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More photos of Allosaurus from the AMNH

Greetings friends. In an earlier post from 2014, I put up some photographs which I took of the two Allosaurus skeletons that are on public display in the American Museum of Natural History (or AMNH for short) in New York City. I’ve recently uncovered some other photos which I took during a visit there in March 2019, and so I’m posting them here. Enjoy!



Allosaurus, revised

Greetings, all. For those who regularly visit this website, you will know that this post has been a long time coming. Years ago, I mentioned that I was planning on re-doing my Allosaurus drawing so that it would be more accurate. However, that project always seemed to be shuffled onto the back-burner in place of other things that I was working on. Well not anymore. I recently completed a detailed drawing of an Allosaurus head (another one of the projects on my to-do list that I never seemed to get around to doing) which you can look at here, and I’m happy to state that after a long delay, I’ve finally completed my updated full-body Allosaurus.

Below is an Allosaurus drawing which I made in July of 2013 and which I posted to this website at that time. This portrays Allosaurus in a color scheme based upon that seen in the 1999 BBC series Walking With Dinosaurs. I must state that, as flawed as this illustration is, this piece was actually itself an updated version of a drawing that I had made a couple of years earlier. Even so, upon reflection, while it was an improvement on my previous work, it still needed more improvement.

And here is my revised Allosaurus drawing, made in July of 2020. This drawing was made in 1:20 scale, which is my preferred scale for illustrating prehistoric animals. From the tip of its nose to the tip of its tail, this drawing measures precisely 21 inches long, which would make the real-life animal 35 feet long; this measurement is regularly given as the maximum size for Allosaurus fragilis. This drawing was made with No.2 pencil on printer paper.

Finally, here is a colorized version of the new drawing. Again, the color scheme is based upon that seen in Walking With Dinosaurs, but the coloration and the color patterns differ slightly from the original image seen at the top. The picture was colored using Crayola colored pencils and No.2 pencil for re-shading.

Nearly everything about my previous drawing was altered in order to make this present artwork. This includes:

  1. The head was changed to be more accurate in appearance. Designing the head took most of the research time.
  2. The shape of the eye’s pupil was changed from a sort of oval slit to being a circle.
  3. The neck was made thicker, more muscular, and not as strongly S-curved.
  4. The body was made deeper.
  5. The arms were slightly enlarged and the hands were changed to be more anatomically accurate.
  6. The legs were thickened to provide extra weight support.
  7. The orientation of the hip bones was shifted.
  8. The tail was thickened to provide better balance to the front of the body. The previous drawing was conspicuously front-heavy.
  9. The tail was slightly elongated.

As you can see, one of the major changes to this drawing was the addition of dermal scutes along its back and sides. Unlike osteoderms, dermal scutes are scales which are enlarged and unusually thick compared to other scales on the rest of the body. There is evidence from preserved skin impressions from stegosaurs and ceratopsians that their skins possessed patterns of dermal scutes, sometimes arranged in lines, and it is therefore possible that theropods had such a feature to their outward appearance as well. It also gives this particular Allosaurus a distinctly reptilian look to it. I decided not to include any type of feathering or some other filamentous structures to the skin.

I also chose to portray this animal in a walking pose rather than running. I think that too many of my drawings of bipedal dinosaurs portray them running Gregory Paul-style, and I wanted to show something more natural. Also, unlike Scott Hartman’s illustrations, the legs are not splayed so widely apart from each other that they’re halfway to performing a split. Mostly, a normal walking stride is about three times the length of the foot. In fact, I actually practiced walking back and forth in front of a mirror, bending my legs theropod-style, in order to get a rough idea of how the leg position on this drawing ought to look.

Keep your pencils sharp, everyone.

Allosaurus head

Hello everyone. Here is a drawing of the head of Allosaurus fragilis, the top predator of the Morrison Formation of Late Jurassic North America. This drawing has been on my to-do list for quite some time, and I’m happy that it’s finally finished. The drawing was made with No. 2 pencil on printer paper.


This is Camptosaurus dispar, a 20 foot long herbivorous dinosaur from the Morrison Formation of western North America during the late Jurassic Period. In most paleo-art, it seems that the only purpose in life for this unfortunate animal is to be Allosaurus‘ lunch! It’s not hard to see why – a large meaty animal with little or no defenses.

Camptosaurus was a primitive member of the iguanodonts, a group of ornithopod ornithischians which could chew their food. This act helped them to process their food better which in turn helped their digestive systems to extract more nutrients. One of the most well-known features of the iguanodonts was the presence of a thumb spike. On Iguanodon, the thumb spike was rather large. Being a primitive member of the iguanodont family, Camptosaurus also had a thumb spike, but it was comparatively tiny, almost the same size as its other finger claws, and would have been pretty much useless as a weapon. But hey, we all have to start off somewhere.

Paleontologists are still arguing whether Camptosaurus was primarily bipedal or quadrupedal. Personally, while I believe that Camptosaurus was capable of going down on all fours (making it a “facultative quadruped”), I think that it was bipedal most of the time.

Below are three stages of the same drawing: an outline, an outline with the color patterns drawn in, and finally a finished colored drawing. The drawing was made on printer paper with No. 2 pencil, Crayola colored pencils, and Prismacolor colored pencils.

Related article:


Haplocanthosaurus: An Enigmatic Sauropod from the Late Jurassic Period


The sauropods are the definitive image of the dinosaur. Almost always, whenever one hears the word “dinosaur”, the image of the long-necked long-tailed four-legged behemoth is what immediately springs to mind. The sauropods were the dominant land herbivores during the Jurassic Period of the Mesozoic Era, and some of our best specimens come from western North America.

In the Rocky Mountains, in the states of Utah, Wyoming, and Colorado lies a massive swath of Jurassic-age rock known as the Morrison Formation. Here are found fossils of some of the most well-known and iconic dinosaur species, names that everyone knows, like Allosaurus, Ceratosaurus, Apatosaurus, Brachiosaurus, Stegosaurus, and Diplodocus. The Morrison Formation was home to a myriad of different species, and not just dinosaurs either. Other prehistoric creatures that have been found in this rock layer include pterosaurs, crocodiles, turtles, lizards, frogs, fish, mammals, and even insects.

While there are a few dinosaur names that stick in people’s memories, the Morrison Formation was home to many dinosaur species. One of them, which is largely unknown by the general public, was a sauropod called Haplocanthosaurus. Part of the reason why this animal doesn’t have the same caché to its name as other Jurassic giants is because it is known from only partial remains, its fossils are extremely rare, and because it is found in the oldest layers of the Morrison Formation, far below the fossil-rich layers of the middle and late strata that have yielded thousands of finds. This article will be an overview of this mysterious and curious, but not quite forgotten, sauropod of the Late Jurassic.


Discovery, Localities, and Dating

In the very early 20th Century, the remains of a sauropod dinosaur were found about eight miles north of Cañon City, Colorado, and they were discovered and excavated by one Mr. W. H. Utterback. In early 1903, John Bell Hatcher gave these bones the identification of Haplocanthus priscus, “the ancient simple spine” (1).

However, Hatcher soon learned that the name was already used for a prehistoric fish, and so later that year, he re-classified the dinosaur as Haplocanthosaurus, “simple-spined lizard”:

“Dr. C. R. Eastman has very courteously called my attention to the fact that the generic name Haplocanthus recently proposed by me for a new Sauropod dinosaur from the Jurassic deposits near Canyon City, Colorado, is essentially preoccupied, Agassiz having employed the name Haplocanthus for a genus of fishes. I would therefore propose the name Haplocanthosaurus for this genus of dinosaurs with simple median spines on the anterior dorsals and posterior cervicals” (2).

Later that same year, Hatcher published a lengthy and detailed description of all of the bones assigned to this new genus (3).

