Whale Vestigial Limbs

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In an article on vestigial organs Live Science writes: “Despite the apparent uselessness, evolution left traces of hind legs behind, and these vestigial limbs can still be seen in the modern whale.”

Editorial Comment: “Apparent uselessness” is the appropriate expression. These bones may look useless when you see them in a museum display of a whale skeleton where they look like useless fragments of bones totally detached from the rest of the skeleton. However, if you put the flesh onto the bones you would see that they form attachment sites for the whale’s reproductive organs. Providing support and stability for soft tissue structures and organs is just as important a function for bones as is their more obvious functions of serving as levers for movement. Some fossil whales such as Basilosaurus had tiny hind limbs but these also had a function in mating, as described by palaeontologist Philip Gingerich, who wrote: “The Pelvis of modern whales serves to anchor reproductive organs even though functional hind limbs are lacking. Thus hind limbs of Basilosaurus are most plausibly interpreted as accessories facilitating reproduction. Abduction of the femur and plantar flexion of the foot, with the knee locked in extension probably enabled hind limbs to be used as guides during copulation which may otherwise have been difficult in a serpentine aquatic animal.” Now you know – if these whale bones were truly vestigial – then the whale would be extinct. Gingerich, et al, Science, vol. 249, pp154-157, 13 Jul 1990. (Ref. cetaceans, vestigial, mammals)

Evidence News, 7 October 2009

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