There are no modern forms of euryapsid. All four groups are now extinct.
Nothosaurs and placodonts both fell victim to the mass extinction that occurred at the Triassic-Jurassic boundary (201 million years ago). This extinction wiped out 20% of all marine families and 50% of all terrestrial vertebrate families, and opened the way for the rise of the dinosaurs.
It used to be thought that ichthyosaurs died out in the mass extinction that killed the dinosaurs, but fossil evidence now indicates that ichthyosaurs disappeared 30 million years before the dinosaurs, in the mid-Cretaceous (Cenomanian-Turonian) extinction event that wiped out roughly 26% of marine genera. It is thought that ichthyosaurs may have died out due to failure to compete with the marine reptiles and advanced sharks that had a similar diet and lifestyle to ichthyosaurs.
Plesiosaurs did manage to persist until the end of the Cretaceous Period, but were wiped out in the K/T (Cretaceous-Tertiary) boundary extinction event that killed the dinosaurs (65 million years ago).
However, there has been speculation from some that plesiosaurs might be alive and well, and living in Loch Ness! Alleged sightings of plesiosaurs in Loch Ness are greeted with scepticism by most scientists, but there are still some who believe it is possible that these animals may be alive today.
Author: Rachel Jennings
Last updated: 22/11/2005
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