Art Corner: How to “Prosauropod”.
Hi, Jack here, and today we’re going to be going over “Prosauropods” or, more correctly, basal sauropodomorphs. It’s been a while since our last Art Corner post. Partly this has been due to exams, but I can’t pretend my poor time management skills aren’t partly to blame either. Anyway, let’s get on with it!
Now, basal sauropodomorphs were a rather diverse group in terms of size, and were hangin’ about from about the mid-to-late Triassic right up to the the early Jurassic when “true” Sauropods (belonging to the group Sauropoda) began to emerge. I’m going to try to cover what I can in one post, but this won’t be a complete guide to basal sauropodomorphs (I’m going to call them “Prosauropods” from now on because it’s easier and catchier).
So, let’s begin!
Right, so for practical purposes, we’re going to split the Prosauropods into two groups: Early Prosauropods and Late Prosauropods. This is not a legitimate taxonomic distinction, but it is useful for getting a grasp on the shapes involved.
Early Prosauropods, like Thecodontosaurus and Pantydraco (haha! Isn’t Welsh funny? It actually means “Dragon of Pant-y-ffynnon”) were small-ish bipedal animals, and probably lived an omnivorous lifestyle, eating plants and small animals. They had long, slender bodies, long legs, and large tails. Below I’ve sketched a Thecodontosaurus, with basic anatomy and joints in blue, and a body outline in red. I’ve not shown integumentary structures, but well get to that later.
Many basal sauropodomorphs share a similar body plan. In earlier species, the head was relatively large, and the neck was not too long. In later Prosauropods, the head became smaller, the neck longer, and the body larger.
You’re going to want references when blocking out the shape of your Prosauropod. Skeletal references. One excellent source of reference is Scott Hartman, who does splendid, up to date skeletal reonstructions. Hartman’s reconstructions can be found on his website skeletaldrawing.com, and are a brilliant resource to get an idea of the proportions of the animal you want to draw. Jaimie Headden also does fantastic skeletal reconstructions, many of which can be found at his website qilong.wordpress.com. I actually used Headden’s Thecodontosaurus skeletal as reference for the above sketch.
Before we get any further, I will warn you: many Prosauropods are very poorly known, and skeletal reconstructions of some Prosauropods may not exist at all. In this circumstance, it is wise to base your reconstruction on better known relatives. The closer the relative, the better. If there are pictures of the fossils, I would advise looking at those, too, as sometimes the bones we do have can show traits that really set one Prosauropod apart from the rest.
The skulls of Prosauropods can be varied in size and shape, but most are fairly long and rectangular. Some may taper a little towards the end of the snout. I’ve sketched a few skulls and also drawn the skin on top to show how they may have looked in life.
You can see that the teeth are blunt and peg-like, and covered with lips. The current thinking is that many Dinosaurs would have had lips. You can also see that I have shown both Plateosaurus and Thecodontosaurus with fuzzy, fur like protofeathers covering much of the head. It is likely that these early Dinosaurs would have had some kind of filamentous covering.
In Prosauropods, the hands also tend to follow a pattern. There are five digits. Digits I, II, and III are clawed, with digit I having a large, curved claw, while the vestigial digits IV and V are not clawed, and are barely visible.
You can see the hand from several angles here. Underlying skeletal anatomy is in blue, and the first two diagrams also show a coating of fuzzy feathers.
Prosauropods could not pronate their wrists, meaning that their palms would have faced oneanother instead of facing backwards. I’ve drawn the arms of a standard Prosauropod from a side view both correctly and incorrectly to illustrate this.
And, while it’s easy to stick to this with bipedal Prosauropods, it’s not so easy with quadrupedal ones. Only a few Prosauropods were quadrupedal as adults (Riojasaurus and the Prosauropods that were very close to “true” Sauropods) although most would have been quadrupedal as hatchlings. When drawing these Prosauropods, it’s very tempting to draw the front feet like those of a cat, with the fingers facing forward. It’s important to remember that Prosauropods couldn’t pronate, even when walking on all fours. They would have walked on their fingers. Below I’ve drawn the forelimbs of a quadrupedal Prosauropod from the front and the side. Notice how the fingers don’t point forward, but also how the first finger, digit I, is tucked backwards to face inward. The fingers of quadrupedal Prosauropods were also noticeably shorter. I’ve also drawn them with a lot of padding, as is often seen in quadrupedal animals.
