When dinosaurs roamed the Earth, mammals did not cower. Fossil records reveal a range of warm-blooded beasts, from the gliding maiopatagiumThe early mammal had wing-like skin membranes to glide like a modern flying squirrel. to the dino-munching repenomamusA badger-sized mammal. In one specimen, researchers found the fossilised remains of a baby dinosaur..

A cat-sized carnivore called didelphodon was "probably a more ferocious fighter than the tyrant dinosaur king", writes Steve Brusatte in his new book The Rise and Reign of the Mammals.

The epic saga of mammals starts in a steamy Carboniferous swamp 325 million years ago. These first proto-mammals evolved into colossal monsters.

Like the 6,000+ species alive today, these ancient mammals had warm blood and fur and breastfed their young.

We don't give these mammals enough attention, says Steve Brusatte. Walking whales, horses with elephant trunks and rodent teeth, giant sloths with scythe-like claws.

Since William Buckland identified megalosaurus in 1824, we have been obsessed with dinosaurs. The T rex had 12-inch flesh-ripping teeth and the strongest bite of any land animal.

Dinosaurs are "big, fierce, extinct - in other words, alluringly scary, but sufficiently safe," says palaeontologist Stephen Jay Gould. In comparison, early mammals like morganucodon, were furry insectivores that hid in burrows and only came out at night.

This is unfair, says zoologist Nick Crumpton. Dinosaurs may have looked scary, but their brains were small relative to their body size. To avoid predators, mammals evolved much better hearing, sight and smell.

And when an asteroid wiped out 75% of life on Earth, mammals filled the gaps left by the giant lizards. They outlived dinosaurs and came to dominate the Earth.

Dinosaurs reigned for 100 million years across every continent, including Antarctica. Their extinction was a "cosmic accident", says palaeontologist Nicholas Longrich. And if the asteroid had missed Earth, "dinosaurs would still rule the planet -and we wouldn't."

"After the dinosaurs died," says Steve Brusatte, "mammals actually got dumber." As species grew bigger, their brains couldn't keep pace. So, "it wasn't intelligence that allowed our ancestors to wrestle the crown from the dinosaurs."

Most of the megafaunaLarge animals weighing more than 1,000 kilos (1 tonne). are now extinct, and an intelligent ape rules the world. But unlike T rex and paraceratherium, we are the first species who can think about what it means to be the most powerful animal on Earth.

Yes: Big teeth aren't everything and a fast mouse can outsmart a giant lizard. Mammals were around before, during and after the dinosaurs. We are history's great survivors, adapting to every environment.

No: There is a reason dinosaurs ruled for so long. And the more we learn about them, the more spectacular they become. Scientists now think they were smarter and faster than originally thought, feathered and brightly coloured.

Or... This isn't a competition. All animals adapt to their environment and are spectacular in their own way. And as mammals ourselves, it is impossible to be objective.