand is missing, bitten off in a run-in with an adult male, but it is long healed, and he gets along fine just with the stump and his other good arm.
He scavenges along the shoreline for a while, crunching at crinoids, and extracting ammonites from their tightly coiled shells by placing a foot on them, while tugging the soft, exposed head and tentacles with his jaws. He's used to eating anything he can find on the islands and beaches, but with this bonanza of free food on offer, he can afford to be picky. He knows that if he searches, he may well be able to find a worthy prize - so long as no adults have got there first.
Having searched the beaches of the island, the male paddles out into the sea to make the short crossing to the neighbouring island. His sensitive nostrils have already smelt something beginning to rot in the warm sun, just across the water, so pausing only to duck under the water for a few seconds, washing his skin and sparse, bristly feathers, he hastens across, swimming powerfully.
After a short while, our male makes it to the shore of the neighbouring island, and sits on the sand for a moment in a sphinx-like position, bathing in the sunlight like a cormorant, allowing himself to dry off. Following his sensitive nose, he tracks the interesting scent around the island, to where he finally finds his prize: a young Cryptoclidus. In plesiosaur years, it was at a similar point of its life to the Eustreptospondylus male. No longer a baby, but not yet an adult. Its banded juvenile patterning was just beginning to fade - but it was quite dead now, washed up during the night. Already many scavengers have already been taking their pick - something has torn off one of its back flippers, and there are cuts along its side where a flock of young Eustreptospondylus had been picking at the leathery skin. The group of young, dappled and web-footed, scatter as the male snaps at them, rumbling a warning to them to stay back. Cannibalism isn't uncommon amongst theropods, and he wouldn't think twice before snapping up the youngsters. Chattering to themselves in high-pitched alarm calls, the babies jump into a large tidepool, where they swim away amongst the seaweed, far more agile and skilled in the water than the sub-adult. With the rivals dealt with for now, the male turns his attention to the dead plesiosaur.


He bites its neck, twisting with his head, just to make sure that it's really dead. Satisfied with the snapping noises and the motionless body, he drops the long, banded neck, and begins to tear away strips of leathery hide from the plesiosaur's back, exposing its fatty flesh - good food for a growing male. Gobbling down chunks of meat whole, his throat poach expands, bulging with the food. He eats all he can, then lies in the sand beside it, bathing in the sunlight. He will eat the rest after a short doze as he digests his meal.
Unfortunately, the young male isn't the only big animal on this archipelago. Another  Eustreptospondylus has caught the scent of the dead plesiosaur, and has swam a long way to reach it. She's a fully grown adult, with a flopping brown comb on her head and a scarred body. She approaches the male, rumbling her warning. He doesn't back down though, instead he arches his neck, bows long, and hisses at her, exposing his serrated tongue. It's an open challenge and a threat. The female charges, hissing in return, and the male tries to fight back, but she is larger, stronger, and more experienced than he is. Her jaws snap shut around his jaws, and she shakes his head from side to side, until she finally lets him go as he kicks at her with his hind legs. With both his pride and his face injured, the male dashes for the sea, paddling away to safety. He'll have a scar across his snout now, but luckily his thick flesh will heal fast, and he isn't too badly injured. He may have lost his meal, but there's sure to be more to eat out here, in this beautiful, primordial paradise . . .

Conclusion:

Eustreptospondylus has a small premaxillary suture, a feature shared by spinosaurids, and a variety of other piscivorous animals, suggesting it included fish in its diet, and as the specimen is not fully grown, the suture may have become more developed as it matured. It and many other megalosaur relatives lived on islands in a shallow sea that once covered much of Europe, but despite previous misconceptions, they have not experienced insular dwarfism, to which I suggest that they were escaping this island rule by being able to move from island to island - basically, they were good swimmers. I support the idea that Eustreptospondylus may have been the ancestor of spinosaurids, and it is certainly the closest relative to them that we have discovered. To conclude, I would suggest that because of this, spinosaurids may have evolved as island-hopping megalosaurids in a tropical shallow ocean, and that the answer to my initial question is yes, spinosaurids were ancestrally semi-aquatic.

 Also, as always I welcome art inspirted by or based on my posts - if you create good art, then it will probably be featured on this blog, along with a link to your art page, such as DeviantArt. Any art is welcome, whether it be directly based on what I wrote here, or just inspired by it, or if it's a completely new and different inteptretation of my idea.


Thanks for reading guys, keep an eye out for part 2 of the spinosaurid saga, and other posts. In part II I will discuss the spinosaurids themselves, having looked at their ancestry - see you then!

Saturday 4 March 2017

Pinacosaurus the Fourth

Pinacosaurus is back, and this time it's got a sneeze and it's not afraid to use it.


This brilliant piece of art was made by HodariNundu, inspired by my post on Pinacosaurus tongues. Take a look at his awesome DeviantArt gallery, it's packed full of imaginative depictions of prehistoric life: here.
I have loved all of the art you guys have done inspired by post, but this has got to be the most imaginative so far. He can explain his idea much better than I can, so I'll quote him here:

 A Velociraptor learns that just because the front end of an ankylosaur lacks a club,
doesn´t mean it's necessarily harmless. I was inspired to draw this by a blog post by fellow deviant in which the idea of Pinacosaurus and other Asian ankylosaurs as possible eaters of social insects is explored.
I had already heard of the idea and drew something inspired by it, as some of you probably remember. However, re-reading it, it occured to me... those guys not only had long tongues, they also seemingly had large cavities in their noses which are sort of a mystery (unless I'm wrong) and have been interpreted as possible air sacs to inflate colorful or resonating sacs. But what if that's not all? What if the insect-eater hypothesis is right, and some ankylosaurs spent most of their early years feeding on ants and whatever social insect was around during the Cretaceous?
What if they, like today's horny toad of the North American deserts, sequestered the formic acid of its prey and concentrated it in their own blood? What if they had lots of vessels on their nose that could burst and squirt relatively large amounts of blood and snot laced with acid to the face of its enemies?
Horny toads squirt acid-laced blood through their eyes, and although this defense doesn´t work as well on birds as it does on mammals, and so one should wonder how much of an effect it would have on a Velociraptor, I still thought it was an interesting idea to portray. In any case, being soaked in sticky blood snot would probably make you sticky and dirty, attract insects, and maybe even larger, hungry predators (if they were around), making ankylosaurs prey to be avoided whenever possible...

By the way, it may seem difficult to believe that an animal as large as an ankylosaur would feed exclusively on insects (even though it's not impossible, seeing how nutritious they are, enough that animals as large as bears dedicate lots of time to find and eat them, and also, c´mon, blue whales and krill?). It may be that the juveniles were the ones eating most insects and eventually shifted to a more vegetarian diet as they grew, not unlike many grain-eating birds that feed their chicks with insects today, because of the protein and all that. Who knows! All speculation here. 

HodariNundu's Edit:

 Forgot to add, some ankylosaurs had armored eyelids too. Why? Did small-ish predators such as Velociraptor have the nasty habit of poking the eyes out of their larger prey to render them defenseless? Were the ankylosaurs feeding on very thorny plants? Or perhaps on biting, stinging or formic-acid rich insects? Who knows, maybe they needed protection against rival ankylosaurs and their ACID SNEEZE

 

This depiction of Pinacosaurus is exactly the sort of thing that I love: speculative and imaginative, not afraid to push the boundaries. Well done HodariNundu, and thanks for your art - the same goes to everybody else who has created images of Pinacosaurus for this.