Now, while some Prosauropods were quadrupedal, most weren’t. all they had to walk on were good old back limbs. These back limbs all followed a basic pattern: four exposed toes with a fifth vestigial metatarsal. And, while digits II, III, and IV were weight bearing and clawed, digit I, the hallux, was less crucial to weight bearing and held a large claw. What this claw was used for, we’re not entirely sure of. Below, I’ve drawn both the skeletal elements and the soft tissue of the foot from the front and the side.
Right, so now we’ve covered all that, let’s move onto the flesh – what their skin was like; what their scales were like; what their feathers were like.
Most reconstructions of Prosauropods show them with wrinkly, scaly skin all over. While we don’t have much in the way of skin impressions, we can make assumptions about what these animals looked like. Prosauropods belong to Dinosauria. Currently, the most likely theory is that filamentous integument is a basal characteristic of Dinosauria. That’s a fancy way of saying “Dinosaurs evolved from fuzzy ancestors”. What this means is that, while many Dinosaur lineages later lost this characteristic, many kept it. And, as sauropodomorpha is one of the oldest dinosaur lineages, Prosauropods may have had feathers. well, I say feathers, but these structures weren’t much like a bird’s feathers. They lacked barbs, and were more like quills or hairs. Smaller Prosauropods, which probably maintained their own body temperature, unlike lizards, amphibians, and crocodilians, probably would have benefited from these hair like structures to help keep them warm. This “fuzz” could have covered most of the body – perhaps even the hands and parts of the feet. Here I’ve sketched both a scaly texture and a fuzzy one, as well as showing a close up of the fuzzy structures.
It is worth noting that whilst the animal could have entirely fuzzy, it could also have had areas which were covered in scales or were just bare skin. The feet, for example, may have been scaly. However, they would not have had podotheca, which are the large scales you would see on a bird’s foot, as these had not evolved yet.
And finally, how do we colour such fantastic beasts? Well, for scales and skin, any range of colours is possible – you can have blues, greens, blacks, whites, reds, purples, pinks, whatever – although it’s likely that drabber colours might be more common in many species, purely because bright colours aren’t just advertising to potential mates, they’re a big, brightly lit billboard attracting predators (though that’s not to say bright colours would certainly not be seen). As for the fuzz, well, we can be fairly certain that only some colours could be shown there, as, unlike today’s birds, Prosauropod fuzz lacked the structures needed to show blues and greens. They were limited to melanin-based colours. Black, white, yellow, red, orange, brown, and other earthy colours were most likely.
Using all of the above information, I have reconstructed the obscure Indian Prosauropod Jaklapallisaurus. Because it’s poorly known, I based it on another member of the group (or “clade”), Plateosauridae, that it belongs: Plateosaurus. to I’ve shown scaly skin on the feet and snout, smooth skin (with a few hair-like quills) on the neck, and a fuzzy covering for the rest of the body, and I’ve coloured it in accordance to what colours we know were possible.
And that’s about it! This guide was mainly produced to help those brave individuals who have volunteered to help A-Dinosaur-A-Day with the art for Prosauropod Hell Week. I have drawn close to one Prosauropod every day for the past week or two, and I am eternally greatful to those who offered to take some of the weight. Hopefully this guide is useful to those people, but also to anyone who, for some unfathomable reason, decided to draw a Prosauropod just for the heck of it. Why would you do that? They are the worst Dinosaurs.
Sorry again for the long Art Corner hiatus, and I’ll do my best to make sure it doesn’t happen again. What would really be useful is suggestions for topics to cover. What do you find difficult? What’s the one thing you just can’t get your head around? What do you want to see on Art Corner? If you have any suggestions, or questions about a previous Art Corner instalment, feel free to message me here, or to message the PalaeoVerse team here.
Thank you for reading, I hope you found this useful! Now, go draw some Dinosaurs!
~Jack