New Study Sheds Light On Dinosaur Size
Dec. 19, 2012 — Dinosaurs were not only the largest animals to roam the Earth — they also had a greater number of larger species compared to all other back-boned animals — scientists suggest in a new paper published in the journal PLOS ONE.
The researchers, from Queen Mary, University of London, compared the size of the femur bone of 329 different dinosaur species from fossil records. The length and weight of the femur bone is a recognised method in palaeontology for estimating a dinosaur’s body mass.
They found that dinosaurs follow the opposite pattern of body size distribution as seen in other vertebrate species. For example, within living mammals there tends to be few larger species, such as elephants, compared to smaller animals, such as mice, which have many species. The evidence from fossil records implies that in contrast there were many species of larger dinosaurs and few small species.
Dr David Hone from Queen Mary’s School of Biological and Chemical Sciences, explains: “What is remarkable is that this tendency to have more species at a bigger size seemed to evolve quite early on in dinosaurian evolution around the Late Triassic period, 225 million years ago, raising questions about why they got to be so big.
“Our evidence supports the hypothesis that young dinosaurs occupied a different ecological niche to their parents so they weren’t in competition for the same sources of food as they ate smaller plants or preyed on smaller size animals. In fact, we see modern crocodiles following this pattern — baby crocodiles start by feeding off insects and tadpoles before graduating onto fish and then larger mammals.”
Dr Eoin Gorman, also from Queen Mary’s School of Biological and Chemical Sciences added: “There is growing evidence that dinosaurs produced a large number of offspring, which were immediately vulnerable to predation due to their smaller size. It was beneficial for the herbivores to grow to large size as rapidly as possible to escape this threat, but the carnivores had sufficient resources to live optimally at smaller sizes.
“These differences are reflected in our analyses and also offer an explanation why other groups do not follow a similar pattern. Several modern-day vertebrate groups are almost entirely carnivorous, while many of the herbivores are warm-blooded, which limits their size.”
Paleo-Ocean Chemistry: New Data Challenge Old Views About Evolution of Early Life
Dec. 23, 2012 — A research team led by biogeochemists at the University of California, Riverside has tested a popular hypothesis in paleo-ocean chemistry, and proved it false.
The fossil record indicates that eukaryotes — single-celled and multicellular organisms with more complex cellular structures compared to prokaryotes, such as bacteria — show limited morphological and functional diversity before 800-600 million years ago. Many researchers attribute the delayed diversification and proliferation of eukaryotes, which culminated in the appearance of complex animals about 600 million years ago, to very low levels of the trace metal zinc in seawater.
As it is for humans, zinc is essential for a wide range of basic cellular processes. Zinc-binding proteins, primarily located in the cell nucleus, are involved in the regulation of gene transcription.
Eukaryotes have increasingly incorporated zinc-binding structures during the last third of their evolutionary history and still employ both early- and late-evolving zinc-binding protein structures. Zinc is, therefore, of particular importance to eukaryotic organisms. And so it is not a stretch to blame the 1-2-billion-year delay in the diversification of eukaryotes on low bioavailability of this trace metal.
But after analyzing marine black shale samples from North America, Africa, Australia, Asia and Europe, ranging in age from 2.7 billion years to 580 million years old, the researchers found that the shales reflect high seawater zinc availability and that zinc concentrations during the Proterozoic (2.5 billion to 542 million years ago) were similar to modern concentrations. Zinc, the researchers posit, was never biolimiting.
Study results appear online Dec. 23 in Nature Geoscience.
“We argue that the concentration of zinc in ancient marine black shales is directly related to the concentrations of zinc in seawater and show that zinc is abundant in these rocks throughout Earth’s history,” said Clint Scott, the first author of the research paper and a former UC Riverside graduate student. “We found no evidence for zinc biolimitation in seawater.”
Scott, now a research geologist with the U.S. Geological Survey, explained that the connection between zinc limitation and the evolution of eukaryotes was based largely on the hypothesis that Proterozoic oceans were broadly sulfidic. Under broadly sulfidic conditions, zinc should have been scarce because it would have rapidly precipitated in the oceans, he explained.
