ABOUT DINOSAURS

ABOUT DINOSAURS

Source: sciencekids.co.nz, amnh.org, activewild.com

Dinosaurs ruled the Earth for over 160 million years, from the Triassic period around 230 million years ago through the Jurassic period and until the end of the Cretaceous period around 65 million years ago.

SCIENCE

While dinosaurs came a long time before us humans, fossils and modern technology have helped us piece together what dinosaurs may have looked like and even how they might have behaved. The first dinosaur to be formally named was the Megalosaurus, back in 1824. Scientists believe that the event leading to the extinction may have been a massive asteroid impact or huge volcanic activity. Events such as these could have blocked out sunlight and significantly changed the Earth’s ecology.

THE DINOSAURS APPEARS

The earliest known dinosaur appeared about 245 million years ago during the Late Triassic Period (250 to 210 million years ago). Dinosaurs evolved into a very diverse group of animals with a vast array of physical features, including modern birds. Contrary to what many people think, not all dinosaurs lived during the same geological period. Stegosaurus, for example, lived during the Late Jurassic Period, about 150 million years ago. Tyrannosaurus rex lived during the Late Cretaceous Period, about 72 million years ago. Stegosaurus was extinct for 66 million years before Tyrannosaurus walked on Earth.
DILOPHOSAURUS
Dilophosaurus is a genus of theropod dinosaur that lived in what is now North America during the Early Jurassic, about 193 million years ago. Three skeletons were discovered in northern Arizona in 1940, and the two best preserved were collected in 1942. At about 7 meters in length, with a weight of about 400 kilograms, Dilophosaurus was one of the earliest large predatory dinosaurs, though it was smaller than some later theropods.
AMARGASAURUS
Amargasaurus is a genus of sauropod dinosaur from the Early Cretaceous epoch (129.4-122.46 mya) of what is now Argentina. The only known skeleton was discovered in 1984 and is virtually complete, including a fragmentary skull, making Amargasaurus one of the best-known sauropods of its epoch. It shared its environment with at least three other sauropod genera, which might have exploited different food sources in order to reduce competition. Amargasaurus probably fed at mid-height, as shown by the orientation of its inner ear and the articulation of its neck vertebrae, which suggest a habitual position of the snout 80 centimeters above the ground and a maximum height of 2.7 meters.
PLATEOSAURUS
Plateosaurus is a genus of plateosaurid dinosaur that lived during the Late Triassic period, around 214 to 204 million years ago, in what is now Central and Northern Europe and Greenland, North America. Plateosaurus is a basal (early) sauropodomorph dinosaur, a so-called "prosauropod". Unusually for a dinosaur, Plateosaurus showed strong developmental plasticity: instead of having a fairly uniform adult size, fully grown individuals were between 4.8 and 10 metres long and weighed between 600 and 4,000 kilograms. Commonly, the animals lived for at least 12 to 20 years, but the maximum life span is not known.
TRICERATOPS
Triceratops is a genus of herbivorous ceratopsid dinosaur that first appeared during the late Maastrichtian stage of the late Cretaceous period, about 68 million years ago (mya) in what is now North America. It is one of the last known non-avian dinosaur genera, and became extinct in the Cretaceous–Paleogene extinction event 66 million years ago. The name Triceratops, which literally means "three-horned face", is derived from the Ancient Greek words τρί- (tri-) meaning "three", κέρας (kéras) meaning "horn", and ὤψ (ōps) meaning "face".
TYRANNOSAURUS REX
Tyrannosaurus is a genus of coelurosaurian theropod dinosaur. The species Tyrannosaurus rex (rex meaning "king" in Latin), often called T. rex or colloquially T-Rex, is one of the most well-represented of the large theropods. Tyrannosaurus lived throughout what is now western North America, on what was then an island continent known as Laramidia. Tyrannosaurus had a much wider range than other tyrannosaurids. Fossils are found in a variety of rock formations dating to the Maastrichtian age of the upper Cretaceous Period, 68 to 66 million years ago. It was the last known member of the tyrannosaurids, and among the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction event.
SPINOSAURUS
Spinosaurus (meaning "spine lizard") is a genus of theropod dinosaur that lived in what now is North Africa, during the upper Albian to upper Turonian stages of the Cretaceous period, about 112 to 93.5 million years ago. This genus was known first from Egyptian remains discovered in 1912.