In fact, Hatcher was mistaken – the name Haplocanthus wasn’t already occupied after all. According to the rules of the ICZN, the original name would have been the correct one to use, except that nobody had called this creature by that name since its discovery. A proposal was submitted in 1989 to have Haplocanthosaurus as the accepted name of this creature due to its common use and the fact that Haplocanthus was not acknowledged by the paleontological community. The request was approved in 1991, and Haplocanthosaurus became the definite name of this dinosaur genus (4).

In 1954, the Cleveland Museum of Natural History really wanted a large grand dinosaur skeleton to put on display, just like the ones that were on display at the American Museum of Natural History in New York City and the Carnegie Museum in Pittsburgh. So an expedition was sent out west to bring back an attention-grabbing huge dinosaur skeleton. The expedition was led, surprisingly enough, by a college undergraduate student named Edwin Delfs (5).

Their first destination was Dinosaur National Monument, located near the Utah-Colorado border, and they hunted for fossils around that area. Unfortunately, they didn’t find anything. However, the team received a tip from some geology students from Louisiana State University that they ought to check out a site in Garden Park, located near Cañon City, Colorado. (6).

Delfs and his teammates relocated to the suggested location, and on the eastern bank of Four Mile Creek, they hit paydirt. Here were the grandiose fossils that the Cleveland Museum was looking for. However, they couldn’t dig anything up yet. The United States had entered the Atomic Age, and due to the Red Scare of the 1950s, the country was manufacturing hundreds of atomic bombs every year. In order to fuel this doomsday machine, the military needed massive amounts of uranium. Many of the fossils that had been discovered out west during the post-WWII years had been discovered accidentally by people who were prospecting for uranium deposits. Due to all of the uranium deposits in the area, Edwin Delfs first had to file a mining claim on the site before he could dig up any fossils (7).

Over the course of three digging seasons, Delfs and his team chipped away at the stone. Part of the reason why it took so long was due to the extremely hard consistency of the rock that the bones were found in. Another reason was that sudden flash floods would completely flood the excavation site, and unfortunately some of the bones were washed away before they could be saved and prepared. After three years of on-off excavations, the team uncovered a large number of vertebrae and parts of the hip. The specimen, which was substantially bigger than Haplocanthosaurus priscus, was named Haplocanthosaurus delfsi by Dr. Jack McIntosh (who is widely regarded as the greatest sauropod expert EVER) and Dr. Michael Williams who served as the curator of vertebrate paleontology at the Cleveland Museum of Natural History. The jacketed bones were brought back to the Cleveland Museum to be prepared. The skeleton was put on display, and it remains one of the main attractions at the Cleveland Museum of Natural History, where it is affectionately known by the nickname “Happy” (8).

There are currently two species of Haplocanthosaurus known to science: H. priscus and H. delfsi. Both of them are known from comparatively few remains in relation to other late Jurassic sauropods. No complete skeleton has ever been found, and there are numerous bones missing from all known specimens, including the skull; no Haplocanthosaurus skull has ever been found, which makes it difficult to precisely place this species within the dinosaur family tree. So far, we have large chunks of the neck and backbones, a shoulder blade, a few vertebrae from the base of the tail, the hip bones, a few leg bones, and that’s it. Most fossils of this animal have been found in Colorado, but one specimen was found in Montana and was nicknamed “Big Monty”. However, this specimen was found on private property, and it is in the hands of a professional fossil collector and dealer (9).

Fossils of both species of Haplocanthosaurus are found in the early and middle levels of the Morrison Formation, although it is rare within both of those levels. It is completely absent from the late Morrison. It is possible that Haplocanthosaurus lived during the latest part of the Middle Jurassic and therefore straddled the boundary between the Middle and Late divisions. However, there are so few places within North America where Middle Jurassic rocks are exposed, and the number of fossils from those rocks has been aggravatingly miniscule. So, the question of whether or not Haplocanthosaurus was a Middle Jurassic leftover that survived into the earliest parts of the Late Jurassic cannot be answered yet (10).



Haplocanthosaurus is distinctive for vertebrae that have only a single dorsal neural spine as opposed to the double-pronged V-shaped dorsal neural spines found in the diplodocid sauropods like Apatosaurus and Diplodocus. It is this anatomical feature that earned it its name “simple-spined lizard”. The neck vertebrae of Haplocanthosaurus have proportionally small centrum disks, high neural arches, a tall dorsal neural spine, and transverse spines that stick out directly sideways. Haplocanthosaurus is also noted for having femur bones that are substantially longer than the shin bones. This hints that Haplocanthosaurus was a very slow-moving animal (11).

Size measurements are difficult to pin down, because paleontologists currently recognize two species of Haplocanthosautrus: H. delfsi and H. priscus. It appears that Haplocanthosaurus priscus measured only 50 feet long, making it the smallest sauropod yet found in North America, while Haplocanthosaurus delfsi measured 70 feet long. This distinction was not known until 1988. John Foster states that H. priscus likely weighed around 23,000 pounds (10,500 kilograms) while H. delfsi weighed 46,200 pounds (21,000 kilograms). The aforementioned size measurements mean that Haplocanthosaurus priscus was one of the smallest – if not the smallest – sauropod found within the Morrison Formation (12).



Haplocanthosaurus is a bit of an oddball as far as sauropods go because paleontologists haven’t quite made up their minds as to how to classify it. Because Haplocanthosaurus is known only from partial skeletons, deciding where it fits within the sauropod cladogram has proved problematic and aggravating, and paleontologists have repeatedly shuffled this genus around according to their own perceptions.

Due to the shape of its vertebrae, which were unlike those of more advanced sauropods, John Bell Hatcher surmised that Haplocanthosaurus must be a quite primitive. In his initial research paper, he described Haplocanthosaurus as most closely resembling Morosaurus, a name that is now recognized as a junior synonym of Camarasaurus. Since we now classify Camarasaurus as a member of the sauropod group Macronaria, a group which contains species known for having boxy heads and large nostrils, it can be inferred that Hatcher would have placed Haplocanthosaurus in that group as well (13).

Except that Haplocanthosaurus wasn’t included in Macronaria alongside Camarasaurus and Brachiosaurus. It was, instead, included in the family Cetiosauridae. The cetiosaurs were a group of sauropods that are associated with the Middle Jurassic, especially in England, India, and China. One reason why Haplocanthosaurus’ designation as a cetiosaur stuck around for so long was because of the shape and size of the leg bones. Cetiosaurs are characteristic for having femurs that are noticeably longer than their fibulae and tibiae. However, some members of other sauropod groups also have unusually long femurs, so this anatomical feature is not 100% diagnostic towards cetiosaurs (14).

From its discovery until the middle 1990s, the established convention was that Haplocanthosaurus was a cetiosaurid. And then, things began to change. During the middle 1990s, paleontologists began to take a new look at sauropod phylogeny, and many felt that Haplocanthosaurus had been misplaced on the sauropod tree. In 1998, Jeffrey Wilson and Paul Sereno proposed that Haplocanthosaurus might indeed be a primitive member of Macronaria, which is closer to what John B. Hatcher was hinting at in 1903. In 1999, Jose Bonaparte proposed that Haplocanthosaurus was unique enough to warrant a family of its own, which he named Haplocanthosauridae, but this idea was not accepted by the majority of paleontologists. In the early 2000s, it was suspected that Haplocanthosaurus might actually be a very primitive member of the super family Diplodocoidea. A survey conducted in 2005 by Mike Taylor and Darren Naish failed to definitely establish where this genus ought to be placed. John Foster, the author of Jurassic West, postulated in his 2007 book that Haplocanthosaurus was either a cetiosaur or a primitive macronarian. As the 2000s transitioned to the 2010s, the idea that Haplocanthosaurus was likely a primitive diplodocoidean began to gain acceptance within the paleontological community, and this is what most paleontologists now consider Haplocanthosaurus to be (15).

