Mystery Human Fossils Put Spotlight On China
ScienceDaily (Mar. 14, 2012) — Fossils from two caves in south-west China have revealed a previously unknown Stone Age people and give a rare glimpse of a recent stage of human evolution with startling implications for the early peopling of Asia.
The fossils are of a people with a highly unusual mix of archaic and modern anatomical features and are the youngest of their kind ever found in mainland East Asia.
Dated to just 14,500 to 11,500 years old, these people would have shared the landscape with modern-looking people at a time when China’s earliest farming cultures were beginning, says an international team of scientists led by Associate Professor Darren Curnoe, of the University of New South Wales, and Professor Ji Xueping of the Yunnan Institute of Cultural Relics and Archeology.
Details of the discovery are published in the journal PLoS ONE. The team has been cautious about classifying the fossils because of their unusual mosaic of features.
“These new fossils might be of a previously unknown species, one that survived until the very end of the Ice Age around 11,000 years ago,” says Professor Curnoe.
“Alternatively, they might represent a very early and previously unknown migration of modern humans out of Africa, a population who may not have contributed genetically to living people.”
The remains of at least three individuals were found by Chinese archaeologists at Maludong (or Red Deer Cave), near the city of Mengzi in Yunnan Province during 1989. They remained unstudied until research began in 2008, involving scientists from six Chinese and five Australian institutions.
A Chinese geologist found a fourth partial skeleton in 1979 in a cave near the village of Longlin, in neighbouring Guangxi Zhuang Autonomous Region. It stayed encased in a block of rock until 2009 when the international team removed and reconstructed the fossils.
The skulls and teeth from Maludong and Longlin are very similar to each other and show an unusual mixture of archaic and modern anatomical features, as well as some previously unseen characters.
While Asia today contains more than half of the world’s population, scientists still know little about how modern humans evolved there after our ancestors settled Eurasia some 70,000 years ago, notes Professor Curnoe.
The scientists are calling them the “Red-deer Cave people” because they hunted extinct red deer and cooked them in the cave at Maludong.
The Asian landmass is vast and scientific attention on human origins has focussed largely on Europe and Africa: research efforts have been hampered by a lack of fossils in Asia and a poor understanding of the age of those already found.
Until now, no fossils younger than 100,000 years old have been found in mainland East Asia resembling any species other than our own (Homo sapiens). This indicated the region had been empty of our evolutionary cousins when the first modern humans appeared. The new discovery suggests this might not have been the case after all and throws the spotlight once more on Asia.
“Because of the geographical diversity caused by the Qinghai-Tibet plateau, south-west China is well known as a biodiversity hotspot and for its great cultural diversity. That diversity extends well back in time” says Professor Ji.
In the last decade, Asia has produced the 17,000-year-old and highly enigmatic Indonesian Homo floresiensis (“The Hobbit”) and evidence for modern human interbreeding with the ancient Denisovans from Siberia.
“The discovery of the red-deer people opens the next chapter in the human evolutionary story — the Asian chapter — and it’s a story that’s just beginning to be told,” says Professor Curnoe.
Two New Extinct Camel Species Discovered at Panama Canal Excavation
ScienceDaily (Feb. 29, 2012) — The discovery of two new extinct camel species by University of Florida scientists sheds new light on the history of the tropics, a region containing more than half the world’s biodiversity and some of its most important ecosystems.
Appearing online this week in the Journal of Vertebrate Paleontology, the study is the first published description of a fossil mammal discovered as part of an international project in Panama. Funded with a grant from the National Science Foundation, UF paleontologists and geologists are working with the Panama Canal Authority and scientists at the Smithsonian Tropical Research Institute to make the most of a five-year window of excavations during Panama Canal expansions that began in 2009.
The discovery by Florida Museum of Natural History researchers extends the distribution of mammals to their southernmost point in the ancient tropics of Central America. The tropics contain some of the world’s most important ecosystems, including rain forests that regulate climate systems and serve as a vital source of food and medicine, yet little is known of their history because lush vegetation prevents paleontological excavations.
