Ichthyosaurus

## Icthyosaurus

Credit: Julio Lacerda.

*Ichthyosaurus* is an extinct genus of icthyosaur that lived in Europe in Asia from the Late Triassic to the Early Jurassic.

## History

*Ichthyosaurus* was first discovered by the first paleontologist; Mary Anning. As the story goes, Anning was walking along the beach, when she found a relatively complete, articulated *Ichthyosaurus* skeleton. She reported the find to the local museum and it was recognized as a new species, and named *Ichthyosaurus communis*. Since then, five new species of *Ichthyosaurus* have been named, one of which, *I. anningae*, was named after Anning.

From a discoverer who was most certainly Mary Anning, a fossil from Lyme Regis in 1818 was taken by Thomas James Birch, a collector who had acquired the specimen. Birch then sold it the Royal College of Surgeons in 1820 to raise funds for the Anning family, who were having difficulties paying rent. At this time, paleontology had been in its early years, and so scholars disagreed on its identity. This specimen was the most complete known at the time, and Everard Home published his findings in 1819, with the name *Proteosaurus* being coined. In May 1941, the college was struck during a German air raid and the specimen was destroyed, with only a single illustration remaining by William Clift. In 2016, Dean Lomax and Judy Massare discovered aged casts within the collections at the Peabody Museum. They soon identified the cast as having been made of the lost specimen, but discovered no records of it ever being produced. The staff has assumed that it was a genuine fossil. Few details are known of it, including when Braun acquired it or who made it. In 2019, Lomax was investigating the collections of the Natural History Museum, Berlin and found another cast of the same specimen, in much better condition. Like the other, little details are known. Study published in 2022 suggests that they were made at different times, and the Yale cast may have been made before Birch had sold the fossil. In the original illustration, they identified several missing bones and other errors. They were able to confirm placement in *Ichthyosaurus*, but not enough diagnostic features could assign a species. This research was published in the same journal it had originally been published in.

## Description

*Ichthyosaurus* is known from a vast record of material ranging as far back as the 1800s, and possibly further in undocumented cases. *Ichthyosaurus* is also known from a vast record of well-preserved fossils, which includes the majority of the skeleton, soft tissue outlines, traces of food in their stomachs, their young, and even a thick layer of blubber. *Ichthyosaurus* looks strikingly similar to the modern dolphin; bearing a long toothy snout, large flippers and a rotund body. *Ichthyosaurus* is smaller than most ichthyosaurs, and bore unusual traits for a reptile. First, *Ichthyosaurus* was viviparous, incubating its young inside its body and birthing them open ocean. Second, *Ichthyosaurus*' skeleton was covered by a thick layer of blubber, and the rest of its body was also covered in a thick layer of skin, presumably for staying warm.

## Paleobiology

### Senses

*Ichthyosaurus* bears solid ear bones, which means that the animal was well adapted for detecting movement through water vibrations. The eyes were massive, with a large sclerotic ring sitting in the orbits to keep their eyes from bursting in deep water. *Ichthyosaurus* was likely a more visually-oriented hunter, since their eyes were so delicate and huge. *Ichthyosaurus* had among the largest eyes of any extinct or extant vertebrate.

### Diet

*Ichthyosaurus* is also known from coprolites, which reveal that *Ichthyosaurus* ate large amounts of fish and squid. Ichthyosaurus hunted in groups, swimming into large shoals of schooling fish. Their jaws are built to pierce the flesh of their food, holding them in place.

### Birthing

Well preserved fossils show that *Ichthyosaurus* birthed their young live, and that they were ready to start basic life functions from the get-go. Their children were fully pelagic, relying only on their mothers, and were born tail first to prevent drowning. It was initially thought that Ichthyosaurus climbed onto land to lay eggs, but it has since been proven false. At no point in their lives did *Ichthyosaurus* climb onto land.

## Species

* *I. communis*
* *I. breviceps*
* *I. conybeari*
* *I. anningae*
* *I. larkini*
* *I. somersetensis*

### Reassigned Species

* *I. acutirostris* (=new genus or nomen dubium)
* *I. aduncus*
* *I. atavus*
* *I. advena*
* *I. aequalis*
* *I. amalthei*
* *I. angustidens*
* I. australis (=*Myopterygius*, =*Platypterygius*, =*Longirostra*)
	+ I. australis
* *I. arietis*
* *I. bambergensis*
* *I. brunsvicensis*
* *I. biscissus*
* *I. bodenbenderi*
* *I. bonneyi*
* *I. brachyspondylus*
* *I. californicus*
* *I. ceramensis*
* *I. campylodon* (=*"Pervushovisaurus" campylodon*, *Myopterygius*)
* *I. chalarodeirus*
* *I. coniformis*
* *I. crassicostatus*
* *I. cuvieri*
* *I. dilatatus*
* *I. entheciodon*
* *I. enthekiodon*
* *I. extremus*
* *I. franciscanus*
* *I. giganteus*
* *I. hectori*
* *I. hexagonus*
* *I. hildesiensis*
* *I. hygrodeirus*
* *I. immanis*
* *I. indicus*
* *I. kokeni*
* *I. lacunosae*
* *I. leptospondylus*
* *I. latifrons*
* *I. longirostris*
* *I. janiceps*
* *I. leucopetraeus*
* *I. longimanus*
* *I. longipes*
* *I. longifrons*
* *I. nasimowii*
* *I. normanniae*
* *I. numismalis*
* I. marathonensis
* *I. ovalis*
* *I. planartus*
* *I. platymerus*
* *"I." posthumus*
* *I. psilonoti*
* *I. quenstedti*
* *I. saladensis*
* *I. sanjuanensis*
* *I. sinuatus*
* *I. steleodon*
* *I. tenuirostris*
* *I. thyreospondylus*
* *I. torrei*
* *I. torulosi*
* *I. trigonodon*
* *I. trigonus*
* *I. triscissus*
* *I. walkeri*
* *I. zollerianus*
* *I. zetlandicus*
* *I. pottsi*

## Synonyms

* *Protoichthyosaurus prosostealis*
* *Tibetosaurus*
* *Eurypterygius*
* *Temnodontosaurus burgundiae*
* *Temnodontosaurus acutirostris*

## Gallery

### Reconstructions

**Credit: Mark Witton.****Credit: Robert Nicholls.****Credit: Joschua Knüppe.****Credit: @DragonsofWales on Twitter.**

## References

* https://en.wikipedia.org/wiki/Ichthyosaurus
* https://paleobiodb.org/classic/basicTaxonInfo?taxon\_no=36558
* https://en.wikipedia.org/wiki/Temnodontosaurus
* https://academic.oup.com/zoolinnean/advance-article-abstract/doi/10.1093/zoolinnean/zlab118/6530503?redirectedFrom=fulltext
* https://incertaesedisblog.wordpress.com/2022/02/06/the-taxonomy-of-myopterygius-and-pervushovisaurus/
* https://www.tandfonline.com/doi/abs/10.1080/03115511003663939
* https://australian.museum/learn/dinosaurs/fact-sheets/platypterygius-australis/
* https://incertaesedisblog.wordpress.com/2022/02/06/the-taxonomy-of-myopterygius-and-pervushovisaurus/
* https://blog.everythingdinosaur.com/blog/\_archives/2022/11/02/marine-reptile-casts-copies-of-priceless-fossil-thought-lost.html