Ice Age Extinction Shaped Australian Plant Diversity
Feb. 12, 2013 — Researchers have shown that part of Australia’s rich plant diversity was wiped out by the ice ages, demonstrating that extinction, probably more than evolution, influences biodiversity.
The research led by the University of Melbourne and University of Tasmania has shown that plant diversity in South East Australia was as rich as some of the most diverse places in the world, and that most of these species went extinct during the ice ages, probably about one million years ago.
The team’s work was recently published in the Proceedings of the National Academy of Sciences.
Dr Sniderman of the University of Melbourne’s School of Earth Sciences said the findings show extinction is just as important to diversity of organisms as evolution.
“Traditionally scientists believed some places have more species than others because species evolved more rapidly in these places. We have overthrown this theory, which emphasizes evolution, by showing that extinction may be more important, ” he said.
The study compared two regions of Southern Australia and South Africa.
“South-western Australia has a huge diversity of tough-leaved shrubs and trees such as eucalypts, Banksia, Grevilleas and Acacias, making it one of the most biodiverse places on Earth,” Dr Sniderman said.
“The southern tip of South Africa is even richer, with astonishing numbers of similar kinds of plants like proteas and ericas.”
Scientists have long maintained that this diversity is somehow related to the poor soils and dry summers of these places.
For the study researchers analysed plant fossils that accumulated in an ancient lake in South Eastern Australia. They found the region had at least as many tough-leaved plants 1.5 million years ago as Western Australia and South Africa do today.
The results were entirely unexpected.
“As Australia dried out over the past several million years, rainforest plants largely disappeared from most of the continent,” said Dr Sniderman
“It has been thought that this drying trend allowed Australia’s characteristic tough-leaved plants to expand and became more diverse. We have shown that the climate variability of the ice ages not only drove rainforest plants to extinction but also a remarkable number of tough-leaved, shrubby plants,” he said. Dr Greg Jordan of the School of Plant Sciences at the University of Tasmanian said not only has the study overturned current thought on the role of extinction in plant diversity, it has implications for understanding how Australian plant diversity will deal with current and future climate change.
“The species that went extinct in SE Australia during the ice ages were likely to be the ones most sensitive to rapid climate change, meaning that the species that now grow in eastern Australia may be more capable of tolerating rapid changes than predicted by current science,” he said.
“However, the species in hotspots of diversity like Western Australia may be much more sensitive to future climate change, because they have been protected from past climate changes.”
The study was done in collaboration with the Nelson Mandela Metropolitan University in South Africa.
New Kind of Extinct Flying Reptile Discovered
Feb. 4, 2013 — A new kind of pterosaur, a flying reptile from the time of the dinosaurs, has been identified by scientists from the Transylvanian Museum Society in Romania, the University of Southampton in the UK and the Museau Nacional in Rio de Janiero, Brazil.
The fossilised bones come from the Late Cretaceous rocks of Sebeş-Glod in the Transylvanian Basin, Romania, which are approximately 68 million years old. The Transylvanian Basin is world-famous for its many Late Cretaceous fossils, including dinosaurs of many kinds, as well as fossilised mammals, turtles, lizards and ancient relatives of crocodiles.
A paper on the new species, named Eurazhdarcho langendorfensis has been published in the online journal PLoS ONE. Dr Darren Naish, from the University of Southampton’s Vertebrate Palaeontology Research Group, who helped identify the new species, says: “Eurazhdarcho belong to a group of pterosaurs called the azhdarchids. These were long-necked, long-beaked pterosaurs whose wings were strongly adapted for a soaring lifestyle. Several features of their wing and hind limb bones show that they could fold their wings up and walk on all fours when needed.
“With a three-metre wingspan, Eurazhdarcho would have been large, but not gigantic. This is true of many of the animals so far discovered in Romania; they were often unusually small compared to their relatives elsewhere.”
The discovery is the most complete example of an azhdarchid found in Europe so far and its discovery supports a long-argued theory about the behaviour of these types of creatures.
Dr Gareth Dyke, Senior Lecturer in Vertebrate Palaeontology, based at the National Oceanography Centre Southampton says: “Experts have argued for years over the lifestyle and behaviour of azhdarchids. It has been suggested that they grabbed prey from the water while in flight, that they patrolled wetlands and hunted in a heron or stork-like fashion, or that they were like gigantic sandpipers, hunting by pushing their long bills into mud.