“We’re discovering this fabulous new diversity of animals that lived in Central America that we didn’t even know about before,” said co-author Bruce MacFadden, vertebrate paleontology curator at the Florida Museum on the UF campus and co-principal investigator on the NSF grant funding the project. “The family originated about 30 million years ago and they’re found widespread throughout North America, but prior to this discovery, they were unknown south of Mexico.”
Researchers described two species of ancient camels that are also the oldest mammals found in Panama: Aguascalietia panamaensis and Aguascalientia minuta. Distinguished from each other mainly by their size, the camels belong to an evolutionary branch of the camel family separate from the one that gave rise to modern camels based on different proportions of teeth and elongated jaws.
“Some descriptions say these are ‘crocodile-like’ camels because they have more elongated snouts than you would expect,” said lead author Aldo Rincon, a UF geology doctoral student. “They were probably browsers in the forests of the ancient tropics. We can say that because the crowns are really short.”
Rincon discovered the fossils in the Las Cascadas formation, unearthing pieces of a jaw belonging to the same animal over a span of two years, he said.
“When I came back to the museum, I started putting everything together and realized, ‘Oh wow, I have a nearly complete jaw,’ ” Rincon said.
The study shows that despite Central America’s close proximity to South America, there was no connection between continents because mammals in the area 20 million years ago all had North American origins. The Isthmus of Panama formed about 15 million years later and the fauna crossed to South America 2.5 to 3 million years ago, MacFadden said.
Barry Albright, a professor of earth science at the University of North Florida who studied the early Miocene fauna of the Gulf Coast Plain, said he was surprised by the similarity of the Central American fauna.
“To me, it’s slightly unexpected,” Albright said. “That’s a large latitudinal gradient between the Gulf Coastal Plain and Panama, yet we’re seeing the same mammals, so perhaps that tells us something about climate over that interval of time and dispersal patterns of some mammals over that interval of time.”
Camels belong to a group of even-toed ungulates that includes cattle, goats, sheep, deer, buffalo and pigs. Other fossil mammals discovered in Panama from the early Miocene have been restricted to those also found in North America at the time. While researchers are sure the ancient camels were herbivores that likely browsed in forests, they are still analyzing seeds and pollen to better understand the environment of the ancient tropics.
“People think of camels as being in the Old World, but their distribution in the past is different than what we know today,” MacFadden said. “The ancestors of llamas originated in North America and then when the land bridge formed about 4 to 5 million years ago, they dispersed into South America and evolved into the llama, alpaca, guanaco and vicuña.”
Researchers will continue excavating deposits from the Panama Canal during construction to widen and straighten the channel and build new locks, expected to continue through 2014. The project is funded by a $3.8 million NSF grant to develop partnerships between the U.S. and Panama and engage the next generation of scientists in paleontological and geological discoveries along the canal. Study co-authors include Jonathan Bloch of UF, and Catalina Suarez and Carlos Jaramillo of the Smithsonian Tropical Research Institute.
T. Rex Has Most Powerful Bite of Any Terrestrial Animal Ever
ScienceDaily (Feb. 28, 2012) — Research at the University of Liverpool, using computer models to reconstruct the jaw muscle of Tyrannosaurus rex, has suggested that the dinosaur had the most powerful bite of any living or extinct terrestrial animal.
The team artificially scaled up the skulls of a human, alligator, a juvenile T. rex, and Allosaurus to the size of an adult T. rex. In each case the bite forces increased as expected, but they did not increase to the level of the adult T. rex, suggesting that it had the most powerful bite of any terrestrial animal.
Previous studies have estimated that T. rex‘s bite had a force of 8,000 to 13,400 Newtons, but given the size of the animal, thought to weigh more than 6,000kg, researchers suspected that its bite may have been more powerful than this. Liverpool scientists developed a computer model to reverse engineer the animal’s bite, a method that has previously been used to predict dinosaur running speeds.
An animal’s bite force is largely determined by the size of the jaw muscles. Using their computer models, researchers tested a range of alternative muscle values, as it is not precisely known what the muscles of dinosaurs were like. Even with error margins factored in, the computer model still showed that the T. rex had a more powerful bite than previously suggested.
The smallest values predicted were around 20,000 Newtons, while the largest values were as high as 57,000 Newtons, which would be equivalent to the force of a medium sized elephant sitting down on the ground.
