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.
Floor of Oldest Fossilized Forest Discovered: 385 Million Years Old
ScienceDaily (Mar. 1, 2012) — Scientists from Binghamton University and Cardiff University, and New York State Museum researchers, and have reported the discovery of the floor of the world’s oldest forest in a cover article in the March 1 issue of Nature.
“It was like discovering the botanical equivalent of dinosaur footprints,” said Dr. William Stein, associate professor of biological sciences at Binghamton University, and one of the article’s authors. “But the most exciting part was finding out just how many different types of footprints there were. The newly uncovered area was preserved in such a way that we were literally able to walk among the trees, noting what kind they were, where they had stood and how big they had grown.”
Scientists are now piecing together a view of this ancient site, dating back about 385 million years ago, which could shed new light on the role of modern-day forests and their impact on climate change.
The recent discovery was made in the same area in Schoharie County where fossils of Earth’s oldest trees — the Gilboa stumps — were discovered in the 1850s, 1920 and again in 2010 and were brought to the State Museum. The Museum has the world’s largest and best collection of Gilboa fossil tree stumps. For decades scientists did not know what the trees connected to the stumps looked like. That mystery was solved when Linda VanAller Hernick, the State Museum’s Paleontology collections manager, and Frank Mannolini, Paleontology collections technician, found fossils of the tree’s intact crown in a nearby location in 2004, and a 28-foot-long trunk portion in 2005. Mannolini, Hernick, and Dr. Christopher M. Berry, a paleobotany lecturer at Cardiff University in Wales, co-authored a Nature article reporting that discovery, as well as the most recent one. Working in conjunction with Stein, Mannolini also developed a sketch of the ancient forest.
“This spectacular discovery and the resulting research provide more answers to the questions that have plagued scientists for more than a century since the first Gilboa stumps were uncovered and brought to the State Museum,” said Hernick, whose passionate interest in the fossils date back to her childhood exposure to the Gilboa fossils. In 2003 Hernick wrote The Gilboa Fossils, a book published by the State Museum, about the history and significance of the fossils and their use in an iconic exhibition about the Earth’s oldest forest that was in the Museum’s former location in the State Education Department building on Washington Avenue. One of the key planners of the exhibition, which influenced generations of paleontologists, was Winifred Goldring, the nation’s first female state paleontologist who was based at the State Museum. She worked tirelessly to study and interpret the Gilboa fossils and named the trees Eospermatopteris, or “ancient seed fern.” In 1924, her paper about the stumps, together with the Museum exhibition, brought the “Gilboa forest” to the attention of the world. One of the Gilboa stumps will be on display in the Museum lobby, beginning March 2. Following the discovery of the tree’s crown, a thorough investigation was conducted by Stein and Dr. Christopher M. Berry, a paleobotany lecturer at Cardiff University in Wales and the other co-author of both Nature articles. They were able to determine that these trees actually resembled modern-day cycads or tree ferns, but interestingly enough, were not related to either one. Many questions still remained about what the surrounding area looked like, whether other plant life co-existed with these trees and how.
In 2010, during ongoing repair of the Gilboa Dam, New York City Department of Environmental Protection (DEP) engineers excavated infill from a quarry in Schoharie County. They agreed to allow researchers to re-examine the site where the fossils had been found when the dam was built in the 1920s. What they found this time was a large, substantially intact portion of the ancient forest horizon, complete with root systems. As they had expected, Eospermatopteris root systems of different sizes were the most abundant. But what they didn’t expect to find was the level of detail of the overall composition of the forest.
The first glimpse of the unexpected complexity of this ancient forest came when Stein, Berry, Hernick and Mannolini found the remains of large scrambling tree-sized plants, identified as aneurophytaleans. These plants were likely close ecological associates to the original trees, living among them on the forest floor like modern ferns, possibly scrambling into the forest canopy much as tropical vines do today. The aneurophytes are the first in the fossil record to show true “wood” and the oldest known group in the lineage that lead to modern seed plants.
Work on the new discoveries also pointed to the vital importance that the State Museum’s collections have played in the paleontological research. “Discovery of scrambling aneurophytaleans at Gilboa was a complete surprise, but pointed to the likelihood that similar material had already been found at the site, but was unrecognized,” said Hernick. “Sure enough in the State Museum collections a wonderful specimen, originally collected in the 1920s, provided additional key evidence.”
The team also came across a tree belonging to the class Lycopsida, or club mosses, which predates an earlier discovery made in Naples, NY and an ecologically important group in the history of land plants. The lycopsids are an ancient group of non-seed plants represented today by low growing forms such as the “running pines” of the northern hardwood forests of New York. They also inhabited swamps and ended up being much of the Pennsylvanian coal we burn today.