“One of the newest ideas is that azhdarchids walked through forests, plains and other places in search of small animal prey. Eurazhdarcho supports this view of azhdarchids, since these fossils come from an inland, continental environment where there were forests and plains as well as large, meandering rivers and swampy regions.”
Fossils from the region show that there were several places where both giant azhdarchids and small azhdarchids lived side by side. Eurazhdarcho’s discovery indicates that there were many different animals hunting different prey in the region at the same time, demonstrating a much more complicated picture of the Late Cretaceous world than first thought.
Features of Southeast European Human Ancestors Influenced by Lack of Episodic Glaciations
Feb. 6, 2013 — A fragment of human lower jaw recovered from a Serbian cave is the oldest human ancestor found in this part of Europe, who probably evolved under different conditions than populations that inhabited more western parts of the continent at the same time, according to research published Feb. 6 in the open access journal PLOS ONE.
The research was carried out by William Jack Rink of McMaster University, Canada, and the international team under the direction of Dušan Mihailović, University of Belgrade, Serbia, and Mirjana Roksandic, University of Winnipeg, Canada.
The fossil was found to be at least 397,000 years old and possibly older than 525,000 years old, a time when distinctly Neandertal traits began to appear in Europe. The evolution of these traits was strongly influenced by periodic isolation of groups of individuals, caused by episodic formation of glaciers. Humans in southeastern Europe were never geographically isolated from Asia and Africa by glaciers, and according to the authors, this resulted in different evolutionary forces acting on early human populations in this region.
Roksandic explains that their study confirms the importance of southeast Europe as a ‘gate to the continent’ and one of the three main areas where humans, plants and animals sought refuge during glaciations in prehistoric times. She adds, “We have very few fossils of hominins in general from this time, a period that was critical for shaping the appearance and evolution of uniquely human morphology and behaviors.”
Previous Unknown Fossilized Fox Species Found
Jan. 23, 2013 — Researchers from Wits University, the University of Johannesburg and international scientists have announced the discovery of a 2-million-year-old fossil fox at Malapa, South Africa, in the Cradle of Humankind World Heritage Site.
In an article published in the journal Transactions of the Royal Society of South Africa, the researchers describe the previously unknown species of fox named Vulpes Skinneri — named in honour of the recently deceased world renowned South African mammalogist and ecologist, Prof. John Skinner of the University of Pretoria.
The site of Malapa has, since its discovery in 2008, yielded one of the most extraordinary fossil assemblages in the African record, including skeletons of a new species of human ancestor named Australopithecus sediba, first described in 2010.
The new fox fossils consist of a mandible and parts of the skeleton and can be distinguished from any living or extinct form of fox known to science based on proportions of its teeth and other aspects of its anatomy.
Dr. Brian Kuhn of Wits’ Institute for Human Evolution (IHE) and the School of GeoSciences, an author on the paper and head of the Malapa carnivore studies explains: “It’s exciting to see a new fossil fox. The ancestry of foxes is perhaps the most poorly known among African carnivores and to see a potential ancestral form of living foxes is wonderful.”
Prof. Lee Berger, also of the IHE and School of GeoSciences, author on the paper and Director of the Malapa project notes: “Malapa continues to reveal this extraordinary record of past life and as important as the human ancestors are from the site, the site’s contribution to our understanding of the evolution of modern African mammals through wonderful specimens like this fox is of equal import. Who knows what we will find next?.”
The entire team has expressed their privilege in naming the new species after “John Skinner, one of the great names in the study of African mammals and particularly carnivores. We (the authors) think that John would be pleased, and it is fitting that this rare little find would carry his name forever.”
Brain of Ampelosaur from Cuenca (Spain) Revealed
Jan. 23, 2013 — Scientists have made a 3D reconstruction of the remains of ampelosaur, found in 2007 in the site of Lo Hueco (Cuenca). The fossils are about 70 million years old (Late Cretaceous).
Up to now, only one species of the genus was known, Ampelosaurus atacis, which was discovered in France. The differences between the Spanish and the French fossils do not rule out that they could represent distinct species.
The researcher from the National Museum of Natural Sciences (CSIC) Fabien Knoll, who has conducted the investigation, considers that “more fossils are necessary to establish that we are dealing with a new species.” For this reason, the team has identified the specimen as Ampelosaurus sp., which leaves open its specific identity.