Because Haplocanthosaurus possesses anatomical features found in both sauropod families, it’s possible that it is a transitional species, a “missing link”, between the cetiosaurs of the middle Jurassic and the diplodocids of the late Jurassic. However, proving such a statement is problematic because of the rarity of finds attributed to this genus. Haplocanthosaurus is known from several partial skeletons, but no skull has ever been found. That’s too bad, because a complete skull would probably settle the argument of where this genus fits on the sauropod tree.

Below is a drawing that I made of Haplocanthosaurus. Because no skull has ever been found, I decided to make a sort of half-cetiosaur half-diplodocid design. The short keratinous scutes that run along the middle of its spine are a reference to such spines (longer ones at that) being found in association with diplodocid sauropods; if this was a primitive member of that family, I’m guessing that such spines would be shorter, if it possessed any at all. The tail is somewhat shorter than what you might expect, more in keeping with a cetiosaurid than a diplodocid. The drawing was made on printer paper with a No. 2 pencil.

Haplocanthosaurus delfsi. © Jason R. Abdale. June 21, 2020.



Due to the scarcity of remains, theories about Haplocanthosaurus’ appearance and phylogenic relationship to other sauropods are largely conjectural. Museum mounts depicting Haplocanthosaurus, such as the one in Cleveland, are composites of known finds and educated guesswork. In terms of cladistics, the in-vogue assessment is that Haplocanthosaurus is a very archaic member of the super family Diplodocoidea. However, this might change in the future depending on any new finds that are uncovered. All that we can hope for is that we keep looking, and hopefully we’ll be able to uncover some more specimens of this mysterious and intriguing North American dinosaur in the years to come.


Source Citations

  1. John Bell Hatcher (February 21, 1903). “A New Sauropod Dinosaur from the Jurassic of Colorado”. Proceedings of the Biological Society of Washington, 16 (1): 1-2).
  2. John Bell Hatcher (1903). “A new name for the dinosaur Haplocanthus Hatcher”. Proceedings of the Biological Society of Washington, 16 (1): 100).
  3. John Bell Hatcher (1903). “Osteology of Haplocanthosaurus, with description of a new species, and remarks on the probable habits of the Sauropoda and the age and origin of the Atlantosaurus beds. Memoirs of the Carnegie Museum, 2: 1–72).
  4. John R. Foster and Mathew J. Wedel (2014). “Haplocanthosaurus (Saurischia: Sauropoda) from the lower Morrison Formation (Upper Jurassic) near Snowmass, Colorado”. Volumina Jurassica, 12 (2): 197).
  5. “Haplocanthosaurus: The Ghost of the Morrison Formation by Dr. Cary Woodruff CMNH Dinofest 2017”.
  6. “Haplocanthosaurus: The Ghost of the Morrison Formation by Dr. Cary Woodruff CMNH Dinofest 2017”.
  7. “Haplocanthosaurus: The Ghost of the Morrison Formation by Dr. Cary Woodruff CMNH Dinofest 2017”.
  8. “Haplocanthosaurus: The Ghost of the Morrison Formation by Dr. Cary Woodruff CMNH Dinofest 2017”.
  9. “Haplocanthosaurus: The Ghost of the Morrison Formation by Dr. Cary Woodruff CMNH Dinofest 2017”; “Is Nate Murphy Holding a Dinosaur for Ransom?”.
  10. John Foster, Jurassic West: The Dinosaurs of the Morrison Formation and their World. Indianapolis: Indiana University Press, 2007. Page 200.
  11. John Bell Hatcher (February 21, 1903). “A New Sauropod Dinosaur from the Jurassic of Colorado”. Proceedings of the Biological Society of Washington, 16 (1): 1-2; John Foster, Jurassic West: The Dinosaurs of the Morrison Formation and their World. Indianapolis: Indiana University Press, 2007. Page 200; “Haplocanthosaurus: The Ghost of the Morrison Formation by Dr. Cary Woodruff CMNH Dinofest 2017”.
  12. John Foster, Jurassic West: The Dinosaurs of the Morrison Formation and their World. Indianapolis: Indiana University Press, 2007. Pages 200-201.
  13. John Bell Hatcher (February 21, 1903). “A New Sauropod Dinosaur from the Jurassic of Colorado”. Proceedings of the Biological Society of Washington, 16 (1): 2.
  14. David Lambert, The Dinosaur Data Book: Facts and Fictions about the World’s Largest Creatures. New York: Avon Books, 1990. Page 65; Don Lessem and Donald F. Glut, The Dinosaur Society Dinosaur Encyclopedia. New York: Random House, Inc., 1993. Page 208; Gregory S. Paul, The Princeton Field Guide to Dinosaurs, 1st Edition. Princeton: Princeton University Press, 2010. Pages 173-177.
  15. Jeffrey A. Wilson and Paul C. Sereno (June 15, 1998). “Early Evolution and Higher-Level Phylogeny of Sauropod Dinosaurs”. Memoir (Society of Vertebrate Paleontology), 5: 1-68; Jose F. Bonaparte (1999). “An armoured sauropod from the Aptian of northern Patagonia, Argentina”. In Proceedings of the Second Gondwanan Dinosaur Symposium, National Science Museum Monographs #15. Y. Tomida, T. H. Rich, and P. Vickers-Rich, eds. Tokyo. Pages 1-12; Mike P. Taylor and Darren Naish (2005). “The phylogenetic taxonomy of Diplodocoidea (Dinosauria: Sauropoda)”. PaleoBios, 25 (2): 1–7; John Foster, Jurassic West: The Dinosaurs of the Morrison Formation and their World. Indianapolis: Indiana University Press, 2007. Page 188; John A. Whitlock (April 2011). “A phylogenetic analysis of Diplodocoidea (Saurischia: Sauropoda)”. Zoological Journal of the Linnean Society, 161 (4): 872–915; Emanuel Tschopp, Octávio Mateus, and Roger B. J. Benson (2015). “A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda)”. PeerJ. 2015; 3: e857; “Haplocanthosaurus: The Ghost of the Morrison Formation by Dr. Cary Woodruff CMNH Dinofest 2017”.



Bonaparte Jose F. (1999). “An armoured sauropod from the Aptian of northern Patagonia, Argentina”. In Proceedings of the Second Gondwanan Dinosaur Symposium, National Science Museum Monographs #15. Y. Tomida, T. H. Rich, and P. Vickers-Rich, eds. Tokyo: 1-12.

Foster, John. Jurassic West: The Dinosaurs of the Morrison Formation and their World. Indianapolis: Indiana University Press, 2007.

John R. Foster and Mathew J. Wedel (2014). “Haplocanthosaurus (Saurischia: Sauropoda) from the lower Morrison

Formation (Upper Jurassic) near Snowmass, Colorado”. Volumina Jurassica, 12 (2): 197–210. https://sauroposeidon.files.wordpress.com/2010/04/foster-and-wedel-2014-haplocanthosaurus-from-snowmass-colorado.pdf.

Hatcher, John Bell (February 21, 1903). “A New Sauropod Dinosaur from the Jurassic of Colorado”. Proceedings of the Biological Society of Washington, 16 (1): 1-2. https://www.biodiversitylibrary.org/page/2345230#page/118/mode/1up.

Hatcher, John Bell (February 21, 1903). “A new name for the dinosaur Haplocanthus Hatcher”. Proceedings of the Biological Society of Washington, 16: 100. https://www.biodiversitylibrary.org/page/2345230#page/118/mode/1up.