Researchers also found that the results for the juvenile T. rex had a relatively the weaker bite than the adult T. rex, even when size differences and uncertainties about muscle size were taken into account. The large difference between the two measurements, despite the error margins factored in, may suggest that T. rex underwent a change in feeding behaviour as it grew.
Dr Karl Bates, from the University’s Department of Musculoskeletal Biology, said: “The power of the T. rex jaw has been a much debated topic over the years. Scientists only have the skeleton to work with, as muscle does not survive with the fossil, so we often have to rely on statistical analysis or qualitative comparisons to living animals, which differ greatly in size and shape from the giant enigmatic dinosaurs like T. rex. As these methods are somewhat indirect, it can be difficult to get an objective insight into how dinosaurs might have functioned and what they may or may not have been capable of in life.
“To build on previous methods of analysis, we took what we knew about T. rex from its skeleton and built a computer model that incorporated the major anatomical and physiological factors that determine bite performance. We then asked the computer model to produce a bite so that we could measure the speed and force of it directly. We compared this to other animals of smaller body mass and also scaled up smaller animals to the size of T. rex to compare how powerful it was in relative terms.
“Our results show that the T. rex had an extremely powerful bite, making it one of the most dangerous predators to have roamed our planet. Its unique musculoskeletal system will continue to fascinate scientists for years to come.”
Polysternon Isonae, a New Species of Turtle That Lived With Dinosaurs in Isona (Spanish Pyrenees)
ScienceDaily (Feb. 27, 2012) — Researchers* have recently published in the online edition of the journal Cretaceous Research the discovery and description of a turtle from the end of the age of dinosaurs.They have named this new species as Polysternon isonae, in recognition of the municipality of Isona I Conca Dellà (Catalonia, Spain), where the fossil remains of the specimen type have been found.
The abundance of dinosaur fossils that lived between 65 and 70 million years ago in the area currently occupied by the Pyrenees It is well known. In this range we find dozens of sites with bones, footprints and eggs of the last dinosaurs that inhabited our planet, the Tremp basin being one of the areas with the highest concentration of fossils.
However, lesser-known are the other organisms that completed the ecosystems at the end of the Cretaceous period, consisting of other vertebrates, invertebrates, plants, fungi, etc. A common feature of these ecosystems were turtles. In the Pyrenean sites, their fossils are relatively abundant and, in general, consist of isolated shell plates or small sets of plates that can help us get a general idea of the morphology and size of the animal. Instead, the entire shell finding is rare and even more exceptional are the findings where parts of the skeleton are preserved within the shell.
In recent years, in the municipality of Isona i Conca Dellà (Catalonia) numerous discoveries of turtle remains have been made, spread over several sites. One of these sites, that of Barranc de Torrebilles, has given fairly complete remains that allowed describing a new species: Polysternon isonae. The remains found consist of dozens of isolated plates derived from the fragmentation of shells through their sutures, and what is more important: a fragment of the ventral side of a shell and an almost entire shell, which without being totally complete, show morphological features of great interest to paleontologists and have allowed to describe this new species. These remains were recovered during two excavation campaigns conducted during the summers of 2008 and 2009.
So far, two species of the genus Polysternon were known : P. provinciale and P. Atlanticum (plus a possible third P. Mechinorum), distributed only in what is know the south of France and the Iberian Peninsula. They were animals adapted to swimming and living in fresh waters, in the deeper areas of rivers and lakes. Specifically, the shell of the new species P. isonae was oval, measuring about 50 centimeters long and 40 wide. The remains were found preserved in a very hard sandstone strata now exposed in the Barranc de Torrebilles. Just over 65 million years ago, when the animal died, this was not a lithified sandstone and consisted of fine sand that was washed away by river streams and that was deposited, along with the remains of other turtles of the Barranc de Torrebilles, at the bottom of one of these rivers.
Unlike other kinds of turtles, it seems that Polysternon did not survive the end of Cretaceous and went extinct with the dinosaurs. The close proximity of the site Barranc de Torrebilles to the geological level that marks the end of the Cretaceous extinction, indicates that Polysternon isonae was possibly one of the last species of the genus Polysternon.
