evidence of adaptation

Fossil evidence
It is thought that modern African and Indian elephants may have originated
in Asia but the earliest fossils of the Proboscidea order have been found in
Africa. The oldest, Moeritherium, which lived about 35-50 million years ago
during what is called the Eocene period was named after Egypt's Lake Moeris
where its remains were found. About a metre tall, Moeritherium was
relatively small with no trunk. It had enlarged incisor teeth (like small
elephant tusks) in both jaws. Living in shallow water, it is thought to have
been amphibious. It is not a direct ancestor of elephants, as it has no known
Later Proboscidean fossils show that, although larger than Moeritherium, the
early Palaeomastodon and Gomphotherium bore little resemblance to
modern elephants. However, as the Proboscidean species evolved, the
animals grew larger with longer limbs, their skull, teeth and tusk size
increased and a mobile trunk developed. Primelephas and the extinct
relatives of modern elephants, Mammuthus (mammoths), Mammut
(mastodons), Anancus and Stegodon were all large animals with pillar-like
legs, tusks and an extended flexible nose.
Proboscidean fossils have been found in Africa, Asia, Europe and North and
South America. They show that the ancestors of modern elephants moved
around the globe.
The earliest Palaomastodon remains have been found in Eocene (35-50
million years old) deposits in Egypt.
During the early Miocene epoch (over 5 million years ago) some
species spread into Asia and from there to North America.
Gomphotherium fossils have been found in Africa, Asia, Europe and
North America.
The elephant-like Primelephas roamed Eastern and Central Africa
during the late Miocene and early Pliocene (7-2 million years ago).
Descendents of Gompthotherium entered South America in the
Pliocene (more than 2 million years ago).
The Elephantidae family contains today's living elephants along with the
extinct mammoths. Reaching over 4m in height, many with very curved
tusks, mammoths were widespread in Europe, northern Asia, North America
and arctic regions. They originated about 1.6million years ago. The last
mammoth species became extinct about 10,000 years ago at the end of the
last Ice Age. It is unclear whether they were driven to extinction by climatic
factors or as a consequence of hunting by early man.