Based on the new research, the team now believes that the area probably enjoyed a wetland environment in a tropical climate. It was filled with large Eospermatopteris trees that resembled weedy, hollow, bamboo-like plants, with roots spreading out in all directions, allowing other plants to gain a foothold. Scrambling among these roots on the forest floor were aneurophytaleans, acting much like ferns do today, and possibly climbing into the forest canopy as vines. The lycopsids, although seemingly rare, may also have been very important in certain places although perhaps not yet as specialized inhabitants of swamps.
But what the research team believes is most important about this particular site is what it was doing to impact the rest of the planet. At the time the Gilboa forest began to emerge — during the Middle Devonian period, about 385 million years ago — Earth experienced a dramatic drop in global atmospheric carbon dioxide levels and the associated cooling led ultimately to a period of glaciation.
“Trees probably changed everything,” said Stein. “Not only did these emerging forests likely cause important changes in global patterns of sedimentation, but they may have triggered a major extinction in fossil record.”
For Stein, it all comes down to one thing — how much we don’t know but need to understand about our ancient past. “The complexity of the Gilboa site can teach us a lot about the original assembly of our modern day ecosystems,” said Stein. “As we continue to understand the role of forests in modern global systems, and face potential climate change and deforestation on a global scale, these clues from the past may offer valuable lessons for managing our planet’s future.”
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
300-Million-Year-Old Forest Discovered Preserved in Volanic Ash
ScienceDaily (Feb. 20, 2012) — Pompeii-like, a 300-million-year-old tropical forest was preserved in ash when a volcano erupted in what is today northern China. A new study by University of Pennsylvania paleobotanist Hermann Pfefferkorn and colleagues presents a reconstruction of this fossilized forest, lending insight into the ecology and climate of its time.
Pfefferkorn, a professor in Penn’s Department of Earth and Environmental Science, collaborated on the work with three Chinese colleagues: Jun Wang of the Chinese Academy of Sciences, Yi Zhang of Shenyang Normal University and Zhuo Feng of Yunnan University.
Their paper was published this week in the Early Edition of the Proceedings of the National Academy of Sciences.
The study site, located near Wuda, China, is unique as it gives a snapshot of a moment in time. Because volcanic ash covered a large expanse of forest in the course of only a few days, the plants were preserved as they fell, in many cases in the exact locations where they grew.
“It’s marvelously preserved,” Pfefferkorn said. “We can stand there and find a branch with the leaves attached, and then we find the next branch and the next branch and the next branch. And then we find the stump from the same tree. That’s really exciting.”
The researchers also found some smaller trees with leaves, branches, trunk and cones intact, preserved in their entirety.
Due to nearby coal-mining activities unearthing large tracts of rock, the size of the researchers’ study plots is also unusual. They were able to examine a total of 1,000 m2 of the ash layer in three different sites located near one another, an area considered large enough to meaningfully characterize the local paleoecology.
The fact that the coal beds exist is a legacy of the ancient forests, which were peat-depositing tropical forests. The peat beds, pressurized over time, transformed into the coal deposits.
The scientists were able to date the ash layer to approximately 298 million years ago. That falls at the beginning of a geologic period called the Permian, during which Earth’s continental plates were still moving toward each other to form the supercontinent Pangea. North America and Europe were fused together, and China existed as two smaller continents. All overlapped the equator and thus had tropical climates.
At that time, Earth’s climate was comparable to what it is today, making it of interest to researchers like Pfefferkorn who look at ancient climate patterns to help understand contemporary climate variations.
In each of the three study sites, Pfefferkorn and collaborators counted and mapped the fossilized plants they encountered.In all, they identified six groups of trees. Tree ferns formed a lower canopy while much taller trees — Sigillaria and Cordaites — soared to 80 feet above the ground. The researchers also found nearly complete specimens of a group of trees called Noeggerathiales. These extinct spore-bearing trees, relatives of ferns, had been identified from sites in North America and Europe but appeared to be much more common in these Asian sites.
They also observed that the three sites were somewhat different from one another in plant composition. In one site, for example, Noeggerathiales were fairly uncommon, while they made up the dominant plant type in another site. The researchers worked with painter Ren Yugao to depict accurate reconstructions of all three sites.
“This is now the baseline,” Pfefferkorn said. “Any other finds, which are normally much less complete, have to be evaluated based on what we determined here.”
The findings are indeed “firsts” on many counts.
