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Greetings all. Every child with a rough grasp of what life was like in Late Jurassic North America probably knows the Morrison Formation’s main characters. If such a child were to be asked to name the meat-eaters from that formation, the name Ornitholestes would definitely pop up, likely somewhere around third or fourth place.
Ornitholestes was a 6-foot long coelurosaurid theropod dinosaur that lived in western North America during the late Jurassic Period, 155-145 MYA. It is commonly depicted scampering about in the forest, or along the edge or the forest, or sneakily hiding in the shadows out of sight of the larger predators. With the likes of Allosaurus and Torvosaurus stomping around, it’s easy to see why paleo-artists have relegated little Ornitholestes to a bit-part on the Jurassic stage.
But I like to think that Ornitholestes‘ part was much bigger in the never-ending drama of Mesozoic life. Let’s look at its body. I’ve already stated that it was 6 feet long and was therefore about 2 feet tall – large enough to bite you on the knee. It likely weighed a hundred pounds or a smidge less than that – certainly not more. Its skull is worth looking at. Contrary to what has been commonly portrayed, it DID NOT have a little Ceratosaurus-like crest on the end of its nose. That mistake was made when a dislocated bone was mis-identified as a nasal crest. The skull was thin and deep, like a battle axe, and based upon its structure and that of its neck, it likley had a very strong bite. The teeth are small, but they are rather thick in cross-section. A powerful bite and thick teeth? This makes Ornitholestes sound like a precursor to the tyrannosaurs, and no wonder, because the tyrannosaurs are, in fact, highly-evolved coelurosaurs – the same group that Ornitholestes belonged too. The eye sockets on this baby were huge, so it is likely that Ornitholestes was a nocturnal hunter. As for its body, it was a bit on the muscular stocky side, so it was physically strong. It was equipped with long arms ending in three hook-like claws on each hand, and it had a long tail. We can also be fairly sure that Ornitholestes had a coat of thin whispy fur-like feathers on its body since other coelurosaurids that were more primitive and more advanced that Ornitholestes had feathers.
So what can we determine? It was strong for its size, its jaws could crack through eggshells and small bones, it could run, and it could grapple. In short, Ornitholestes was the hyena of the Jurassic savannah.
Hyenas are nothing to laugh at (I’m sorry, that was bad). Hyenas have a reputation for being scavengers, likely because they are commonly seen picking at the leftovers of the lions’ dinner, and because their jaws are the strongest jaws pound-for-pound of any meat-eating animal on the African plains – good for cracking hrough thick bones of carcasses. But in reality, hyenas are effective hunters as well. They are pack hunters, like lions or wolves, and it’s not unusual to see a gaggle of them, panting and bare-teethed, running down a zebra or a wildebeest.
Was Ornitholestes the same way? Unfortunately, fossils rarely provide evidence for animal behavior. The fact that Ornitholestes fossils are so rare doesn’t help matters. But I dare say that these carnivorous critters were a serious threat to dinosaur mothers who had eggs to protect, they likely did significant danage to hatchlings, they preyed upon smaller animals like thick-boned mammals, and asuredly were seen scavenging carcasses leftover by other larger meat-eating dinosaurs.
A while back, I drew a picture of Ornitholestes and posted it to this blog. However, it was an “old school” picture portraying Ornitholestes covered in scales. I have recently made an updated version, and I’m posting that image below.
In addition to the feathers, I’ve also slightly altered the shape of the skull to be a little more accurate. I always try to improve my work, and I dare say that a few years from now after my skills have improved further, I’ll make a drawing of this guy that’s even better than the one you see here.
Keep your pencils sharp, people.
This is an idea that I’ve had knocking around in my head for a while. A recent post by fellow paleo-blogger Chase (who has a special interest in eastern North American Mesozoic life) on Dryptosaurus has spurred me to action in terms of writing a short article as well as doing some much delayed artwork.
For those of you who are too lazy to read Chase’s excellent article about this animal, Dryptosaurus was a medium-sized theropod dinosaur, approximately 20-25 feet long which lived in eastern North America during the late Cretaceous Period. Unfortunately, our total knowledge of this dinosaur is known from only a few fragmentary remains, including a hand claw that seems way too big in proportion with the rest of this animal’s body.