Little evolved brain
The ampelosaur pertains to the sauropod group, large-sized dinosaurs that settled widely during the Mesozoic Era (which began 253 million years ago and ended 66 million years ago). More precisely, it is a titanosaur, a group of plant eating animals that were dominant during the last half of the Cretaceous (last period of the Mesozoic). The first sauropods appeared about 160 million years earlier than the ampelosaur.
However, despite being the product of a long evolution, the brain of the ampelosaur does not show any notable development. Knoll explains: “This saurian may have reached 15 m in length; nonetheless its brain was not in excess of 8 cm.” According to the CSIC researcher: “Increase in brain size was not favored in the course of sauropod evolution.”
Another of the characteristics yielded by the reconstruction of the Cuenca ampelosaur brain is the small size of the inner ear. According to Knoll: “This may suggest that the ampelosaur would not have been adapted to quickly move either its eyes or its head and neck.”
In January of 2012, Knoll conducted the investigation that led to the reconstruction of another sauropod, Spinophorosaurus nigeriensis. The simulation in 3D of its brain revealed that that species, in contrast to what the study of the ampelosaur braincase demonstrated, presented a fairly well-developed inner ear.
According to the one of the researchers, “It is quite enigmatic that sauropods show such a diverse inner ear morphology whereas they have a very homogenous body shape; more investigation is definitely required.”
A Relative from the Tianyuan Cave: Humans Living 40,000 Years Ago Likely Related to Many Present-Day Asians and Native Americans
Jan. 21, 2013 — Ancient DNA has revealed that humans living some 40,000 years ago in the area near Beijing were likely related to many present-day Asians and Native Americans.
An international team of researchers including Svante Pääbo and Qiaomei Fu of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, sequenced nuclear and mitochondrial DNA that had been extracted from the leg of an early modern human from Tianyuan Cave near Beijing, China. Analyses of this individual’s DNA showed that the Tianyuan human shared a common origin with the ancestors of many present-day Asians and Native Americans. In addition, the researchers found that the proportion of Neanderthal and Denisovan-DNA in this early modern human is not higher than in people living in this region nowadays.
Humans with morphology similar to present-day humans appear in the fossil record across Eurasia between 40,000 and 50,000 years ago. The genetic relationships between these early modern humans and present-day human populations had not yet been established. Qiaomei Fu, Matthias Meyer and colleagues of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, extracted nuclear and mitochondrial DNA from a 40,000 year old leg bone found in 2003 at the Tianyuan Cave site located outside Beijing. For their study the researchers were using new techniques that can identify ancient genetic material from an archaeological find even when large quantities of DNA from soil bacteria are present.
The researchers then reconstructed a genetic profile of the leg’s owner. “This individual lived during an important evolutionary transition when early modern humans, who shared certain features with earlier forms such as Neanderthals, were replacing Neanderthals and Denisovans, who later became extinct,” says Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology, who led the study.
The genetic profile reveals that this early modern human was related to the ancestors of many present-day Asians and Native Americans but had already diverged genetically from the ancestors of present-day Europeans. In addition, the Tianyuan individual did not carry a larger proportion of Neanderthal or Denisovan DNA than present-day people in the region. “More analyses of additional early modern humans across Eurasia will further refine our understanding of when and how modern humans spread across Europe and Asia,” says Svante Pääbo.
Parts of the work were carried out in a new laboratory jointly run by the Max Planck Society and the Chinese Academy of Sciences in Beijing.
Earliest Sea Cow Ancestors Originated in Africa, Lived in Fresh Water
Jan. 16, 2013 — A new fossil discovered in Tunisia represents the oldest known ancestor of modern-day sea cows, supporting the African origins of these marine mammals. The find is described in research published January 16 in the open access journal PLOS ONE by Julien Benoit and colleagues from the University of Science and Technology in Montpellier, France.
Some fossils of sea cow ancestors have been found in Jamaica, but the Tunisian fossil is more primitive and pre-dates these, revealing an older ancestor for sea cows that emerged at the same time as other modern mammals. Unlike whales and dolphins, the evolutionary origins of the sea cow family have been obscure.
They share an ancestor with elephants, and it is thought that their oldest relatives were terrestrial animals that gradually adapted to an aquatic life. The last common ancestor of the two species may have lived in freshwater swamps well before the time that the new species described in this study lived.
Though this specimen may not have been the common link between modern day sea cows and elephants, the authors’ analyses suggest that this new species lived in fresh water, not sea waters.
