This is very interesting. It's about one of our distant ancestors.

Distant human ancestor was an insect-eating shrew-like creature

By PHILIPPA WARR

8 February 2013

A reconstructed image of the ancestor of all placental mammals (including humans) has been published in the journal

The picture shows a furry rodent-adjacent creature about the size of a shrew and with a very long tail. Contained within said creature are likely to have been a two-horned uterus, a brain with a convoluted cerebral cortex and (during pregnancy) a placenta.

The study recorded observable traits of 86 placental mammal species in order to create a massive dataset dealing with things like the presence or absence of teeth, types of hair cover and the structure of the brain.

Mapping these traits according to phenomic and genomic data as well as comparing the features with those of closely related species allowed the research group to work out which features were likely to be present in a common ancestor. "Analysis of this massive dataset shows that placental mammals did not originate during the Mesozoic," said lead author Maureen O'Leary, a research associate at the American Museum of Natural History. "Species like rodents and primates did not share the Earth with non-avian dinosaurs but arose from a common ancestor -- a small, insect-eating, scampering animal -- shortly after the dinosaurs' demise."

In this instance "shortly" means 200,000 to 400,000 years after the mass extinction event which wiped out the dinosaurs, as well as many other life forms.

PHENOMICS

MAMMALS

PLACENTAL MAMMALS

BIOLOGY

SCIENCE

ANCESTORS

EVOLUTION

Researchers Reconstruct the Common Ancestor of Placental Mammals