Dinosaur In a Haystack - A Website About Stephen Jay Gould's ...

vestiges of hips. He also notes that other extended transitions of the same magnitudehave been well-documented, such as two of the jaw bones in reptiles becoming ear bonesin mammals [ELP 6], the transition of the lobe-fin fish’s swimming paddle to a tetrapod’swalking limb [ELP 4], and of course archaeopteryx and Lucy [TPT 11]. There are thereare actually three different orders of mammals, he notes, in which some or all membershave made the land-to-sea transition. There are the Carnivores, which include dogs, cats,and bears, but also seals, sea lions, and walruses; the manatees and their kin, which arerelated to elephants; and the cetaceans, which are descendants of an extinct order ofmammals called mesonychids (or their close relatives). Mesonychids were relativelylarge, predatory animals related to modern even-toed undulates such as antelopes;imagine a wolf with hooves. Nonetheless, he acknowledges that the transition betweenwalking legs and a ropey tail to no legs and a large fluke is a massive change that easilylends itself to question, if not ridicule. But the fossil record finally provided some harddata. Gould presents the story of discovery in four parts, with a fifth added in anepilogue.Case One, as Gould refers to it, is the discovery of Pakicetus, the oldest whale (so far),found in Pakistan in 1983. Only the skull was found, but numerous features identify it asan early whale. The teeth closely resemble those of mesonychids, as expected. Oneimportant intermediate feature is that the ear still worked as in terrestrial animals, via anear hole; additional analysis in 1993 confirmed that the pad of fat in the jaw, whichconducts sound to the inner ear in modern whales, was not present. A second importanttransitional feature is that the sinuses contained air, rather than blood as in all modernwhales, making deep diving impossible; this is consistent with the discovery of Pakicetusin shallow sediments associated with the mouth of a river. The creature lived in themiddle Eocene period, about 52 million years ago. While exciting to scientists, theabsence of tail and/or hind leg fossils precludes it from dousing creationist arguments.Case Two is the discovery of the rear legs of a previously known whale, Basilosaurus.This early whale lived between about 47 and 42 million years ago, and so is considerablyyounger than Pakicetus. In 1990, a team successfully joined bones from manyindividuals to form a composite leg, including femur, tibia, fibula, kneecap, and toebones. Evidence indicates that the leg did “stick out” through the side of the whale, butwas only a foot or two long – a small fraction of a 50-foot animal. While once againfascinating, the legs could serve no function on land (or probably even in water), andtherefore do not meet the “transitional” criteria that Gould is seeking. Those with openminds see such artifacts and remnants as evidence that evolution occurs [see, forexample, TPT 1]; but to a modern creationist, it means no more than free-floating hipremnants in modern whales.Case Three is the discovery in 1993 of a whale called Indocetus, of intermediate agebetween Pakicetus and Basilosaurus. It contains fragments of the hips and legs thatindicate that the rear limbs were large enough to support the animal on land; however,their fragmentary nature precludes them from supporting a claim of victory.37