By
Jason PalmerScience and technology reporter, BBC News
The
creature that gave rise to all the placental mammals - a huge group that
includes whales, elephants, dogs, bats and us - has at last been pinpointed.
An
international effort mapped out thousands of physical traits and genetic clues
to trace the lineage.
Their
results indicate that all placental mammals arose from a small, furry,
insect-eating animal.
A report in
Science resolves the debate as to when the creature lived; it came
about after the demise of dinosaurs.
That
had been a hotly debated question over years of research.
Placental
mammals - as opposed to the kind that lay eggs, such as the platypus, or carry
young in pouches, such as the kangaroo - are an extraordinarily diverse group
of animals with more than 5,000 species today. They include examples that fly,
swim and run, and range in weight from a couple of grams to hundreds of tonnes.
A
wealth of fossil evidence had pointed to the notion that the group, or clade,
grew in an "explosion" of species shortly after the dinosaurs' end
about 65 million years ago.
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