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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.
I know that it’s been a while, but here is my latest addition of paleo-art to this blog. Behold – Alamosaurus, a behemoth of a sauropod that roamed Texas during the late Cretaceous Period. Alamosaurus was a member of the “titanosaur” family, which is more well-known from species found in South America, Europe, and Africa. No complete skeleton of Alamosaurus has ever been found, so we only have a rough idea about what it looked like, and we’re not even sure how big it was when it was fully grown. The most common estimate that I’ve seen is that it was somewhere around 65 – 70 feet long, but it might have been bigger than that.
Because no complete specimen of Alamosaurus has been found, you’re going to see a lot of variation in paleo-art reconstructions of this animal. From what I’ve gathered, a lot of the pictures that are visible on the internet these days are inaccurate. Alamosaurus had a massively thick neck, but its tail was not correspondingly long or massive. The presence of osteoderms along its back are a guess, since other titanosaurs, notably Saltasaurus, were known to have had them.
In January, I published a post in which I hypothesized that Dryptosaurus, a Late Cretaceous theropod found in Eastern North America, was misidentified. For the longest time, Dryptosaurus was believed to be a tyrannosaur, possibly a rather primitive one. However, with discoveries made within the past two decades, I came to question this taken-for-granted identification.
The megaraptorids are a weird bunch, since nobody knows for certain where exactly they fit. When the type species Megaraptor was found in Argentina by the paleontologist Fernando Novas, it was believed to be a giant dromaeosaur – hence the “raptor” name – measuring at least 25 feet long, which would have made it the largest raptor ever discovered up to that point.
Then in 2010, a study conducted by Benson, Carrano, and Brusatte claimed that the megaraptorids were more related to the allosaurs than the dromaeosaurs. Specifically, the study stated that the megaraptorids were very closely related to Neovenator. It certainly helped when a complete arm was discovered, which showed that the 15-inch long killing claw didn’t come from the foot, but actually came from the hand, similar to Baryonyx.
In 2012, Fernando Novas conducted his own study of Megaraptor and its relatives. He and his colleagues said that while Neovenator and the carcharodontosaurids were close relatives of each other, and that both belonged within the superfamily Allosauroidea, he also stated that Megaraptor and its ilk did not belong in this group. Instead, he stated that the megaraptorids were actually coelurosaurs, and were more closely related to the tyrannosaurs.
In 2014, more evidence to back up a connection between the megaraptorids and the tyrannosaurs came to light when a juvenile Megaraptor was described by J. D. Porfiri, Fernando Novas, and others. Porfiri even placed Eotyrannus, long thought to be a primitive tyrannosaur, as a member of Megaraptora. Because of this, the megaraptorids are thought of by some to be either close relatives of the tyrannosaurs or possibly even an offshoot of the tyrannosaur family.
As a result of learning all of this, I began to wonder if Dryptosaurus was actually a member of Megaraptora, and I published a post saying as much. However, Chase Brownstein, a paleontologist specializing in eastern North American dinosaurs who works at the Stamford Museum, and who I have been in contact with on a fairly regular basis, immediately challenged my hypothesis. He stated that while Dryptosaurus might have had some features that made it visibly look like a megaraptorid, the animal itself was not a member of the megaraptorid family. He put these physical similarities down to convergent evolution – when two different kinds of animals evolve in such a way that they look similar to each other. Convergent evolution is most often brought about by environmental conditions, which infers that both Dryptosaurus and the megaraptorids lived in similar environments, had similar lifestyles, or both.
I recently discovered that my hypothesis was not unique. An internet search showed that at least by 2014, other people had been looking at Drytposaurus with questioning eyes and were wondering if it was actually a megaraptorid. Damn, this happens all the time. Every time that I think I’ve come up with a new idea, it turns out that some has already thought of it before. Oh well.
While my assessment of Dryptosaurus as a megaraptorid may or may not be correct – we’ll never know the real answer until more Dryptosaurus specimens are found and analyzed – I feel that my drawing of Dryptosaurus is nevertheless accurate. A phylogenic analysis conducted in 2013 placed Dryptosaurus between Raptorex (which, according to some, is actually a misidentified juvenile Tarbosaurus) and Alectrosaurus. Both Raptorex and Alectrosaurus had similarly-shaped skulls, so I gave my rendition of Dryptosaurus a skull that was very similar to these two species. I gave it the massive thumb claws that are seen on the holotype specimen. I also gave my creation a mane of fibrous feathers, since many primitive three-fingered tyrannosaurs are known to have had feathers covering some or most of their bodies.