Lambert, David. The Dinosaur Data Book: Facts and Fictions about the World’s Largest Creatures. New York: Avon Books, 1990.

Lessem Don; Glut, Donald F. The Dinosaur Society Dinosaur Encyclopedia. New York: Random House, Inc., 1993.

Paul, Gregory S. The Princeton Field Guide to Dinosaurs, 1st Edition. Princeton: Princeton University Press, 2010.

Taylor Mike P.; Naish, Darren (2005). “The phylogenetic taxonomy of Diplodocoidea (Dinosauria: Sauropoda)”. PaleoBios, 25 (2): 1–7

Tschopp, Emanuel; Mateus, Octávio; Benson, Roger B. J. (2015). “A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda)”. PeerJ. 2015; 3: e857. Published online on April 7, 2015. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4393826/.

Whitlock, John A. (April 2011). “A phylogenetic analysis of Diplodocoidea (Saurischia: Sauropoda)”. Zoological Journal of the Linnean Society, 161 (4): 872–915. Published online on January 12, 2011. https://academic.oup.com/zoolinnean/article/161/4/872/2732063

Wilson Jeffrey A.; Sereno Paul C. (June 15, 1998). “Early Evolution and Higher-Level Phylogeny of Sauropod Dinosaurs”. Memoir (Society of Vertebrate Paleontology), 5: 1-68.

Inverse. “Is Nate Murphy Holding a Dinosaur for Ransom?”, by Jacqueline Ronson (July 5, 2016). https://www.inverse.com/article/17806-sauropod-dinosaur-discovery-montana-fossil-hunter-paleontology-nate-murphy.

YouTube. ExtermCentral. “Haplocanthosaurus: The Ghost of the Morrison Formation by Dr. Cary Woodruff CMNH Dinofest 2017” (November 12, 2017). https://www.youtube.com/watch?v=-NWL7pjrPbI.

Head-Butting, Face-Biting, and Tail-Whacking: Dinosaur Intra-Species Combat

The image of Nature “red in tooth and claw” is a compelling vision which appeals to the popular imagination. Time and again, paleo-art illustrations depict dinosaurs and other prehistoric animals actively engaged in fighting, hunting, and killing. It’s a well-known fact that violence sells, and it’s also a well-known fact that the animal kingdom can sometimes be very brutal. But was the Mesozoic world really a landscape of perpetual violence and bloodshed with animals constantly engaged in the savage business of survival?

Most naturalists, biologists, and animal behaviorists today would say “probably not”. Animals do not engage in a perpetual brawl-fest with each other. Even so, animals do have violent interactions, not only among different species (inter-species combat), but also within the same species (intra-species combat). The dinosaurs were no exception to this, and we have many pieces of evidence that individuals within certain dinosaur species engaged in violent behavior towards each other.

Before I get into the particulars of the paleontological evidence, it’s important to establish some ground rules as to the sort of intra-species combat that animals engage in today, and what the dinosaurs likely engaged in during the past. Physical combat between individuals or at least physical harm inflicted by one individual upon another is typically rooted in either social or environmental causes. Animals hurt each other for a variety of reasons, but seldom is it done purely for the hell of it – only people do that. Social reasons for intra-species combat include violence associated with mating and with mate selection. Bighorn sheep rival males cranially collide with each other until one contestant or another gives up. Other individuals within numerous animal species fight each other in order to assert their right to mate. Mating-based violence can also include some very rough love – some males within certain shark species will actually bite the females in order to assert their power over the female. Speaking of this, asserting dominance is also one of the main causes for intra-species violence, regardless of whether or not mating is involved. This involves dominance within a hierarchy system, such as a lion pride or a wolf pack. Other reasons for intra-species combat are environmental, and are usually tied to the availability of food and other resources. Territorial defense in a strong motivator in this behavior, and this is strongly tied to yet another reason, which is competition of food.

Now that we have established some of the motivating factors behind why modern animals hurt each other, let’s examine the sort of intra-species combat that dinosaurs would have engaged in. For instance, many animals will kick either out of aggression, self-defense, or purely to express annoyance. One dinosaur that possibly engaged in combative kicking was the late Cretaceous ornithopod Parksosaurus. This small speedy herbivore possessed unusually long scythe-like claws on its feet. One may hypothesize that Parksosaurus engaged in kicking contests like in cockfights, or like the modern-day Australian cassowary bird. Then again, Parksosaurus could have also used these long claws for better traction when running, like the cleats on a runner’s shoes, or could have used them like digging tools to scratch into the dirt to search for food or water.

Of course, when people imagine kicking dinosaurs, the first thing that likely pops into their minds are the “raptor” dinosaurs, such as Deinonychus, Velociraptor, and Troodon. Did raptor dinosaurs, with their killing claws, do the same? The large hook-shaped toe claws were certainly used for a specific function, either ripping prey open or pinning it to the ground. I can easily imagine two bird-like raptors squabbling with each other and kicking out with their feet, like a pair of roosters, but this is purely speculative as there is no hard evidence for raptors engaging in kicking each other.

Acheroraptor. © Jason R. Abdale. July 16, 2014.

Years ago, it was proposed that another meat-eater, the late Jurassic carnivore Ceratosaurus, could momentarily balance itself on its thick tail like a kangaroo and kick out. However, this idea has since been disproven. In order for this kicking behavior to work, the tail has to be very thick and muscular and at the same time be very flexible. Ceratosaurus’ tail was deep, but thin in cross-section, more like a crocodile’s tail than a kangaroo’s. Furthermore, it only had limited up-down flexibility. For the most part, the tail was held stiff for balance, and its range of flexibility was largely confined to side-to-side motion, not up-and-down.

Ceratosaurus. © Jason R. Abdale. April 23, 2012.

Ceratosaurus is famous for having a prominent horn on the end of its nose, hence its name. However, the horn was very thin and blade-like in form, and was certainly used for display rather than offensive action. However, there were dinosaurs and other animals in the past that likely used their heads as weapons. “Head-butting”, when animals engage in combat by using their heads as hammers, possibly occurred in earlier animals, such as the dinocephalians of the Permian Period. They had thick flattened skulls, and either pressed and shoved against one another or might have collided cranium against cranium. The dinosaurs which are most associated with head-butting are the marginocephalians, “the wide skulls”, the group that includes pachycephalosaurs and ceratopsians. At first glance, their skulls seem to have been specially designed for head-on physical combat. The eponymous Pachycephalosaurus had a rounded skull that was a solid foot thick, and many scientists have automatically assumed that such skulls were used in head-butting contests, like with modern-day bighorn sheep. A recent study by the University of Wisconsin has found that 20% of pachycephalosaur skulls exhibit head trauma, suggesting with some certainty that the pachycephalosaurs did indeed engage in head-butting behavior.

Pachycephalosaurus. © Jason R. Abdale. October 19, 2013.

But what about the other members of the marginocephalians? The ceratopsians, “the horned faces”, which include the likes of Triceratops and Styracosaurus, have also been assumed to have been highly combative animals, with their spikes, horns, and frills. In recent years, the idea of these horned behemoths duking it out with each other or impaling predators on their sharpened horns has come under intense criticism. Many of their frills are dominated by wide holes which served to lighten the weight but also made them practically useless for protection. Some scientists think that the frills and horns were primarily there for display and species recognition, and their use in defense was only an afterthought.

Chasmosaurus. © Jason R. Abdale. March 31, 2016.

