linkedin post 2020-09-12 03:35:59

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WHALE ANCESTORS. "All cetaceans, including whales, dolphins and porpoises, are descendants of land-dwelling mammals of the Artiodactyl order (even-toed ungulates). Both are related to the Indohyus, an extinct semi-aquatic deer-like ungulate, from which they split around 54 million years ago. These primitive cetaceans first took to the sea about 50 million years ago and became fully aquatic about 5-10 million years later." https://lnkd.in/d3tQ2S7 View in LinkedIn
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linkedin post 2020-09-12 03:33:56

linkedin post 2020-09-12 03:33:56

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LAND ANCESTORS OF WHALES. "Although early whale fossils had been known at least as early as the 1830s, they were often mistaken for giant marine reptiles, as evidenced by the genus name Basilosaurus (Greek for ‘king lizard’), a long, snake-like whale from the Late Eocene [38–34 million years ago (Mya)]." https://www.researchgate.net/profile/Michael_Mcgowen/publication/275671338_A_Whale_of_a_Tale/links/558bce1608ae681f47160178.pdf View in LinkedIn
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linkedin post 2020-09-12 03:32:02

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AMPLE FOSSIL EVIDENCE. "A number of important fossil finds in the 1980s to 2000s revealed several forms that displayed an elegant sequence of incremental adaptations to life beneath the waves. Since then, the evolution of cetaceans has emerged as an example of one of the most well-documented phenotypic transitions in the vertebrate fossil record." https://lnkd.in/d-3T5AM View in LinkedIn
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linkedin post 2020-09-12 03:30:32

linkedin post 2020-09-12 03:30:32

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TRANSITION TO LAND. "Many amniote groups (e.g. sauropterygians, squamates, cetaceans, sirenians, pinnipeds) made the evolutionary transition from a fully terrestrial to a semi- or fully aquatic life. This required major morphological and physiological changes that are best developed in the most specialized aquatic forms, like extant cetaceans and sirenians, which now live totally independent of the terrestrial environment." http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0118409 View in LinkedIn
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linkedin post 2020-09-12 03:22:34

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FRAGMENT FROM NATURE explores the remarkable story of the largest and biggest-brained creatures on earth, who after accomplishing the monumental transition from the water to land, returned to the sea: namely the whales. This involved massive changes in their reproduction, anatomy, metabolism, physiology, social life, and feeding behavior. It is a stunning story of the plasticity of organisms to evolve, and then reverse the evolutionary step. View in LinkedIn
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linkedin post 2020-09-13 03:16:38

linkedin post 2020-09-13 03:16:38

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LAND BIRTH. "Preservation of an intact near-term fetal skull and partial skeleton indicates that birth in early archaeocetes involved a single calf that was born head-first as in land mammals, not tail-first as in living whales. This, in turn, indicates that birth almost certainly took place on land during this phase of early whale evolution." http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0004366 View in LinkedIn
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linkedin post 2020-09-13 03:14:49

linkedin post 2020-09-13 03:14:49

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BIRTH ORIENTATION. "Cephalic presentation at birth is generally held to be advantageous on land as it enables a newborn to breath during labor. Caudal presentation at birth, in contrast, is generally held to be advantageous at sea as it may reduce the risk of drowning. Caudal presentation may also hold an advantage in water, because it orients the newborn calf to swim parallel to the mother rather than away from her." http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0004366 View in LinkedIn
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