The Rise and Reign of the Mammals: A New History, from the Shadow of the Dinosaurs to Us

Putting this evidence together, mothers must have started nursing early in mammal history, probably right around the time the first mammals like Morganucodon were scuttling around in the Triassic, and definitely by the time docodonts were flourishing in the Jurassic. It is probably no coincidence that enlarged brains appeared right around the same

two key features of mammals. The olfactory bulbs—which orchestrate the sense of smell—are massive. And the top of the cerebrum boasts a new structure: a six-layered mass of nervous tissue called the neocortex,

with an all-you-can-eat buffet of greenery that grew, constantly, from the soil.

survive as the forests shrank? What we do know is that these early hominins started walking on two legs before sprouting big brains and learning to shape tools from stone.

changes involves the brain: it often gets smaller, probably to save energy, because big brains are expensive to maintain.

turbinates

We see something similar

If the hothouse

Carrier’s constraint, which plagues amphibians and reptiles that wiggle their bodies sideways, left to right, during their sprawling walks. Such lateral flexion means that one lung is always expanded while the other is compressed, making it difficult for these animals to move and breathe at the same time, greatly limiting their speed and agility. C