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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 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.

ornitholestes-with-feathers

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.

Requests for articles and artwork

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:

  • Abelisaur
  • Allosaurus courting
  • Allosaurus head
  • Allosaurus walking
  • Australovenator
  • Deinonychus
  • Dinosaurs of Texas
  • Dracorex head
  • Elasmosaurus
  • Iguanodon head
  • Neovenator
  • Pachycephalosaurus keeping shelter
  • Styracosaurus
  • 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.

News: New raptor dinosaur discovered in Canada

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

 

Dryptosaurus: A possible North American megaraptorid?

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.

Dryptosaurus

Keep your pencils (and minds) sharp, everybody.

Anzu

Anzu

Anzu was a caenagnathid from the Hell Creek Formation. I wrote of its discovery and naming in an earlier post that you can read here. The caenagnathids were a primitive group of oviraptorosaurs, the “egg thief” dinosaurs. Anzu is so far the largest species from this group found in North America, measuring 10-13 feet long from nose-tip to tail-tip, and it was also one of the last of its kind.

In terms of this picture, the chicken-like wattles are purely conjecture on my part, as are the types of feathers and color patterns.

Acheroraptor, revised

In December 2013, scientists announced the discovery of a new raptor dinosaur from the Hell Creek Formation, which they named Acheroraptor. When news first came out about it, I wrote a post, which you can read here. Ever since I put it up, it has remained one of my most-viewed posts on this website. Accompanying the article, I included a drawing, which you can see below:

Acheroraptor

I very quickly hashed this drawing out, and to tell you the truth, I wasn’t at all pleased with it, despite the fact that the post got a heck of a lot of hits. It was an improvement (though not by much) of an earlier feathered raptor drawing that I had done: Troodon. Due to the rushed need to get a drawing out as quickly as possible, I didn’t spend a whole lot of time coming up with a unique color scheme. So, the color pattern on the above drawing and the Troodon drawing are almost identical. One feature that I included right away was a fluffy feathery ridge running down its back. The head is rather scary and menacing looking, and somewhat boxy – very Jurassic Park-ish. In retrospect, since Acheroraptor was a close relative of Velociraptor, its head probably didn’t look like this.

Today, I finished a revised and probably more accurate drawing of what Acheroraptor would have looked like. I kept the overall shape, but I changed the shape of the head and I put some more detail in the arm feathers. The most obvious change is the striking black-white color scheme, which I based upon the coloration of the Northern Goshawk. If this drawing was in color, I would have given my creature transparent glassy red eyes.

Acheroraptor revised

Making this drawing was a real pleasure, and I’m surprised that doing it didn’t take as long as I had expected – only five days. Please comment on my work and on the “before-after” transition. Keep your pencils sharp!

News: “Egg thief” dinosaur from Hell Creek FINALLY named!

All I can say is “It’s about time!!!”

After sitting around for years without an official description, a bird-like dinosaur found in the Hell Creek Formation has finally been given a name. I’m very happy about that. What I’m not happy about is the name that was actually chosen – Anzu wyliei, a name that I REALLY don’t find appealing.

Last year, I read that a bird-like dinosaur more commonly found in the Gobi Desert was discovered in North America. Furthurmore, I found out that it was actually on display in Pittsburgh, and had been for several years – it shows just how horribly behind the times I am. However, I was aghast when I learned that this creature didn’t even have a name. I asked “What the hell’s been taking them (meaning the scientists) so long?” Well now the wait is over.

Anzu (I’m actually shuddering as I’m writing the name – I just loathe the way that it sounds) was a member of a family of dinosaurs called Caenagnathidae. The caenagnathids were a sub-group within a super-family of theropods known as the oviraptorosaurs, or “egg thief lizards”. These very bird-like dinosaurs are well-known from Asia, especially China and Mongolia, but they are almost unheard of anywhere else. Oviraptorosaurs ranged in size from five to twenty-five feet long, and might have evolved from the ornithomimids, the “bird mimics”, commonly known as “ostrich mimics” due to their ostrich-like appearance. The most famous of them was Oviraptor, “egg thief” found in Mongolia by the adventurous Roy Chapman Andrews. The name came from the discovery of a partial skeleton lying on top of a nest of eggs. Chapman and his colleagues thought that the animal was in the process of plundering the nest when it was killed. It wasn’t until later when the insides of the eggs were carefully examined that paleontologists discovered that the preserved embryos were that of other oviraptorosaurs. This animal wasn’t preying upon the eggs – it was the mother.

