Call it an evolutionary beta test. About 125 million years ago a dinosaur stalked the world, and this predator had a familiar shape: It stood on strong back legs but had runty forelimbs, had a whip-like tail, and had a disproportionately large head with vicious teeth. But while that sounds like a description of the mighty Tyrannosaurus rex, this beast actually lived 35 million years before T. rex–and it was only 9 feet tall.
The discovery of the new species, which has been named Raptorex kriegsteini, has upended previous theories about how the king of the lizards evolved. Says study coauthor Stephen Brusatte: “The thought was these signature Tyrannosaurus features evolved as a consequence of large body size…. They needed to modify their entire skeleton so they could function as a predator at such colossal size” [The New York Times]. Instead, it appears that these features evolved in the early ancestors of T. rex, and that over the epochs the animals simply scaled up.
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A prehistoric armadillo-like animal swung its tail like a baseball bat, taking advantage of the “sweet spot” the same way tennis and baseball players do today, according to a study published in the journal Proceedings of the Royal Society B.
The tail sported spikes at a specific location that allowed the mammals, known as glyptodonts, to deliver a strong blow while minimizing the risk of harming the tail, the researchers found; spiny-tailed dinosaurs may have used the same mechanism. Known as the “sweet spot” today in sports like baseball, this so-called “center of percussion” helps athletes avoid wrist injuries. “The center of percussion is a point where you can deliver a very powerful blow with a baseball bat, a tennis racket, a sword, an axe or any hand-held implement, but the forces against your hands are almost zero” [Discovery News], said lead author Rudemar Ernesto Blanco. The glyptodont, which went extinct about 8,000 years ago after its emergence about 2.5 million years ago, would have swung its tail about 15 meters per second–about as fast as a modern-day tennis player swinging his or her racket.
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The oldest known tree-dwelling vertebrate lived 30 million years before the dinosaurs, scientists have found. The animal, known as Suminia getmanovi, had opposable thumbs and long hands, which would have allowed it to live in trees, according to a study published in the journal Proceedings of the Royal Society B.
A team of researchers found that Suminia, which lived about 260 million years ago, had disproportionately long arms and slender, curved fingers that were well-adapted to grabbing tree branches. But perhaps most importantly, one finger on each hand and foot was “opposed” to the rest, much like a thumb. “It’s the first time in the fossil record that we’ve seen evidence of an opposable thumb,” [said lead researcher Jorg Frobisch], adding that the creature was an early ancestor of mammals [BBC News]. The 12 well-preserved Suminia skeletons the scientists analyzed, which were found in Russia the 1990s, predate by 100 million years what was previously thought to be the earliest tree-dwelling animal.
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Some dinosaurs coped with the cold of winter by venturing beneath the Earth’s surface, according to a study to be published in the journal Cretaceous Research. Three fossilized burrows found in southeastern Australia are the second group of such tunnels found on Earth and, dating back 110 million years, are the oldest.
When dinosaurs roamed the Earth, these burrows were within the Antarctic Circle and temperatures dipped below freezing during the winter. Also, periods of little sunlight likely led to cyclical shortages in vegetation. The burrows support the hypothesis that instead of migrating to escape the cold winters of the Cretaceous period, dinosaurs ventured underground, like modern animals such as alligators and coyotes. The only other known dinosaur burrow was discovered in 2005 in Montana, US. Described two years later, this burrow dated from 95 million years ago and contained the bones of an adult and two juveniles of a small new species of dinosaur called Oryctodromeus cubicularis [BBC News]. Burrows that snaked below the ground may have provided a haven offering protection from predators, along with stable temperatures, constant humidity levels and a place to tend to offspring.
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Dinosaurs are objects of eternal fascination to we puny humans because of their sheer size. Some, like the long-necked sauropods, are thought to have had eight times the mass of an African elephant, the largest modern land animal.
Now a new model from zoologist Brian McNab suggests that the secret of dinosaurs‘ size was really quite simple: They had plenty to eat, and didn’t have to expend much energy in their daily lives. Says McNab: “Like couch potatoes sitting within easy reach of high calorie foods, the gargantuan size of dinosaurs most likely stems from the abundance of resources available, coupled with low energy expenditures” [Telegraph]. McNab’s findings also contribute to the long-running debate between paleontologists about whether dinosaurs were warm-blooded or cold-blooded creatures.
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The duck-billed dinosaurs have been giving up their secrets lately. Just yesterday researchers revealed new details of how hadrosaurs chewed their food, using a set of teeth that look like a “cranial cuisinart.” Today, paleontologists have put the hadrosaur’s skin on display, thanks to a “mummified” creature that shows the shape of its soft tissue and cell-like structures.
Such a discovery was possible because the dinosaur’s skin fossilized before bacteria had a chance to eat up the tissue. It is “absolutely amazing to be able to identify organic molecules from soft tissue that belonged to a beast that died over 66 million years ago…. This is the closest you’re going to get to patting the animal” [National Geographic News], says lead researcher Phillip Manning.
