Late Triassic - Late Cretaceous.
Coelophysis bauri, 200 Ma. was a small, lightly-built theropod dinosaur from the Upper Triassic and Early Jurassic of North America. One of the earliest theropods and averaging lengths of three metres, it is in fact one of the better understood of all theropod dinosaurs, having been found in large concentrations at mass grave-sites. This prompted palaeontologists to speculate that Coelophysis was a gregarious animal and travelled in packs. Due to their early position in the theropod family tree, the coelophysids may have been more reptilian than later advanced theropods and possibly still laid soft eggs.
Sinraptor, 160 Ma. meaning Chinese Thief, was a large predatory carnosaur from China. Although its name might suggest an affinity with other 'raptors' such as the famous Velociraptor, Sinraptor lived during the Late Jurassic period 160 Ma, and is part of a family of dinosaurs called the Metriacanthosauridae within the Allosauroidea. Allosaurs were the dominant predators in most Late Jurassic environments. With long, thin heads and steak-knife teeth, they are considered to have been pack hunters, living or collecting together to bring down the giant sauropods on which they would have likely fed.
Ceratosaurus nasicornis 150 Ma. was a medium-sized theropod dinosaur from the Late Jurassic period of North America and gives its name to the family Ceratosauridae. Ceratosaurus possessed larger teeth for its size than any other predatory dinosaur, and a prominent nasal horn, possibly used to protect its snout during episodes of intra-species rivalry. Ceratosaurus nasicornis shared its world with the much larger allosaurid dinosaurs and would likely have favoured a different habitat and lifestyle.
Abelisaurus comahuensis, 80 Ma. known from South America, belongs to a family of medium-sized predators that emerged during the Cretaceous period in the Southern hemisphere and have only been discovered in recent years. Unlike most predatory dinosaurs, the abelisaurids had short faces and small teeth, but studies of their neck musculature would indicate they could use their entire heads to produce a powerful downward bite.
Mononykus olecranus 70 Ma. from the Late Cretaceous of Mongolia, is a member of a group of interesting small dinosaurs, the Alvarezsauridae, named after Alvarezsaurus, the first member of the family to be described. Like many small theropod dinosaurs, they are known to have been feathered and lived in the shadow of the giant tyrannosaurs, carcharodontosaurs and abelisaurs that dominated most Cretaceous environments. The origins of the Alvarezsauridae go back to the late Jurassic period, but it is not until the Late Cretaceous that they make a more significant appearance. Although considered a sister taxon to birds, the Alvarezsauridae followed their own specialised evolutionary path, with large eyes, dramatically reduced arms and a single large digit on each hand. They were most likely insectivorous, possibly hunting at night.
Ink on paper.
X Close Info