Australia’s Stampeding Dinosaurs Take a Dip: Largely Tracks of Swimming Rather Than Running Animals
Jan. 8, 2013 — Queensland paleontologists have discovered that the world’s only recorded dinosaur stampede is largely made up of the tracks of swimming rather than running animals.
The University of Queensland’s (UQ) PhD candidate Anthony Romilio led the study of thousands of small dinosaur tracks at Lark Quarry Conservation Park, central-western Queensland.
Mr Romilio says the 95-98 million-year-old tracks are preserved in thin beds of siltstone and sandstone deposited in a shallow river when the area was part of a vast, forested floodplain.
“Many of the tracks are nothing more than elongated grooves, and probably formed when the claws of swimming dinosaurs scratched the river bottom,” Romilio said.
“Some of the more unusual tracks include ‘tippy-toe’ traces — this is where fully buoyed dinosaurs made deep, near vertical scratch marks with their toes as they propelled themselves through the water.
“It’s difficult to see how tracks such as these could have been made by running or walking animals.
“If that was the case we would expect to see a much flatter impression of the foot preserved in the sediment.”
Mr Romilio said that similar looking swim traces made by different sized dinosaurs also indicated fluctuations in the depth of the water.
“The smallest swim traces indicate a minimum water depth of about 14 cm, while much larger ones indicate depths of more than 40 cm,” Mr Romilio said.
“Unless the water level fluctuated, it’s hard to envisage how the different sized swim traces could have been preserved on the one surface.
“Some of the larger tracks are much more consistent with walking animals, and we suspect these dinosaurs were wading through the shallow water.”
Mr Romilio said the swimming dinosaur tracks at Lark Quarry belonged to small, two-legged herbivorous dinosaurs known as ornithopods.
“These were not large dinosaurs,” Mr Romilio said.
“Some of the smaller ones were no larger than chickens, while some of the wading animals were as big as emus.”
The researchers interpreted the large spacing among many consecutive tracks to indicate that the dinosaurs were moving downstream, perhaps using the current of the river to assist their movements.
Given the likely fluctuations in water depth, the researchers assume the tracks were formed over several days, maybe even weeks.
Previous research had identified two types of small dinosaur tracks at Lark Quarry: long-toed tracks (called Skartopus) and short-toed tracks (called Wintonopus).
The UQ scientists found that just like you ‘shouldn’t judge a book by its cover’, you also ‘shouldn’t judge a track by its outline’.
“3D profiles of ‘Skartopus’ tracks reveal that they were made by a short-toed trackmaker dragging its toes through the sediment, thereby elongating the tracks,” explained Romilio.
“In this context, they are best interpreted as a just another variant of Wintonopus.”
Romilio’s supervisor and coauthor of the new paper, Dr Steve Salisbury, added that, “3D analysis of the Lark Quarry tracks has allowed us to greatly refine our understanding of what this site represents.
“It is also allowing us to learn more about how these dinosaurs moved and behaved in different environments,” Dr Salisbury said.
For the past 30 years, the tracks at Lark Quarry have be known as the world’s only record of a ‘dinosaur stampede’.
Previous research by Romilio and Salisbury in 2011 also showed the larger tracks at Lark Quarry were probably made by a herbivorous dinosaur similar to Muttaburrasaurus, and not a large theropod, as had previously been proposed.
“Taken together, these findings strongly suggest Lark Quarry does not represent a ‘dinosaur stampede’,” Romilio said.
“A better analogy for the site is probably a river crossing.”
Dr Salisbury said regardless of how it was interpreted, these findings took nothing away from the importance of the site.
“Lark Quarry is, and will always remain, one of Australia’s most important dinosaur tracksites,” Dr Salisbury said.
The new study was published in the January 2013 issue of Journal of Vertebrate Paleontology.
Dinosaur Shook Tail Feathers for Mating Show
Jan. 4, 2013 — A University of Alberta researcher’s examination of fossilized dinosaur tail bones has led to a breakthrough finding: some feathered dinosaurs used tail plumage to attract mates, much like modern-day peacocks and turkeys.
U of A Paleontology researcher Scott Persons followed a chain of fossil evidence that started with a peculiar fusing together of vertebrae at the tip of the tail of four different species of dinosaurs, some separated in time and evolution by 45 million years.
Persons says the final vertebrae in the tails of a group of dinosaurs called oviraptors were fused together forming a ridged, blade-like structure. “The structure is called a pygostyle” says Persons. “Among modern animals only birds have them.”
