By | September 9, 2016

Spinosaurids were huge, sail-backed dinosaurs that lived in swamps and estuaries. With their crocodile like snouts and powerful clawed hands, they were ideally built for catching the monster fish of the time. They were also skilled at hunting on land.


Key features
■ Crocodile-like heads and snouts
■ Big conical teeth
■ Large sail on back
■ Stiff tails, held out for balance

Spinosaurids first appeared in the Late Jurassic, 155 million years ago. They died out in the Late Cretaceous, 93 million years ago, when sea levels dropped on Earth and the swamps that spinosaurids lived in dried up.

Spinosaurus (SPINE-oh-SORE-us)


When: 97 million years ago (Late Cretaceous)

Fossil location: Morocco, Libya, Egypt

Habitat: Tropical swamps

Length: 60 ft (18 m)

Diet: Fish and other animals

Even bigger than Tyrannosaurus, Spinosaurus was the largest land-dwelling predator of all time. What made it spectacular was an enormous “sail” running along its back. This was supported by spines made of bone, which were as tall as a man—giving it the name Spinosaurus, meaning “spine lizard.” It may have hunted on land and in water, just like crocodiles today. It probably ate smaller dinosaurs, turtles, and birds, as well as fish.

Smooth sailing


Spinosaurus’s skeleton

Spinosaurus’s sail might have had various uses. Some scientists think it was for display or that it acted as a radiator, helping Spinosaurus to keep cool in the hot climate. Others think the sail was a hump that stored body fat for energy, as in modern camels.

Irritator (IH-rih-tay-tore)


When: 110 million years ago (Early Cretaceous)

Fossil location: Brazil

Habitat: Lakesides

Length: 26 ft (8 m)

Diet: Meat and fish

In 1996 this spinosaurid’s long, crocodile-like skull was discovered in Brazil by a fossil hunter. Its name is the result of a clumsy attempt to mend the snout with plaster, which irritated the scientists who tried to undo the damage. In addition to a sail along its back, it may also have had a small crest on the back of its head.


Irritator used its long teeth to grab and hold on to fish. It may have fed on dead meat and land animals, too.

Baryonyx (bah-ree-ON-ix)



When: 125 million years ago (Early Cretaceous)

Fossil location: British Isles, Spain, Portugal

Habitat: Riverbanks

Length: 30 ft (9 m)

Diet: Fish and meat

Remains of partly digested dinosaurs were found in Baryonyx’s fossilized stomach, indicating that it ate land animals as well as fish. It had a very long, low skull, and its jaws had 96 pointed teeth—twice as many as other members of its family. Baryonyx may have had a ridge on its back and a small crest on its snout.



Replica of a Baryonyx’s claw

Baryonyx means “heavy claw,” referring to its huge, hooklike thumb claws, which it may have used to spear fish, as grizzly bears do today.

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