At the start of the Triassic Period, all dinosaurs were small and stood low on the ground. Over time, a group of mainly plant-eating dinosaurs called the prosauropods grew taller and heavier than their competitors. They evolved long necks and tails and strong back legs that allowed them to stand up and reach high tree branches.
FAMILY FACT FILE
■ Small heads
■ Long, flexible necks
■ Very long thumb claws
■ Hindlimbs longer than forelimbs
Prosauropods first appeared in the Late Triassic, 217 million years ago. They died out in the Middle Jurassic, 184 million years ago.
■ When: 220–210 million years ago (Late Triassic)
■ Fossil location: Germany, Switzerland, Norway, Greenland
■ Habitat: Plains of western Europe
■ Length: 25 ft (8 m)
■ Diet: Plants
Plateosaurus was one of the largest of the prosauropods. It walked on its hind legs, mainly feeding on plants at ground level. It could also stand like a kangaroo, rearing up on its hindlimbs and stretching its long neck to eat leaves from trees. More than 50 complete skeletons of Plateosaurus have been found.
■ When: 200–183 million years ago (Early Jurassic)
■ Fossil location: S. Africa
■ Habitat: Woodlands of S. Africa
■ Length: 13–20 ft (4–6 m)
■ Diet: Plants
Massospondylus had five-fingered hands, which it used to grasp and pull down branches. It may also have used its long thumb claws to tear off pieces of plant material. Small, coarse teeth suggest that it could chew both meat and plants. It may also have swallowed small stones to help digest its food, as many “stomach stones” have been found among its bones. Several complete skeletons and skulls of Massospondylus have been discovered in South Africa.
Some eggs containing embryos have also been found.
■ When: 225–208 million years ago (Late Triassic)
■ Fossil location: British Isles
■ Habitat: Wooded offshore islands of western Europe
■ Length: 7 ft (2 m)
■ Diet: Plants
Thecodontosaurus was the first prosauropod to be discovered, and was named “sockettoothed” after its unusual leaf-shaped, sawlike teeth. Unlike lizards today, whose teeth are fused to their jaw bones, this prosauropod’s teeth were rooted in separate sockets in its jaw bones.
As it is smaller than its relatives, scientists think it may have lived on islands, since animals that live on islands are often small in size. Many fossils of Thecodontosaurus have been found in caves, and may have been washed there by rising sea levels.
DID YOU KNOW…?
During World War II, a bomb set fire to the Bristol City Museum in Britain, destroying a precious fossil kept in it. This fossil was of Thecodontosaurus—the oldest dinosaur ever found in Britain. Luckily, some bones were saved and can still be seen in the museum.
■ When: 200–180 million years ago (Early Jurassic)
■ Fossil location: China
■ Habitat: Woodlands of Asia
■ Length: 20 ft (6 m)
■ Diet: Plants, including cycad and conifer leaves
Lufengosaurus was a heavy, stout-limbed dinosaur. Its head was deep and narrow, with bony lumps around its snout and jaws. It used its widely spaced, bladelike teeth to eat tough plants or to nibble on leaves from trees. It may have also eaten small animals. Lufengosaurus probably moved around on two legs most of the time and could rear up to reach higher branches. Its broad hands had long fingers, and each of its thumbs had a massive claw.