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What other 'throwback' features have been seen in humans or animals
On October 28, 2006, Japanese fishermen captured a four-finned dolphin off the coast of western Japan, and donated the whale to the Taiji Whaling Museum where it is currently being studied. This bottlenose dolphin has an extra set of hindlimbs, two well-formed palm-sized flippers that move and flap like the normal fore-flippers (see Figure 2.2.2). As with other atavistic structures, these limbs are likely the result of a rare mutation that allows an underlying, yet cryptic, developmental pathway to become reactivated. These limbs are prima facie evidence of the dolphin's four-limbed ancestry, as predicted from the common ancestry of dolphins and other land-dwelling mammals.