Evolution What the Fossils Say and Why it Matters

344 Evolution? The Fossils Say YES!

The next development occurred a few years later, when Gingerich et al. (1990) described

new specimens of the archaeocete Basilosaurus from the middle and upper Eocene deposits

of Egypt (in a locality just west of the Pyramids). Although it was like other archaeocetes in

being fully aquatic, these new specimens had something never previously preserved: the

hind limbs. In most whales, there are no external hind limbs, but the remnants of the hip and

thigh bones are buried in muscles along the spine halfway down the body (fig. 4.9). These

specimens, however, had tiny hind limbs (about as large as a human arm on a 24-meter-long

FIGURE 14.16. Evolution of whales from land creatures, showing the many transitional fossils now documented
from the Eocene beds of Africa and Pakistan. (Drawing by Carl Buell)

Artiodactyls (Hippopotamus)

Pakicetus

Ambulocetus

Dalanistes

Rodhocetus

Takracetus

Gaviocetus

Basilosaurus

Dorudon

Mysticetes

Odontocetes

Paleocene Eocene Oligocene Miocene

65 60 55 50 45 40 35 30 25 million years ago