Plant Eating Dinosaur Discovered in Antarctica
ScienceDaily (Dec. 19, 2011) — For the first time, the presence of large bodied herbivorous dinosaurs in Antarctica has been recorded. Until now, remains of sauropoda — one of the most diverse and geographically widespread species of herbivorous dinosaurs — had been recovered from all continental landmasses, except Antarctica. Dr. Ignacio Alejandro Cerda, from CONICET in Argentina, and his team’s identification of the remains of the sauropod dinosaur suggests that advanced titanosaurs (plant-eating, sauropod dinosaurs) achieved a global distribution at least by the Late Cretaceous*.
Their work has just been published online in Springer’s journal Naturwissenschaften – The Science of Nature.
Sauropoda is the second most diverse group of dinosaurs, with more than 150 recognized species. It includes the largest terrestrial vertebrates that ever existed. Although many sauropod remains have been discovered in North and South America, Africa, Asia, Australia and Europe, there is no previous record of sauropoda in Antarctica. Other important dinosaur discoveries have been made in Antarctica in the last two decades — principally in the James Ross Basin.Dr. Cerda and colleagues report the first finding of a sauropod dinosaur from this continent and provide a detailed description of an incomplete middle-tail vertebra, recovered from James Ross Island. The specific size and morphology of the specimen, including its distinctive ball and socket articulations, lead the authors to identify it as an advanced titanosaur.
These titanosaurs originated during the Early Cretaceous and were the predominant group of sauropod dinosaurs until the extinction of all non-bird dinosaurs at the end of the Cretaceous. Although they were one of the most widespread and successful species of sauropod dinosaurs, their origin and dispersion are not completely understood.
The authors conclude: “Our discovery, and subsequent report, of these sauropod dinosaur remains from Antarctica improves our current knowledge of the dinosaurian faunas during the Late Cretaceous on this continent.”*The Cretaceous Period spanned 99.6-65.5 million years ago, and ended with the extinction of the dinosaurs.
North America’s Biggest Dinosaur Revealed
ScienceDaily (Dec. 7, 2011) — New research from Montana State University’s Museum of the Rockies and the State Museum of Pennsylvania has unveiled enormous bones from North America’s biggest dinosaur.
In a paper published Dec. 6 in Acta Palaeontologica Polonica, MSU researcher Denver W. Fowler and coauthor Robert M. Sullivan from Harrisburg, Pa., describe two gigantic vertebrae and a femur that the team collected in New Mexico from 2003 to 2006. Carrying the vertebrae alone took most of a day and was a “killer” because the paleontologists carried them 1.2 miles through 100-degree heat, Fowler said.
The bones belong to the sauropod dinosaur Alamosaurus sanjuanensis: a long-necked plant eater related to Diplodocus. The Alamosaurus roamed what is now the southwestern United States and Mexico about 69 million years ago.
“Alamosaurus has been known for some time; its remains were first described in 1922 from the Naashoibito beds of New Mexico. Since then, more bones have been discovered in New Mexico, Utah, some really nice material from Texas, and Mexico, including a few partial skeletons,” Fowler said.
The sheer size of the new bones caught the researchers by surprise, however.
“We used to think that a fully grown Alamosaurus measured around 60 feet long and weighed about 30 tons; but a 2009 study by another MSU researcher, Dr. Holly Woodward, found that a femur thought to belong to an adult was still growing,” Fowler said. “This told us that Alamosaurus got even bigger, but we didn’t imagine that it could get quite this big.”
How big? The enormity of the new bones puts Alamosaurus in the same size league as other giant sauropods from South America, including Argentinosaurus which weighed about 70 tons, and is widely considered to be the biggest dinosaur of all.
“Over the past 20 years, Argentinean and Brazilian paleontologists have been unearthing bigger and bigger dinosaurs, putting the rest of the world in the shade,” Fowler said. “However, our new finds not only show that Alamosaurus is newly recognized as the biggest dinosaur from North America, but also that it was right up there with the biggest South American species: the US is back in the fight for the No.1 spot.”
