Welcome to Superoceras, a blog about science and natural history, slightly biased towards paleontology and zoology, but inclusive of all sciences. Started in October of 2009, my goal is to communicate scientific knowledge (and the occasional piece of nonsense) in an informative and entertaining manner. Feel free to contact me with questions, comments, concerns, or criticism at superoceras(at)gmail(dot)com, and follow me on Twitter @Superoceras for all that and more in 140 characters or less!

Tuesday, March 02, 2010

ART Evolved: Life's Time Capsule: The Therizinosaur Gallery

ART Evolved: Life's Time Capsule: The Therizinosaur Gallery

It's about time I showcase another blog that I follow - "ART Evolved: Life's Time Capsule". For over a year now, the ART Evolved Crew has hosted 6 successful paleo-art themed online galleries, and for their one year anniversary, I decided to throw my hand in at a submission to their most recent, The Therizinosaurs Gallery. As indicated by the name, ART Evolved is a paleo themed blog where they offer reconstruction tips, advice on "going pro", host online galleries, and live blog pieces being created. I've found their input helpful, and their posts entertaining, and if you're even remotely interested in creating or viewing paleo-art or reconstructions of extinct organisms, head on over.

Therizinosaurs in general have a complicated history within the field of paleontology. Upon the first discovery of therizinosaur (then known as segnosaurs) skeletal remains, paleontologists were confused by the mixed bag of traits that these animals possessed. They had wide set hips, long necks, and four toed hind limbs like the commonly known sauropod dinosaurs (the "long necks"). Their partially fused, backwards pointing hip bones were like those seen in the ornithischian dinosaurs (the "leaf eaters"). Their long, scythe-like claws and hands however, looked like those of theropod dinosaurs (the "meat eaters"). Their skulls were strange for a theropod dinosaur though. They were very small in relation to the rest of their body, and their jaws were full of serrated, leaf-shaped teeth (where they had teeth at least), indicative of a herbivorous diet (Holtz 2007).

Mystery of mysteries, paleo-artists had an equally difficult time reconstructing these bizarre dinosaurs. Early reconstructions had them walking around on all fours, which we now know to be highly improbable due to the configuration of their wrists. Later on, reconstructions were drawn showing the animal as a vicious carnivore that used its long claws to attack and disembowel prey. But the discovery of new species of therizinosaur, including those at the base of the "family tree" have helped paleontologists and artists alike get a better understanding of how these animals lived and looked.

Turns out that at some point in their evolutionary history (before the "intermediary" species like Falcarius came onto the scene around 126 million years ago), a group of maniraptoran dinosaurs started down an evolutionary path that saw them abandoning their primarily predatory nature (ultimately, therizinosaurs weren't the only group to end up doing so). Maybe in the beginning, this allowed the group to become more omnivorous than carnivorous, expanding their dietary range and giving them a better chance at survival. But ultimately this group became more and more specialized for feeding on leafy greens, the end result being the oddly shaped, enigmatic group of herbivorous, "carnivorous" dinosaurs we call the Therizinosauroidea (Senter 2007).

As I mentioned, I submitted two pieces for this months "Time Capsule". And given the hodgepodge of traits these animals possess, I found them a little difficult to reconstruct in the beginning. The first piece I submitted to ART Evolved was a reconstruction I did of a Therizinosaurus back in 2000. It was one of the first "proper" reconstructions I had ever attempted, and probably one of the more difficult ones at that. The trouble with Therizinosaurus is that there is not a lot of actually fossil material for the genus. At first, only one of the huge claws was discovered. The paleontologist who first described it thought it belonged to a huge, turtle-like reptile (Maleev 1954). Later, more claws, some teeth, parts of the fore and hind limbs, and parts of the foot were discovered. This helped establish that the animal was not a turtle, but it still didn't paint a full picture of the organism. This is both good and bad for people like me who want to reconstruct a creature that no one will ever see in life. With little material to reference, you won't know exactly what to include in your reconstruction. But that also means you can be creative, and use other closely related organisms to infer things about your subject.

