Why is a plesiosaur not a dinosaur?
When dinosaurs ruled on land, these reptiles prowled the seas. Plesiosaurs inhabited the seas from around 200 million to 65 million years ago. They were not dinosaurs, despite living at the same time as dinos. It is thought that plesiosaurs fed mainly on fish, breathed air and laid their eggs on beaches.
Is Spinosaurus a plesiosaur?
While other ancient creatures, such as the plesiosaur and mosasaur, lived in the water, they are marine reptiles rather than dinosaurs, making Spinosaurus the only-known semi-aquatic dinosaur.
Are mosasaurus still alive?
The mosasaurs ruled the ocean in the late Cretaceous period. Mosasaurs went extinct 65.5 million years ago in the same mass extinction event that wiped out the dinosaurs, Live Science previously reported.
How are dolphins and ichthyosaurs similar?
Ichthyosaurs resembled both modern fish and dolphins. Their limbs had been fully transformed into flippers, which sometimes contained a very large number of digits and phalanges. At least some species possessed a dorsal fin.
What kind of animal is a plesiosaur or ichthyosaur?
Ichthyosaur and Plesiosaur by Édouard Riou, 1863. Ichthyosaurs (Greek for “fish lizard” – ιχθυς or ichthys meaning “fish” and σαυρος or sauros meaning “lizard”) are large marine reptiles.
What kind of eyes did ichthyosaurs have?
Ichthyosaurs had large eyes for seeing in deep water, vertical tail fins (like tuna fish), and some species had a dorsal fin. Little is known about their ancestors – terrestrial reptiles that returned to the sea – or why they went extinct, only that plesiosaurs replaced them as the sea’s top predators.
How are ichthyosaurs different from other vertebrates?
Pelycosaurs were primitive ‘synapsids’ – vertebrates whose skulls have one opening to the rear of each eye socket (reptiles have two openings). Mammals are the only surviving synapsids. Ichthyosaurs were shaped like modern dolphins, a streamlined body that made them the fastest of marine reptiles.
What kind of reptiles are plesiosaurs and Sauropsida?
Plesiosauria. The Plesiosauria ( /ˌpliːsiəˈsɔːriə, -zi-/; Greek: πλησίος, plesios, meaning “near to” and sauros, meaning “lizard”) or plesiosaurs are an order or clade of Mesozoic marine reptiles (marine Sauropsida ), belonging to the Sauropterygia . Plesiosaurs first appeared in the latest Triassic Period,…