“However, a 2011 research paper in Nature also published by our group at UCR demonstrated that Proterozoic oceans were more likely broadly ferruginous — that is, low in oxygen and iron-rich — and that sulfidic conditions were more restricted than previously thought,” said Scott, who performed the research in the lab of Timothy Lyons, a professor of biogeochemistry and the principal investigator of the research project.
The research team argues that ferruginous deep oceans, combined with large hydrothermal fluxes of zinc via volcanic activity on the seafloor, maintained high levels of dissolved zinc throughout the oceans and provided a relatively stable marine reservoir of the trace metal over the past 2.7 billion years.
“The key challenge in understanding the early evolution of life is recognizing the environmental conditions under which that life first appeared and diversified,” Lyons said. “We have taken a very direct approach that specifically tracks the availability of essential micronutrients, and, to our surprise, zinc supplies in ancient seawater were much higher and less variable than previously imagined.
“We can imagine for the first time,” he quipped, “that zinc supplements were not on the shopping lists of our early eukaryotic ancestors, and so we better find another reason to explain the mysterious delay in their rise in the ocean.”
Scott, who graduated with a doctoral degree in geological sciences from UCR in 2009, and Lyons were joined in the study by Noah J. Planavsky, a former UCR graduate student in Lyons’ lab; Chris L. Dupont at the J. Craig Venter Institute, La Jolla, Calif.; Brian Kendall and Ariel D. Anbar at Arizona State University; Benjamin C. Gill at Virginia Polytechnic Institute and State University and also a former member of the Lyons lab; Leslie J. Robbins and Kurt O. Konhauser at the University of Alberta, Canada; Kathryn F. Husband and Simon W. Poulton at the University of Leeds, United Kingdom; Gail L. Arnold at the Max Planck Institute for Marine Microbiology, Germany; Boswell A. Wing at McGill University, Canada; and Andrey Bekker at the University of Manitoba, Canada.
The idea for the study was a direct consequence of the 2011 Nature paper by Planavsky, Scott, Lyons and others that challenged the hypothesis of broadly sulfidic oceans.
The international collaboration received funding for the study from numerous sources. In the U.S., funding came from the National Science Foundation, the NASA Astrobiology Institute and the Agouron Institute.
Evidence Contradicts Idea That Starvation Caused Saber-Tooth Cat Extinction
Dec. 26, 2012 — In the period just before they went extinct, the American lions and saber-toothed cats that roamed North America in the late Pleistocene were living well off the fat of the land.
That is the conclusion of the latest study of the microscopic wear patterns on the teeth of these great cats recovered from the La Brea tar pits in southern California. Contrary to previous studies, the analysis did not find any indications that the giant carnivores were having increased trouble finding prey in the period before they went extinct 12,000 years ago.
The results, published on Dec. 26 in the scientific journal PLOS ONE, contradicts previous dental studies and presents a problem for the most popular explanations for the Megafaunal (or Quaternary) extinction when the great cats, mammoths and a number of the largest mammals that existed around the world disappeared.
“The popular theory for the Megafaunal extinction is that either the changing climate at the end of the last Ice Age or human activity — or some combination of the two — killed off most of the large mammals,” said Larisa DeSantis, assistant professor of earth and environmental sciences at Vanderbilt, who headed the study. “In the case of the great cats, we expect that it would have been increasingly difficult for them to find prey, especially if had to compete with humans. We know that when food becomes scarce, carnivores like the great cats tend to consume more of the carcasses they kill. If they spent more time chomping on bones, it should cause detectable changes in the wear patterns on their teeth.”
In 1993, Blaire Van Valkenburgh at UCLA published a paper on tooth breakage in large carnivores in the late Pleistocene. Analyzing teeth of American lions, saber-tooth cats, dire wolves and coyotes from La Brea, she found that they had approximately three times the number of broken teeth of contemporary predators and concluded, .” ..these findings suggest that these species utilized carcasses more fully and likely competed more intensely for food than present-day large carnivores.”
The latest study uses a new technique, called dental microwear texture analysis (DMTA), developed by co-author Peter Ungar at the University of Arkansas. It uses a confocal microscope to produce a three-dimensional image of the surface of a tooth. The image is then analyzed for microscopic wear patterns. Chowing down on red meat produces small parallel scratches. Chomping on bones adds larger, deeper pits. Previous methods of dental wear analysis relied on researchers to identify and count these different types of features. DMTA relies on automated software and is considered more accurate because it reduces the possibility of observer bias.
