What’s the News: The oldest recovered dinosaurs, including two-legged predators like Herrerasaurus, tromped around Argentina and Brazil some 230 million years ago. But exactly what happened after those beasts is a mystery: paleontologists have puzzled over an evolutionary gap in the fossil record between these early creatures and the more complex theropods, a suborder of bipedal dinosaurs—including Tyrannosaurus rex—that eventually comprised all dino carnivores. In the rocks of New Mexico’s Ghost Ranch, paleontologists have discovered the skull and vertebrae of a new dinosaur species that may fill this evolutionary gap. Dubbed Daemonosaurus chauliodus, this up-to-five-feet long, 205-million-year old predator has characteristics of both the first dinosaurs and the more advanced predators. As Hans-Dieter Sues, a paleontologist at the National Museum of Natural History in Washington, D.C., told National Geographic, the skull is unusual because “it has a … short snout and these monstrous front teeth. That’s a kind of skull structure for a predatory dinosaur that’s really unexpected for this early point in time.”
When it come to dinosaurs, names say a lot: “tyrant lizard king” sums up the towering stature and carnivorous ways of Tyrannosaurus rex, and “arm lizard” gestures toward the Brachiosaurus‘s long front legs. And the same is true for the newest discovered dinosaur species, which has been dubbed “thunder-thighs.” That’s because scientists think its muscular thighs were so strong that it used them to boot its enemies.
The official name of this new sauropod species is Brontomerus mcintoshi. The first name is Greek for “thunder-thighs,” and the species name honors the Wesleyan University physics professor and amateur paleontologist Jack McIntosh. This dino is believed to have bigger leg muscles than any other sauropod.
A team of American and British scientists discovered the dinosaur in a quarry in Utah, and published their findings in the journal Acta Palaeontologica Polonica. Fragments from two skeletons were found: one from an adult (believed to be the mother) and a juvenile. These specimens are roughly 110 million year old, and the larger one would have weighed in at six tons and measured over 45 feet long.
Titanoceratops—it’s a fittingly majestic name for a monster dinosaur. That’s the moniker paleontologist Nicholas Longrich has bestowed on his new find, and he claims his 74-million-year-old discovery is the common ancestor of the famous Triceratops and its cousin in the triceratopsin family, the Torosaurus.
The species weighed in at around 6,800 kilograms [15,000 pounds] and had an enormous 8-foot skull — rivaling Triceratops for size. It is very similar to Triceratops, but with a thinner frill, longer nose and slightly bigger horns. Titanoceratops lived in the American Southwest during the Cretaceous period, about 74 million years ago, and is the earliest known triceratopsin. [Wired]
Actually, Titanoceratops is not a “new” discovery—but the fossil was mistakenly classified for years, Longrich says. The partial skeleton was turned up in 1941 in New Mexico, and left alone until 1995. At that point scientists dug it up and erected the skeleton in the Sam Noble Oklahoma Museum of Natural History as a dinosaur called Pentaceratops sternbergi (in the right side of the image, the shaded parts represent missing pieces that were filled into to model the skull as Pentaceratops). The Pentaceratops lived about 73 to 75 million years ago, but it was much smaller overall than a triceratopsin.
Clunky, clumsy, and slow–these are the words that some scientists have associated with Tyrannosaurus rex in the past decade, using these physical traits as evidence that it was more of a scavenger than a hunter. But another group of researchers has held to the notion of T. rex as a fierce predator worthy of the name “tyrant lizard king.” It’s a debate that just won’t go extinct, and this week brings an interesting new argument for the predator position.
In the past several years, scientists have pointed out that T. rex had small eyes and a good sense of smell, and have argued this as evidence that it was a scavenger.
Meet Linhenykus monodactylus, the dinosaur that gave the world the finger. This parrot-sized theropod isn’t being surly. It just doesn’t have a choice: it’s the first single-digit dinosaur ever discovered.
