Mesozoic

Victor ta Yr4 4 blue

Triassic

• Animals• Pleseosaurus or flat lizard: Plateosaurus was an herbivore

(it ate only plants). This long-necked dinosaur ate leaves high in the trees (like those of conifers and cycads) with sharp, leaf-shaped teeth. Plateosaurus was about 27.5 feet (8 m) long and weighed about 1,500 pounds (700 kg). It had a long neck, a very long tail, a small head with a long snout, and large, five-fingered hands with a large thumb claw (and smaller claws on the other fingers). Plateosaurus may have been able to use its hand for grasping in addition to walking. Its back legs were larger than its front legs.

Jurassic

• Allosaurs• Diet: Allosaurus was a carnivore (meat-eater) who may have hunted in packs. In these groups,

Allosaurus could have ambushed even the very large sauropods (like Diplodocus and Camarasaurs.

• Size This bipedal predator was up to 38 feet (12 m) long and weighed roughly 1 to 5 tons. It had

solid, heavy bones, long claws on its 3-fingered hands, and large, powerful jaws.

Cretaceous

• Cretaceous

Centrosaurus was an herbivore (a plant eater) that ate low-lying plants This ceratopsian dinosaur had a large, forward-pointing snout horn 18 inches (46 cm) long. The skull

was over 3 ft (1 m) long. Its scalloped frill had two hooked spikes near the centre. Centrosaurus

was about 20 feet (6 m) long, 6 feet (1.8 m) tall, and weighed up to 3 tons.

Plants in Triassic • Leptocycas was a cycad, a primitive seed plant from the late Triassic period. It was a palm-like

tree with a long, woody trunk and tough leaves. It lived in warm climates. This tree was about 4

• .8 ft (1.5 m) tall.

• The dinosaurs evolved early in the Mesozoic Era, during the Triassic period (about 228 million years ago). At the start of the Mesozoic Era, the continents of the Earth were jammed together into the supercontinent of Pangaea; this land mass had a hot, dry interior with many deserts. The

polar regions were moist and temperate.

Plants in Jurassic

• Conifers (like Araucarioxylon) were the dominant land plant during the Jurassic

period. Other land plants included Ginkgophytes (like Ginkgos), club mosses, horsetails, ferns, seed ferns, Sphenopsids (like Neocalamites), Filincophyta (like Matonidium), Cycadeodia (like Otozamites, Ptilophyllum, and Cycadeoidea), and cycadophytes.

Plants in Cretaceous• Williamsonia sewardiana was a cycadeoidphyte (a bennettitalean). It had a woody

stem and simple leaves. It lived from the Jurassic period through the late Cretaceous period. Williamsonia was a bennettitalean (a primitive gymnosperm that resembled cycads but was not a cycad). Williamsonia had a long, thin, branching, woody trunk covered with spirals of broken-off leaf scars

Environment in Cretaceous• It was a warm tropical place in which many angiosperms (flowering plants) developed and

became dominant. Because of this, many new herbivores appeared and others went extinct.

During the Cretaceous the climate was warmer than today. In the seas, marine

invertebrates flourished, and bony fishes evolved. On land, flowering plants arose, and insects, bees in particular, began their thriving partnership with them. Mammals and birds remained inconspicuous throughout the Cretaceous, while the reptiles continued their dominance. The dinosaurs reached the peak of their evolution during this period but rather suddenly became extinct at its end.

Environment in Jurassic • The Jurassic landscape was much greener and more lush than in the Triassic. There was a wider

variety of vegetation. The tall tree ferns made up the second understory of trees, and the smaller ferns and horsetails were the most common low growing foliage. There were successive

accumulations of marine sandstones, limestones, and shales. • Barley is a cereal grain related to wheat, oats, and rice. Barley seeds (the part of the plant that is

highest in nutrition) grow in spikes at the tips of the stems - it resembles wheat. This important crop is grown in temperate areas and is used as animal feed, for malt (used in making beer, malted milk, and food flavoring), and for human consumption (used as a flour, a thickener, a cereal, in soups, etc.). Barley was cultivated thousands of years ago; it was grown by the Egyptians from 5,000 to 7,000 years ago. The countries that produce the most barley are Russia, Canada, and Germany. Classification: family Poaceae (Gramineae) (grasses), genus Hordeum, species H. vulgare.

Environment in Triassic • The Triassic Period was born 250 million years ago (mya) from the violent close of the

Permian Period. It was here that thousands of doomed species witnessed the collision of the world’s continents, and the subsequent formation of the super continent, Pangea. The land trembled and buckled as great mountains thrust their way into the sky, volcanoes erupted and other lands sank beneath the waves. During the geologically brief existence of Pangea, the rest of the earth was covered by one vast ocean, Panthalassa.

Although the primary cause is not known, during the turbulent birth of Pangea great stresses so plagued the global environment that 95% of all species disappeared from the face of the earth.

When history’s greatest known extinction ended, the environment was ripe for the rise of thousands of new species, including early dinosaurs and small mammals. Most species living today would not exist were it not for the mysterious global disaster that marked the birth of the Triassic.

The Triassic Period came to its own violent end about 200 mya as great convective forces deep within the earth split apart the northwestern region of Pangea, and set North America adrift from what would become the African continent. With the death of Pangea and the Triassic, the Jurassic was born. This would be the time of the dinosaurs, great and small, and they would rule the earth for the next 135 million years.