DeSantis and Ungar, with the assistance of Blaine Schubert from East Tennessee State University and Jessica Scott from the University of Arkansas, applied DMTA to the fossil teeth of 15 American lions (Panthera atrox) and 15 saber-tooth cats (Smilodon fatalis) recovered from the La Brea tar pits in Los Angeles.
Their analysis revealed that the wear pattern on the teeth of the American lion most closely resembled those of the present-day cheetah, which actively avoids bones when it feeds. Similarly, the saber-tooth cat’s wear pattern most closely resembled those of the present-day African lion, which indulges in some bone crushing when it eats. (This differs from a previous microwear study using a different technique that concluded saber-tooth cats avoided bone to a far greater extent.)
The researchers examined how these patterns changed over time by selecting specimens from tar pits of different ages, ranging from about 35,000 to 11,500 years ago. They did not find any evidence that the two carnivores increased their “utilization” of carcasses throughout this period. If anything, their analysis suggests that the proportion of the carcasses that both kinds of cats consumed actually declined toward the end.
The researchers acknowledge the high rate of tooth breakage reported in the previous study, but they argue that it is more likely the result of increased breakage when taking down prey instead of when feeding.
“Teeth can break from the stress of chewing bone but they can also break when the carnivores take down prey,” DeSantis pointed out. Species like hyenas that regularly chew and crack bones of their kills are as likely to break the rear teeth they use for chewing as their front canines. Species like the cheetah, however, which avoid bones during feeding are twice as likely to break canines than rear teeth. This suggests that they are more likely to break canines when pulling down prey.
The researchers report that previous examinations of the jaws of the American lions and saber-tooth cats from this period found that they have more than three times as many broken canines and interpret this as additional evidence that supports their conclusion that most of the excess tooth breakage occurred during capture instead of feeding.
In addition, the researchers argue that the large size of the extinct carnivores and their prey can help explain the large number of broken teeth. The saber-toothed cats were about the size of today’s African lion and the American lion was about 25 percent larger. The animals that they preyed upon likely included mammoths, four-ton giant ground sloths and 3,500-pound bison.
Larger teeth break more easily than smaller teeth. So larger carnivores are likely to break more canine teeth when attempting to take down larger prey, the researchers argue. They cite a study that modeled the strength of canine teeth that found the canines of a predator the size of fox can support more than seven times its weight before breaking while a predator the size of lion can only support about four times its weight and the curved teeth of the saber-toothed cats can only support about twice its weight.
“The net result of our study is to raise questions about the reigning hypothesis that “tough times” during the late Pleistocene contributed to the gradual extinction of large carnivores,” DeSantis summarized. “While we can not determine the exact cause of their demise, it is unlikely that the extinction of these cats was a result of gradually declining prey (due either to changing climates or human competition) because their teeth tell us that these cats were not desperately consuming entire carcasses, as we had expected, and instead seemed to be living the ‘good life’ during the late Pleistocene, at least up until the very end.”
Researchers Find First Evidence of Ice Age Wolves in Nevada
Dec. 13, 2012 — A University of Nevada, Las Vegas research team recently unearthed fossil remains from an extinct wolf species in a wash northwest of Las Vegas, revealing the first evidence that the Ice Age mammal once lived in Nevada.
The metapodial, or foot bone, was uncovered late last year by UNLV geologist Josh Bonde during a survey of the Upper Las Vegas Wash. They have now confirmed that the bone comes from a dire wolf.
The discovery site is near the proposed Tule Springs Fossil Beds National Monument, a fossil-rich area known for its diversity and abundance of Ice Age animal remains. Scientists estimate the fossil to be 10,000 to 15,000 years old during the Late Pleistocene period.
“Dire wolves are known to have lived in almost all of North America south of Canada, but their historical presence in Nevada has been absent until now,” said Bonde, a UNLV geology professor. He was a Ph.D. student at the university when he discovered the bone.
“The Tule Springs area has turned up many species, but it’s exciting to fill in another part of the map for this animal and reveal a bit more about the Ice Age ecosystem in Southern Nevada.”
The dire wolf, a larger relative of the gray wolf, was present in much of North and South America for more than a million years. Scientists theorize that competition from other wolf species and a possible food scarcity led to its extinction roughly 10,000 years ago.
