The one about how it was a comet and not an asteroid? Forget it. We're back to a Manhattan-sized asteroid. And things got toasty.
A new look at conditions after a Manhattan-sized asteroid slammed into a region of Mexico in the dinosaur days indicates the event could have triggered a global firestorm that would have burned every twig, bush and tree on Earth and led to the extinction of 80 percent of all Earth's species, says a new University of Colorado Boulder study.
Led by Douglas Robertson of the Cooperative Institute for Research in Environmental Sciences, or CIRES, the team used models that show the collision would have vaporized huge amounts of rock that were then blown high above Earth's atmosphere. The re-entering ejected material would have heated the upper atmosphere enough to glow red for several hours at roughly 2,700 degrees Fahrenheit -- about the temperature of an oven broiler element -- killing every living thing not sheltered underground or underwater.
The CU-led team developed an alternate explanation for the fact that there is little charcoal found at the Cretaceous-Paleogene, or K-Pg, boundary some 66 million years ago when the asteroid struck Earth and the cataclysmic fires are believed to have occurred. The CU researchers found that similar studies had corrected their data for changing sedimentation rates. When the charcoal data were corrected for the same changing sedimentation rates they show an excess of charcoal, not a deficiency, Robertson said.
"Our data show the conditions back then are consistent with widespread fires across the planet," said Robertson, a research scientist at CIRES, which is a joint institute of CU-Boulder and the National Oceanic and Atmospheric Administration. "Those conditions resulted in 100 percent extinction rates for about 80 percent of all life on Earth."
A paper on the subject was published online this week in theJournal of Geophysical Research-Biogeosciences, a publication of the American Geophysical Union. Co-authors on the study include CIRES Interim Director William Lewis, CU Professor Brian Toon of the atmospheric and oceanic sciences department and the Laboratory for Atmospheric and Space Physics and Peter Sheehan of the Milwaukee Public Museum in Wisconsin.
Geological evidence indicates the asteroid collided with Earth about 66 million years ago and carved the Chicxulub crater in Mexico's Yucatan Peninsula that is more than 110 miles in diameter. In 2010, experts from 33 institutions worldwide issued a report that concluded the impact at Chicxulub triggered mass extinctions, including dinosaurs, at the K-Pg boundary.
The conditions leading to the global firestorm were set up by the vaporization of rock following the impact, which condensed into sand-grain-sized spheres as they rose above the atmosphere. As the ejected material re-entered Earth's atmosphere, it dumped enough heat in the upper atmosphere to trigger an infrared "heat pulse" so hot it caused the sky to glow red for several hours, even though part of the radiation was blocked from Earth by the falling material, he said.
But there was enough infrared radiation from the upper atmosphere that reached Earth's surface to create searing conditions that likely ignited tinder, including dead leaves and pine needles. If a person was on Earth back then, it would have been like sitting in a broiler oven for two or three hours, said Robertson.
The amount of energy created by the infrared radiation the day of the asteroid-Earth collision is mind-boggling, said Robertson. "It's likely that the total amount of infrared heat was equal to a 1 megaton bomb exploding every four miles over the entire Earth."
A 1-megaton hydrogen bomb has about the same explosive power as 80 Hiroshima-type nuclear bombs, he said. The asteroid-Earth collision is thought to have generated about 100 million megatons of energy, said Robertson.
Some researchers have suggested that a layer of soot found at the K-Pg boundary layer roughly 66 million years ago was created by the impact itself. But Robertson and his colleagues calculated that the amount of soot was too high to have been created during the massive impact event and was consistent with the amount that would be expected from global fires.
U of A Paleontology researcher Scott Persons followed a chain of fossil evidence that started with a peculiar fusing together of vertebrae at the tip of the tail of four different species of dinosaurs, some separated in time and evolution by 45 million years.
Persons says the final vertebrae in the tails of a group of dinosaurs called oviraptors were fused together forming a ridged, blade-like structure. "The structure is called a pygostyle" says Persons. "Among modern animals only birds have them."
Researchers say fossils ofSimilicaudiptery, an early oviraptor, reveals feathers radiating from the fused bones at the tail tip.Similicaudiptery was not known to be a flying dinosaur and Persons contends its tail feathers evolved as a means of waving its feathered tail fans.
No direct fossil evidence of feathers has been found with the fossils of the oviraptors that followedSimilicaudiptery, but Persons says there is still strong evidence they had a feathered tail.
Persons reasons that because the later oviraptor had the same tail structure as the featheredSimilicaudipteryx, the tails of later oviraptors' still served the same purpose, waving feathered tail fans.
