In “Recalibrated DNA clock suggests we can stop looking for early primate fossils” (Ars Technica April 13, 2012), Diana Gitig reports,
The earliest primate fossils unearthed thus far are only 56 million years old, but molecular estimates of the rate of primate evolution predict that there should be some dating back to the Late Cretaceous, closer to 82 million years ago.
However, some researchers have thought up a fix:
The authors found that primates have gotten larger over time; our last common ancestor was quite small, similar in size to a mouse lemur. Moreover, size is inversely proportional to molecular rates of evolution, so as primates have gotten larger, our evolution has slowed down. Extinct primates thus evolved more quickly than had previously been thought, accounting for the fact that they show up later in the fossil record than molecular estimates indicated they should. The new, “corrected” molecular clock generated here puts the earliest primates between 63 and 70 million years ago, closer to where the fossils have been found.
Aw, maybe. For some reason, it smells like a fudge factory around here ….