( A new complete 'tree of life' tracing ...)Dinosaur extinction didn't cause the rise of present-day mammals, claim researchers

The study was undertaken in the UK by scientists at Imperial College London and the Zoological Society of London (ZSL). It contradicts the previously accepted theory that the Mass Extinction Event (MEE) that wiped out the dinosaurs 65 million years ago prompted the rapid rise of the mammals we see on the earth today.

The multinational research team has been working for over a decade to compile the tree of life from existing fossil records and new molecular analyses. They show that many of the genetic 'ancestors' of the mammals we see around us today existed 85 million years ago, and survived the meteor impact that is thought to have killed the dinosaurs. However, throughout the Cretaceous epoch, when dinosaurs walked the earth, these mammal species were relatively few in number, and were prevented from diversifying and evolving in ecosystems dominated by dinosaurs.

The tree of life shows that after the MEE, certain mammals did experience a rapid period of diversification and evolution. However, most of these groups have since either died out completely, such as Andrewsarchus (an aggressive wolf-like cow), or declined in diversity, such as the group containing sloths and armadillos.

The researchers believe that our 'ancestors', and those of all other mammals on earth now, began to radiate around the time of a sudden increase in the temperature of the planet ?ten million years after the death of the dinosaurs.

Professor Andy Purvis from Imperial College London's Division of Biology explains: "Our research has shown that for the first 10 or 15 million years after the dinosaurs were wiped out, present day mammals kept a very low profile, while these other types of mammals were running the show. It looks like a later bo
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Source:Imperial College London