For as far back as I can remember, Dryptosaurus was classified as a tyrannosaur. But recently, I have my doubts about this classification. Even very primitive tyrannosaurs such as Guanlong and Proceratosaurus don’t have some of the anatomical features that Dryptosaurus appears to possess.
My curiosity centered around that claw. It didn’t look like a tyrannosaur claw – to me, it looked more like an allosaur claw. An unusually large hand claw also reminded me of another animal – Megaraptor, from South America. Originally, this was thought to be a gigantic dromaeosaur, but then it was hypothesized to be more closely related to the allosauroids, like Neovenator, Giganotosaurus, and Carcharodontosaurus. The allosaur-like claw would make this classification a good fit. Then I saw a picture of the skeletal remains of Australovenator, a megaraptorid that was discovered in (you guessed it) Australia. I immediately noticed similarities in the hand and body structure between Australovenator and Dryptosaurus.
- Massive thumb claws in comparison with the other finger claws.
- Short muscular arms and huge hands
- Slender lower jaws with small closely-packed hook-shaped teeth.
What I find really interesting is that in 2012, a hypothesis was put forward by Fernando Novas and other paleontologists that the megaraptorids might actually be extremely primitive members of the tyrannosaur family. In 2014, fragments from a juvenile Megaraptor were discovered, including part of the upper jaw. The structure of the juvenile Megaraptor’s maxilla was very similar to the structure of the dentary from Australovenator. That year, Juan Porfiri re-iterated Novas’ hypothesis that the megaraptorids might be primitive tyrannosaurs.
So, with all of that being said, I hypothesize that Dryptosaurus was a member of Megaraptora, which would make it the first of its kind found within North America.
How did Dryptosaurus feed? The large hook-shaped claws and the small hook-shaped closely-packed teeth seem to indicate that Dryptosaurus and other megaraptorids were fish-eaters. The fossils of Dryptosaurus were discovered in the New Egypt Formation and the Navesink Formation, the later of which is known for both dinosaur fossils as well as fossilized shells. Also, Australovenator was found in deposits that indicate a swampy still wetlands environment, full of bivalves, fish, and turtles. The fact that this megaraptorid was found in a water-rich environment full of aquatic life leads me to suspect that Dryptosaurus might have had a similar lifestyle.
To conclude this short article, I have a drawing of the enigmatic Dryptosaurus portrayed as a megaraptorid rather than as a typical often-illustrated tyrannosaurid. Who knows – maybe my less-than-scholarly idea about Dryptosaurus being a fish-eating megaraptorid will prove out to be right. Only time and the discovery of more specimens will tell.
Keep your pencils (and minds) sharp, everybody.
Torvosaurus tanneri (“Nathan E. Tanner’s savage lizard”) was one of the largest theropod dinosaurs in the Morrison Formation. It measured 35 feet long, the same size as Allosaurus. However, Torvosaurus came from a more primitive line of theropods, the megalosaurs. As such, it retained some more primitive features compared to more advanced theropods living at that time like Allosaurus, and was probably less intelligent than Allosaurus (although not by much, apparently, since Allosaurus wasn’t exactly the brightest bulb either, according to studies of Allosaurus’ brain).
Torvosaurus and Allosaurus may have lived in the same location at the same time, but Allosaurus was clearly the most numerous theropod in the Morrison Formation. Very few remains of its competitor have been found. The first fossils of this animal were discovered in Colorado in 1971, and the species was officially named and described in 1979. Another species, T. gurneyi, was found in Portugal’s Lourinhã Formation, also dated to the late Jurassic. Although known from incomplete remains, it’s evident that the European species has a more boxy rectangular skull than its North American counterpart.
Torvosaurus and Allosaurus had the same length, but they possessed different physical proportions. These anatomical differences no doubt drove these two species to develop different hunting styles. It seems that Torvosaurus was a Jurassic analog for a tyrannosaur, since it had an unusually large head and unusually small arms in proportion to its body. Its body was long and shallow, whereas the body of Allosaurus was short and deep – good for a large heart and lungs, indicating an active lifestyle. Torvosaurus’ neck was short and muscular, while Allosaurus’ neck was longer and more sinuous. Torvosaurus had short arms and small hands (but unusually large thumb claws), while Allosaurus had longer arms, huge hands, and absolutely huge claws – obviously used for grabbing and ripping things. Torvosaurus seems to be rather front heavy (good for physically slamming it’s jaws onto prey) while the weight on Allosaurus appears to be more evenly distributed. Allosaurus also had an unusually long tail in proportion with its body – a definite feature of an agile runner. Therefore, it seems that Torvosaurus was primarily a short-distance chase ambush hunter who relied upon its jaws to do most of the work. By contrast, Allosaurus was a very active energetic predator who was capable of impressive speed and quick turns.
