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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.
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
This is an idea that I’ve had knocking around in my head for a while. A recent post by fellow paleo-blogger Chase (who has a special interest in eastern North American Mesozoic life) on Dryptosaurus has spurred me to action in terms of writing a short article as well as doing some much delayed artwork.
For those of you who are too lazy to read Chase’s excellent article about this animal, Dryptosaurus was a medium-sized theropod dinosaur, approximately 20-25 feet long which lived in eastern North America during the late Cretaceous Period. Unfortunately, our total knowledge of this dinosaur is known from only a few fragmentary remains, including a hand claw that seems way too big in proportion with the rest of this animal’s body.
For as far back as I can remember, Dryptosaurus was classified as a tyrannosaur. But recently, I have my doubts about this classification. Even very primitive tyrannosaurs such as Guanlong and Proceratosaurus don’t have some of the anatomical features that Dryptosaurus appears to possess.
My curiosity centered around that claw. It didn’t look like a tyrannosaur claw – to me, it looked more like an allosaur claw. An unusually large hand claw also reminded me of another animal – Megaraptor, from South America. Originally, this was thought to be a gigantic dromaeosaur, but then it was hypothesized to be more closely related to the allosauroids, like Neovenator, Giganotosaurus, and Carcharodontosaurus. The allosaur-like claw would make this classification a good fit. Then I saw a picture of the skeletal remains of Australovenator, a megaraptorid that was discovered in (you guessed it) Australia. I immediately noticed similarities in the hand and body structure between Australovenator and Dryptosaurus.
- Massive thumb claws in comparison with the other finger claws.
- Short muscular arms and huge hands
- Slender lower jaws with small closely-packed hook-shaped teeth.
What I find really interesting is that in 2012, a hypothesis was put forward by Fernando Novas and other paleontologists that the megaraptorids might actually be extremely primitive members of the tyrannosaur family. In 2014, fragments from a juvenile Megaraptor were discovered, including part of the upper jaw. The structure of the juvenile Megaraptor’s maxilla was very similar to the structure of the dentary from Australovenator. That year, Juan Porfiri re-iterated Novas’ hypothesis that the megaraptorids might be primitive tyrannosaurs.
So, with all of that being said, I hypothesize that Dryptosaurus was a member of Megaraptora, which would make it the first of its kind found within North America.
How did Dryptosaurus feed? The large hook-shaped claws and the small hook-shaped closely-packed teeth seem to indicate that Dryptosaurus and other megaraptorids were fish-eaters. The fossils of Dryptosaurus were discovered in the New Egypt Formation and the Navesink Formation, the later of which is known for both dinosaur fossils as well as fossilized shells. Also, Australovenator was found in deposits that indicate a swampy still wetlands environment, full of bivalves, fish, and turtles. The fact that this megaraptorid was found in a water-rich environment full of aquatic life leads me to suspect that Dryptosaurus might have had a similar lifestyle.
To conclude this short article, I have a drawing of the enigmatic Dryptosaurus portrayed as a megaraptorid rather than as a typical often-illustrated tyrannosaurid. Who knows – maybe my less-than-scholarly idea about Dryptosaurus being a fish-eating megaraptorid will prove out to be right. Only time and the discovery of more specimens will tell.
Keep your pencils (and minds) sharp, everybody.
Unless you’ve been hiding under a rock somewhere, then you’ve likely heard that there will be a fourth Jurassic Park movie released this year called Jurassic World. There have been rumors of a fourth movie ever since the third one came out when I was a freshman in high school fourteen years ago. However, this movie was stuck in what’s known as “development hell” ever since that time.
Among the new features of this movie is a mosasaur, which I am totally geeking out about since I LOVE mosasaurs! They are some of my favorite prehistoric animals. However, the creature that is getting the most press is a large tyrannosaur-esque creature which goes by the name of either Diabolus rex or Indominus rex, depending on which website you look at. This creature is a genetic hybrid of a T. rex, a Velociraptor, a venemos pit viper, and a cuttlefish. I wasn’t really sure how something like that would look, and there were a few speculative concept drawings and photoshopped images circulating on the internet. However, I’ve recently seen a picture of what the beast in question actually looks like, and all I can say is…wow, and not “wow” in a good way, either.