“This is the first such forest reconstruction in Asia for any time interval, it’s the first of a peat forest for this time interval and it’s the first with Noeggerathiales as a dominant group,” Pfefferkorn said.
Because the site captures just one moment in Earth’s history, Pfefferkorn noted that it alone cannot explain how climate changes affected life on Earth. But it helps provide valuable context.
“It’s like Pompeii: Pompeii gives us deep insight into Roman culture, but it doesn’t say anything about Roman history in and of itself,” Pfefferkorn said. “But on the other hand, it elucidates the time before and the time after. This finding is similar. It’s a time capsule and therefore it allows us now to interpret what happened before or after much better.”
The study was supported by the Chinese Academy of Science, the National Basic Research Program of China, the National Natural Science Foundation of China and the University of Pennsylvania.
University of Pennsylvania (2012, February 20). 300-million-year-old forest discovered preserved
Why Do Dinosaur Skeletons Look So Weird?
ScienceDaily (Feb. 16, 2012) — Many fossilized dinosaurs have been found in a twisted posture. Scientists have long interpreted this as a sign of death spasms. Two researchers from Basel and Mainz now come to the conclusion that this bizarre deformations occurred only during the decomposition of dead dinosaurs.
More or less complete and articulated skeletons of dinosaurs with a long neck and tail often exhibit a body posture in which the head and neck are recurved over the back of the animal. This posture, also known from Archaeopteryx, has been fascinating paleontologists for more than 150 years. It was called “bicycle pose” when talking with a wink, or “opisthotonic posture” in a more oppressive way of speaking.
The latter alludes to an accessory symptom of tetanus, well known in human and veterinarian medicine. Usually, an “opisthotonic posture” like that is the result of vitamin deficiency, poisoning or damage to the cerebellum.
Basically, the cerebellum is a brain region that controls fine muscle movement, which includes the body’s antigravity muscles that keep the head and tail upright. If the cerebellum ceases to function, the antigravity muscles will clench at full force, tipping the head and tail back, and contracting the limbs.
A syndrome like that as a petrified expression of death throes was discussed for the first time about 100 years ago for some vertebrate fossils, but the acceptance of this interpretation declined during the following decades. In 2007, this “opisthotonus hypothesis” was newly posted by a veterinarian and a palaeontologist. This study, generously planned, received much attention in the public and the scientific community.
Now, five years later, two scientists from Switzerland and Germany have re-evaluated the revitalized “opisthotonus hypothesis” and examined one of its icons, the famous bipedal dinosaur Compsognathus longipes from the “Solnhofen Archipelago” (Germany). It is widely acknowledged that this 150-millions-years-old land-living dinosaur was embedded in a watery grave of a tropical lagoon.
“In our opinion, the most critical point in the newly discussed scenario of the preservation of an opisthotonic posture in a fossil is the requirement that terrestrial vertebrates must have been embedded immediately after death without substantial transport. But consigning a carcass from land to sea and the following need of sinking through the water column for only a few decimetres or meters is nothing else” says sedimentologist Achim Reisdorf from University of Basel’s Institute of Geology and Paleontology.
Biomechanics in Watery Graves Convinced that the back arching was generated, not by death throes, but by postmortem alterations of a decaying carcass, the researchers made experiments with plucked chicken necks and thoraxes, immersed in water. Submersed in water, the necks spontaneously arched backwards for more than 90°. Ongoing decay for some months even increased the degree of the pose. Thorough preparation and dissection combined with testing revealed that a special ligament connecting the vertebrae at their upper side was responsible for the recurved necks in the chickens. This ligament, the so-called Ligamentum elasticum, is pre-stressed in living chickens, but also in dead ones.
“Veterinarians may often have to do with sick and dying animals, where they see the opisthotonic posture in many cases. Vertebrate palaeontologists, however, who want to infer the environment in which the animals perished and finally were embedded have to elucidate postmortem processes and biomechanical constraints too” says palaeontologist Michael Wuttke from the Section of Earth History in the General Department for the Conservation of Cultural History Rhineland Palatinate in Mainz (Germany).
“A strong Ligamentum elasticum was essential for all long necked dinosaurs with a long tail. The preloaded ligament helped them saving energy in their terrestrial mode of life. Following their death, at which they were immersed in water, the stored energy along the vertebra was strong enough to arch back the spine, increasingly so as more and more muscles and other soft parts were decaying” conclude the researchers. “It is a special highlight that, in the Compsognathus specimen, these gradual steps of recurvature can be substantiated, too. Therefore, biomechanics is ruling the postmortem weird posture of a carcass in a watery grave, not death throes.”
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.”
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.