As you’ve probably seen by now, most of the animals which have physical features that can be used in combat are herbivores. Why? Because they sometimes have to physically fight in order to stay alive and avoid being eaten by carnivores. Aside from teeth and claws, the meat-eating theropod dinosaurs don’t seem to have much in the way of special features that would be involved in fighting, not just eating. Ceratosaurus’ nasal horn was too thin and flimsy for attacking something, and so too were the eyebrow horns of its larger contemporary Allosaurus. However, another carnivore did possess eyebrow horns which very well might have been used in fighting – Carnotaurus, one of my personal favorites. Ever since its discovery in the 1970s, paleontologists and paleo-artists have imagined this dinosaurian toro engaged in head-butting clashes with other members of its kind. However, based upon the build of the skull, it seems more likely that it was engaged in cranial “shoving matches”, in which both competitors would press their skulls against one another (hence the Velcro-like arrangement of bumps and nodules on the top of their heads in between the horns) and proceed to push and shove in a demonstration of pure muscular strength until one side or another decided that their opponent was too strong, and retreated.

While predators might not necessarily have physically struck each other with their skulls, they could have used their heads in another way that is far more common among carnivorous animals of all sorts today – face-biting. Face-biting is a way to assert dominance among individuals, especially in communal or pack-hunting societies. Several modern carnivorous animals, such as lions, foxes, and wolves, engage in this behavior. The infamous creature known as “Jane”, who might be either a Nanotyrannus or a juvenile Tyrannosaurus (to this day, nobody is exactly sure), has evidence of face-biting. Since many animals today who engage in face biting do so in order to assert their position of dominance in a pack society, this could be further evidence that this animal was itself a pack hunter, at least as a juvenile. At least one specimen of a juvenile Daspletosaurus also has evidence of face-biting. Sue the T. rex possesses marks on the jaw which were previously thought to have been the result of bites, but were later proven to have actually been caused by a bone infection.

Predators aren’t the only animals today that engage in face-biting, so there may have been herbivorous dinosaurs that engaged in the same behavior. The most likely candidate for this is the small African herbivore Heterodontosaurus. The tusks on this creature could have been wielded in actual biting, or they could have been used for fang-bearing contests like modern baboons. Many animals bear their fangs or canines when aggressive, and Heterodontosaurus possibly did this to intimidate rivals and scare off predators. Another animal that can be compared with Heterodontosaurus is the musk deer. However, their long saber-like canine teeth are grown for display, not combat. Musk deer grow huge teeth instead of growing antlers in order to over-awe rival males and to impress females.

Another possibility for serious dinosaur fights was among the sauropods. With their massive builds, any hit, no matter how light, likely would have caused some kind of damage. One modern long-necked animal that uses its body in sheer brute force is the giraffe – a rather placid-looking animal, but don’t make it angry. During the mating season, male giraffes will proceed to whack each other, swinging their long stiffened necks around like baseball bats, with the short stumpy horns on the tops of their heads inflicting some serious pounds-per-square-inch. Some sauropods, like Apatosaurus, had very massive thick necks in proportion with their body size. This leads some to speculate that Apatosaurus and its ilk used their bruiser builds to inflict bruises on others.

Apatosaurus louisae. © Jason R. Abdale. May 11, 2020.

But what about the opposite end of a sauropod? For many of them, the tail was just as long, or longer, than the neck. Tails can be effective weapons. Crocodilians and monitor lizards engage in tail whacking as a way to ward off threats. Many sauropods had thick tails, but others, like Diplodocus, have very long thin tails, and some believe that these long whip-like tails were indeed used like whips. A sharp crack across the side would make any Allosaurus wary.

Diplodocus carnegii. © Jason R. Abdale. May 11, 2020.

Of course, there are dinosaurs that almost certainly used their tails specifically for combat: the stegosaurs and the ankylosaurs. Evidence has been found for injuries inflicted by these animals upon predators, but I’m not certain if any evidence exists for stegosaur spikes or ankylosaur clubs being used upon members of their own kind. However, I can’t imagine it NOT happening.

Well, if you don’t have any biological weaponry on your side, like fangs, horns, spikes, clubs, or whatever, then raw physical force is your go-to option. There is evidence that predator species tangled with prey. The famous fossil find of a Velociraptor and a Protoceratops perpetually locked in a mutual mortal combat proves this. But this is likely an example of an attack-gone-wrong. Did dinosaurs of the same species physically grab onto and grapple with each other? Did dinosaurs wrestle, the way that some lizard species do today? Monitor lizards are a prime example of this, when two males will attack each other by essentially doing reptilian ju jitsu. Did dinosaurs wrestle? I’m not sure, but I’m leaning towards no, especially for the larger ones. Many small dinosaurs had thin delicate bones that could be easily broken, and many of the larger dinosaurs simply did not have the arm dexterity to do rough-and-tumble wrestling maneuvers the way that you see monitor lizards doing today. Furthermore, with their large size, being body-slammed to the ground would have done a lot of damage. As they say, the bigger they are, the harder they fall. Many dinosaurs show signs of physical trauma, including broken bones. Many led a very brutal life, with some skeletons being covered with injuries. For those reasons, I would say that most dinosaurs wanted to avoid intense physical combat.

Sometimes, the violence goes to its absolute extreme, and animals deliberately kill each other. Like intra-species fighting, intra-species killing has several motivating factors, both environmental and social. Animals kill each other to either reduce or totally eliminate competition over limited resources. Animals will also kill rivals to increase their own chances for mating, as well as killing the offspring of rivals to increase their own offspring’s chances for survival. As an example, new male lions that take over an existing pride will often kill all of the pride’s cubs in order to completely eliminate the legacy of the preceding male leader.

The most extreme form of intra-species combat is killing followed by cannibalism. Although it is largely taken for granted that prehistoric carnivorous animals ate their own kind under certain circumstances, there is little evidence to support this hypothesis. Some animals will kill and eat the young of other individuals in order to improve the chances of survival for their own young. Others may kill and eat their own kind out of starvation. Still others, like alligators, may view other members of their own kind as a legitimate food source, no different than any other prey item, and actively hunt, kill, and eat each other.

For a long time, it was believed with the firmest dogmatic conviction that the late Triassic dinosaur Coelophysis practiced cannibalism. However, this long-held belief has come into question upon closer examination of the famous Ghost Ranch specimens. It now appears that many of the bones which were previously believed to be inside the ribcages of others were actually lying underneath the ribcages. Furthermore, some of the bones previously identified as juvenile specimens have recently been re-identified as belonging to other reptile species. For the record, I am not stating that Coelophysis never engaged in cannibalism. I am stating that the evidence for cannibalism in this species is not as clear-cut as once believed and needs to be taken with a certain degree of doubt. If the study of paleontology has taught me anything, it’s that there is no such thing as dogma.

Coelophysis. © Jason R. Abdale. April 26, 2015.

Although there’s questionable evidence for cannibalism in Coelophysis, there is more compelling evidence in another dinosaur from the opposite end of the Mesozoic spectrum – Majungasaurus, an abelisaurid from Madagascar who lived at the very end of the Cretaceous Period. In 2007, scientists published findings that tooth marks discovered on some Majungasaurus bones matched the teeth in Majungasaurus’ jaws. So far, this is the only conclusive proof that a theropod species killed and/or ate the flesh of its own kind. I would like to say one thing, though: just because there’s evidence that an animal was cannibalized, that doesn’t necessarily mean that this individual was killed by the animal feeding off of it. As said before, scavengers will sometimes eat the dead bodies of their own kind. To them, meat is meat, no matter where it comes from. Others will not usually eat their own kind, but will do it if they’re desperate enough and cannot find other sources of food. As an example, most humans who have engaged in cannibalism do it out of necessity, not out of habit.

In conclusion, animals will hurt each other and kill each other for a variety of reasons, not only between species but also within species. Competition for mates, competition for food and territory, and establishing your position within the social hierarchy are all seen within the modern animal kingdom, and it’s highly likely that dinosaurs did the same.

Ornitholestes with feathers

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 of 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 likely 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 to. 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 through 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 damage to hatchlings, they preyed upon smaller animals like thick-boned mammals, and assuredly were seen scavenging carcasses left 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.

