Nothosaurs

By | September 9, 2016

In the middle of the Triassic, when the first dinosaurs were beginning to walk on land, the seas were home to a family of reptiles known as nothosaurs. A bit like today’s seals and sea lions, the nothosaurs were fish hunters that evolved from land animals. They weren’t fully adapted to life in water and some had clawed feet—a sign they could still walk on land.

Pachypleurosaurus (PACK-ee-ploo-roe-SORE-us)

pleurosaur


When: 225 million years ago (Middle Triassic)

Fossil location: Italy, Switzerland

Habitat: Oceans

Length: 12–16 in (30–40 cm)

Diet: Fish

Pachypleurosaurus is sometimes classified as a nothosaur and sometimes as a member of a separate but closely related family (pachypleurosaurs). It was a small animal with a long, slender body and a long neck and tail. It swam by moving its body in a wavelike pattern, using paddlelike limbs for steering and balance. Most of its fossils have been discovered in rocks formed from marine sediments.

STREAMLINED

pachypleurosaurus-fossil

Pachypleurosaurus fossil

With its legs flat against the body, Pachypleurosaurus had a streamlined, almost snakelike shape. It could dart quickly through the water, powered by a long and muscular tail.

Nothosaurus (NO-tho-SORE-us)

nothosaurus-1


When: 240–210 million years ago (Early to Late Triassic)

Fossil location: Europe, N. Africa, Russia, China

Habitat: Oceans

Length: 4–13 ft (1.2–4 m)

Diet: Fish

Like a seal, Nothosaurus hunted in the water but probably came ashore to rest. It had amazingly long and needle-sharp teeth to seize fish. The teeth interlocked to form a cage, trapping prey in the mouth. Nothosaurus had a long and muscular neck. Some experts think it could twist its head sideways like a crocodile to grab passing fish—a trick known as “snap feeding.”

SWIMMING

nothosaurus-swimming

Nothosaurus probably swam like an otter, waving its long, powerful tail to drive itself through the water. The webbed feet were better suited to walking on land than swimming, but they may have helped Nothosaurus make sharp twists and turns as it chased its prey.

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