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However, viruses are still poorly understood and may have arisen before "life" itself, or may be a more recent phenomenon. Major extinctions in terrestrial vertebrates and large amphibians. Earliest examples of armoured dinosaurs. 195 Ma First pterosaurs with specialized feeding (Dorygnathus). First sauropod dinosaurs.
Major spatial differences existed in calcareous nannoplankton diversity patterns; in the Southern Hemisphere, the extinction was less severe and recovery occurred much faster than in the Northern Hemisphere. [47] Following the extinction, survivor communities dominated for several hundred thousand years.
John M. Cys argued that dinosaurs went extinct because they were unable to hibernate during the winter, leaving them doomed by Earth's changing climate. [23] 1968. Daniel I. Axelrod and Harry Paul Bailey proposed that the dinosaurs were driven extinct when Earth's climate began exhibiting more marked seasons rather than stable conditions year ...
An international team found dinosaurs had been evolving and expanding, but showed a sudden downturn around 76 million years ago. Dinosaurs were in decline up to 10 million years before asteroid ...
"Dinosaurs started small, playing a minor role in their ecosystems during the Triassic," Heath said. "They lived in the shadows of bigger, more dominant animals. However, dinosaurs had some ...
The creature existed some 40 million years before dinosaurs evolved. Researchers have long examined such ancient predators to uncover the origins of tetrapods: four-legged animals that clambered onto land with fingers instead of fins and evolved to amphibians, birds and mammals including humans.
Scientists have revealed fossils of a giant salamanderlike beast with sharp fangs that ruled waters before the first dinosaurs arrived. ... The creature existed some 40 million years before ...
Just before the K-Pg extinction event, the number of non-avian dinosaur species that existed globally has been estimated at between 628 and 1078. [280] It remains uncertain whether the diversity of dinosaurs was in gradual decline before the K-Pg extinction event, or whether dinosaurs were actually thriving prior to the extinction.