When the Dinos Went Away, Mammals Came Out (in Daylight) to Play
While it’s challenging to imply one caused the other, a new study shows that mammals came into the light of day soon after the dinos disappeared
Paleontologists believe that the first mammals to evolve on Earth were small nocturnal creatures that used a keen sense of smell and hearing to operate in the dark, which was a good place to be in the age of the dinosaurs. These days, many mammal species spend most of their time operating during the daytime, and many other species are crepuscular, which means they do most of their hunting, mating and interacting in the early morning and twilight hours.
But when did mammals make the switch from the night life to day life? Now, reports Gretchen Vogel at Science, a new study pinpoints the time in the distant past when mammals came out of the dark. And it turns out, it’s immediately after the demise of the dinosaurs.
As Vogel reports, paleontologists have had difficulty determining the behavior of ancient animals just by looking at their fossils. Typically, they assume an animal is nocturnal if it has features like large eye sockets and certain configurations of the nasal cavity. But that work is largely speculative and can’t answer the question of when mammals first waddled into the daylight.
In search of answers, a group of researchers from University of College-London and Tel Aviv University worked backward, analyzing the lifestyles and behavior of 2,415 mammal species that exist today, writes George Dvorsky for Gizmodo. Using an algorithm, they were able to reconstruct the likely behavior of their ancestral mammals back to the beginning, when mammals evolved from a reptilian ancestor 220 to 160 million years ago, Agence France-Presse reports.
The researchers used two different variations of the mammalian family tree, according to a press release, but the results were the same. Mammals came into the light between 52 and 33 million years ago. The dinosaurs died out 65 million years ago. The research appears in the journal Nature Ecology & Evolution.
“We were very surprised to find such close correlation between the disappearance of dinosaurs and the beginning of daytime activity in mammals, but we found the same result unanimously using several alternative analyses,” Ph.D students and lead author Roi Maor of Tel Aviv University says in the press release.
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by Jason Daley
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I'd hide from velociraptors, too!
LOL Yep it's not like rocket science. RUN... HIDE ... stay hidden.....
Even back in the day, when I studied anthropology, this was a theory. Proving it, was a whole different story. Really cool findings. Thanks for the info Bob.
The source, smithsonianmag.com , is a treasure trove. I'll try to seed from it more frequently.
It is fascinating what must have taken place before recorded history. Human beings have been on this planet a mere 200,000 years (being generous). Given an age of the Earth of 4.5 billion years, 22,500 of our little 200,000 year durations took place before we started ours. We are on the tip of the tail - super late comers to the game. And if we consider that we have recorded history for at best 20,000 years the planet experienced 225,000 of our 20,000 year durations before we got the baton.
Feel insignificant yet?
Always, in the scope of things. Whether we are talking about mankind's small time on this planet, or the fact that this planet is like a grain of sand in this expansive universe.
There are times when all the world's asleep,
The questions run too deep
For such a simple man.
Yep....life evolved rather early on back in the day with the emergence of the stromatolites.
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And these forms are still with us today.
Our ancestors were little four legged creatures like shrews or rats! Richard Dawkins lays it all out in
"The Ancestor's Tale"
Most amazing of all, many species of dinosaur looked a lot like our present day chickens, having evolved from some small dino's that survived the extinction event.
Here in Colorado, not far from downtown Denver, on a hogback called Dinosaur Ridge, there are dinosaur bones in the Morrison Formation on the west side of the ridge, and dinosaur tracks, ripple marks, and other trace fossils in the Dakota Group of formations on the east side. These formations tilt steeply upward toward the West. Not far away, at the famous Red Rocks theater, the 300 Million year old Fountain Formation also angles steeply upward and rests upon the 1,700,000 year old Precambrian Idaho Spring Formation....a very large time gap or "unconformity"
A few miles North, a short distance from the Colorado School of Mines, is "Triceratops Trail" that was a former clay pit that abuts the "Fossil Trace" golf course. Here are footprints of the coolest of dinosaurs, Triceratops, other fossils of which have also been found around metro Denver, one just recently in the Thornton area. At the bottom of the pit, on the vertically standing Laramie Formation, is the unmistakable trace fossil of a palm frond, and nearby are some impressions of what the experts say are raindrops. It's fun to think of a long ago thunderstorm blowing down the palm frond, back when what is Colorado was much closer to the Equator.
Life was stubborn...once it appeared a series of extinction events failed to stamp it out...and here we are, talking about it.