The enormous meteor that smashed into Mexico’s Yucatan peninsula 65 million years ago didn’t deal a death blow to the dinosaurs, a new study declares. Based on a close examination of sediment layers from that epoch, a team of researchers led by Gerta Keller has previously argued that the Chicxulub impact happened 300,000 years before the mass extinction known as the Cretaceous-Tertiary extinction event. Now, Keller has found supporting evidence that the impact had little immediate effect on the planet’s biome. Says Keller: “It didn’t kill the dinosaurs. In fact, it didn’t cause much damage that we can determine from the geological record” [The Scientist].
Since the 112-mile-wide Chicxulub crater was discovered in 1978, many researchers have come to believe that the massive impact caused clouds of dust to shroud the earth, cooling the planet and killing the dinosaurs along with many other species. But Keller’s new study, to be published in the Journal of the Geological Society, offers a serious challenge to that theory.
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A small dinosaur that once roamed northeastern China was covered with a stiff, hairlike fuzz, a discovery that suggests feathers began to evolve much earlier than many researchers believe — maybe even in the earliest dinosaurs [AP]. A newly discovered fossil sporting traces of feather-like structures surprised researchers, because it belongs to the ornithischian group of dinosaurs. All previous fuzzy dinosaurs have been found in the saurischian group–specifically among therapods, which includes carnivores like Tyrannosaurus and Velociraptor. “Finding a Chinese dinosaur with feathers is not remarkable, but finding one on the wrong side of the dinosaur family tree is,” says Lawrence Witmer, a vertebrate paleontologist [Science News].
Finding proto-feathers on both side of the family tree suggests that the feature may have evolved around 220 million years ago in a common ancestor for ornithischians and saurischians; previously, researchers posited that the first feathered dinosaurs appeared around 150 million years ago. This has raised the question of whether many more of the creatures may have been covered with similar bristles, or “dino-fuzz” [BBC News].
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North America’s newest dinosaur had the makings of a monster: razor-sharp claws, a runner’s body, and similarities with the Velociraptor of Jurassic Park infamy. If only it’d been bigger than a chicken [National Geographic News]. The four-pound Hesperonychus elizabethae has claimed the title of the smallest carnivorous dinosaur to have tromped on North American soil. Study coauthor Nick Longrich says that while Hesperonychus was a fierce hunter, only small creatures learned to fear it. “My guess is that it was a small-game hunter, taking down mammals and birds and baby dinosaurs” [Reuters], he says.
The identification of the new genus and species wasn’t based on a new fossil find. The tiny bones—originally assumed to come from a youngster—had languished in a collection at the University of Alberta in Edmonton for 25 years before Longrich and a fellow researcher decided to take another look at them. On closer examination, they noticed that the pelvis was fused, an indication that the 75-million-year-old dino that it came from had reached maturity and stopped growing [Scientific American].
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Two handprints pressed into the mud of an ancient lakeshore 198 million years ago has given paleontologists new insights into the anatomy and evolution of early carnivorous dinosaurs. The theropod who crouched down had a bird-like forelimb structure with palms that always faced inwards, says lead researcher Andrew Milner, which indicates that they stopped using their forelimbs for walking early in their evolutionary history.
The handprints discovered in Utah are part of a larger track that clearly show the hind feet and, occasionally, the dragging tail. But at one point, Milner said, the theropod apparently stopped and crouched to rest. At that point, between the footprints, is the clear circular impression of the ischium or pelvis, “basically a butt print,” Milner said. And to each side of the tracks are the handprints, which are mirror images of each other. They clearly show the third digit pressed into the ground and traces of the second digit, with the claw curling inward. The hands were positioned as they would be for “holding on to a basketball rather than dribbling it,” [Los Angeles Times], comments paleontologist Tom Holtz, who wasn’t involved in the research.
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A close examination of over 400 Triceratops skulls suggests that the iconic dinosaurs used their powerful horns to clash with rivals over mates, territory, and dominance. In a new study, researchers looked carefully for traces of scrapes and healed fractures on the fossilized skulls, and say the pattern they found fits the theory that the three-horned herbivores were going head-to-head. “The most likely culprit for all of the wounds on Triceratops frills was the horns of other Triceratops,” [lead researcher Andrew] Farke said. “Our findings provide some of the best evidence to date that Triceratops might have locked horns with each other, wrestling like modern antelope and deer” [Times Online].
The researchers compared the Triceratops skulls to those of another dinosaur called Centrosaurus, which also boasted three horns and a bony protective frill around its face. The two species were related, but Centrosaurus died out about 75 million years ago and had its largest horn on its snout, while Triceratops lasted until 65 million years ago and had more prominent horns over its eyes. With such different horn patterns, the researchers assumed that if the dinosaurs were horn-butting with members of their own species the injuries of Triceratops and Centrosaurus should also be different from each other. But if they weren’t poking and butting one another with those horns, the injuries should be relatively similar, perhaps due to random nicks from clumsily running into a tree or head butts from predators, Farke said [LiveScience].
