A BRIEF HISTORY OF MAMMALS

CARBONIFEROUS PERIOD

325 MILLION YEARS AGO

The mammal lineage – synapsids – diverged from the reptile lineage, diapsids.

PERMIAN PERIOD

299-252 MILLION YEARS AGO Synapsids proliferated. Early synapsids called pelycosaurs were replaced by synapsids called therapsids, who held their limbs underneath the body rather than in a reptile-like sprawl.

END-PERMIAN EXTINCTION

252 MILLION YEARS AGO

Synapsids were decimated but some species survived, including mammal ancestors with hair and fast metabolisms – the cynodonts.

TRIASSIC PERIOD

252-201 MILLION YEARS AGO True mammals evolved, including the monotremes, marsupials and placentals.

MIDDLE JURASSIC

174-164 MILLION YEARS AGO: Jaws, teeth and ears rapidly evolved to adapt to changing environments.

EARLY CRETACEOUS

130-122 MILLION YEARS AGO Diverse communities of mammals lived alongside feathered dinosaurs in China. Ecosystems were occasionally buried by volcanic eruptions, producing fossils.

CRETACEOUS PERIOD

145-66 MILLION YEARS AGO Flowering plants originated and evolved rapidly alongside their insect pollinators, providing new food sources for mammals.

END-CRETACEOUS EXTINCTION 66 MILLION YEARS AGO

An asteroid hit Earth, killing the dinosaurs and many mammals. Placentals survived.

PALEOCENE EPOCH

66-56 MILLION YEARS AGO

The surviving placentals got bigger, developed a variety of diets and locomotory styles, and spread globally.

PALEOCENE-EOCENE THERMAL MAXIMUM

56 MILLION YEARS AGO

Sudden global warming causes mammals to diversify. Early relatives of bats, whales and elephants emerge.