For that first reconstruction I kept things pretty basic. I hand drew the skeleton of a Therizinosaurus from a reference image in the DK Dinosaur Enclclopedia, fleshed it out, and covered it in fine, filamentous proto-feathers (a/k/a "dino fuzz") with a couple secondary feathers on the tail for display. Some of the first people I showed the image to questioned my choice of integument. There is no direct evidence that Therizinosaurus was covered in any type of feathers or feather-like structures, but a lot of other maniraptorans (and coelurosaurs, and maybe even some ornithischians as well) were, so the chances that Therizinosaurus shared this characteristic with some of its kin are pretty good. Looking back on it now, it's not a half bad job for an early attempt, but there are things about the posture and musculature that don't sit well with me. Luckily, I had the opportunity to try again when I found out about the ART Evolved Gallery.

My second submission, Therizinosaurus cheloniformis is still not perfect, but I think it shows substantial improvement. I corrected the posture and musculature a little bit to what I think might have been more realistic given the form and lifestyle of the animal. To ferment all of the plant material they ate, therizinosaurs had a large gut stuck between their outset hips. This put a lot of the weight towards the back of the animal, and help offset the weight of the huge claws up front. The spine is oriented less horizontally and at more of angle, the tail is a bit shorter, and I tried to put some more muscle on the legs to help support the weight of the body (Paul 2005).

I'll admit, I had a bit of a hard time with the feet. The ones on the previous reconstruction were very thin, and I knew that wouldn't work with an animal of that size. I also wasn't sure if the animal would have walked digitigrade or plantigrade, as I've heard arguments for both methods of locomotion. And if I decided to make it digitigrade, should it have a giant fatty pad, like those seen in modern elephants, to help support the weight and act as a shock absorber? If it was plantigrade, does that mean that the hallux would have touched the ground when it walked, serving as a proper fourth toe? Ultimately, I decided to stick with the traditional digitigrade pes, but I did drop the hallux down to ground level. This would allow the weight of the animal to be spread over four toes instead of three.

I didn't fold the arms under the body or put the palms facing down (ok, well one of them is, but its not in life position) as is often seen theropod reconstructions, primarily because that's not how they held their arms or hands. But also because I imagine the larger therizinosaurs (like Therizinosaurus cheloniformis) to have had a lifestyle very similar to those of the extinct giant ground sloths. They probably used their giant claws to gather in branches closer to their mouths so they could devour the leaves. They may have even rested on their partially fused pubis and ischium, with feet in a plantigrade position, just munching away, as some reconstructions show.

With all the little differences, there was one thing I kept pretty much the same. I still covered it with feather-like filaments. Beipiaosaurus, another basil therizinosaur, was covered in not one, but two different types of feathers. The first were of the standard, downy, dino-fuzz variety, but they were a little longer than previously seen, and covered most of the body (Xu et al. 1999). The second variety were elongate, stiff, hollow at the base, and consisted of a single unbranched filament (Xu et al. 2009), almost making them "quill-like". Neither of these feather-like structures were used for flight, but more likely for insulation and display. Again, using a closely related animal to infer the appearance of another, I covered my restoration in both types (and left the secondary feathers on the tail, because I just like the way it looked the first time around).

There are a few things I would still work on the next time around: the head may be a bit large for the body, and I think the arms might be a little too short, but all in all, I think it worked out pretty well, and I'm very grateful to the ART evolved crew for displaying both of my pieces in their gallery. I'm also looking forward to their May gallery that will showcase the icthyosaurs, the dolphin-like marine reptiles of the Mesozoic Era.

What do you think of my therizinosaurs? Please feel free to comment on this, or any other post here at Superoceras. I'm always looking for feedback, criticism, and would love to answer any questions the readers have. As always, thanks for stopping by!


Holtz, T. R., Jr. & Rey, L. V. (illustrations). 2007. Dinosaurs: The Most Complete Up-To-Date Encyclopedia for Dinosaur Lovers of All Ages. Random House, New York.

Setner, P. 2007. A new look at the phylogeny of Coelurosauria (Dinosauria: Theropoda). Journal of Systematic Paleontology 5, 429-463.

Maleev, E. A. 1954. New turtle-like reptile in Mongolia. Priroda 3, 106-108.

Paul, G. S. 2005. "Body and Tail Posture in Theropod Dinosaurs"
. In Carpenter, K.. (Ed.), The Carnivorous Dinosaurs, 238-246. Indiana University Press, Bloomington.

Xu, X., Tang, Z-L., Wang, X-L. 1999. A therizinosauroid dinosaur with integumentary structures from China. Nature 399, 350-354.

Xu X., Zheng X.-t., You, H.-l. 2009. A new feather type in a nonavian theropod and the early evolution of feathers. Proceedings of the National Academy of Sciences (Philadelphia), 106, 832-834.

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