Home » Posts tagged 'marine'
Tag Archives: marine
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.
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.
Once again, I’ve noticed that a switch from paleontology to history-related material has resulted in my website views taking a nosedive. So, to appease the public, I am putting more prehistoric stuff on here.
Allow me to introduce Megalneusaurus. This creature was a large 25-foot marine reptile which lived in the Pacific Ocean along North America’s western coast as well in as the shallow Sundance Sea, which covered much of north-central North America, during the late Jurassic, approximately 155 MYA. It was a member of a group of animals called the pliosaurs, whose most famous members consisted of Kronosaurus and Liopleurodon.
So far, the only evidence that we have of this creature is what might be a single fragmentary skeleton discovered towards the end of the 19th Century consisting of some vertebrae, one flipper, a few ribs, and most of the pelvis. In 2007, scientists published a report in which they re-discovered the original locality where these bones were uncovered. Among the finds found were the stomach contents, consisting of the remains of belemnites – primitive squid-like creatures.
Since a complete or even reasonably-complete specimen of Megalneusaurus has not been found, paleo-artists have a slight degree of elbow room in terms of how this animal looked in life. This drawing is heavily-based upon an old and inaccurate illustration of a Liopleurodon skeleton from the 1960s(http://plesiosauria.com/images/line_drawings/liopleurodon2_newman&tarlo.jpg). Firstly, Liopleurodon’s skull was actually a bit flatter than shown in that drawing. It also had more teeth in its jaws – the old illustration shows only the front teeth. Finally, and most obviously, it is depicted with a short somewhat triangular tail fin. I kept the head’s structure more or less as it was, put more teeth in the jaws, and made the tail fin diamond-shaped to make it more symmetrical. It’s unknown whether or not pliosaurs like Megalneusaurus actually had a tail fin, but I kept it here since it looked interesting. Besides, until a couple of years ago, no one would have guessed that mosasaurs like Prognathodon would have had shark-like tail fins, but there you go, that’s paleontology for you.
Check out the two websites below for more information on this creature:
Hot off the presses! Scientists have an idea about what color Mesozoic marine reptiles, which are sometimes Romantically referred to as “sea dragons”, were in life. Apparently, some of them were dark or even black in color.
The findings were published in an article in the scientific journal Nature. A group of paleontologists led by Prof. Johan Lindgren analyzed the well-preserved remains of an ichthyosaur from the early Jurassic (193 MYA), a late Cretaceous mosasaur (85 MYA) and a leatherback turtle from the Tertiary Period (55 MYA). Fossil skin and other soft tissues is extremely rare because they usually decompose before fossilization can take place. Fossils that are so well preserved that you can actually see pigmentation cells under a microscope are almost unheard of; only a handful of other examples have been uncovered within the past ten or so years.
The pigmentation cells in question here are called “melanosomes”. For those of you who have a vague knowledge of ancient Greek, you’ll know that anything that has “mela” in it means that it’s black – skin cancer is called menaloma due to the dark patches it forms, unusually dark colored animals are called menanistic, and other examples. So, melanosomes are pigmentation cells that are black or very very dark in coloration.
For a marine reptile, being black all over would be a big benefit. It is commonly taught in elementary schools that black absorbs heat. Reptiles are cold-blooded, and staying warm is a constant concern, especially when they spend a considerable portion of their time in the water. As examples, the modern-day American Alligator and the Marine Iguana of the Galapagos Islands are both colored very dark. Being colored black would help them absorb heat more quickly than if they were colored light. Even most whales and dolphins, which are technically warm-blooded, are colored black in order to absorb heat, due to the often frigid conditions of the water that they dwell in.
The modern-day Leatherback Turtle is black on top, whith a little bit of white speckling and stripes along the top of its shell ridges. Therefore, it isn’t surprising that its early Cenozoic ancestor would be dark-colored as well.
Mosasaurs were enormous aquatic lizards which could reach over 50 feet long. Their closest surviving relatives are monitor lizards, like the Komodo Dragon. This isn’t the first time that mosasaurs have been in the news. Not so long ago, it was revealed that they may have suffered from “the bends”.
Lindgren and his colleagues propose that the ichthyosaur may have been colored completely dark all over, rather than being dark on top and light on the bottom (this is called “counter-shading”).
Note: This does NOT mean that ALL ichtyosaurs and mosasaurs were colored in this fashion. It merely means that membes of these particular species were colored this way.
Well, the new year certainly has gone off with a bang. I can’t wait to see what the other eleven and a half months will bring.
- Fox News. “Ancient Sea Monsters were Black, Study Finds”. http://www.foxnews.com/science/2014/01/09/ancient-sea-monsters-were-black-study-finds/
- National Geographic. “Dinosaur-Era Swimming Reptiles Had Black Skin”. http://news.nationalgeographic.com/news/dinosaur-era-swimming-reptiles-had-black-skin/
- Nature. “Skin pigmentation provides evidence of convergent melanism in extinct marine reptiles”. http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12899.html
- Sci-News. “Fossils Reveal True Color of Mosasaurs, Ichthyosaurs, Prehistoric Turtles”. http://www.sci-news.com/paleontology/science-color-mosasaurs-ichthyosaurs-turtles-1672.html