* Josep Marmi, Angel Lujan, Angel Galobart from Institut Català de Paleontologia Miquel Crusafont (ICP), Rodrigo Gaete from the Museu de la Conca Dellà (MCD) and Violeta and Oms Oriol Riera from the Universitat Autònoma de Barcelona (UAB
Entire Genome of Extinct Human Decoded from Fossil
ScienceDaily (Feb. 7, 2012) — The Max Planck Institute for Evolutionary Anthropology, in Leipzig, Germany, has completed the genome sequence of a Denisovan, a representative of an Asian group of extinct humans related to Neandertals.
In 2010, Svante Pääbo and his colleagues presented a draft version of the genome from a small fragment of a human finger bone discovered in Denisova Cave in southern Siberia. The DNA sequences showed that this individual came from a previously unknown group of extinct humans that have become known as Denisovans. Together with their sister group the Neandertals, Denisovans are the closest extinct relatives of currently living humans.
The Leipzig team has now developed sensitive novel techniques which have allowed them to sequence every position in the Denisovan genome about 30 times over, using DNA extracted from less than 10 milligrams of the finger bone. In the previous draft version published in 2010, each position in the genome was determined, on average, only twice. This level of resolution was sufficient to establish the relationship of Denisovans to Neandertals and present-day humans, but often made it impossible for researchers to study the evolution of specific parts of the genome. The now-completed version of the genome allows even the small differences between the copies of genes that this individual inherited from its mother and father to be distinguished.
On February 8 the Leipzig group makes the entire Denisovan genome sequence available for the scientific community over the internet.
“The genome is of very high quality,” says Matthias Meyer, who developed the techniques that made this technical feat possible. “We cover all non-repetitive DNA sequences in the Denisovan genome so many times that it has fewer errors than most genomes from present-day humans that have been determined to date.”
The genome represents the first high-coverage, complete genome sequence of an archaic human group — a leap in the study of extinct forms of humans. “We hope that biologists will be able to use this genome to discover genetic changes that were important for the development of modern human culture and technology, and enabled modern humans to leave Africa and rapidly spread around the world, starting around 100,000 years ago” says Pääbo. The genome is also expected to reveal new aspects of the history of Denisovans and Neandertals.
The group plans to present a paper describing the genome later this year. “But we want to make it freely available to everybody already now” says Pääbo. “We believe that many scientists will find it useful in their research.”
The project is made possible by financing from the Max Planck Society and is part of efforts since almost 30 years by Dr. Pääbo’s group to study ancient DNA. The finger bone was discovered by Professor Anatoly Derevianko and Professor Michail Shunkov from the Russian Academy of Sciences in 2008 during their excavations at Denisova Cave, a unique archaeological site which contains cultural layers indicating that human occupation at the site started up to 280,000 years ago. The finger bone was found in a layer which has been dated to between 50,000 and 30,000 years ago.
Fossils in South Africa Reveal Dinosaur Nesting Site: 190 Million Years Old
ScienceDaily (Jan. 23, 2012) — An excavation at a site in South Africa has unearthed the 190-million-year-old dinosaur nesting site of the prosauropod dinosaur Massospondylus — revealing significant clues about the evolution of complex reproductive behaviour in early dinosaurs.
A new study, published in the Proceedings of the National Academy of Sciences (PNAS), was led by Canadian palaeontologist Prof. Robert Reisz, a professor of biology at the University of Toronto at Mississauga, and co-authored by Drs. Hans-Dieter Sues (Smithsonian Institute, USA), Eric Roberts (James Cook University, Australia), and Adam Yates (Bernard Price Institute (BPI) for Palaeontological Research at Wits).
The study reveals clutches of eggs, many with embryos, as well as tiny dinosaur footprints, providing the oldest known evidence that the hatchlings remained at the nesting site long enough to at least double in size.
Prof. Bruce Rubidge, Director of the BPI at Wits, says: “This research project, which has been ongoing since 2005 continues to produce groundbreaking results and excavations continue. First it was the oldest dinosaur eggs and embryos, now it is the oldest evidence of dinosaur nesting behaviour.”
The authors say the newly unearthed dinosaur nesting ground is more than 100 million years older than previously known nesting sites.
