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Tag Archives: Late Cretaceous

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Caenagnathus, or Chirostenotes, or…um…something…

During the early 1920s, Charles W. Gilmore, a paleontologist from the Smithsonian Institute in Washington, DC, was prospecting for fossils in Alberta, Canada. While on this trip, he would discover several new species of dinosaurs, including a strange creature known only from a pair of incomplete hands. These hands had long slender fingers, which was highly unusual for theropods known at the time. He officially named and described them as Chirostenotes pergracilis in 1924.

Chirostenotes was originally believed to be a member of the family Elmisauridae. This is an enigmatic group of dinosaurs, whose members consist of only one genus, Elmisaurus. This animal lived in Mongolia during the late Cretaceous Period about 80 MYA, and the only evidence that we have of its existence is one incomplete foot and a hand found in 1970. Scientists recognized that the hands of Chirostenotes and Elmisaurus looked similar, and so Chirostenotes was placed into that family. By 1990, Elmisauridae was recognized as an invalid family name, and it was discarded.

Chirostenotes is now classified as a member of the family Caenagnathidae, named after the genus Caenagnathus, which might actually be the same animal as Chirostenotes (as early as 1990, scientists suspected that these two might actually be the same animal). The canaegnathids were a group of bird-like theropod dinosaurs who belonged to a much larger group called the oviraptorosaurs, who are well-known from Asia. Their presence in North America only adds further proof to a faunal exchange between Asia and North America. Caenagnathids are distinguished from oviraptorids by their feet, which look more like those of the ornithomimids, more commonly-known as “ostrich dinosaurs”. This suggests that the oviraptorosaurs evolved from the ornithomimids. According to current phylogenic analysis, the ornithomimids are more primitive than the oviraptorosaurs, so this hypothesis might be plausible.

Because Caenagnathus and Chirostenotes are known from incomplete specimens, nobody can make up their minds as to whether or not they’re two separate genera or if they’re the same animal. Some paleontologists firmly believe the former, while others firmly believe the latter. Because of their incompleteness, we are also not 100% sure what the animal looked like. It’s reasonably certain that it bore a strong resemblance to Oviraptor, Citipati, or Anzu, but any recreation of what the entire animal looked like is guesswork. During the 80s and 90s, there were a wide range of images crafted by various paleoartists which took a stab at what the whole animal would look like if it were fleshed out. Ever since the discovery of Anzu, which is both the largest and most well-known caenagnathid, the diversity of images has largely disappeared. Now, modern depictions of both Caenagnathus and Chirostenotes, if you can find them, are really nothing more than clone copies of Anzu, which I disagree with not only as a paleontology buff, but also as an artist.

Below is my own rendition of what I think Caenagnathus, or possibly Chirostenotes, or both, would have looked like. Since no complete skull of either species has been found, the design for the head is based upon a hypothetical skull drawing made by Tracy Ford. My drawing was made on printer paper with No. 2 pencil, Crayola and Prismacolor colored pencils, and a black felt-tiped marker. Since my scanner has a tendency to wash out a lot of the detailing, I had to do a bit of touching-up on my computer to replicate how the image looks in real life. Hope you enjoy, and keep your pencils sharp.

 

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Habrosaurus, a Late Cretaceous siren amphibian from the Hell Creek Formation

The Hell Creek Formation of the north-central United States is famous for its dinosaur fossils, notably those of Tyrannosaurus, Triceratops, and others whose names are well-known to children and adults. However, this fossilized environment was home to more than just dinosaurs. The Hell Creek Formation was home to a wide range of fish, amphibians, reptiles, and mammals. One of the animals that called this landscape home during the late Cretaceous was Habrosaurus.

Despite its name, Habrosaurus was not a dinosaur, and it wasn’t even a reptile. It was, in fact, an amphibian, and a large one at that. Habrosaurus dilatus was a three-foot long siren, a type of salamander that bears more of a resemblance to an eel than the lizard-like forms that we associate slamanders with. Unlike most salamanders, sirens are fully-aquatic amphibians that retain gills throughout their whole lives, unlike other amphibian species that possess gills only in the early development stages of their lives. Sirens also possess small rudimentary lungs, and are able to breath air. There are four species of sirens that are alive today, and all of them are found within North America. Depending upon the species, they can have one to three gill slits on each side of the head. They have completely lost their hind limbs, and their front limbs have shrunk considerably, with three or four short stubby fingers on each hand. Sirens have tiny eyes and no eyelids, and possess a long tail reminiscent of an eel or a sea snake – ideal for swimming. Sirens prefer to live in slow-moving or static bodies of water with lots of underwater vegetation and muddy bottoms. They might occasionally come onto land during the night if the ground is wet or if it’s raining.

Habrosaurus is, to date, the oldest-known siren genus. So far, there are two species known: H. prodilatus, which was found in Alberta, Canada in rocks dating to the Campanian Phase (83-70 MYA) of the late Cretaceous, and H. dilatus, which is much more widespread in the western United States, being found in Montana and Wyoming (with more specimens being found in Wyoming) and dating to the Maastrichtian Stage (70-65 MYA) of the late Cretaceous, as well as being found in the early Paleocene Epoch of the Tertiary Period. This means that H. dilatus was one of several species to survive the K-T Extinction, if only for a short while. It may be possible that H. dilatus is simply the evolved form of H. prodilatus.

