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The origins and early evolution of primates is shrouded in mystery due to lack of fossil evidence. They are believed to have split from plesiadapiforms in Eurasia around the early Eocene or earlier. The first true primates so far found in the fossil record are fragmentary and already demonstrate the major split between strepsirrhines and ...
The traditional hypothesis of cetacean evolution, first proposed by Van Valen in 1966, [9] was that whales were related to the mesonychians, an extinct order of carnivorous ungulates (hoofed animals) that resembled wolves with hooves and were a sister group of the artiodactyls (even-toed ungulates). This hypothesis was proposed due to ...
The first fully terrestrial vertebrates were reptilian amniotes — their eggs had internal membranes that allowed the developing embryo to breathe but kept water in. This allowed amniotes to lay eggs on dry land, while amphibians generally need to lay their eggs in water (a few amphibians, such as the common Suriname toad, have evolved other ways of getting around this limitation).
Whales evolved from land-living mammals, and must regularly surface to breathe air, although they can remain underwater for long periods of time. Some species, such as the sperm whale, can stay underwater for up to 90 minutes. [2] They have blowholes (modified nostrils) located on top of their heads, through which air is taken in and expelled.
The larynx evolved when the first land vertebrates started breathing air and needed to separate food from air to prevent choking. Whales evolved from land mammals roughly 50 million years ago. The ...
Whales share this characteristic with extinct marine reptiles, but not present-day marine mammals. [61] A very derived form of hyperphalangy, with six or more phalanges per digit, evolved convergently in rorqual whales and oceanic dolphins, and was likely associated with another wave of signaling within the interdigital tissues. [62]
A baby monkey struggles and squirms as it tries to escape the man holding it by the neck over a concrete cistern, repeatedly dousing it with water. In another video clip, a person plays with the ...
A pair of Humpback whales were photographed mating for the first time ever recently. Both were males. The finding has shocked the scientific community, who never have been able to document whales ...