At least ten nests have been discovered at several levels at this site, each with up to 34 round eggs in tightly clustered clutches. The distribution of the nests in the sediments indicate that these early dinosaurs returned repeatedly (nesting site fidelity) to this site, and likely assembled in groups (colonial nesting) to lay their eggs, the oldest known evidence of such behaviour in the fossil record.
The large size of the mother, at six metres in length, the small size of the eggs, about six to seven centimetres in diameter, and the highly organised nature of the nest, suggest that the mother may have arranged them carefully after she laid them.
“The eggs, embryos, and nests come from the rocks of a nearly vertical road cut only 25 metres long,” says Reisz. “Even so, we found ten nests, suggesting that there are a lot more nests in the cliff, still covered by tons of rock. We predict that many more nests will be eroded out in time, as natural weathering processes continue.”
The fossils were found in sedimentary rocks from the Early Jurassic Period in the Golden Gate Highlands National Park in South Africa. This site has previously yielded the oldest known embryos belonging to Massospondylus, a relative of the giant, long-necked sauropods of the Jurassic and Cretaceous periods.
“Even though the fossil record of dinosaurs is extensive, we actually have very little fossil information about their reproductive biology, particularly for early dinosaurs,” says David Evans, a University of Toronto at Mississauga alumnus and a curator of Vertebrate Palaeontology at the Royal Ontario Museum.
“This amazing series of 190 million year old nests gives us the first detailed look at dinosaur reproduction early in their evolutionary history, and documents the antiquity of nesting strategies that are only known much later in the dinosaur record,” says Evans.
Ancient domesticated dog skull found in Siberian cave: 33,000 years old
ScienceDaily (Jan. 23, 2012) — A 33,000-year-old dog skull unearthed in a Siberian mountain cave presents some of the oldest known evidence of dog domestication and, together with an equally ancient find in a cave in Belgium, indicates that modern dogs may be descended from multiple ancestors.
If you think a Chihuahua doesn’t have much in common with a Rottweiler, you might be on to something.
An ancient dog skull, preserved in a cave in the Altai Mountains of Siberia for 33,000 years, presents some of the oldest known evidence of dog domestication and, together with equally ancient dog remains from a cave in Belgium, indicates that domestication of dogs may have occurred repeatedly in different geographic locations rather than with a single domestication event.
In other words, man’s best friends may have originated from more than one ancient ancestor, contrary to what some DNA evidence previously has indicated.
“Both the Belgian find and the Siberian find are domesticated species based on morphological characteristics,” said Greg Hodgins, a researcher at the University of Arizona’s Accelerator Mass Spectrometry Laboratory and co-author of the study that reports the find.
“Essentially, wolves have long thin snouts and their teeth are not crowded, and domestication results in this shortening of the snout and widening of the jaws and crowding of the teeth.”
The Altai Mountain skull is extraordinarily well preserved, said Hodgins, enabling scientists to make multiple measurements of the skull, teeth and mandibles that might not be possible on less well-preserved remains. “The argument that it is domesticated is pretty solid,” said Hodgins. “What’s interesting is that it doesn’t appear to be an ancestor of modern dogs.”
The UA’s Accelerator Mass Spectrometry Laboratory used radiocarbon dating to determine the age of the Siberian skull.
Radioactive carbon, or carbon-14, is one of three carbon isotopes. Along with naturally occurring carbon dioxide, carbon-14 reaches the surface of Earth by atmospheric circulation, where plants absorb it into their tissues through photosynthesis.
Animals and humans take in carbon-14 by ingesting plants or other animals that have eaten plants. “Carbon-14 makes it into all organic molecules,” said Hodgins. “It’s in all living things.”
“We believe that carbon-14 production is essentially constant over time,” said Hodgins. “So the amount of carbon-14 present in living organisms in the past was similar to the levels in living organisms today. When an animal or plant dies, the amount of carbon-14 in its remains drops at a predictable rate, called the radioactive half-life. The half-life of radiocarbon is 5,730 years.”
“People from all over the world send our laboratory samples of organic material that they have dug out of the ground and we measure how much carbon-14 is left in them. Based on that measurement, and knowing the radiocarbon half-life, we calculate how much time must have passed since the samples had the same amount of carbon-14 as plants and animals living today.”