Torvosaurus: The Grizzly Bear of the Jurassic

NOTE: The original article concerning Torvosaurus was published on August 8, 2015. It was completely overhauled and re-published on December 9, 2020, with more information and new artwork.


The Morrison Formation of western North America, dated to the late Jurassic Period approximately 155 to 145 million years ago (MYA), is one of the richest fossil beds anywhere on Earth. Ever since the 1870s, the rocks that make up this formation have been intensively studied by paleontologists, geologists, environmental scientists, and amateur fossil hunters. It is from these rocks that hundreds of thousands of dinosaur bones have been uncovered, including the skeletons of some of the most famous dinosaurs ever like Allosaurus, Stegosaurus, and Diplodocus. Their skeletons are on display in museums around the world, and both their names and their physical appearance are instantly recognizable. For some species, so many specimens have been uncovered that we know practically everything that there is to know about their anatomy.

However, not all dinosaur species are so richly attested. There are several species from the Morrison Formation which are known only from one skeleton, or from partial remains, and in some cases from just a single tooth. One of these is a creature which has increasingly gained attention in popular media for the past ten or so years – a large meat-eating dinosaur named Torvosaurus.

Torvosaurus was one of the largest carnivorous dinosaurs that lived in the Morrison Formation. It measured 35 feet long, the same size as its contemporary Allosaurus, nicknamed “the Lion of the Jurassic”. However, there were many anatomical differences between these two species. Torvosaurus and Allosaurus may have lived in the same location at the same time, but Allosaurus was clearly the most numerous theropod within that environment. In fact, we have more fossils of Allosaurus than any other carnivorous dinosaur anywhere in the world. By contrast, very few remains of its competitor Torvosaurus have been found.

Discovery, Phylogeny, and Geographic Diversity

The first fossils of this animal were discovered in 1899 by Elmer Riggs in the “Freeze-out Hills” of southeastern Wyoming, located about eleven miles northwest of the town of Medicine Bow. The material consisted of bones from the left foot and right hand of a meat-eating dinosaur. These fossils were taken to the Field Museum of Natural History in Chicago, Illinois…where they remained untouched, collecting dust in storage, for nearly eighty years, until they were “found” and re-examined. The fossils were officially described in 2013 (Hanson and Makovicky, 2013). It is a tale that is unfortunately common in the realm of natural history museums: specimens are collected in the field, they are brought back to the institution, they are put on a shelf, and then they are completely forgotten about for decades until somebody finds them again. I have personal experience in this.

In 1971 at a place called Calico Gulch Quarry, located in northwestern Colorado, a single gigantic thumb claw was seen sticking out of the ground. Unfortunately, a search of the surrounding area resulted in a dead end – there were no other associated bones nearby (Galton and Jenson, 1979).

A Torvosaurus hand claw. Photo by Matt Heaton, FossilEra (June 3, 2015). Image used with permission. https://imgur.com/ppceR6a. https://www.fossilera.com/blog/torvosaurus-king-of-the-real-jurassic-world-unearthed.

Afterwards, this claw was shown to Prof. Jim Jensen of Brigham Young University in Provo, Utah. In response, the following year in 1972, he and a team of paleontologists turned their attention to a place called Dry Mesa Quarry, a very rich bonebed dated to the late Jurassic which was located in west-central Colorado, in an attempt to find anything that could match the claw that had been found a year earlier. There, they found the partial remains of a large meat-eating dinosaur which Jensen assumed (and that’s the key word here) belonged to the same animal as that enormous claw. The bones which were uncovered were remarkable in many respects, and the team were confident that they had discovered a new species. In 1979, Jim Jensen and his colleague Peter M. Galton published an article concerning this previously-unknown dinosaur, which was officially named Torvosaurus tanneri (“Nathan E. Tanner’s savage lizard”) (Galton and Jenson, 1979).

Fossils of Torvosaurus discovered at Dry Mesa Quarry, housed at Brigham Young University. Photo by Jim Kirkland, posted to Twitter (April 24, 2015). Image used with permission.

A preliminary description of Torvosaurus tanneri was given in Galton and Jenson’s original 1979 report, and subsequent descriptions were published in 1985 and 1991. The last of these studies claimed that the large thumb claw which had been found in 1971 should not be included with the rest of the Torvosaurus remains because it was isolated and found over 150 miles away from the rest of the fossils, and it could not be stated with absolute certainty that they belonged to the same species (Jenson, 1985; Britt, 1991).

Torvosaurus was obviously a meat-eating theropod dinosaur, but where exactly did it fit into the dinosaur tree? In 1985, Jim Jensen assigned this animal to its own family, Torvosauridae, which was intended to include any heavily-built theropod which possessed short-but-powerful arms as well as finger claws that were unusually large in proportion with the overall size of its arms (Jensen, 1985). However, by the late 1980s, it was recognized that Torvosaurus’ hip bones looked remarkably similar to those seen in Megalosaurus, a theropod from the middle Jurassic Period of Europe, and people began to wonder if Torvosaurus itself was a megalosaur; I know of one children’s book dated to 1989 which definitely says that it was (Sattler, 1989). In 1991, Brooks Britt stated that since many of Torvosaurus’ bones were similar to those in Megalosaurus, it therefore ought to be officially re-classified as a megalosaurid (Britt, 1991). It has remained within that theropod family ever since.

By the early 1990s, at least three individuals were identified as belonging to Torvosaurus (two adults and one juvenile) with the remains having been discovered in Wyoming, Utah, and Colorado. No complete specimen of Torvosaurus has been found, so it is difficult to precisely determine its length. However, most sources that I have seen place it as being somewhere between 30 to 35 feet long. Reports which gave a larger measurement of 40 feet or more are believed to have exaggerated its size (Bakker et al, 1992).

My Drawing

Within this article is a detailed drawing which I made of the North American species Torvosaurus tanneri. The drawing was made with No.2 and No.3 pencil on printer paper in 1:20 scale, and it measures 21 inches long, which would make the real-life animal 35 feet long. This illustration is actually the third iteration that I have made of this animal. The first drawing was made back in the middle 2000s when I was an undergrad in college. I knew nothing about Torvosaurus’ anatomy at the time, and all I did was stick a Megalosaurus head onto an Allosaurus body. Not very scientific. My second drawing which I made in 2015 was more in-line with what the animal looked like. However, it was based very heavily on Scott Hartman’s skeletal drawing of this animal, in particular its widely splayed legs, and I definitely did not want to be accused of artistic plagiarism. So, the time came for me to update my work once again. The image that you see here is the finished result based upon what we presently know of the creature’s anatomy.

Torvosaurus tanneri. © Jason R. Abdale (December 5, 2020).

I have also made a colorized version of this animal. I’ve always associated Torvosaurus with the color brown, which I blame on being impressioned by that 1989 children’s book that I read when I was a kid. Consequently, I’ve given it a color scheme of medium brown with a light tan underside and decked out with a camouflage pattern of light tan diamonds framed with black. I’ve also put black feet on it just for some added color contrast.

Torvosaurus tanneri, colorized. © Jason R. Abdale (December 5, 2020).

Torvosaurus comes from a more ancient lineage than Allosaurus. My Allosaurus drawing, which you can see here, was done in a sort of stippling effect to replicate the tiny round scales which have been found associated with Allosaurus skin impressions. Since Torvosaurus comes from an earlier and more primitive line of theropods, I decided to have its primitive nature reflected by giving it large crocodilian-like polygonal scales and rows of decorative dermal scutes. So far, no skin impressions have been found with Torvosaurus, or indeed with any megalosaur to my knowledge, so I cannot be certain if this scale texture is accurate or not.