This drawing took a long time, as you can assume from its high amount of detail. Every individual scale was drawn one by one. To give you a better appreciation of the time to draw this, in real life this drawing frome nose-tip to tail-tip is only 21 inches long – 1/20 scale, as most of my prehistoric drawings are. Medium was No. 2 pencil on copy paper, along with some touch-up on my computer to fix the places where the two pieces of paper were joined together.
Keep your pencils sharp, everybody.
Well, it was that time of year again! Every April or so, at around the time of Easter, the Garvies Point Museum and Preserve, located in Glen Cove, Nassau County, New York, holds it annual “Dinosaur Day”. This is one of the days that I really look foward to for a few reasons. First, I get to work at a place that I absolutely love and meet with some good friends. Secondly, I get to be out of NYC for a little while, which is something that I ALWAYS look foward to. Third, I get to talk about a subject that has fascinated me since my earliest days – paleontology.
Veronica, the museum’s de facto head of administration, did a wonderful job along with other members of the museum staff of setting up the classroom where the day’s major activities would be taking place. Recently, the museum’s library was substantially increased. The Sands Point Museum and Preserve had closed down its library a short while ago, and all of the books and papers were sent to the GPM. I should state, though, that almost all of these documents were originally part of the GPM collections anyway, and they just got them back, that’s all. However, Louis (one of the workers at the Garvies Point Museum, but works primarily at the Old Bethpage Village – another place that I really love) has been working hard to re-catalogue all of these books and papers back into the museum’s database.
The name of the event was somewhat misleading, as it concerned all prehistoric life, not just dinosaurs. We had exhibits on primitive mammal-like-reptiles, dinosaurs, and prehistoric mammals.
Here are some pictures of what the room looked like both during and after the hoards of kids showed up.
Most of the really young children gravitated immediately towards the dino toy area and the fossil digsite. The older children and a lot of the adults were interested in the information that I and others were giving. They were especially interested in Dimetrodon, the famous sail-backed pelycosaur from the early Permian Period. I don’t think that I have ever had to say the name”Dimetrodon” so many times within the course of a single day! It seemed to be the only thing that many of them wanted to talk about!
Some of the major topics of interest on this day were: the Permian Mass Extinction, which occured about 251 million years ago, when an estimate 95% of all life was wiped out; of course, T. rex was a favorite; as too was Allosaurus, who competed with its larger relative for attention from the crowds. This was helped in no small part to the fact that we had a lot of Allosaurus “stuff” arrayed for them: a picture of the skull, a hand model, bone casts, a model, and my drawing which you might recognize from an earlier post on this blog.
Finally, here’s a picture of me, “the Dinosaur Man” as several members of the museum staff call me, dressed up as an amateur paleontologist. In addition to my olive drab Garvies Point Museum shirt, I also wore a khaki utility vest, because apparently ALL paleontologists wear khaki utility vests! I thought that wearing it would help to enhance my ethos with the audience, and by my reckoning, it worked.
Here’s a drawing that I did a while ago, but for some reason, my computer screwed it up. It’s only recently that I’ve rescanned it and fixed it up.
Camarasaurus was the most common sauropod dinosaur within the Morrison Formation of western North America during the late Jurassic Period. Other species like Apatosaurus and Diplodocus might be more familiar to the ear, but in terms of the sheer numbers of specimens that have been found, this big guy tops the list. As far as size goes, it was a tad on the small side for a sauropod, measuring only 60 feet long. Its relatively small size (that is, compared with the other larger sauropods that it shared its habitat with) and meaty build likely made it one of the preferred targets for a mob of Allosaurus to take down. The reason why Camarasaurus was the most common species of its kind might be due partly to its smaller-than-average size (smaller stomachs mean more food to go around for everyone, and by extent leads to having larger populations) and partly to its apparently generalistic diet. Creatures which have a specialized diet are often hit hard when catastrophies arise, whereas dinosaurs that are more adaptable and flexible in terms of what they eat come out more favorably.
