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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 ...
While this change was favorable to freshwater vertebrates, those that prefer marine environments, such as sharks, suffered. [130] However, sea level fall as a cause of the extinction event is contradicted by other evidence, namely that sections which show no sign of marine regression still show evidence of a major drop in diversity. [279]
The map of North America with the Western Interior Seaway during the Campanian. The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, or the Western Interior Sea) was a large inland sea that split the continent of North America into two landmasses for 34 million years.
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.
Numerous theories have been proposed as to why this extinction event happened including an asteroid known as the Chicxulub asteroid, volcanism, or sea level changes. While the mass extinction is well documented, there is much debate about the immediate and long-term climatic and environmental changes caused by the event. [ 1 ]
The coincidental drop in sea level at this time period led to a drop in the population of phytoplankton that would have otherwise ingested the excess CO 2. The unchecked CO 2 levels would make it difficult for warm-blooded dinosaur eggs buried in nests to obtain enough oxygen through passive gas exchange with the atmosphere and the embryos ...
However, it is not universally accepted that even this local diversity drop was caused by sea level fall. [197] A pronounced sea level change in latest Triassic records from Lake Williston in northeastern British Columbia, which was then the northeastern margin of Panthalassa, resulted in an extinction event of infaunal (sediment-dwelling ...