The scutes on the feet were also changed. I have seen numerous posts on the internet claiming that the rectangular bird-like scutes which are traditionally seen in paleo-art, arranged in rows along the toes and metatarsals of dinosaurs is, in fact, very inaccurate. Therefore, I made these foot scutes smaller, and in so doing, they have taken on a somewhat crocodilian appearance. I must say that it fits with the overall appearance of the animal.

Torvosaurus Fossils in Europe and Africa

For nearly three decades, Torvosaurus fossils had been found exclusively within North America. Then in the year 2000, the bones of a large meat-eating dinosaur were found in Portugal’s Lourinha Formation, also dated to the late Jurassic Period. These fossils looked very similar to those that had been discovered in North America, but there were some slight differences in the anatomy. In 2014, it was officially named Torvosaurus gurneyi. Although known from incomplete remains, it’s evident that the European species has a more boxy skull than its North American counterpart (Hendrickx and Mateus, 2014).

Elsewhere in Europe, isolated fragments which were discovered in England within clay dated to about 155-150 MYA are believed to have come from a megalosaur. Although it was proposed that these fragments might belong to Torvosaurus, it could not be stated with any degree of certainty (Benson & Barrett 2009; Carrano et al. 2012).

In the 2010s, a partial maxilla (one of the bones that forms the upper jaw) was discovered in the Ornatenton Formation in northwestern Germany, at a spot which is not far from the ancient Teutoburg battlefield. An examination of this bone revealed that it was almost identical to the maxillae of Torvosaurus. However, there was one glaring red flag – the Ornatenton Formation occurred millions of years earlier than both the Morrison Formation of the United States and the Lourinha Formation of Portugal. The rock layers of both the Morrison and Lourinha are dated to the Kimmeridgian and Tithonian Stages of the late Jurassic Period, about 155-145 MYA. However, the rocks of the Ornatenton Formation of Germany are dated to the Callovian Stage of the middle Jurassic Period, approximately 166-161 MYA. During this stage, other megalosaur species roamed Europe such as Wiehenvenator, a megalosaur which lived in Germany during that same stage (Rauhut et al, 2016). Therefore, it is possible that this maxilla, which was identified as belonging to Torvosaurus, might be mis-identified. However, a tooth was also discovered within this maxilla, and it is this tooth which is diagnostic. This tooth, in particular the size and pattern of its serrations, does not match those known from either Megalosaurus or Wiehenvenator. A closer examination of the skull fragment showed features which were present in Torvosaurus, but which were absent in other megalosaur genera. Therefore, it is likely that these German fossils belong to an as-yet unconfirmed species of Torvosaurus. This adds further evidence to the idea that megalosaurs like Torvosaurus originated in Europe and then radiated outwards, spreading into North America, Africa, and Asia. It is also possible that the genus Torvosaurus originated in Europe during the middle Jurassic, and then migrated into North America during the late Jurassic. (Rauhut et al, 2020).

In Africa, fossil bones of a large meat-eating dinosaur were found in the Tendaguru Formation of Tanzania, dated to the late Jurassic Period. In 2011, these bones were ascribed as belonging to the super-family Megalosauroidea – it was unclear as to whether it was a megalosaur or a spinosaur (Rauhut, 2011). In 2020, theropod teeth that had been discovered in the Tendaguru Formation, which had formerly been given the unofficial classification of “Megalosaurus ingens”, were ascribed to Torvosaurus, thus potentially creating a third species, Torvosaurus ingens. However, more specimens would need to be collected before this can become officially recognized (Soto et al, 2020)

Torvosaurus in Popular Culture

From its official naming in 1979 up until the early 2010s, Torvosaurus was an obscure species that not many people knew about. Most dinosaur books didn’t even mention it, and the few that did didn’t have that much to say – scarcely a single paragraph in most cases – and much of it was general information that could be given to any theropod dinosaur.

Then in 2011, that changed. That year, the Discovery Channel released a mini-series entitled Dinosaur Revolution, which was intended to be a docu-drama series in the vein of Walking with Dinosaurs, but having a more comic book like feel to it. The second episode, “The Watering Hole”, takes place in Portugal during the late Jurassic Period, and Torvosaurus appeared on screen for the first time. It was portrayed as a massive terrifying beast with a huge head and enormous teeth and was the top predator in its environment. Virtually overnight, Torvosaurus got thrown into the spotlight and its notoriety sky-rocketed.

Comparative Anatomy: Allosaurus fragilis versus Torvosaurus tanneri

Torvosaurus tanneri lived alongside Allosaurus within the Morrison Formation of western North America, but Torvosaurus came from a more primitive line of theropods, the megalosaurs. During the middle Jurassic Period, about 170-160 MYA, these animals ruled the world as the dominant carnivores of their environments. They were the top predators in Europe, Africa, and as far away as China. However, by the late Jurassic, five million years later, these animals were being phased out by newer and more advanced theropods, such as the allosaurs. The megalosaurs had become outdated obsolete relics of a bygone era. By 150 MYA, only a couple of megalosaur species still remained worldwide, Torvosaurus being one of them – all of the others had gone extinct – and it seems that it too was just barely hanging on. By the end of the Jurassic Period five million years later, the last of the megalosaurs would die out.

Both Torvosaurus tanneri and Allosaurus fragilis had the same maximum length of 35 feet or thereabouts, but they possessed different physical proportions. These anatomical differences no doubt drove these two species to develop different hunting styles. Below is an overlay of an Allosaurus (blue) with a Torvosaurus (red) which shows the difference in body proportions. I will be getting into specifics as we go on.

Color contrast between Allosaurus fragilis (blue) and Torvosaurus tanneri (red) © Jason R. Abdale (December 5, 2020).

As a member of the family Megalosauridae, Torvosaurus retained some anatomical features that were primitive compared to more advanced theropods living at that time like Allosaurus. It was also probably less intelligent than Allosaurus as well, although not by much apparently, since Allosaurus wasn’t exactly the brightest bulb either, according to studies of its brain (Allosaurus: A Walking With Dinosaurs Special).

Torvosaurus’ head was much larger in proportion to body size than Allosaurus’ head was. In fact, Torvosaurus’ head was 1.5 times bigger than the biggest Allosaurus skull that we have found. Torvosaurus’ teeth were also freakishly huge, so big that it’s hard to imagine how they could even fit into its mouth. I should state, however, that most museum mounts show Torvosaurus as having much longer teeth than it had in reality because the teeth are extended out of their sockets and half of the root is exposed. Yet even if you were to shorten the teeth to their correct length, the sight is still a fearsome one to behold. Its demonic grinning maw of over-sized steak knives reminds me of the ape-beast “Fluffy” from the 1982 movie Creepshow. By contrast, Allosaurus had very small teeth in proportion to skull size. However, the one thing that both of these animals had in common was the fact that they had flat skulls with sideways-facing eyes. These animals had NO depth perception at all, and they would almost assuredly have to slightly bob their heads back-and-forth from side-to-side, like a shark swimming or a dog scent-tracking, in order to get an alternating left-right-left-right picture of what was in front of them.

Of course, a big heavy head needs a strong neck to hold it up. As such, Torvosaurus’ neck was short and thickly muscular, while Allosaurus’ neck was longer and more sinuous. Allosaurus had the ability to flex its neck to a great degree, especially in an up-down motion (this is known as “ventral flexion”), but the thick layers of muscle on Torvosaurus’ neck would have greatly reduced its mobility.

Torvosaurus had short squat arms and small hands, but the claws are mind-bogglingly massive. When your head is so large and weighs so much, and the majority of your killing power is centered on your jaws, your arms become rather un-necessary. It seems that Torvosaurus was a Jurassic analog of a tyrannosaur, since it had an unusually large head and unusually small arms in proportion to its body. By contrast, Allosaurus also had huge claws, but it also had longer arms and huge hands to go with them; obviously these were used for grabbing and ripping things. Why Torvosaurus, which possessed such short arms, would need such huge claws is beyond my comprehension.