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The duck-billed dinosaurs more properly known as hadrosaurs were the most prolific vegetarians of the late Cretaceous period, and researchers think their unusual mouth mechanics may have played a role in their evolutionary success. A new study of the hadrosaur Edmontosaurus examined the animal’s fossilized teeth in unprecedented detail. Using an electron scanning microscope, researchers were able to examine minute scratches on individual dino teeth made by daily wear and tear 65 million to 68 million years ago to test competing theories about how the creatures may have munched [Scientific American].
The mouth of a hadrosaur has been compared to a “cranial Cuisinart,” with hundreds of teeth lined up in rows to chop up the tough plants of the late Cretaceous. But the dinosaurs didn’t have the complex jaw joint that mammals have, leaving scientists to puzzle over exactly how hadrosaurs did all that chewing [MSNBC]. The study, published in the Proceedings of the National Academy of Sciences, found scratches indicating that the movements of a hadrosaur’s teeth was a complicated matter, involving sideways and front to back motions as well as the traditional up and down chomp.
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Most paleontologists believe that a group of dinosaurs evolved into today’s birds, but in trying to understand that gradual process they’ve been bedeviled by some details. Yesterday, researchers announced that they may have solved one of those small conundrums. A fossilized dinosaur found in China appears to settle the matter of exactly how the bones in dinosaurs’ feet evolved into the digits hidden in bird wings.
The newly discovered ceratosaur belonged to a group of dinosaurs called theropods, which are thought to have given rise to modern birds and which included the mighty Tyrannosaurus rex. But unlike its T. rex cousin, this ceratosaur appears to have been a vegetarian. Says study coauthor James Clark: “It’s a really weird animal – it’s got no teeth, had a beak and a very long neck, and very wimpy forelimbs…. Then when we looked closely at the hand, we noticed it was relevant to a very big question in palaeontology” [BBC News].
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The lumbering, long-necked dinosaurs known as sauropods are a staple of natural history museums and gift shops, but a new debate has broken out that challenges the poses of the museums’ life-sized replicas and the toy shops’ plastic figurines. The mighty sauropods Brachiosaurus and Diplodocus are commonly positioned with their long necks stretched before them, but a controversial new study argues that they actually stretched their necks up to the treetops. If sauropods did indeed hold their heads aloft like giraffes, some would have stood almost 50 feet tall.
For the new study, published in the journal Acta Palaeontologica Polonica, paleontologist Mike Taylor and his colleagues took the straight-forward approach of studying the x-rays of 10 different groups of vertebrate animals. Says Taylor: “Unless sauropods carried their heads and necks differently from every living vertebrate, we have to assume the base of their neck was curved strongly upwards. In some sauropods this would have meant a graceful S-curve to the neck, and a look different from the recreations we are used to seeing today” [The Australian].
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Scientists say they have found fossils near the Colorado-New Mexico border that prove some dinosaurs survived the mass extinction that most researchers believe was caused by a meteor impact 65 million years ago. James Fassett, a scientist with the U.S. Geological Survey, says he has found evidence that a sizable population of ceratopsians and sauropods, a class of giant, dim-witted leaf-eaters such as the brachiosaurus, hung on for another 500,000 years in the [San Juan] basin. “There might even have been some T. rexes, based on some teeth we found” [Los Angeles Times], he said.
The bones of hadrosaurs, tyrannosaurs, anklyosaurs, and several other species were found together in a sandstone formation that dates to the Paleocene epoch—the time period after the so-called Cretaceous-Tertiary (K-T) extinction event, which is thought to have killed off the dinosaurs [National Geographic News]. To prove that the bones he found were indeed older than the extinction and eliminate the possibility that they had not simply been incorporated into newer rocks, Fassett points to his discovery of 34 bones from a single hadrosaur: If they had been washed away from their original location, they would almost certainly have been separated, not found together [Los Angeles Times].
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Continuing the controversy over whether tissue can be extracted from fossils, cell-like structures resembling blood cells have been found in the leg bone of a dinosaur excavated from a Montana site. The researchers, led by Mary Schweitzer, have sequenced a set of proteins belonging to the 80-million-year-old remains of a duck-billed hadrosaur…. confirmed the presence of collagen, laminin and elastin proteins from the bone…. [and] independently verified amino acids in dinosaur tissues [GenomeWeb].
In 2007, Schweitzer first reported finding soft tissue, and then collagen, from the leg bone of a 68-million-year-old Tyrannosaurus rex excavated two years prior. But her team’s research later proved controversial, with some questioning whether the samples they had obtained had become contaminated with proteins from modern species [Nature News]. So the team set out to replicate its findings, and searched for dinosaur fossils buried in deep sandstones, which were likely to be well preserved, and they speeded up the process of getting them from the field to the lab [Cosmos].
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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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