According to news from CNN.com, (though technically, AP), mammals weren’t itching to take over the newly vacated niches left behind by the dinosaurs 65 mya.
A new phylogenetic study of mammals, reported that there was no burst of activity following the demise of the dinosaurs. There was some flurry of speciation in animals that left no descendants, but all extant mammals remained pretty low key until around 55-35 mya.
As is typical for these studies, the results are somewhat controversial. Some folks are questioning the dating methods used, while others are both shocked and impressed with the results.
Though the AP sticks in the hyperbolic: “…challenges a long-standing theory.” statement, I doubt we’ll be seeing textbooks getting rewritten anytime soon.