As the researchers report in the journal PLoS ONE, the Triceratops skulls showed a pattern of old injuries in one specific part of the bony frill that would likely have been impacted if two individuals were banging their heads together, but the Centrosaurus showed no such pattern.
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For feathered dinosaurs, it appears that fashion came before function. A new study of a dinosaur fossil found in northeast China has revealed that the dinosaur, Beipiaosaurus, not only had the soft downy feathers that have been spotted in other fossils, it also had a more primitive type of feather that appears to have been used only for peacock-like displays. These primitive feathers don’t cover the dinosaur’s entire body, they’re found only on the creature’s head, neck and tail. The filaments couldn’t have generated lift, so they’re not flight worthy, and they’re too sparse to have retained the creature’s body heat. [Lead researcher Xing] Xu and his colleagues therefore speculate that the filaments served as display structures, just as many similarly placed feathers do on modern birds [Science News].
The feathers detected on the Beipiaosaurus, which lived in the Cretaceous Period, have a very basic structure. The modern-day feathers sported by birds are elaborate constructions with numerous fibers that branch out from a central filament and hook together. This arrangement is so complicated that many scientists theorize it could have evolved only once…. But paleontologists have proposed that a variety of simpler structures — including peculiar, branched structures colloquially called “dinofuzz” — evolved before feathers [Science News]. The new discovery reveals an even earlier piece of the evolutionary puzzle: the proto-feathers that Beipiaosaurus sported on its head, neck and tail are long filaments without any branches.
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Don’t let their fierce looks fool you: Some male carnivorous dinosaurs were actually devoted dads, researchers say. A new study examined the bones of three species of dinosaurs found sitting on fossilized egg clutches and declared that in these species, it was the males who sat on the nests and cared for the young. The three types of dinosaurs, Troodon, Oviraptor and Citipati, lived roughly 75 million years ago and were theropods — the primarily meat-eating group that also includes monstrous beasts like Tyrannosaurus rex and Giganotosaurus [Reuters].
The new findings upend some notions of dinosaur family life, and also suggest that birds, which are believed to have evolved from small, feathered dinosaurs, may have inherited this behavioral trait. Study coauthor Frankie Jackson says the study “sheds light on the origins of parental care systems in birds.” … Males protect or support offspring in more than 90 percent of bird species — a distinctly rare attribute in the animal world. In mammals, males provide parental care in 5 percent of species, and it’s even rarer in reptiles [Washington Post].
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An asteroid that crashed into the earth 65 million years ago may not have been the cause of the dinosaurs‘ extinction, a group of researchers are arguing. Instead, that impact may have been just a prelude to the main event, when a wave of volcanic eruptions spewed out massive clouds of sulfur dioxide, clouding the air and bringing showers of acid rain. The researchers are basing their theory on studies of an area in India called the Deccan Traps, which was convulsed with volcanic activity around 65 million years ago. At least four waves of massive eruptions spread successive sheets of thick basalt across the land for more than 500 miles, and they piled into a plateau more than 11,000 feet high over thousands of years [San Francisco Chronicle].
The new research on the Deccan Traps volcanoes, announced at the ongoing meeting of the American Geophysical Union, are the first major challenge to the asteroid theory that has dominated dinosaur extinction studies for three decades. That theory posits that a six-mile-wide asteroid slammed into Mexico’s Yucatan peninsula, creating the Chicxulub crater and cooling the climate so drastically that the majority of life forms went extinct in what’s known as the Cretaceous-Tertiary (or K-T) extinction. But geologist Gerta Keller and her colleagues argue that the impact occurred well before the massive die-offs began. By examining sediment layers, the team found that the crater impact appears to have occurred about 300,000 years before the K-T boundary, with virtually no effects to biota. “There is essentially no extinction associated with the impact,” Keller said [LiveScience].
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The genome of the woolly mammoth is halfway sequenced and science-fiction fanatics are once again talking about resurrecting extinct species–except this time, the scientists are talking too. Researchers at Pennsylvania State University extracted DNA from the hair of two woolly mammoths found in the permafrost of Siberia; one lived about 20,000 years ago, the other about 60,000 years ago. Reporting in Nature [subscription required], the researchers say they have already sequenced more than three billion base pairs of the mammoth genome, and they say there should be no technical obstacles to sequencing the complete genome. “It’s a technical breakthrough,” says ancient-DNA expert Hendrik N. Poinar [Scientific American].
Access to clumps of preserved mammoth hair was essential to the researchers’ success. The tough keratin that makes up the hair encased the mammoth’s DNA and separated it from any alien fragments, keeping these samples more pure [New Scientist]. Horns and feathers are also made of keratin, broadening the prospects of sequencing other extinct species from museum specimens.