The caenagnathids have had a confusing history, dating back to the early 20th Century. In the early 1920s, the famous paleontologist Charles W. Gilmore was fossil hunting in Alberta, Canada, when he found the remains of a new and strange creature known only from a pair of incomplete hands. In 1924, he gave them the name Chirostenotes pergracilis. Another dinosaur was named based upon an incomplete foot, and it was called Macrophalangia. By the late 1970s, scientists realized that these two animals were the same, and Chirostenotes became the official name.

But what sort of creature was Chirostenotes? It was clearly a theropod – a bipedal meat-eater – but the bone structure was unlike any other theropod known. In fact, it looked very bird-like. It was believed that Chirostenotes was most similar to another mysterious dinosaur called Elmisaurus, which came from Mongolia during the late Cretaceous Period.

For a long time, Chirostenotes was the only North American oviraptorosaur, specifically a caenagnathid. It was found in rocks dated to the Campanian Stage (80-70 MYA) of the Cretaceous Period. Then, in the 1960s, another oviraptorosaur – and a very early primitive one at that – was found, named Microvenator, “the little hunter”. It lived in Montana approximately 100 million years ago alongside Deinonychus and Tenontosaurus. This showed that oviraptorosaurs were present in North America for much longer than previously suspected.

It had been believed for a while that Chirostenotes and its kind had become extinct a millions of years before the dinosaurs’ exinction. However, in the 1990s, fossils of an animal which might have been an oviraptorosaur were found in Montana in rocks that dated to the very end of the Cretaceous Period – the famous Hell Creek Formation, the home of Tyrannosaurus rex. No oviraptorosaur fossils had ever been found there before. In 1994, Canadian paleontologist Phil Currie, an expert on theropod dinosaurs, published a paper on a fragment of a lower jaw found at the “Sue” site. Based upon it’s shape, it was obviously an oviraptorosaur, specifically a member of the family Caenagnathidae. However, this specimen was significantly larger than any previously-known specimens. It could have been a larger specimen of Chirostenotes, or it might have been a new species.

The problem was that Chirostenotes was known only from a few fragmentary finds – a complete or nearly-complete skeleton had never been found. Then, a pair of incomplete skeletons were found in Hell Creek, and were described in 1995. Ever since then, they have been housed in the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania. The staff at the Carnegie Museum even took these two skeletons, composited them together, and put the creature on display for the public! However, the creature still did not have a definitive identification. Paleontologists were uncertain as to whether “the Triebold specimens”, as they were called, were Chirostenotes or maybe another larger species.

In 2011, Matt Lamanna and other scientists announced that they were studying the Hell Creek oviraptorosaur in more detail. Based upon a preliminary view, they stated that it was very similar to Chirostenotes, but they shied away from going so far as to claim that it was a distinct species.

In 2013, a team from the Burpee Museum (the same museum famous for “Jane”, which might be either a Nanotyrannus or a juvenile T. rex, depending on who you ask) discovered the partial skeleton of a caenagnathid oviraptorosaur near the small town of Ekalaka, Montana. The bones were so large that they originally thought that they had found a T. rex; Professor Thomas Holtz of Maryland rushed to the site and confirmed the animal’s identity. This specimen was even larger than the Triebold specimens in the Carnegie Museum. It was affectionately nicknamed “Pearl”.

In 2014, Matt Lamanna and three other colleagues published a paper on the Triebold specimens collected from North and South Dakota. After an exhaustive analysis of the bones, they concluded that the Triebold specimens were not Chirostenotes or Caenagnathus, but constituted an entirely separate genus. They called it Anzu wyliei. According to Lamanna’s own report, the dinosaur was named after Anzu, a feathered bird-like demon from Mesopotamian mythology, and measured somewhere between ten to fifteen feet long.

What the heck does a Mesopotamian demon, feathered or otherwise, have to do with a North American dinosaur? I can understand if the fossils were found in Iraq, but they weren’t. I would actually be highly surprised if ANY dinosaur fossils were uncovered in Iraq. It would be a lot more fitting if it was given a traditional Greco-Latin name, something like Dakotaraptor, or maybe even named after a being from native Sioux Indian folklore, like Wakinyanoraptor (“Wakinyan” is the Sioux name for the thunderbird sky spirit).

But then again, what the heck does the white-skinned feathered serpent god from central Mexico have to do with an unusually large pterosaur from Texas, which neither looked anything remotely like a serpent, nor had feathers, nor came from Mexico? I’m talking about Quetzalcoatlus, for those of you who haven’t caught on. So I suppose I shouldn’t be too harsh. Still, Anzu … it just sounds SOOOOO wrong. Unfortunately, we’re all stuck with it.

The specimen uncovered by the team from the Burpee Museum is also likely a specimen of Anzu.