Many times, you’ll see these dinosaurs illustrated Gregory Paul-style, with thin spindly legs. I decided that the biomechanics of this simply weren’t feasible, and so I gave my animal suitably thicker more elephant-like legs, able to hold up the tens of tons of weight. Also notice that, contrary to other artistic renderings of this species, the neck is NOT held straight vertically upright, but is thrust more fowards in a 45 degree S-shaped curve. This is also one of the few dinosaur drawings that I’ve done in color. In terms of the color pattern, I’ve always imagined Camarasaurus colored in the scheme that you see above, even as a little kid – tan body with broad brown stripes and a somewhat yellowish-tan underbelly. I simply cannot imagine this species colored in any other way.
Keep your pencils sharp, people.
Today, I learned some very heart-breaking news. Stephen Czerkas, one of the true greats of paleo-art, recently died. He was 63 years old. The cause of death was liver cancer.
Czerkas was famous for his life-sized dinosaur sculptures, and he developed a very distinctive style – you could immediately recognize a Czerkas sculpture. His horned Allosaurus graced many children’s dinosaur books and TV shows, and his life-sized Carnotaurus was truly epic. However, his most famous work was his pack of Deinonychus raptors. Czerkas was one of the first paleo-artists to have his theropods adorned with feathers, and he also discovered that at least some species of sauropods had spines on their backs, which was incorporated into the BBC series Walking with Dinosaurs.
To all of those dino-lovers of my generation – those who came of age during the 1990s – Stephen Czerkas’ work would have been an integral part of your life. Czerkas was one of THE paleo-artists of the late 1980s and early 1990s, the time when I was becoming exposed to dinosaurs and other prehistoric life. The sheer awesomeness of his work influenced me profoundly both as an artist and as a person who dedicated his life to studying the past.
The paleontological and artistic spheres have lost one of the true greats of their domain, but his work will last and I dare say will continue to influence artists, scientists, and children generations from now.
RIP Stephen Andrew Czerkas (1951-2015) 😦
Hot off the presses! A new carnivorous dinosaur from Portugal has been officially named – Torvosaurus gurneyi.
The fact that Torvosaurus came from Portugal isn’t a revelation – it was, after all, featured prominently in an episode of the Discovery Channel mini-series Dinosaur Revolution (which I didn’t particularly care for). For years, people have known that there have been megalosaurid dinosaur fossils from Portugal, specifically the Lourinha Formation, which dates to the late Jurassic Period, about 150 million years ago. These fossils were tentatively ascribed to the species Torvosaurus tanneri, known from the Morrison Formation of the USA. However, upon closer examination, there are a few minor differences in the bone structure, so the Portuguese specimens were named Torvosaurus gurneyi, named after the famous paleo-artist James Gurney.
Torvosaurus was one of the last megalosaurid theropods, as they were being replaced by the allosaurids and the coelurosaurids. Torvosaurus and its kind ruled Europe durring the middle and late Jurassic Period. It measured 30-35 feet long, giving Allosaurus a serious run for its money, and possibly weighed somewhere in the realm of four to five tons.
As if this wasn’t news enough, there are some dinosaur embryos from Portugal which might belong to Torvosaurus as well.
For more info, check out the websites listed below:
- SciNews.com. “Torvosaurus gurneyi: New Giant Dinosaur Discovered in Portugal” (March 6, 2014). http://www.sci-news.com/paleontology/science-torvosaurus-gurneyi-giant-dinosaur-portugal-01794.html
- National Geographic Daily News. “Largest Predatory Dinosaur in Europe Found, Was ‘Big Bruiser'”, by Christine Dell’Amore (March 5, 2014). http://news.nationalgeographic.com/news/2014/03/140305-dinosaurs-biggest-europe-torvosaurus-gurneyi-animals-science/
- Nature. “Filling the gaps of dinosaur eggshell phylogeny: Late Jurassic theropod clutch with embryos from Portugal”, by Ricardo Araújo et al (May 30, 2013). http://www.nature.com/srep/2013/130530/srep01924/full/srep01924.html