Page 10 - Dog

Evolution of the dog family

Thirty million years ago, during the Oligocene period, the first
doglike creature, Cynodictis (a mongoose-like animal with a long
muzzle), appeared on Earth. It replaced the earlier widespread group of
carnivores – the creodonts. All the earliest fossils of the dog family
have been found in North America and date from this period. Another
canid-like carnivore, Tomarctus, evolved during the Miocene period,
about 24 million years ago. In turn, the genus Canis evolved, which
gradually developed into Canis lupus, or the wolf, some 300,000 years
ago. The first domestic dogs date from around 12,000 years ago. There
BE SIRIUS were also creatures that looked similar to these dog ancestors, such as
The brightest star in the sky is the
Dog Star (Sirius) in the Canis the hyaenodonts from the Oligocene, but they were not related to true
Major constellation. Just as vast hyenas, which are closer to the cat family. From ancestral carnivores like
changes have taken place over
millions of years in space, so the Cynodictis, the canids evolved into fast-running meat eaters that hunted
family of dogs has evolved over prey on open grasslands, and most of
millions of years on Earth.
Cranium today’s living species have
(brain box) inherited this way of life.

Nasal
bone

Upper
jaw
bone

Orbit for eye

Ear bone
Upper carnassial
tooth for tearing flesh
Foramen magnum –
entrance for the spinal Upper THIRTY-MILLION-YEAR-OLD HEAD
cord to the brain Cranium molar This is the fossilized skull of one of
Side view of Cynodictis skull Palatal bone the ancestors of the dog family. It
was a mongoose-like animal called
Orbit Cynodictis, and it lived about
Palatal view of Cynodictis skull 30 million years ago.

DIRE CONSEQUENCES
The extinct dire wolf (below) lived in California during
the period of the Ice Ages. It was huge – much larger
than any living wolf – and it preyed on the mammoth
and other large Ice Age mammals.

Reconstruction of a scene at
the tar pits of La Brea near
Los Angeles, showing
Restoration dire wolves and a Smilodon
of dire wolf attacking a mammoth (right)

(c) 2011 Dorling Kindersley. All Rights Reserved.