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Researchers have used a CT scanner to peer inside the hollow, fossilized skulls of a group of meat-eating dinosaurs that dominated the Jurassic Period, and found that the Tyrannosaurus rex had another advantage besides its size, speed, and pointy teeth–it also had an excellent sense of smell. Study coauthor Darla Zelenitsky says the scans show the impressions left on the skull by different brain regions, and says the T. rex had the biggest olfactory bulb, which regulates the sense of smell.
Zelenitsky says the findings suggest that the T. rex relied on smell extensively. “It’s probably fairly significant, because the sense of smell was likely used for foraging or searching for food,” Zelenitsky said. “And as well, it could have been used for patrolling relatively large home ranges. So, in that respect, it would have been a significant part of the biology and daily activities of the animal” [Calgary Herald].
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The tiny skull of a juvenile dinosaur with a strange set of chompers has delighted paleontologists, who believe it proves that the species was a transitional phase between carnivorous dinosaurs and herbivores. The Heterodontosaurus has both sharp canine teeth for biting and molars for grinding, suggesting that the species dined on both small reptiles and insects as well as leafy greens.
Says study coauthor Laura Porro: “It’s likely that all dinosaurs evolved from carnivorous ancestors. Since Heterodontosaurs are among the earliest dinosaurs adapted to eating plants, they may represent a transition phase between meat-eating ancestors and more sophisticated, fully herbivorous descendants” [Telegraph]. The omnivorous dino lived 190 million years ago in the Early Jurassic period, Porro says.
Only two other Heterodontosaurus fossils have been found previously, and those both belonged to adults. This newly discovered fossilized skull measures less than 2 inches in length and belonged to a juvenile weighing less than two sticks of butter… [The researchers] studied the juvenile’s skull and determined the individual was probably buried alive in a sandstorm, a mode of death that left its remains in “relatively good condition” [Discovery News].
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Researchers have found a “bizarre” feathered dinosaur with a hodgepodge of characteristics, including four long tail feathers that researchers say may have evolved for display purposes–perhaps to attract a mate or scare off a rival. The well-preserved fossil of the new species, named Epidexipteryx hui, shows that the beast was covered in short, fluffy feathers but lacked the “contour feathers” that help modern birds fly; researchers say Epidexipteryx must have been flightless.
Paleontologist expert Angela Milner commented that the find “shows that feathers were likely being used for ornamentation for many millions of years before they were modified for flight. It provides fascinating evidence of evolutionary experiments with feathers that were going on before small dinosaurs finally took to the air and became birds” [BBC News].
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Engineers have designed a robotic spy plane that is modeled on the pterodactyls that swooped through the sky between 228 million to 65 million years ago, while dinosaurs tromped over the land below. Perhaps unsurprisingly, researchers say that their prototype is the first aircraft inspired by a pterosaur (the broader scientific name for all winged lizards).
Paleontologist Sankar Chatterjee partnered with engineer Rick Lind to design their “Pterodrone;” the two men say the work was driven in part by their admiration for the vesatility of pterosaurs. With lightweight bones and an intricate system of collagen fibers that strengthened their wings, [pterosaurs] ranged from the size of a sparrow to the size of a Cessna plane. “These animals take the best parts of bats and birds. They had the maneuverability of a bat but could glide like an albatross. Nothing alive today compares to the performance and agility of these animals” Chatterjee said [AP].
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A 33-foot long, carnivorous dinosaur that lived 85 million years ago had a breathing system similar to that used by modern birds, and researchers say the finding is further evidence of the evolutionary link between dinosaurs and birds. A fossil found in a riverbank in Argentina shows evidence of efficient air sacs that pumped air into the dinosaur’s lungs.
Lead researcher Paul Sereno named the new dinosaur Aerosteon riocoloradensis, which means “air bones from the Rio Colorado.” Instead of lungs that expand and contract, Sereno thinks this beast had air sacs that worked like a bellows, blowing air into the beast’s stiff lungs, much like modern birds…. Most paleontologists believe birds evolved from small, feathered meat-eating dinosaurs, and the earliest known birds were strikingly similar to these dinosaurs [Reuters].
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Paleontologists have dug up the bones of a chicken-sized dinosaur that scampered through the Cretaceous forest 70 million years ago, feasting on termites and other insects. The Albertonykus borealis is believed to have lived like an anteater, using strong claws to rip apart logs for insects as food [Globe and Mail]. The dinosaur, found in fossil-rich Alberta, Canada, is the smallest ever discovered in North America.
The small dinosaur looks like a creature from a Dr. Seuss book, said [researcher Nick] Longrich, who called the findings “pretty cool.” … Most of the bones dug up in North America have been from large animals, he said. “Now that we are finally starting to find some of the smaller ones it is suggesting that our picture of the fauna is skewed. We are primarily picking up the big skeletons. They just preserve better” [CBC].
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