They belonged to a group called pakicetids.
Professor Thewissen said: "The body looks
basically like a large dog. The head has all the features of a whale
in the teeth and the ear.
"It's different from most land mammals in that the eyes are very
close set, the snout is very long and the tail is very muscular and
The animals had distinctive ankle bones like those of
cloven-hoofed mammals. They also had bones in their ears that are
unique to the whale family.
The new fossils superbly document the link between modern whales
and their land-based forebears, said Christian de Muizon, of the
Centre National de la Recherche Scientifique, Paris, France.
"The first whale was not swimming but walking on land," he said.
The two other newly found fossils are of later creatures further
down the path towards aquatic life.
The skeletons are approximately 47 million years old, and also
come from Pakistan.
These early whales used powerful webbed hind legs to swim, like
otters, and could probably move on land as well.
University of Michigan palaeontology professor Philip Gingerich
discovered the fossils after a decade-long search.
Professor Gingerich said: It's clear that these animals could
hitch their way out of water and back in like sea lions do today,
but they were more aquatic than I realised."