Nothosaurs

I have not posted in a very long time, and I’m afraid I need only two words to explain that: college applications. Things may remain like this for a while.

On a different note, I was recently given the opportunity during an oceanography class to research anything ocean-related that I wanted. The only stipulation for this project was that I must ultimately present my research is some way to the class at some point during the semester. Once a week for the entire quarter, the entire class was given free reign with laptops and whatever supplies the teacher had in her classroom. For me, this was the result:

            I tend to gravitate towards animals and fantastic monsters that don’t seem like they could possibly be real, so I naturally decided to start in the Triassic. I started surfing the web and collecting information, and eventually ended up with a Word page filled with jumbled facts about nothosaurs. Nothosaurs are a less well-known species of ancient reptiles—not dinosaurs—that I stumbled across while looking for large species of marine and coast animals. My original intention was to do a comparative analysis of Triassic-era to modern-day ocean life; to find an animal from each time period that more or less matched up, and then list the common traits between the two. As I worked, however, I realized that I’d been spending almost all of my time researching nothosaurs, and that I had almost no information on placodonts, mosasaurs, or ichthyosaurs. I decided to switch.

            Nothosaurs were a species of aquatic reptile that lived during the Triassic (240-225 million years ago). They spent most of their lifetime in the water and were physically adapted for swimming, but many of their fossils have been found above ancient shorelines and suggest that they laid their eggs on land much like modern-day crocodiles and alligators. They’re classified under the family Sauropterygia and the genus Nothosauria, and there are over a dozen known individual species. Their name, originating from ancient Greek, means ‘false lizard’.

Nothosaur skull

Physically, nothosaurs were built like modern-day lizards: four legs oriented outward, with a low, dragging belly, long, sinuous neck and equally long tail. Their legs were adapted for swimming, with longer forelegs and webbed toes that they used as rudders. Their swimming motion was very much like that of modern crocodiles and alligators—a horizontal undulating motion of the body, head and tail that utilized their tail for propulsion and their feet for steering. Their heads were designed for swimming and fishing—they were long, narrow, flat, and triangular, with jaws that extended all the way back to their cheeks and long needle teeth that were longer in the front and locked together like a bear trap. They were very aerodynamic, and their teeth were designed for nabbing fish—their primary food source—out of the water. Like crocodiles, their eyes and nostrils were located on the tops of their heads, an adaptive trait that allowed them to breathe and see over the surface of the water without exposing the rest of their heads. To give you an idea of scale, I will recount that they have been known to be anywhere from a few inches to twenty feet long (a normal school bus is about forty feet).  

Crocodile skull

            Now, a comparison to crocodiles does seem to cover many of the physical details that describe a nothosaur, but there are certain details in habit and structure that appear to separate the two. Both are reptiles, but the manner in which their skeletons are oriented is very different. Crocodiles, when they swim, look like a straight, flat log with their nose and neck perfectly level with their back. Their legs are held either tucked flat against their sides or allowed to splay out directly sideways. Nothosaurs, by comparison, appear to swim more like seals, with a slight arch to the neck and their legs tucked downward. Seals also happen to share the upward-facing nostrils and eyes that both nothosaurs and crocodiles display, though they are (obviously) mammals, and their skulls are much rounder and shorter. (Note: this comparison is mostly my own conjecture, and may not be accurate.) All three animals shared similar lifestyle habits, raising their young on land but primarily living and hunting in the water. Similar living species during the Triassic include the Askeptosaurus, which were very similar in appearance to the nothosaurs save for their much narrower snouts and long, whip-like tails. There was also the plesiosaur (the loch-ness monster is supposed to be one of these), which paleontologists surmise may have evolved from nothosaurs. Fossils of nothosaurs have been found in Europe, North Africa, and Asia embedded in sea rocks, which further supports the theory that they were aquatic reptiles that came onto land to lay their eggs.

            In conclusion, will state that my knowledge of this species is very incomplete. This was a high-school science project, the internet was my main source of information, and a lot of the conjectures I offered up could be completely, fantastically incorrect. Furthermore, if any of my readers are, in fact, well-acquainted with the order Nothosaurioidea, I would greatly appreciate any input and will repost an update in two weeks on what people have to offer. Feel free to leave comments below.

            In the meantime, I’ll try my best to keep up on blog posts through the perpetual bog of schoolwork I’ve been slogging through, and I wish you, as ever, happy reading.

S. R. Koch

http://palaeo.gly.bris.ac.uk/palaeofiles/fossilgroups/euryaps/notho.html

http://dinosaurs.wikia.com/wiki/Triassic_Period

http://www.seaworld.org/animal-info/info-books/killer-whale/diet.htm

http://www.enchantedlearning.com/subjects/dinosaurs/dinos/Nothosaurs.shtml

http://crocodilian.com/cnhc/csl-maps.htm

http://animals.nationalgeographic.com/animals/reptiles/nile-crocodile/

http://www.factmonster.com/dk/science/dinosaurs/below-the-waves.html

http://www.dinosaurfact.net/Marine/Nothosaurus.php