Persons says the hypothesis of oviraptor tail waving is supported by both the bone and muscle structure of the tail.
Individual vertebrae at the base of an oviraptor's tail were short and numerous, indicating great flexibility. Based on dissections of modern reptile and bird tails, Persons reconstruction of the dinosaur's tail muscles revealed oviraptors had what it took to really shake their tail feathers.
Large muscles extended far down the tail and had a sufficient number of broad connection points to the vertebrae to propel oviraptor's tail feathers vigorously from side to side and up and down.
Oviraptors were two-legged dinosaurs that had already gone through major diversifications from the iconic, meat eating dinosaur family. Oviraptors were plant eaters that roamed parts of China, Mongolia, and Alberta during the Cretaceous period, the final age of the dinosaur.
"By this time a variety of dinosaurs used feathers for flight and insulation from the cold, "said Persons. "This shows that by the Late Cretaceous dinosaurs were doing everything with feathers that modern birds do now," said Persons.
In addition to feathered-tail waving, oviraptors also had prominent bone crests on their head, which Persons says the dinosaur also may have used in mating displays.
"Between the crested head and feathered-tail shaking, oviraptors had a propensity for visual exhibitionism," said Persons.
Which reminds me of this chestnut by James and Bobby Purify.
What may be the most ancient dinosaur ever found — or at least a very close relative to the oldest currently known examples — could push the appearance of the awesome beasts back to 243 million years ago.
Paleontologist Rex Parrington of the University of Cambridge in England discovered the fossil in the early 1930s, preserved in a rock formation known as the Manda Beds in Tanzania’s Ruhuhu Valley. Now, a team of scientists has taken a fresh look atNyasasaurus parringtoni. It lived during the Anisian age of the Middle Triassic period, about 10 million to 15 million years earlier than the oldest confirmed dinosaurs. The finding suggests dinosaurs evolved and diversified over a longer time frame than scientists thought, the team reports online December 4 in Biology Letters.
So far only fragments of the creature’s backbone and upper arm bone have been found, but these bear telltale features of dinosaurs, such as rapid bone growth. More fragments are needed to determine whether the fossil is in fact the oldest dinosaur or a member of the nearest sister group.
At 2 to 3 meters long and no more than 1 meter tall, Nyasasaurus was hardly a king of the beasts. It would have been slightly larger than a golden retriever but with a very long tail, says Sterling Nesbitt, a paleontologist at the University of Washington in Seattle. Nesbitt and colleagues estimate that the creature weighed about 20 to 60 kilograms.
The team examined the fossil’s structure and microscopic anatomy and then compared it with members of known animal family trees. Computer analyses showed that Nyasasaurus was either part of the dinosaur lineage or an as-yet-unknown group that’s even closer than dinosaurs’ nearest currently known relatives, silesaurids.
“In this case, there’s just not enough evidence to decide which of these two family trees it is,” says paleontologist Stephen Brusatte of the American Museum of Natural History in New York City, who was not involved with the study. “The only way to really figure out what the specimen is is to find more material,” he says.
Regardless of whether Nyasasaurus was a true dinosaur, the finding helps fill in a gap in the fossil record between dinosaurs and the branch that led to them, says paleontologist Randall Irmis of the University of Utah in Salt Lake City.
The earliest confirmed dinosaur fossils are from Argentina, and Nyasasauruslends further support to the notion that dinosaurs arose in the southern part of the supercontinent Pangaea.
After Parrington discovered the fossil, his doctoral student Alan Charig studied the specimen for 50 years, but never published his work. With their new study, Nesbitt and colleagues have finally brought Nyasasaurus out of obscurity.
As new finds push the dinosaur record back further and further, it gets closer to the end-Permian mass extinction, which wiped out up to three-quarters of terrestrial species 252 million years ago. “It appears dinosaurs arose in the shadow of the greatest extinction of all time,” Nesbitt says.
For a decade, scientists largely ignored a fossil of a juvenile, late-Jurassic flying reptile that’s just 14 centimeters long. It appeared to be just another of some 120 specimens of the genus Rhamphorhynchusexcavated at Germany’s famed Solnhofen limestone beds.
Closer inspection now shows it’s something new, David Hone of the University of Bristol in England and his colleagues report July 5 in PLoS ONE. They’re creating a genus dubbedBellubrunnus, or Brunn beauty, to honor the German quarry where it was unearthed.