Researchers say fossils of Similicaudiptery, an early oviraptor, reveal feathers radiating from the fused bones at the tail tip. Similicaudiptery was not known to be a flying dinosaur and Persons contends its tail feathers evolved as a means of waving its feathered tail fans.
No direct fossil evidence of feathers has been found with the fossils of the oviraptors that followed Similicaudiptery, but Persons says there is still strong evidence they had a feathered tail.
Persons reasons that because the later oviraptor had the same tail structure as the feathered Similicaudipteryx, the tails of later oviraptors’ still served the same purpose, waving feathered tail fans.
Persons says the hypothesis of oviraptor tail waving is supported by both the bone and muscle structure of the tail.
Individual vertebrae at the base of an oviraptor’s tail were short and numerous, indicating great flexibility. Based on dissections of modern reptile and bird tails, Persons reconstruction of the dinosaur’s tail muscles revealed oviraptors had what it took to really shake their tail feathers.
Large muscles extended far down the tail and had a sufficient number of broad connection points to the vertebrae to propel oviraptor’s tail feathers vigorously from side to side and up and down.
Oviraptors were two-legged dinosaurs that had already gone through major diversifications from the iconic, meat eating dinosaur family. Oviraptors were plant eaters that roamed parts of China, Mongolia, and Alberta during the Cretaceous period, the final age of the dinosaur.
“By this time a variety of dinosaurs used feathers for flight and insulation from the cold, “said Persons. “This shows that by the Late Cretaceous dinosaurs were doing everything with feathers that modern birds do now,” said Persons.
In addition to feathered-tail waving, oviraptors also had prominent bone crests on their head, which Persons says the dinosaur also may have used in mating displays.
“Between the crested head and feathered-tail shaking, oviraptors had a propensity for visual exhibitionism,” said Persons.
Giant Fossil Predator Provides Insights Into the Rise of Modern Marine Ecosystem Structures
Jan. 7, 2013 — An international team of scientists has described a fossil marine predator measuring 8.6 meters in length (about 28 feet) recovered from the Nevada desert in 2010 as representing the first top predator in marine food chains feeding on prey similar to its own size.
A paper with their description will appear the week of Jan. 7, 2013 in the early electronic issue of Proceedings of the National Academy of Sciences.
Scientists who studied the fossil include lead author Dr. Nadia Fröbisch and Prof. Jörg Fröbisch (both at Museum für Naturkunde Leibniz-Institut für Evolutions- und Biodiversitätsforschung), Prof. P. Martin Sander (Steinmann Institute of Geology, Mineralogy, and Paleontology, Division of Paleontology, University of Bonn), Prof. Lars Schmitz (W. M. Keck Science Department, Claremont McKenna, Pitzer, and Scripps Colleges, Claremont, California) and Dr. Olivier Rieppel (The Field Museum, Chicago, Illinois).
The 244-million-year-old fossil, named Thalattoarchon saurophagis (lizard-eating sovereign of the sea) is an early representative of the ichthyosaurs, a group of marine reptiles that lived at the same time as dinosaurs and roamed the oceans for 160 million years. It had a massive skull and jaws armed with large teeth with cutting edges used to seize and slice through other marine reptiles in the Triassic seas. Because it was a meta-predator, capable of feeding on animals with bodies similar in size to its own, Thalattoarchon was comparable to modern orca whales.
Remarkably, only eight million years prior to the appearance of Thalattoarchon, a severe extinction at the end of the Permian period killed as many as 80 to 96 percent of species in the Earth’s oceans. The rise of a predator such as Thalattoarchon documents the fast recovery and evolution of a modern ecosystem structure after the extinction.
“Everyday we learn more about the biodiversity of our planet including living and fossil species and their ecosystems” Dr. Fröbisch said. “The new find characterizes the establishment of a new and more advanced level of ecosystem structure. Findings like Thalattoarchon help us to understand the dynamics of our evolving planet and ultimately the impact humans have on today’s environment.”
“This discovery is a good example of how we study the past in order to illuminate the future,” said Dr. Rieppel of The Field Museum.
The ichthyosaur was recovered from what is today a remote mountain range in central Nevada. Most of the animal was preserved, including the skull (except the front of the snout), parts of the fins, and the complete vertebral column up to the tip of the tail. Supported by a grant from the National Geographic Society’s Committee for Research and Exploration, the team of paleontologists took three weeks to unearth the ichthyosaur and prepare it for its transport by helicopter and truck out of the field.