The researchers use a machine called an accelerator mass spectrometer to measure the amount of radioactive carbon remaining in a sample. The machine works in a manner analogous to what happens when a beam of white light passes through a prism: White light separates into the colors of the rainbow.
The accelerator mass spectrometer generates a beam of carbon from the sample and passes it through a powerful magnet, which functions like a prism. “What emerges from it are three beams, one each of the three carbon isotopes,” said Hodgins. “The lightest carbon beam, carbon-12, bends the most, and then carbon-13 bends slightly less and carbon-14 bends slightly less than that.”
The relative intensities of the three beams represent the sample’s carbon mass spectrum. Researchers compare the mass spectrum of an unknown sample to the mass spectra of known-age controls and from this comparison, calculate the sample’s radiocarbon age.
At 33,000 years old, the Siberian skull predates a period known as the Last Glacial Maximum, or LGM, which occurred between about 26,000 and 19,000 years ago when the ice sheets of Earth’s last ice age reached their greatest extent and severely disrupted the living patterns of humans and animals alive during that time. Neither the Belgian nor the Siberian domesticated lineages appear to have survived the LGM.
However, the two skulls indicate that the domestication of dogs by humans occurred repeatedly throughout early human history at different geographical locations, which could mean that modern dogs have multiple ancestors rather than a single common ancestor.
“In terms of human history, before the last glacial maximum people were living with wolves or canid species in widely separated geographical areas of Euro-Asia, and had been living with them long enough that they were actually changing evolutionarily,” said Hodgins. “And then climate change happened, human habitation patterns changed and those relationships with those particular lineages of animals apparently didn’t survive.”
“The interesting thing is that typically we think of domestication as being cows, sheep and goats, things that produce food through meat or secondary agricultural products such as milk, cheese and wool and things like that,” said Hodgins.
“Those are different relationships than humans may have with dogs. The dogs are not necessarily providing products or meat. They are probably providing protection, companionship and perhaps helping on the hunt. And it’s really interesting that this appears to have happened first out of all human relationships with animals.”
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.
LARGE NEST OF JUVENILE DINOSAURS, FIRST OF THEIR GENUS EVER FOUND
The findings were reported in the most recent issue of the Journal of Paleontology.
David Fastovsky, URI professor of geosciences, said the bowl-shaped nest measuring 2.3 feet in diameter was found in the Djadochta Formation at Tugrikinshire, Mongolia.
“Finding juveniles at a nest is a relatively uncommon occurrence, and I cannot think of another dinosaur specimen that preserves 15 juveniles at its nest in this way,” he said.
The analysis of the 70-million-year-old nest by Fastovsky and his colleagues found that all 15 dinosaurs — at least 10 of which are complete specimens — were about
the same size and had achieved the same state of growth and development, suggesting they represent a single clutch from a single mother. The discovery also indicates that the young dinosaurs remained in the nest through the early stages of postnatal development and were cared for by their parents.
Protoceratops grew to about 6 feet long and may have taken as long as 10 years to reach full size. Those Fastovsky found in the nest were likely less than one year old when they died.
“I suspect that the preserved animals were rapidly buried by the shifting, accumulating sands that must have constituted the bulk of sedimentation in this setting,” he said. “Death likely occurred during a desert sandstorm. My guess is that the initial and present-day dryness contributed significantly to the superb preservation, not just of Protoceratops, but of all the fossils from this unit.”
Fastovsky calls Protoceratops “a fascinating and unexpected mass of contradictions.” It is an herbivore that lived in a sand sea much like the Sahara Desert and likely bestowed significant parental care on a relatively large number of offspring, perhaps because it lived where mortality was quite high.
A wide variety of theropod dinosaurs lived in Mongolia at the time, some of which, including the notorious Velociraptor, probably ate young Protoceratops‘.
“Juvenile Protoceratops mortality may have been rather high, not only from predation but from a potentially stressful environment, and large clutches may have been a way of ensuring survival of the animals in that setting,” he said. “Nonetheless, if preservation is any indicator of abundance in life, then during the time represented by the Djadochta Formation, Protoceratops were a very common feature of Mongolian Late Cretaceous desert landscapes.”