Spinosaurus was among the largest of all known carnivorous dinosaurs, nearly as large as or even larger than Tyrannosaurus, Giganotosaurus and Carcharodontosaurus.
VELOCIRAPTOR
Velociraptor is a genus of dromaeosaurid theropod dinosaur that lived approximately 75 to 71 million years ago during the latter part of the Cretaceous Period.

Two species are currently recognized, although others have been assigned in the past.

Velociraptor (commonly shortened to "raptor") is one of the dinosaur genera most familiar to the general public due to its prominent role in the Jurassic Park motion picture series. In real life, however, Velociraptor was roughly the size of a turkey, considerably smaller than the approximately 2 m tall and 80 kg reptiles seen in the films.
DILOPHOSAURUS
Dilophosaurus is a genus of theropod dinosaur that lived in what is now North America during the Early Jurassic, about 193 million years ago.

Three skeletons were discovered in northern Arizona in 1940, and the two best preserved were collected in 1942. At about 7 meters in length, with a weight of about 400 kilograms, Dilophosaurus was one of the earliest large predatory dinosaurs, though it was smaller than some later theropods. It was slender and lightly built, and the skull was proportionally large, but delicate.
IGUANODON
Iguanodon is a genus of ornithopod dinosaur that existed roughly halfway between the first of the swift bipedal hypsilophodontids of the mid-Jurassic and the duck-billed dinosaurs of the late Cretaceous.

While many species have been classified in the genus Iguanodon, dating from the late Jurassic Period to the early Cretaceous Period of Asia, Europe, and North America, research in the first decade of the 21st century suggests that there is only one well-substantiated species.
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THE TRIASSIC, JURASSIC & CRETCEOUS PERIODS

Dinosaurs lived in the Mesozoic Era, which is also known as the ‘Age of Reptiles’. The Mesozoic Era began around 252 million years ago, and ended around 66 million years ago. It is subdivided into three smaller periods: the Triassic, Jurassic and Cretaceous periods. The earliest dinosaurs began to appear between around 231 and 243 million years ago, during the Triassic period. They were small, and walked on two legs.
Around 201.3 million years ago, a worldwide extinction event took place. This marked the end of the Triassic period and the beginning of the Jurassic period. Dinosaurs became the dominant land vertebrates (animals with backbones) after the Triassic–Jurassic extinction event. They remained so throughout the Jurassic and Cretaceous periods. Their reign came to an end with another extinction event – the Cretaceous–Paleogene extinction event – which occurred around 66 million years ago. This caused all of the non-avian dinosaurs to become extinct.

DINOSAURS EXTINCT?

Let’s clear something up right away. Dinosaurs aren’t extinct. Not entirely. Every magpie, pigeon, penguin, and ostrich alive today – every single bird – is a dinosaur. They’re all descendants of small, toothy, feathery dinosaurs that hopped and fluttered around from the Jurassic era onwards, meaning that birds are dinosaurs in the same way that bats are mammals. Some scientist does not agree… In 1991, scientists discovered a huge 110-mile-long crater, or hole, in the Gulf of Mexico. They think this crater was made by a giant, fiery, 6-mile-wide asteroid from space that smashed into the Earth about 65 million years ago. The impact was more powerful than any bomb we have ever known. Scientists believe this event killed most plant and animal life – including the dinosaurs. The asteroid probably caused shockwaves, earthquakes, fireballs, wildfires, and tidal, or really big, waves. It also sent huge amounts of dust and gas into the atmosphere, which is like a big blanket of air that surrounds the Earth. That was really bad for the planet.

SURVIVORS?

Technically, dinosaurs survived – although we now call them ‘birds’ – but with the Cretaceous–Paleogene extinction event the age of the giant reptiles was over. The reign of the dinosaurs lasted for around 170 million years. Homo sapiens (modern humans) have only been around for 200,000 years. We’ve still got a long way to go! Scientists now think that all of today’s birds are descended from therapods, which were Saurischian dinosaurs. Many therapods are believed to have had feathers – even Tyrannosaurus Rex! The most bird-like of the therapods branched off into a group called Coelurosauria, which comes from the Greek meaning ‘hollow-tailed lizards’.