Although comparison of the new Alamosaurus bones with the South American species gave the researchers an idea of size, giant specimens of sauropods like Alamosaurus and Argentinosaurus are only known from very fragmentary remains offering only a tantalizing glimpse of what a complete Alamosaurus might look like, Fowler said.
“We’d love to find more complete material,” Fowler continued. “Fortunately, Alamosaurus bones are quite common in the Naashoibito of New Mexico, so we have a good chance of going back and finding more, but in order to dig up one of the world’s biggest dinosaurs you need one of the world’s biggest dinosaur digging teams and large digging equipment.”
The Pennsylvania State Museum field crew is typically just two or three people, so there are limits on how many bones can be collected in one season, Fowler said. Even so, many new and important specimens have been recovered over the past 10 to 15 years, including new species, and other members of the fauna including the iconic carnivore Tyrannosaurus.
“We found a shed Tyrannosaurus tooth with another Alamosaurus neck bone that we were excavating,” Fowler said. “The Tyrannosaurus may have lost its tooth while feeding on an Alamosaurus carcass.”
The Alamosaurus discovery goes beyond just “size” bragging-rights, and may have important implications for other dinosaurs, Fowler said. Recent discoveries by paleontologist Jack Horner’s paleo lab at the Museum of the Rockies have emphasized the importance of understanding growth and ontogeny in interpreting dinosaur evolution.
“Increasingly, we’re finding that very large or small individuals often look very different, and are often described as different species,” Fowler said. “Our findings show that Alamosaurus was originally described based on immature material, and this is a problem as characteristics that define a species are typically only fully gained at adult size. This means that we might be misinterpreting the relationships of Alamosaurus and possibly other sauropod dinosaurs too.”
‘Skin Bones’ Helped Large Dinosaurs Survive, New Study Says
ScienceDaily (Nov. 29, 2011) — Bones contained entirely within the skin of some of the largest dinosaurs on Earth might have stored vital minerals to help the massive creatures survive and bear their young in tough times, according to new research by a team including a University of Guelph scientist.
Guelph biomedical scientist Matthew Vickaryous co-authored a paper published in Nature Communications about two sauropod dinosaurs — an adult and a juvenile — from Madagascar.
The study suggests that these long-necked plant-eaters used hollow “skin bones” called osteoderms to store minerals needed to maintain their huge skeletons and to lay large egg clutches. Sediments around the fossils show that the dinosaurs’ environment was highly seasonal and semi-arid, with periodic droughts causing massive die-offs.
“Our findings suggest that osteoderms provided an internal source of calcium and phosphorus when environmental and physiological conditions were stressful,” he said. As a researcher in the Department of Biomedical Sciences in Guelph’s Ontario Veterinary College, Vickaryous studies how skeletons develop, regenerate and evolve.
He worked with paleontologist Kristina Curry Rogers and geologist Raymond Rogers at Macalaster College in Minnesota, and paleontologist Michael D’Emic, now at Georgia Southern University on the study. Vickaryous helped to interpret the results of CT scans and fossilized tissue cores taken from the dinosaurs.
Shaped like footballs sliced lengthwise and about the size of a gym bag in the adult, these bones are the largest osteoderms ever identified. The adult specimen’s bone was hollow, likely caused by extensive bone remodelling, said Vickaryous.
Osteoderms were common among armoured dinosaurs. Stegosaurs had bony back plates and tail spikes, and ankylosaurs sported heavily armoured bodies and bony tail clubs. Today these “skin bones” appear in such animals as alligators and armadillos.
Such bones were rare among sauropod dinosaurs and have appeared only in titanosaurs. These massive plant-eaters included the largest-ever land animals. “This is the only group of long-necked sauropods with osteoderms,” he said.
Other studies have shown that female titanosaurs laid dozens of volleyball-sized eggs. Modern crocodiles and alligators also lay clutches of dozens of eggs and are known to reabsorb minerals from their osteoderms.
The researchers found the new osteoderms along with two skeletons of the titanosaur Rapetosaurus. Unlike the hollow adult specimen, the juvenile specimen was solid and showed little evidence of remodelling. That suggests that osteoderms became more important mineral stores as the animals grew, Vickaryous said.