[News]: Ichthyosaurs were bird-eaters

Sordes

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The biggest known eyes belonged in fact to ichthyosaurs. Ophtalmosaurus is often mentioned in this case, but it had only the biggest known eyes compared to its body-length among all ichthyosaurs. The larger species had large eyes too, and some of the ichthyosaurs became really huge. One skeleton which was discovered in Canada some years ago belonged to an animal which was about 23m in length, and isolated vertebras must have belonged to specimens with a minimum length of 27m. The eyeballs of this animals were surely even larger than those of Mesonychoteuthis (which woulb be only a snack for them).
It seems that many, especially the larger ichthyosaurs were very specialized squid hunters, which even lost their teeth when they became older. They had similar hyoidal structures to beaked whales, which probably allowed them to "inhalate" squid and fish like a vacuum cleaner. Fish is in fact only very rarely found in ichthyosaurs stomachs, most of them show only cephalopod remains. Only from one big and orca-like form named Temnodontosaurus also predation on smaller marine reptiles is known, but even they preyed in general on smaller prey.
 

Phil

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Crikey, talk about a Lazarus thread, it's over three years old!

Thank you, that's a very interesting post there Sordes. I had no idea that fish remains were uncommon in ichthyosaur stomachs. Playing devil's advocate here though, I wonder if teuthid and belemnite hooklets are more often preserved simply due to their barbs latching into the stomach and gut linings. I reckon that hooks might be more resilient to being passed as they were more likely to be internally impaled. Perhaps this might lead to an inflated impression as to how much a part of the diet they comprised, compared to an easily digested slippery fish?

I really have not got a clue though, just a thought.
 
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made good sense to me Phil, gotta keep them blinkers off !
I recently read an article on Spinosaurus from North Africa, which appears to have been pigeon holed as a fish eater due to it's long narrow snout. Being an ex-wild fowler & experienced in the fine art of locomotion on soft soggy aquatic terrain, I'd love to see a demo of a 56 foot therapod dinosaur doing the same - I don't think so !

Keef
 

Sordes

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I think many ichthyosaurs were more like modern beaked whales, which are mainly squid-eaters, although they also sometimes eat fish.
The argument with the fossilization is really good, I didn`t think about it. But there are several very good fossils from Holzmaden in Germany which shows not only all bones and the content of the stomach, but also the silhouette of the animals. If such a great fossilization happens, it would be strange if fish bones wouldn´t survive. Toady I was on the paleontological museum of Tübingen, and made some photos of the cephalopods there. I also looked at the ichthyosaur fossils, which had also all only relics of cephalopods in their stomaches.
Something about the Spinosaurus: In the stomach region of Baryonyx which was very similar to Spinosaurus, fossils of large fish were found, and the skull of this and other similar theropods like Suchomimus or Irritator were really so long and narrow, and also comparably small in relation to their bodies, that it is very hard to imagine that they hunted other dinosaurs. Furthermore their long claws on the fingers woulb be perfect to catch big fish, similar as grizzlies do it.
We still don´t know enough about the ancient ecosystems and the animals which belonged to it, to make really clear statements.
 

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