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Their simple shells evolved into complex spirals like the one still used by the nautilus. Without many vertebrates to compete with, the cephalopods were top predators. Although the first vertebrates emerged during this time period, it wasn’t until millions of years later that they came to rule the seas.
A tetrapod ( / ˈtɛtrəˌpɒd /; [5] from Ancient Greek τετρα- (tetra-) 'four', and πούς (poús) 'foot') is any four- limbed vertebrate animal of the superclass Tetrapoda ( / tɛˈtræpədə / ). [6] Tetrapods include all extant and extinct amphibians and amniotes, with the latter in turn evolving into two major clades, the sauropsids ...
In oxygen poor waters, some fish (aptly called lungfish) evolved many blood vessels on their swim bladder allowing them to gasp some air and have the oxygen diffuse from their bladder into their blood. This eventually became the lungs. 14 votes, 10 comments. So I recently learned that mammals can breath because of the negative pressure in the ...
1 Phylogenetic History: The Evolution of Marine Mammals. Think for a moment about marine mammals: seals, walruses, dugongs and whales. Seals and walruses are primarily cold-water species that eat mostly fish and can spend part of their time on land (or ice). Dugongs and manatees are tropical herbivores and are entirely aquatic.
May 21, 2007 · Marine Mammal Diversity. Living groups of marine mammals vary greatly in their diversity. Rice (1998; Table 1 therein) reports that living Cetacea include 83 species in 39 genera; living Pinnipedia include 36 species in 21 genera; and Recent Sirenia include 5 species in 3 genera. Since then, several new species of cetaceans have been described ...
The evolution of the whale has been long and varied. From land mammals to marine mammals, many adaptations were needed. Whales evolved from early land mammals, adapting to life in the oceans by losing their hind limbs, growing a flat tail, developing flippers, and streamlining their bodies. This article looks at the whale’s evolution, how it ...
Jan 27, 2015 · The marine mammals shared the traits needed to live in a marine environment, but they developed their traits separately – a process called convergent evolution. "We were wondering what the ...
