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They are currently the most successful and diverse group of living reptiles, with more than 10,000 extant species. The only major group of terrestrial lizards to go extinct at the end of the Cretaceous were the polyglyphanodontians, a diverse group of mainly herbivorous lizards known predominantly from the Northern Hemisphere. [109]
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.
Juvenile spinosaurid fossils are somewhat rare. However, an ungual phalanx measuring 21 mm (0.83 in) belonging to a very young Spinosaurus indicates that Spinosaurus, and probably by extent other spinosaurids, may have developed their semiaquatic adaptations at birth or at a very young age and maintained the adaptations throughout their lives ...
The largest carnivorous dinosaur was Spinosaurus, reaching a length of 12.6 to 18 meters (41 to 59 ft) and weighing 7 to 20.9 metric tons (7.7 to 23.0 short tons). [154] [155] Other large carnivorous theropods included Giganotosaurus, Carcharodontosaurus, and Tyrannosaurus. [155] Therizinosaurus and Deinocheirus were among the tallest of the ...
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.
Extinct due to destruction of nesting habitat by introduced goats, and predation by cats. [56] Zacatecas Worthen's sparrow: Spizella wortheni browni: Northwest Zacatecas, Mexico Last recorded in 1961. Extinct due to habitat loss to agriculture, overgrazing and erosion by cattle herding, and decline of native herbivores which maintained the bird ...
Artist's depiction of the end-Cretaceous impact eventSince the 19th century, a significant amount of research has been conducted on the Cretaceous–Paleogene extinction event, the mass extinction that ended the dinosaur-dominated Mesozoic Era and set the stage for the Age of Mammals, or Cenozoic Era.
Neck reconstructions of Sigilmassasaurus (top) and Baryonyx. The validity of Sigilmassaurus, however, did not go unchallenged shortly after it was named.In 1996, Paul Sereno and colleagues described a Carcharodontosaurus skull (SGM-Din-1) from Morocco, as well as a neck vertebra (SGM-Din-3) which resembled that of "Spinosaurus B," which they therefore synonymized with Carcharodontosaurus. [11]