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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.
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 ...
Most other tetrapods weighing more than 25 kg (55 lb) also became extinct, with the exception of some ectothermic species such as sea turtles and crocodilians. [4] It marked the end of the Cretaceous period, and with it the Mesozoic era, while heralding the beginning of the current era, the Cenozoic .
Sea-level falls: 12, of which seven were associated with significant extinctions. [f] Asteroid impacts: one large impact is associated with a mass extinction, that is, the Cretaceous–Paleogene extinction event; there have been many smaller impacts but they are not associated with significant extinctions, [105] or cannot be dated precisely enough.
To avoid confusion between the phylogeny, the evolutionary relationships, and the morphology, the way the animal is built, long-necked forms are therefore called "plesiosauromorph" and short-necked forms are called "pliosauromorph", without the "plesiosauromorph" species necessarily being more closely related to each other than to the ...
Several temnospondyl groups did become extinct near the end of the Triassic despite earlier abundance, but it is uncertain how close their extinctions were to the end of the Triassic. The last known metoposaurids (" Apachesaurus ") were from the Redonda Formation , which may have been early Rhaetian or late Norian .
This loss of lead could have been caused by heat from the hypothesized impact event. [112] The Western Interior Seaway of North America 95 million years ago. 1994. Smith and others concluded that the Late Cretaceous drop in sea levels constituted the most severe marine regression of the entire Mesozoic Era. [102]
Oxygen depletion when combined with high levels of sulfide is called euxinia. Though less toxic, ferrous iron (Fe 2+ ) is another substance which commonly forms in anoxic waters. [ 70 ] Anoxia is the most common culprit for the second pulse of the Late Ordovician mass extinction and is connected to many other mass extinctions throughout ...