AN IDENTIKIT picture of the small furry ancestor that gave rise to humans and most other mammals has been pieced together by scientists.
The shrew-like creature weighed less than half a pound, had a long tail, and ate insects.
It evolved some 200,000 years after a massive asteroid impact led to the extinction of the dinosaurs 66 million years ago.
From this small beginning sprang every "placental" mammal that gives birth to mature live young, including dogs, cats, rodents, whales and humans.
Placental mammals are the largest branch of the mammalian family tree, with more than 5,100 living species.
An artist's impression of the earliest placental ancestor was published yesterday based on the results of a six-year long investigation by scientists.
Experts recorded 4,500 physical traits for 86 mammalian species, including 40 that are now extinct.
The features, which include the presence or absence of wings, teeth, and bone types, produced a data set 10 times larger than any used before to study mammalian ancestry.
Combined with molecular information from DNA samples, it allowed the scientists to pinpoint the likely start of the story of placental mammals.