for National Geographic News
Scientists have acquired new data supporting the idea that the last ancestor shared by all living primates walked with the dinosaurs more than 80 million years ago. The results came from a new technique used to reconstruct the course of animal evolution.
Previously, opposing scientific camps estimated that the animal that gave rise to the primates lived as recently as 55 million years ago and as long ago as 90 million years. The newly proposed date is closer to the older end of the range.
That's significant because the older estimate, which was derived from studies based on molecular genetics, identifies the earliest primates as contemporaries of the dinosaurs. The younger date, which was based on fossil records, represents a period after the dinosaurs had already become extinct.
"Our results agree broadly with a molecular estimate [and] contradict widely accepted palaeontological estimates," Simon Tavaré of the University of Southern California and his colleagues reported in the journal Nature.
Their finding sprang from a scientific collaboration that straddled the fields of biology and mathematics and spanned research centers from California to the Swiss Alps.
Working with colleagues from Harvard University, the University of Washington, Chicago's Field Museum, and institutions in England and Switzerland, Tavaré used a novel mathematical approach to help answer a major piece of the evolutionary puzzle.
The search for the first primatethat is, the last animal to have been an ancestor of all members of the primate family treehas long intrigued scientists and others interested in humanity's evolutionary origins.
From the oldest known fossil remains of primates, paleontologists have determined that some ancient members of our evolutionary family lived and died at least as far back as 55 million years ago.
Fossils alone, however, cannot disclose precisely when members of the last common ancestral species began to segregate into distinct populations that eventually gave rise to the modern array of some 200 primate species.
That's because the fossil record is incomplete. Paleontologists can't tell how close any particular specimen was to the progenitor of the primates.
So, to approach the problem from another angle, scientists in the field of molecular genetics have compared subtle differences in the DNA of living primates.
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