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News: Some prehistoric marine reptiles may have been dark in color

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.

Cretoxyrhina and Squalicorax

Cretoxyrhina and Squalicorax

Let’s change from dinosaurs to some other prehistoric life. Here are two prehistoric sharks. The large gray one on top is called Cretoxyrhina mantelli, more commonly known as the Ginsu Shark. The smaller blue one underneath is called Squalicorax falcatus, more commonly known as the Crow Shark. These two species are only a handful of prehistoric animals that have common names ascribed to them – most paleo-critters have only their scientific names.

Both of these prehistoric sharks lived in what was called the Niobrara Sea, also called the Western Interior Sea, which covered the central third of North America during the late Cretaceous Period. Both of these sharks are classified as being lamniform sharks, also known as mackerel sharks. This is the same group which includes the Mako and the Great White. “Modern” sharks first appeared on Earth towards the end of the Mesozoic Era, and both of these species are good examples of early modern sharks.

Cretoxyrhina was a large twenty-foot shark. It lasted from 100-82 MYA, and it was probably the top predator in its environment during that time. However, during the Cretaceous Period, a new group of marine carnivores appeared called mosasaurs. These creatures were literally oceanic lizards – in fact, their closest relatives are today’s monitor lizards, like the ten-foot Komodo Dragon. But mosasaurs got much bigger than this, with some reaching over forty feet long. The mososaurs out-competed this large shark for food and drove it into extinction.

The smaller Crow Shark appears to have been much more versatile. It evolved into several different species, some measuring six feet long, while others reached as high as sixteen feet in length.

One of the things that you’ll immediately notice about this drawing is that it’s in color. I very rarely make color drawings – I usually just stick to grayscale. The reason why is because I haven’t really gotten the knack for making illustrations in color yet. I’ve been working in black-and-white for a long time, and I dare say (at the risk of tooting my own horn) that I’ve gotten pretty good at it. I don’t like using color because it washes out all of the texture and detail. Well, it’s a learning process. I’m sure that I’ll get the hang of it sooner or later.

Keep your pencils sharp.