Foot bones of the extinct dire wolf are difficult to distinguish from those of the gray wolf. Researchers conclude bone is likely from a dire wolf because of the abundance of dire wolf fossils―and scarcity of gray wolf fossils―in similar-aged excavation sites throughout the Southwest.
Fossil remains of dire wolves are abundant in the La Brea tar pits and have been found in other Southwestern states. Many of the same species of Ice Age animals found at La Brea have also been recovered in the Las Vegas Valley, including Columbian mammoths, camels, horses, bison, and ground sloths.
“This discovery helps flesh out Southern Nevada’s Pleistocene ecosystem and shows that there are still important discoveries to be made in the Upper Las Vegas Wash,” said UNLV geology professor Steve Rowland, a collaborator with Bonde on the study of local Ice Age fossils. “To understand why certain species became extinct and others did not, we need to learn as much as possible about predatory habits and which species were especially sensitive to changes in the environment.”
The announcement comes on the heels of a recent discovery in the same wash of a saber-tooth cat by researchers from the San Bernardino County Museum. Like dire wolves, saber-tooth cats were Pleistocene predators that had been conspicuously absent from the Southern Nevada fossil record.
According to Rowland, Tule Springs was a spring-fed, swampy area during periods of the Late Pleistocene, an ideal spot for plant-eating animals and their carnivorous predators.
The recent discoveries come exactly 50 years after scientists conducted a ‘big dig’ at Tule Springs, revealing the site to be rich with Ice Age fossils.
“Tule Springs likely had the highest density of large animals in the area during the Late Pleistocene, and the marshy environment was very good for preserving at least some of the bones and teeth of animals that died there,” said Rowland.
“In the 50 years since the ‘big dig,’ the scientists have confirmed that humans interacted with Ice Age animals. We now have a new list of questions about life and death in the Pleistocene, and a new tool kit of research techniques to help us get the answers.”
The identity of the find was confirmed by Xiaoming Wang of the Los Angeles County Museum of Natural History, an expert on extinct species of the dog family. Bonde has been surveying the Tule Springs area since 2007, and he and a group of UNLV undergraduate studentss are prospecting for more fossils.
The center of the original ‘big dig’ is on the same parcel of land where Bonde discovered the wolf fossil.
The dire wolf bone, in addition to other bones collected by UNLV researchers, are cataloged, studied, and stored at UNLV.
Rare Fossil Related to Crabs, Lobsters, Shrimp: Exceptionally Well Preserved, Including Shell and Soft Parts
Dec. 12, 2012 — An international team of researchers have made an extremely rare discovery of a species of animal — related to crabs, lobsters and shrimps — that is new to science.
Scientists from the universities of Leicester, Oxford, Imperial and Yale have announced their discovery of a new and scientifically important fossil species of ostracod in the journal Proceedings of The Royal Society B. The research was funded by the Natural Environment Research Council.
The discovered species, which is up to 10 millimetres long, is special because it is exceptionally well preserved, complete with not only the shell but also the soft parts — its body, limbs, eyes, gills and alimentary system. Such discoveries are extremely rare in the fossil record.
The discovery of the tiny shelled arthropod was made in 425 million year old rocks in Herefordshire, Welsh Borderland. The rocks at the site date to the Silurian period of geological time, when southern Britain was a sea area on a small continent situated in warm, southerly subtropical latitudes. The ostracods and associated marine animals living there were covered by a fall of volcanic ash that preserved them frozen in time.
Professor David Siveter, of the University of Leicester Department of Geology, said: “The two ostracod specimens discovered represent a genus and species new to science, named Pauline avibella. The genus is named in honour of a special person and avibella means ‘beautiful bird’, so-named because of the fancied resemblance of a prominent feature of the shell to the wing of a bird.”
“Ostracods are the most abundant fossil arthropods, occurring ubiquitously as bivalved shells in rocks of the last 490 million years, and are common in most water environments today. The find is important because it is one of only a handful preserving the fossilised soft-tissues of ostracods. Its assignment to a particular group of ostracods based on knowledge of its biology is at odds with its shell form, thus urging caution in interpreting the classification of fossil ostracods based on shell characters alone.”