Torvosaurus’ body was long and shallow and possessed an elongated trunk with a low back. By contrast, the body of Allosaurus was short and deep, with a compressed trunk, an arched back, and a deeper ribcage. This is a good body structure for an animal that has a large heart and lungs, indicating an active lifestyle. A small shallow body makes me wonder if a large heavy animal like Torvosaurus ran out of breath quickly. Allosaurus also had large well-built hip bones, which served as attachment points for the muscles that pull the legs back and forth. This means that Allosaurus’ legs were very strong and had the ability to run at full-tilt if it wanted to. By contrast, Torvosaurus’ hip bones were small and not as robustly built – not a design suitable for a runner.

Allosaurus had a tail that was slightly longer than what you would expect when compared with its overall body. This is often given as a definite feature of an agile runner, which needs a long tail to balance the body when it’s making quick tight turns. The tail of Torvosaurus, while long, would probably have to be very thick in order to balance out the weight of the front half of the body. The thick layers of muscle meant that it would not have been able to pivot back-and-forth as easily as the tail of Allosaurus. No tight turns for this beast.

On the whole, Torvosaurus seems to be rather front heavy (good for physically slamming its jaws onto prey) while the weight on Allosaurus appears to be more evenly distributed. Of course, an animal which weighed that much would need some seriously thick legs in order to hold up all of its massive bulk. As such, Torvosaurus’ legs were noticeably thick and robust, far more so than the legs of Allosaurus.

If you look at the detailed picture above, you may think that Torvosaurus’ legs look far too short in proportion with the rest of its body. Surely this was a mistake and the legs ought to be longer, right? Sorry, but the legs are indeed the correct size. It’s true that Torvosaurus’ legs were shorter than Allosaurus’ legs, but they were only slightly shorter. It’s just that Torvosaurus’ head, body, and tail are so utterly huge and massive that the legs look short and under-developed by comparison. It’s an optical illusion. The combination of thick legs, a shallow stretched-out ribcage, and unpronounced hip bones gives Torvosaurus a low-slung appearance. In fact, while I was looking at the entire body, I was struck that Torvosaurus’ build was reminiscent of a rauisuchid. The rauisuchids were a group of archosaurus from the Triassic Period which were related to modern-day crocodiles. Unlike their prestosuchid relatives such as Prestosuchus and Saurosuchus, which were exclusively quadrupedal, the rauisuchids might have been bipedal. The skeletons of rauisuchids such as Postosuchus show a large head, a heavily-built body, short stumpy arms, and short thick legs balanced out by a long tail. The rauisuchids were one of a few groups of non-dinosaurian reptiles which were experimenting with walking on two legs. Torvosaurus’ overall anatomy seems to harken back to an earlier time.

In total, one gets the impression that Torvosaurus was an animal that was not designed for the active chase. It seems that Torvosaurus was primarily an ambush hunter that was built for short-distance bursts, lunging forwards in a straight line, who relied upon its jaws to do most of the work and killing the prey through sheer impact force and by causing deep lacerations with its ungodly-sized choppers. By contrast, Allosaurus was a very active energetic predator who was capable of impressive speed and quick agile turns. If Allosaurus really was “the Lion of the Jurassic”, as it is commonly referred to, then Torvosaurus was the grizzly bear of the Jurassic.



  • Sattler, Helen Roney. Tyrannosaurus Rex and its Kin. Illustrated by Joyce Ann Powzyk. New York: Lothrop, Lee, & Shepard Books, 1989.


  • Bakker, Robert T.; Siegwarth, James; Kralis, Donald; Filla, James. “Edmarka rex, a new, gigantic theropod dinosaur from the middle Morrison Formation, Late Jurassic of the Como Bluff outcrop region”. Hunteria, volume 2, issue 9 (1992). Pages 1-24.
  • Benson, Roger B. J.; Barrett, Paul M. 2009: “Dinosaurs of Dorset: Part I, the carnivorous dinosaurs (Saurischia, Theropoda)”. Proceedings of the Dorset Natural History and Archaeological Society, volume 130 (2009). Pages 133-147.
  • Britt, Brooks. “Theropods of Dry Mesa Quarry (Morrison Formation, Late Jurassic), Colorado, with emphasis on the osteology of Torvosaurus tanneri”. Brigham Young University Geology Studies, volume 37 (1991). Pages 1-72. http://geology.byu.edu/home/sites/default/files/geol-stud-vol-37-britt.pdf.
  • Carrano, Matthew T.; Benson, Roger B. J.; Sampson, Scott D. “The phylogeny of Tetanurae (Dinosauria: Theropoda)”. Journal of Systematic Palaeontology, volume 10, issue 2 (2012). Pages 211-300.
  • Galton, Peter Malcolm; Jensen, James A. “A new large theropod dinosaur from the Upper Jurassic of Colorado”. Brigham Young University Geology Studies, volume 26, issue 1 (1979). Pages 1-12. geo-stud-vol-26-part-2-galton-jensen.pdf (byu.edu).
  • Hanson, Michael; Makovicky, Peter J. “A new specimen of Torvosaurus tanneri originally collected by Elmer Riggs”. Historical Biology, volume 26, issue 6 (2014). Pages 775-784. https://www.tandfonline.com/doi/abs/10.1080/08912963.2013.853056?scroll=top&needAccess=true&journalCode=ghbi20.
  • Hendrickx, Christophe; Mateus, Octavio. “Torvosaurus gurneyi n. sp., the Largest Terrestrial Predator from Europe, and a Proposed Terminology of the Maxilla Anatomy in Nonavian Theropods”. PLOS One, volume 9, issue 3 (2014). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3943790/.
  • Jensen, James A. “Uncompahgre dinosaur fauna: A preliminary report”. Great Basin Naturalist, volume 45, issue 4 (1985). https://scholarsarchive.byu.edu/gbn/vol45/iss4/8/.
  • Rauhut, Oliver W. M. “Theropod dinosaurs from the Late Jurassic of Tendaguru (Tanzania)”. Special Papers in Palaeontology, volume 86 (2011). Pages 195-239.
  • Rauhut, Oliver W. M.; Hübner, Tom R.; Lanser, Klaus-Peter. “A new megalosaurid theropod dinosaur from the late Middle Jurassic (Callovian) of north-western Germany: Implications for theropod evolution and faunal turnover in the Jurassic”. Palaeontologia Electronica, 19.2.26A (2016). Pages 1-65.
  • Rauhut, Oliver W. M.; Schwermann, Achim H.; Hübner, Tom R.; Lanser, Klaus-Peter. “The oldest record of the genus Torvosaurus (Theropoda: Megalosauridae) from the Callovian Ornatenton Formation of north-western Germany”. Geologie und Paläontologie in Westfalen, volume 93 (2020). Pages 1-13. https://www.lwl.org/wmfn-download/Geologie_und_Palaeontologie_in_Westfalen/GuP_Heft_93_14_Seiten.pdf.
  • Soto, Matías; Toriño, Pablo; Perea, Daniel. “A large sized megalosaurid (Theropoda, Tetanurae) from the Late Jurassic of Uruguay and Tanzania”. Journal of South American Earth Sciences, volume 98 (2020): 102458.


  • Allosaurus: A Walking With Dinosaurs Special. BBC, 2000.
  • Dinosaur Revolution. Episode 2 – “The Watering Hole”. The Discovery Channel, 2011.

Dinosaur Day 2015 at the Garvies Point Museum

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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.

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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.

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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 re-scanned 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 forwards 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.