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

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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.

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1 Comment

  1. Jackie B. says:

    I was actually planning to post an article about the color of reptiles and what the benefits are of being dark in color for them. Great post!

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