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Spinosaurus is known to have eaten fish and small to medium terrestrial prey as well. [5] Evidence suggests that it was semiaquatic; how capable it was of swimming has been strongly contested. Spinosaurus's leg bones had osteosclerosis (high bone density), allowing for better buoyancy control.
Coccolithophorids and mollusks (including ammonites, rudists, freshwater snails, and mussels), and those organisms whose food chain included these shell builders, became extinct or suffered heavy losses. For example, it is thought that ammonites were the principal food of mosasaurs, a group of giant marine reptiles that became extinct at the ...
This is a list of North American animals extinct in the Holocene that covers extinctions from the Holocene epoch, a geologic epoch that began about 11,650 years before present (about 9700 BCE) [A] and continues to the present day. [1] Recently extinct animals in the West Indies and Hawaii are in their own respective lists.
The smallest genus known from good material is Irritator, which was between 6 and 8 meters (20 and 26 feet) long and around 1 metric ton (1.1 short tons; 0.98 long tons) in weight. [ 22 ] [ 23 ] Ichthyovenator , Baryonyx , and Suchomimus ranged from 7.5 to 11 m (25 to 36 ft) long, and weighed between 1 and 5.2 t (1.1 and 5.7 short tons; 0.98 ...
Researchers report that the Cretaceous Chicxulub asteroid impact that resulted in the extinction of non-avian dinosaurs 66 million years ago, also rapidly acidified the oceans producing ecological collapse and long-lasting effects on the climate, and was a key reason for end-Cretaceous mass extinction.
Definite evidence of Late Cretaceous sauropods in North America was first discovered in 1922, when Charles Whitney Gilmore described Alamosaurus sanjuanensis. [1] The term "sauropod hiatus" was coined by researchers Spencer G. Lucas and Adrian P. Hunt in 1989 to describes how fossils of the clade become scarce in western North America near the beginning of the Late Cretaceous.
Luis Walter Alvarez, left, and his son Walter, right, at the K–T Boundary in Gubbio, Italy, 1981. The Alvarez hypothesis posits that the mass extinction of the non-avian dinosaurs and many other living things during the Cretaceous–Paleogene extinction event was caused by the impact of a large asteroid on the Earth.
However, pinpointing the extinction of these different land reptile groups is difficult, as the last stage of the Triassic, the Rhaetian, and the first stage of the Jurassic, the Hettangian, each have few records of large land animals; some paleontologists have considered only phytosaurs and procolophonids to have become extinct at the Triassic ...