An advanced dating technique has revealed that the non-avian dinosaurs bit the dust 66 million years ago, which paved the way for the Age of Mammals, aka. the Tertiary, aka. the Cenozoic. The final blow for the dinosaurs came when a large rock hit the Earth, ending the Mesozoic Era, which began about 250 million years ago. The argon-argon technique indicates that the Dinosaurs Went Extinct Almost Immediately After [the] Mexican Asteroid Strike.
Scientists using a new and highly precise dating technique have concluded that the late Cretaceous asteroid strike in Mexico's Yucatan Peninsula coincided almost exactly with the extinction of the dinosaurs — give-or-take a few tens of thousands of years. While it's clear that other factors were contributing to the rapidly deteriorating environmental conditions, it's now obvious that the asteroid was the final coup-de-grace for the dinosaurs.
Indeed, all was not well on Earth when the asteroid struck. Volcanoes in India [resulting in the Deccan Traps] were wreaking havoc to the planet's ecosystems, and earlier asteroid strikes may have contributed to an already fragile environment. Other research shows that Earth experienced six abrupt temperature shifts of two degrees or more in mean temperatures in the one million years before the impact. In one instance, the temperature swung 6-8 degrees...
Researchers Paul Renne, Jan Smit and colleagues determined that the Yucatan impact event happened 66,038,000 years ago — give or take 11,000 years. It's an extraordinarily precise measurement, as it was only a few decades ago that the margins for error were measured in the millions of years.
The scientists also updated the date of dinosaur extinction. It happened about 33,000 years after the asteroid impact, which is a revision from the previous estimate of 300,000 years (which, when considering the cataclysmic effects of the impact, didn't really make a lot of sense). Given the narrow margins of error for the dating technique, it's very likely, therefore, that the asteroid impact coincided almost exactly with the demise of the dinosaurs. Consequently, the researchers are describing the event as the final blow. It was not the only factor, they admit, but it was certainly a major contributor.
The extinction of the big dinosaurs opened the door for the adaptive radiation of the mammals during the Cenozoic. And there is news about that, too, as we learn in Placental mammal diversity exploded after [the] age of dinosaurs.
An international team of researchers has reconstructed the common ancestor of placental mammals—an extremely diverse group including animals ranging from rodents to whales to humans—using the world's largest dataset of both genetic and physical traits...
"Analysis of this massive dataset shows that placental mammals did not originate during the Mesozoic," said lead author Maureen O'Leary, an associate professor in the Department of Anatomical Sciences in the School of Medicine at Stony Brook University and a research associate at the American Museum of Natural History...
[image left, text below, from the Science article Ancestor of All Placental Mammals Revealed — "The ancestor to all placental mammals was a tiny insect-eating creature that evolved soon after the mass extinctions that wiped out the dinosaurs.]
The fossil record has long suggested that even though mammals existed long before dinosaurs died off, most likely at the hands of an asteroid impact, the furry critters didn't really diversify or reach a large size until their reptilian competitors were out of the picture and ecosystems had recovered, says Maureen O'Leary, a paleontologist at Stony Brook University in New York. And even though the earliest placental mammals don't appear in the fossil record until after the dino die-offs, previous genetic analyses of living species have hinted that placental mammals may have evolved as much as 100 million years ago, tens of millions of years before that mass extinction.
To help settle the debate, O'Leary and her colleagues reconstructed the family tree of placental mammals using evidence from a large number of living and extinct species. The team's database included more than 4500 characteristics for each of 86 species...
Results suggest that the ancestor of all placental mammals evolved less than 400,000 years after the mass extinctions that wiped out the dinosaurs, the researchers report online today in Science. The hypothetical creature, not found in the fossil record but inferred from it, probably was a tree-climbing, insect-eating mammal that weighed between 6 and 245 grams—somewhere between a small shrew and a mid-sized rat.
It was furry, had a long tail, gave birth to a single young, and had a complex brain with a large lobe for interpreting smells and a corpus callosum, the bundle of nerve fibers that connects the left and right hemispheres of the brain.
The period following the dinosaur die-offs could be considered a "big bang" of mammalian diversification, with species representing as many as 10 major groups of placentals appearing within a 200,000-year interval [in the Paleocene], O'Leary says.
Long before I started writing about the environment, energy and the economy, I studied paleontology and the history of the Earth. Even today, though I am often busy exposing typical economic or financial fraud and inquality, I try to keep current in those subjects, which is easy to do in so far as describing pressing scientific concerns regarding the Earth and Climate are also part of my daily reporting.
I would never have been able to write this blog the way I do if I hadn't spent all those years developing the perspective which only a prolonged consideration of geological time can offer. According to these latest results, the ancestor of all current mammals, including the primates, including the hominids, and thus including Homo sapiens, was some kind of placental tree shrew which was furry, had a long tail, ate insects, and had a complex but very, very tiny brain.
That this hypothetical animal had an opportunity to be the last common ancestor of all current placental mammals was due only to the fact that a large asteroid impact in what is now the Yucatan wiped out the large non-avian dinosaurs. This random event opened up previously unavailable ecological niches for the mammals, thus spurring the evolution which gave rise to new types (the placentals), and these developments over 66 million years eventually "culminated" in big-brained bipedal primates like us.
If that doesn't put things in perspective, I don't know what would.
Bonus Video — this video has had only 587 views on youtube so far. Why don't you boost that number? If only to further indicate that not all humans are myopic, doomed, irredeemable dimwits. Or, you can be one with the primitives by watching Jon Stewart and Bill O'Reilly.
The choice is yours, assuming you aren't free will-challenged, as almost all humans are.