In this week’s Proceedings of the National Academy of Sciences, Xu Xing and colleagues document their find, which turned up in a fossil-rich part of northern China. Linhenykus is probably about 80 million years old.
Linhenykus monodactylus is a member of the theropod dinosaurs, the group of two-legged carnivores that includes Tyrannosaurus rex and Velociraptor. Most theropods had three fingers on each hand. But Linhenykus belongs to a family known as the alvarezsauroids: small, long-legged dinosaurs that had one big finger alongside two barely functional nub fingers. [National Geographic]
In the ground of Argentina, paleontologists are digging deeper into dinosaur history, back to the point more than 200 million years ago when this group emerged. Now a group says in the journal Science that it has recovered one of the oldest dino fossils ever found: a 230-million-year-old tiny forerunner of the T. rex, called Eodromaeus.
At four feet in length and sporting impressive teeth, the new dino species appears to have been a speedy carnivore—and, possibly, adorable.
“It was very cute; you’d want it as a pet,” said Paul Sereno, a paleontologist at the University of Chicago and one of the study’s authors. “But it might be best as a guard dinosaur, to keep the dogs away.” [The New York Times]
Sereno’s analysis of Eodromaeus, which lived at the time that present-day Argentina was southwestern Pangea, turned up evidence that he says places it early in the line of the theropods, T. rex‘s group.
The demise of the dinosaurs 65 million years ago opened the door of opportunity for mammals to take over the Earth—that much is clear. What’s coming into focus, thanks to a study out in Science, is just how fast mammals maxed out their size once the terrible lizards were out of the way.
“For the first 140 million years of our evolutionary history we really did nothing—we were really kind of boring,” Felisa Smith, an associate professor of biology at the University of New Mexico and coauthor of the new study. … But across all of the major continents, during the first 25 million years after the dinosaurs were wiped out, mammals underwent an explosive growth spurt. By 42 million years ago, however, the researchers found, the intense growth had leveled off. [Scientific American]
Smith’s team surveyed fossils from around the world, including 32 different mammalian orders. No matter where they looked, she says, they saw the same pattern. Mammals that survived the extinction event were small, mostly rodent-sized. Then all over the planet they exploded in size during that period of 20 to 25 million years.
Fossilized dinosaur embryos, found still in their eggshells, have claimed the title of the oldest vertebrate embryos ever seen–they were fossilized in the early Jurassic Period, around 190 million years ago, researchers say. The embryos are from the species Massospondylus, a prosauropod, the family of dinosaurs which gave rise to iconic sauropods like the Brachiosaurus.
Robert Reisz and his team found the embryos when analyzing a clutch of fossilized eggs collected in South America in 1976. The find was just published in the Journal of Vertebrate Paleontology.
“This project opens an exciting window into the early history and evolution of dinosaurs,” said Professor Reisz. “Prosauropods are the first dinosaurs to diversify extensively, and they quickly became the most widely spread group, so their biology is particularly interesting as they represent in many ways the dawn of the age of dinosaurs.” [BBC News]
New bone evidence suggests that Tyrannosaurus rex was not only a scavenger but also a cannibal.
While researchers frequently find evidence of bites on bone fossils, Nicholas Longrich was surprised to find big, predator-sized tooth marks on T. rex bones–because the T. rex was the only large carnivore in the area, and therefore the only dinosaur who could have left those marks.
“These animals were some of the largest terrestrial carnivores of all time, and the way they approached eating was fundamentally different from modern species,” Longrich added. “There’s a big mystery around what and how they ate, and this research helps to uncover one piece of the puzzle.” [The Guardian].
Longrich found a total of four bones–three from T. rex feet and one from an arm–that show marks of cannibalism. The location of the bite marks suggest that they were made after death; for example, some of the markings are in areas that would have been obscured by joints in a living animal. One toe bone showed multiple bite marks made by a smaller animal, and Longrich notes that a large T. rex probably wouldn’t let another T. rex gnaw on its foot. There had to be another explanation, Longrich says: