On the Trail of the First Placental Mammals
By Maureen Ann O'Leary
A matrix of phenomic, genomic, and fossil evidence supports the scientific account of how the animals exploded in diversity 65 million years ago.
This Article From Issue
May-June 2014
Volume 102, Number 3
Page 190
DOI: 10.1511/2014.108.190
In view of the nearly countless, wildly varying forms of life that surround us, it is easy to forget that all the species living on Earth today represent only the tip of the iceberg of evolutionary history. By most scientific estimates, 99 percent of the species that have ever inhabited our planet are now extinct.
Courtesy of the mammal Tree of Life project.
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