Actually, the exact words that came out of my mouth when I first saw a clear picture of it was, “Wow, that’s ugly enough to be an abelisaur!” I’m sure fans of the abelisaurs are going to either laugh at that statement or hate me for it. The abelisaurs were a group of primitive carnivorous dinosaurs that lived in South America, Africa, and Europe during the middle to late Cretaceous Period. They are closely related to the ceratosaurs, another primitive theropod family. Both abelisaurs and ceratosaurs have osteoderms – bony bumps embedded in the skin. They all adhered to a more or less uniform body form: large boxy head, short puny arms that would make tyrannosaur arms look “pumped”, and thin slashing teeth. The most famous and most easily recognized member of the abelisaur family is Carnotaurus, “the meat-eating bull”, which was featured as the main villain in the computer animated Disney movie Dinosaur back in 2000. However, based upon the hybrid dinosaur’s skull structure, it actually bears more of a resemblance to another famed abelisaur, Majungasaurus (also called Majungatholus, but that name has since fallen out of usage, since it has been proven that the two are actually the same species).
The second thing that I said when I saw it was Danny Glover’s famous quote from the movie Predator 2: “You are one ugly mother-“.
In truth, I was disappointed with the animal’s appearance. To my sense of aesthetics, it appeared ugly, crude, more dragon-like than dinosaur-like. To see a picture of the beast, click here.
- “Abelisauridae”. http://en.wikipedia.org/wiki/Abelisauridae
- “Ceratosaurus”. https://dinosaursandbarbarians.wordpress.com/2013/11/27/ceratosaurus/
- “The presence and usage of osteoderms in dinosaur paleo-art”. https://dinosaursandbarbarians.wordpress.com/2013/07/26/the-presence-and-usage-of-osteoderms-in-dinosaur-paleo-art/
Today, I learned some very heart-breaking news. Stephen Czerkas, one of the true greats of paleo-art, recently died. He was 63 years old. The cause of death was liver cancer.
Czerkas was famous for his life-sized dinosaur sculptures, and he developed a very distinctive style – you could immediately recognize a Czerkas sculpture. His horned Allosaurus graced many children’s dinosaur books and TV shows, and his life-sized Carnotaurus was truly epic. However, his most famous work was his pack of Deinonychus raptors. Czerkas was one of the first paleo-artists to have his theropods adorned with feathers, and he also discovered that at least some species of sauropods had spines on their backs, which was incorporated into the BBC series Walking with Dinosaurs.
To all of those dino-lovers of my generation – those who came of age during the 1990s – Stephen Czerkas’ work would have been an integral part of your life. Czerkas was one of THE paleo-artists of the late 1980s and early 1990s, the time when I was becoming exposed to dinosaurs and other prehistoric life. The sheer awesomeness of his work influenced me profoundly both as an artist and as a person who dedicated his life to studying the past.
The paleontological and artistic spheres have lost one of the true greats of their domain, but his work will last and I dare say will continue to influence artists, scientists, and children generations from now.
RIP Stephen Andrew Czerkas (1951-2015) 😦
A series of dinosaur tracks were found by a hiker in Moab, Utah. These footprints were discovered in 2009, but it had been kept secret until recently. These tracks are dated to 125 million years ago, the early Cretaceous Period, when creatures like Iguanodon dominated much of the Northern Hemisphere. Among the 200 or so footprints found here might be those of a large raptor, which is very exciting. Trackways include not only dinosaurs, but also a mudslide from a crocodile.
Volunteers and workers from various government divisions are working on the site to get it ready for public display. The Bureau of Land Management wants to have the site ready by October 2014.
- Nature World News. “125-Million-Year-Old Dino Tracks Discovered in Utah”, by Jenna Iacurci (August 21, 2014)