Habrosaurus dilatus was named by the eminent paleontologist Charles W. Gilmore in 1928. To my knowledge, six specimens have been found of this animal, and all of them have been found in stream channel deposits. The presense of this type of animal, as well as its impressive size of three feet in length, indicates the presence of large bodies of fresh water, such as slow-moving rivers or ponds. However, the possibility of a dry year was ever-present, and for a fully-aquatic or mostly-aquatic animal like Habrosaurus, that could spell doom. During dry periods or droughts, modern-day sirens are able to dig burrows into the mud and encase themselves in a cocoon, like a lungfish, and Habrosaurus might have adopted the same strategy.

Habrosaurus had rows of blunt teeth arranged in the roof of its upper jaw, which indiates that these jaws were designed for crushing rather than grabbing. Presumably, it fed upon tiny mollusks and arthropods, such as snails and shrimp. Modern-day sirens feed mainly upon worms, aquatic snails, shrimp, and occasionally algae. Like fish, sirens possess lateral lines to find prey by indicating differences in water pressure and underwater vibrations.

An appropriate modern-day analog for the three-foot long Habrosaurus dilatus is the Greater Siren (Siren lacertina), which also grows to three feet long and is the largest siren species in the world today.

Below is a simple drawing of a Habrosaurus that I made with a felt-tipped marker. This style is a considerable departure from my usual style of highly-detailed pencil drawings, but I wated to do some artistic experimenting.

Ornithomimus, Before and After

Hello all. I’ve recently finished an important writing project that I’ve been laboring upon for months. Now that it’s finished, I have a little breathing room to do art, and this is what I’ve done so far. I decided to do an updated version of an old illustration that I had made of an Ornithomimus. While the general color scheme was what I had in mind, I was never truly happy with the end-product. This latest version is much more in line with what I was imagining the “Bird Mimic” would look like.

Here is the “before” picture, made in 2013.

 

And here is the “after”, made today.

 

You’ll notice several differences right away, the most noteable of them being the re-shaping of its wing feathers. While Ornithomimus, or perhaps ornithomimids in general, had pennaceous feathers, I don’t think that they had primaries, because those would have been attached onto the wrist and the hand. This would have been difficult for ornithomimids because, unlike “raptor” dinosaurs (dromaeosaurids and troodontids), ornithomimids could not flex their hands backwards. I also increased the size of its tail feathers, made the neck thicker, changed the shape of the skull so that it was more anatomically accurate, and added Secretary Bird-style feathers to the back of its head. So much for form. In terms of color, I made it more vibrant, with deeper richer yellows and oranges and a lot more black patches. I changed the color of its bare skin from pink to a mixture of tan and black. I made its beak black, I changed its eye from yellow to blood red, and gave it black feet.

I can definitely see this character rushing about on the plains of the Hell Creek Formation. This shows that artists should never be stagnant. They must always strive to improve their work, and in so doing, improve their skill.

This drawing was made on computer printer paper with a No. 2 pencil, Prismacolor colored pencils, markers, and a black felt-tiped pen. The size of the drawing, from the tip of its nose to the tip of its tail feathers, measures 10.75 inches long, which is almost 1/12 scale, as the real animal possibly measured 12 feet long with its neck and tail fully stretched out.

Keep your pencils sharp.

Alamosaurus

alamosaurus

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.

Tyrannosaurus rex with scales

Tyrannosaurus full body with scales

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:

  1. Slightly changing the shape of the skull – my original one looked a little too much like Tarbosaurus rather than Tyrannosaurus.
  2. Not making the face as shrink-wrapped as the original head drawing was.
  3. Making the neck more detailed and fuller.
  4. Changing the position of the hands to be more anatomically correct.
  5. Making its body fatter – the original was too skinny.
  6. Making the tail thicker and fatter to properly counter-balance the now-heavier front half of the body.
  7. 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.

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.

Chasmosaurus

Chasmosaurus

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.

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.

Lonchidion, a prehistoric shark

Lonchidion

This is a drawing of Lonchidion, a hybodont shark from the Mesozoic Era. There were at least eleven different species, one of which was found in the Hell Creek Formation. I won’t get into all of the particulars regarding this genus or the Hell Creek species in particular (L. selachos). Their size depended upon the species, some being very small. Lonchidion selachos may have been three feet long, judging by the size of its dorsal spines. The drawing is based upon the preserved remains of other hybodont sharks, because specimens from the Hell Creek Formation consist mostly of teeth, well-preserved specimens of any Lonchidion species are very rare, and as far as I am aware, they looked more or less like other well-known hybodonts.

Hybodont sharks are identified by their large dorsal fin spines as well as the four large spines atop their heads, which are really overly-enlarged denticle scales found all over the rest of the body. Hybodonts first appeared during the Carboniferous Period, but it was during the Jurassic that they came into their own. However, by the Cretaceous Period, they were being replaced by so-called “modern” sharks very similar to the ones we see today. Lonchidion was one of the last surviving members of its kind before the whole hybodont group (the few species that remained, anyway) was completely wiped out at the end of the Mesozoic Era 65 million years ago.

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!