The tiny flyer has fewer teeth and a more flexible tail than other Rhamphorhynchus-like pterosaurs. And the outermost bone of each wing curves outward, distinguishing it from any known flying vertebrate alive or extinct. This would have made flying somewhat harder, Hone explains, but afforded somewhat improved maneuverability to this animal, which had a perhaps meter-wide wingspan at maturity.
Ever think about dinosaur sex? Paleontologists do. And they've come up with some surprisingly specific ideas about how the prehistoric beasts were able to mate despite their enormous size and weight--and despite the horns and other bony appendages that might have proven bothersome when the creatures got hot and bothered.
The males and females of modern-day birds and reptiles have a single body opening for urination, defecation, and reproduction--something called a cloaca (Latin for sewer). Paleontologists believe that dinosaurs had the same basic equipment, and that they coupled by pressing their cloacas together.
No penis is needed to perform a "cloacal kiss." But some birds have penises and crocodiles sport penis-like "intromittent organs," and male dinosaurs might have had something similar. As you might imagine, a dinosaur penis might have been pretty big--perhaps up to 12 feet in length for T. Rexes.
But how did Mr. Dino ever get his cloaca near Ms. Dino's? By mounting her from behind. At least that's the view of many paleontologists, including one Beverly Halstead, an Englishman who became known for his candid talk about dinosaur mating before his death in 1991. For an article that appeared in the now-defunct science magazine "Omni" magazine in 1988, Dr. Halstead said:
All dinosaurs used the same basic position to mate. Mounting from the rear, he put his forelimbs on her shoulders, lifting one hind limb across her back and twisting his tail under hers to align the cloaca.
Some of Halstead's present-day counterparts concur that that's the way dinos did it.
"I don't think there's much doubt about that," Dr. Gregory M. Erickson, an evolutionary biologist at Florida State University, told The Huffington Post in a telephone interview. But, he acknowledged, "It must have been a hell of a thing to see."
Early dinosaurs probably looked a lot more like Big Bird than scientists once suspected. A newly discovered, nearly complete fossilized skeleton hints that all dinosaurs may have sported feathers.
“It suggests that the ancestor of all dinosaurs might have been a feathered animal,” says study author Mark Norell, a paleontologist at the American Museum of Natural History in New York.
Researchers have found feathered dinosaurs before, but this one is more distantly related to birds than any previously discovered. CalledSciurumimus albersdoerferi, it belongs to a group of massive dinosaurs called megalosaurs that had sharp teeth, claws and a heavy-duty frame. The specimen — a youngster that lived about 150 million years ago — is only 70 centimeters long, but it could have grown up to 10 meters, about the length of a school bus.
The fossil’s feathers aren’t the only things getting paleontologists all aflutter. The skeleton’s condition is exciting, too.
“It’s a gorgeous specimen,” says Luis Chiappe, a paleontologist at the Natural History Museum of Los Angeles County. “Probably one of the best meat-eating dinosaurs ever preserved.”
The skeleton rests in a bed of limestone, back arched, mouth gaping, tail curled behind its head. Its bones are unbroken and still carry remnants of flesh, scientists report online July 2 in the Proceedings of the National Academy of Sciences. “There aren’t many more things you can ask of a fossil,” Chiappe says.
Bits of smooth, scaleless skin anchor long, fine feathers to the tail. Unlike modern feathers, these “protofeathers” or “type 1 feathers” look like simple strands of hair. The thin, flexible feathers are ancient versions of the broad, branching plumage —“type 2 feathers” — that adorn modern birds. Though the feathers look different, both are made from the same basic ingredients.
In life, the hairlike feathers would have given the dinosaur a thick coat and a bushy tail. (Part of the dinosaur’s name, Sciurumimus, derives from the Greek for “squirrel mimic.”) “It looks like it was a pretty fluffy kind of thing,” Norell says. “Kind of like a baby chick.”
Eventually, the study’s authors hope to figure out the color of the dinosaur’s feathers. But because color tests require fossil snippets, scientists would have to clip bits from the dinosaur’s remains. And since this specimen is one of a kind, researchers aren’t quite ready to disturb it.
So far, nearly all of the feathered dinosaurs ever discovered have come from eastern Asia. But excavators unearthed this fossil in southern Germany. Even in places collectors picked over for 150 years, Norell says, new things keep turning up. “There’s always more out there,” he says.
I like dinosaurs. Liked 'em since I was a little kid. Anyway, almost a hundred years ago and father and son named Sternberg found some dinosaur fossils in Canada. The fossils ended up in The Natural History Museum in London, but because they looked so groaty they were put up on a back shelf and forgotten.
And then someone took them down and looked at them. This is what the "Steinbergs' spine face " looked like:
More details here.