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The earliest marine reptiles arose in the Permian. During the Mesozoic many groups of reptiles became adapted to life in the seas, including ichthyosaurs, plesiosaurs, mosasaurs, nothosaurs, placodonts, sea turtles, thalattosaurs and thalattosuchians. Marine reptiles were less numerous after mass extinction at the end of the Cretaceous.
Marine reptiles are reptiles which have become secondarily adapted for an aquatic or semiaquatic life in a marine environment. Only about 100 of the 12,000 extant reptile species and subspecies are classed as marine reptiles, including marine iguanas , sea snakes , sea turtles and saltwater crocodiles .
They have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process. Sponges do not have nervous, digestive or circulatory systems. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes.
While today's blue whale has long held the title, scientists have dug up fossils from an ancient giant that could tip the scales. ... 13 vertebrae from the whale’s backbone, four ribs and a hip ...
This is an accepted version of this page This is the latest accepted revision, reviewed on 8 December 2024. Group of animals including lepidosaurs, testudines, and archosaurs This article is about the animal class. For other uses, see Reptile (disambiguation). Reptiles Temporal range: Late Carboniferous–Present PreꞒ Ꞓ O S D C P T J K Pg N Tuatara Saltwater crocodile Common box turtle ...
The evolution of tetrapods began about 400 million years ago in the Devonian Period with the earliest tetrapods evolved from lobe-finned fishes. [1] Tetrapods (under the apomorphy-based definition used on this page) are categorized as animals in the biological superclass Tetrapoda, which includes all living and extinct amphibians, reptiles, birds, and mammals.
Blue whales have returned to a part of the Indian Ocean where the species was once wiped out by whaling decades ago. Researchers in the Seychelles have captured footage of the marine mammals in ...
The blue whale is the largest animal known ever to have existed. [42] [43] [44] Some studies have estimated that certain shastasaurid ichthyosaurs and the ancient whale Perucetus could have rivalled the blue whale in size, with Perucetus also being heavier than the blue whale with a mean weight of 180 t (180 long tons; 200 short tons).