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Hello, the Senesaic era of Earth's history started about 65 million years ago and runs

to this day.

It began with the extraordinary K-T event, a supposed asteroid impact that's said to have destroyed the dinosaurs and incorporates

the breakup of Pangea, the enormous landmass that eventually formed the continents we know

today.

This is known as the age of mammals and it's a period

in which warm-blooded lactating often furry animals diversified rapidly and

spread across the globe on land and in the sea. According to evolutionary theory, what conditions

created the opportunity for mammals to thrive? What environmental factors

led to the characteristics they share and the features they don't? And how

did they become the most intelligent class of animals

on the planet? With me to discuss the rise of the mammals is Richard Corfield, a senior lecturer

in Earth Sciences at the Open University. Steve Jones, Professor of Genetics in the Galton Laboratory at University College London,

and Jane Francis, Professor of Paleoclimatology at the University of Leeds.

Richard Corfield, can you tell us when the first mammals started to emerge in

Earth's history and what they were like?

Yes, I think the most extraordinary thing about the evolution of the mammals is how very very ancient they are. The

K-T boundary took place 65 million years ago when the asteroid hit the Earth, but

the mammals actually date back to 200 million years,

which is very close to the beginning of the second great era of visible life, the Mesozoic.

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