Figure 1. Skull of Alectrosaurus. Illustration by Tracy Ford (I think). http://www.paleofile.com/Dinosaurs/Theropods/Alectrosaurus.asp.
Figure 2. Skeleton of Raptorex. Photo by Kumiko (September 24, 2011). https://commons.wikimedia.org/wiki/File:Raptorex_vs_Psittacosaurus.jpg.
Figure 3. My own drawing of Dryptosaurus.
Behold my masterpiece.
This is the fifth T. rex drawing that I’ve posted to this blog, and it is the hardest drawing that I have ever had to make. Every individual scale was done by hand, one by one. This drawing took me months to finish. To give you a better idea about the utterly insane amount of detail, the actual drawing of the dinosaur itself from the tip of its nose to the tip of its tail measures precisely 24 inches. Most of the drawn scales measure at only one millimeter in diameter.
As you can see, it is done in the same pose as my previous two full-body T. rex drawings, but I made some noteable improvements:
- Slightly changing the shape of the skull – my original one looked a little too much like Tarbosaurus rather than Tyrannosaurus.
- Not making the face as shrink-wrapped as the original head drawing was.
- Making the neck more detailed and fuller.
- Changing the position of the hands to be more anatomically correct.
- Making its body fatter – the original was too skinny.
- Making the tail thicker and fatter to properly counter-balance the now-heavier front half of the body.
- Changing the shape of the feet.
This drawing was made on several sheets of 8.5 x 11 printer paper, with just an ordinary No. 2 pencil…and a whole lot of patience.
A while back, I asked you, the reader, if you had any requests for articles and artwork that you would like me to do, but I received no reply. However, I recently looked at the search terms that come up on this blog’s administration page. Most of the terms concern subjects that I’ve already written about or illustrated, but there were a few others on subjects that I haven’t touched yet, or have only just alluded to. Terms which showed up frequently were (in order of frequency):
- Alamosaurus (12)
- Caenagnathus / Chirostenotes (9)
- Pterosaurs (8)
- Liopleurodon (7)
- Mosasaurs (6)
- Dakotaraptor (5)
- Velociraptor (in color) (5)
- Suchomimus (4)
- Carnotaurus (3)
- Oviraptor (3)
Others caught my interest as potential future art or writing projects, including:
- Allosaurus courting
- Allosaurus head
- Allosaurus walking
- Dinosaurs of Texas
- Dracorex head
- Iguanodon head
- Pachycephalosaurus keeping shelter
- Triceratops eating
- Tyrannosaurus juvenile
- Lacrimal horns on dinosaurs
- Mesozoic turtles
- What dinosaurs lived on Long Island?
The last three sound like interesting research projects. Anyway, based upon what I have seen, I think that I can gauge what you would like me to do. So, I’m treating these statistics pretty much like a to-do schedule. Right now, I’m really hammering on a super-detailed drawing of a full-body T. rex, which I hope to have finished within one or two weeks, and then put up here for you to admire and comment on. After that, I’ll focus on the items on these two lists – the “frequency list” will take priority. I’m happy to say that some of these terms are on things that I’ve had in the back of my mind for a while, so this will give me the impetus to do them. Take care everybody, and keep your pencils sharp.
A new feathered terror has been added onto an ever-growing list. Boreonykus, “the northern claw”, is a new species of dromaeosaurid theropod discovered in Canada in rocks dated to 72 MYA. It was one of the larger of the Late Cretaceous rapors, with an estimated length of 13 feet. Its contemporaries would have been such well-known creatures as Albertosaurus, Daspletosaurus, Dromaeosaurus, Ornithomimus, Chasmosaurus, Styracosaurus, Centrosaurus, and Parasasaurolophus.
For more info, look here:
Philip R. Bell and Philip J. Currie (2016). “A high-latitude dromaeosaurid, Boreonykus certekorum, gen. et sp. nov. (Theropoda), from the upper Campanian Wapiti Formation, west-central Alberta”. Journal of Vertebrate Paleontology, vol. 36, no. 1; doi: 10.1080/02724634.2015.1034359
Chasmosaurus was a common genus of ceratopsian dinosaur found in North America, especially Alberta, Canada circa 75 MYA. This creature is so recognizable due to its rectangle-shaped frill that it has given its name to a whole slew of other ceratopsians that are related to it – the “chasmosaurine” ceratopsians.
Made with regular no. 2 pencil on plain white printing paper. The actual drawing of the creature from the tip of the beak to the tip of the tail measures just a smidge over seven inches. Scanned at 600DPI to show as much of the detail as possible.
Keep your pencils sharp, everybody.