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Beginning of animal evolution. [54] [55] 720–630 Ma Possible global glaciation [56] [57] which increased the atmospheric oxygen and decreased carbon dioxide, and was either caused by land plant evolution [58] or resulted in it. [59] Opinion is divided on whether it increased or decreased biodiversity or the rate of evolution. [60] [61] [62 ...
The first ancestors of fish, or animals that were probably closely related to fish, were Haikouichthys and Myllokunmingia. [ 6 ] [ 3 ] These two genera all appeared around 530 Mya . Unlike the other fauna that dominated the Cambrian, these groups had the basic vertebrate body plan : a notochord , rudimentary vertebrae, and a well-defined head ...
The evolution of fishes took place over a timeline which spans the Cambrian to the Cenozoic, including during that time in particular the Devonian, which has been dubbed the "age of fishes" for the many changes during that period. The Late Devonian extinctions played a crucial role in shaping the evolution of fish, or vertebrates in general. [1]
These fish evolved in shallow and swampy freshwater habitats, where they evolved large eyes and spiracles. Primitive tetrapods ("fishapods") developed from tetrapodomorphs with a two-lobed brain in a flattened skull, a wide mouth and a medium snout, whose upward-facing eyes show that it was a bottom-dweller, and which had already developed ...
As they evolved from lunged fish, amphibians had to make certain adaptations for living on land, including the need to develop new means of locomotion. In the water, the sideways thrusts of their tails had propelled them forward, but on land, quite different mechanisms were required.
The human population exploits a large number of other animal species for food, both of domesticated livestock species in animal husbandry and, mainly at sea, by hunting wild species. [ 172 ] [ 173 ] Marine fish of many species are caught commercially for food.
The first tetrapods probably evolved in the Emsian stage of the Early Devonian from Tetrapodomorph fish living in shallow water environments. [ 36 ] [ 37 ] The very earliest tetrapods would have been animals similar to Acanthostega , with legs and lungs as well as gills, but still primarily aquatic and unsuited to life on land.
The evolution of the molluscs is the way in which the Mollusca, one of the largest groups of invertebrate animals, evolved. This phylum includes gastropods, bivalves, scaphopods, cephalopods, and several other groups. The fossil record of mollusks is relatively complete, and they are well represented in most fossil-bearing marine strata.