The Evolution of Whales
The origin of modern day whales, a mystery that has puzzled paleontologists for years, may have just been solved with the discovery of an ankle bone. This discovery might sound simple and unimportant, but the bones of these ancient animals hold many unanswered questions and provide solid proof of origin and behavior. The relationship between whales and other animals has proven to be difficult because whales are warm-blooded, like humans, yet they live in the sea. The fact that they are warm-blooded suggests that they are related to some type of land animal. However, the questions of exactly which animal, and how whales evolved from land to water, have remained unanswered until now.
In 2000, Dr. Philip D. Gingerich, a paleontologist from the University of Michigan, and his associates discovered two primitive whale fossils in the Balochistan Province of Pakistan. By dating the limestone located in the Habib Rahi Formation of the Balochistan Province, Gingerich estimated these fossils to be about 47 million years old. According to author David Braun of National Geographic News, “The researchers have classified one, Rodhocetus balochistanensis, as a new species of an existing genus, and the other, Artiocetus clavis, as a new species and new genus” (Braun, 5). The discovery of these two fossils suggests that the closest living relative of these primitive whales could possibly be the modern day hippopotamus. This suggested relationship is based on similarities in the bone structure between the two animals.
Hippopotami belong to a group of animals called artiodactyls. This group of animals, which includes deer, camels, sheep, pigs, and cows, are “named for the even number of fingers and toes (two or four) found on each hand and foot” (Braun, 2). Gingerich’s discoveries are unique in that they are the only fossils to contain both bones from a whale skull and sheep-like ankle bones in the same skeleton. Ankle bones and tarsal [foot] bones are the most diagnostic elements of the artiodactyls (Gingerich et al., 2), meaning that these bones are the most telling bones when distinguishing what group of animals a fossil may have come from. The presence of these two types of bones together in Gingerich’s discovery suggests that this primitive whale indeed could have been related to the hippopotamus. The skeletons of these animals contain similar bones; therefore both are thought to be artiodactyls. In a recent article in Science, Kenneth D. Rose, of the Johns Hopkins University School of Medicine, says, “While ankles from primitive ancient whales have been discovered before, these are the first that are well-preserved enough to provide clues about whale ancestry” (Braun, 3). Paleontologists strongly believe that the bones of this discovery are all from the same animal. According to Gingerich, “No other mammalian specimens were found in the vicinity; all (fossils) are similar in size, color, and preservation;...