When it comes to prehistoric critters, usually Dinosaurs are the first critters to come to mind, but really that’s just the tip of the iceberg. Among the many strange critters cruising the Mesozoic seas were the Ichthyosaurs. They’re not dinosaurs at all, even though they’re often lumped into the same pile. So if they’re not dinosaurs, what are they exactly? Here are five fast facts to help demystify these swimming reptiles…
1. First things first, how do you say that?!
I recently realized I’ve been pronouncing this word wrong all my life. I’ve been saying “Itch-theo-sore”. But that’s with English phonetics. The word comes from the Greek ichthys (fish) and sauros (lizard or reptile). With that in mind, this is what it should sound like…
So now my little girl calls them “icky-saurs” instead of “itchy-saurs”. 😀
2. Ok, so what exactly is an “icktheosaur”?
Long story short, they are reptiles specially adapted to live in water. They were born, grew up, had babies, and died in water. Basically, reptilian “fish”. Or reptilian “dolphins”.
They appeared during the Triassic period, around the same time the first dinosaurs started running around. They shared a “golden age” with dinosaurs in the Jurassic period, but most died out by the time the Cretaceous period arrived. A few species held on a while longer, but they missed out on the big asteroid that hit Earth.
3. Why do they look so much like fish/dolphin/shark…things?
If it isn’t broken, why fix it? The fish/dolphin/shark body shape works so well for a lifestyle in water, multiple animals have adopted it. A streamlined, torpedo body with stabilizing fins is perfect for slicing through water efficiently, so very little effort is needed to move around.
It’s a perfect example of what is called convergent evolution, which is when several completely unrelated animals (i.e. fish, reptile, mammal) develop similar body plans or lifestyles.
Personally? I think it’s an interesting coincidence that so many unrelated animals developed the same body shape and lifestyle…very interesting indeed. 😀
4. Wait a sec…How do we know they looked like that?
That’s an easy one. Some Ichthyosaur fossils have preserved the soft tissue of the animal, so we can see the streamlined outline, as well as a shark-like tail and fins. Many fossils also preserve things that give us clues on behavior, like a mother giving birth to live young. The fossil captures the newborn Ichthyosaur mid-birth!
5. No way…how do you know it wasn’t eating the smaller one?
Paleontologists can tell that the smaller Ichthyosaur was not there for some random reason because of where it is. The little one was halfway inside the larger one (instead of just layered under it), but clearly in the right place for a baby, and not lunch.
And speaking of lunch, some fossils preserve that too! In many of their stomachs, we find tiny hooks similar to what some modern squid have on their tentacles. Mesozoic oceans were not a bounty of fish, as we might think, but there were squids, octopuses, and all their extinct cousins with them. (lots of them had little hooks like switchblades on their tentacles.)
Of course an Ichthyosaur will eat whatever it can get, including fish, but the squidy things where just soo common. Sheer numbers means they get eaten more often.
Want to find out more? Just take a look at this awesome post by Duane Nash at his blog, Antediluvian Salad.
So there you go, “Ick-theosaurs” in a nutshell. 😀 Reptiles that dove into the water, took the life and body shape of a shark, and lived alongside the dinosaurs eating calamari.
Quick Question: We all make mistakes, and sometimes a pronunciation mistake can be pretty funny (like my little girl’s “itchy-saur”). Have you ever pronounced something a certain way, only to find out it’s something totally different later? It could be a dinosaur name, or something else. I’d love to hear from you in the comments! 😀