“The preservation of soft-parts of animals is a very rare occurrence in the fossil record and allows unparalleled insight into the ancient biology, community structure and evolution of animals — key facts that that would otherwise be lost to science. The fossils known from the Herefordshire site show soft-part preservation and are of global importance.”
The fossils were reconstructed ‘virtually’, by using a technique that involves grinding each specimen down, layer by layer, and photographing it at each stage. Ten millimetres is relatively tiny, but at an incremental level of 20 µm (micrometres) that yields 500 slices, which can then be pieced together in a computer to provide a full, three-dimensional image of each fossil, outside and in.
Professor Siveter added: “Fossil discoveries in general help elucidate our own place in the tree of life. This discovery adds another piece of knowledge in the jigsaw of understanding the diversity and evolution of animals.”
“It is exciting to discover that a common group of fossils that we thought we knew a lot about may well have been hood-winking us as to their true identity, which we now realise because we have their beautifully fossilised soft-parts. A case of a ‘wolf in sheep’s clothing’.”
The research was undertaken together with Professor Derek Siveter and Dr Sarah Joomun (Oxford), Dr Mark Sutton (Imperial College London) and Professor Derek Briggs (Yale, USA).
Note: The genus is named in honour of Pauline Siveter, in memoriam, late wife of the lead author of the paper.
Scientists Find Oldest Dinosaur — Or Closest Relative Yet
ScienceDaily (Dec. 4, 2012) — Researchers have discovered what may be the earliest dinosaur, a creature the size of a Labrador retriever, but with a five foot-long tail, that walked the Earth about 10 million years before more familiar dinosaurs like the small, swift-footed Eoraptor and Herrerasaurus.
The findings mean that the dinosaur lineage appeared 10 million to 15 million years earlier than fossils previously showed, originating in the Middle Triassic rather than in the Late Triassic period.
“If the newly named Nyasasaurus parringtoni is not the earliest dinosaur, then it is the closest relative found so far,” according to Sterling Nesbitt, a University of Washington postdoctoral researcher in biology and lead author of a paper published online Dec. 5 in Biology Letters, a journal of the United Kingdom’s Royal Society.
“For 150 years, people have been suggesting that there should be Middle Triassic dinosaurs, but all the evidence is ambiguous,” he said. “Some scientists used fossilized footprints, but we now know that other animals from that time have a very similar foot. Other scientists pointed to a single dinosaur-like characteristic in a single bone, but that can be misleading because some characteristics evolved in a number of reptile groups and are not a result of a shared ancestry.”
The researchers had one humerus — or upper arm bone — and six vertebrae to work with. They determined that the animal likely stood upright, measured 7 to 10 feet in length (2 to 3 meters), was as tall as 3 feet at the hip (1 meter) and may have weighed between 45 and 135 pounds (20 to 60 kilograms).
The fossilized bones were collected in the 1930s from Tanzania, but it may not be correct to say dinosaurs originated in that country. When Nyasasaurus parringtoni lived, the world’s continents were joined in the landmass called Pangaea. Tanzania would have been part of Southern Pangaea that included Africa, South America, Antarctica and Australia.
“The new findings place the early evolution of dinosaurs and dinosaur-like reptiles firmly in the southern continents,” said co-author Paul Barrett at the Natural History Museum, London.
The bones of the new animal reveal a number of characteristics common to early dinosaurs and their close relatives. For example, the bone tissues in the upper arm bone appear as if they are woven haphazardly and not laid down in an organized way. This indicates rapid growth, a common feature of dinosaurs and their close relatives.
“We can tell from the bone tissues that Nyasasaurus had a lot of bone cells and blood vessels,” said co-author Sarah Werning at the University of California, Berkeley, who did the bone analysis. “In living animals, we only see this many bone cells and blood vessels in animals that grow quickly, like some mammals or birds.”
“The bone tissue of Nyasasaurus is exactly what we would expect for an animal at this position on the dinosaur family tree,” she added. “It’s a very good example of a transitional fossil; the bone tissue shows that Nyasasaurus grew about as fast as other primitive dinosaurs, but not as fast as later ones.”
Another example is the upper arm bone’s distinctively enlarged crest, needed to anchor the upper arm muscles. The feature, known as an elongated deltopectoral crest, is also common to all early dinosaurs.
“Nyasasaurus and its age have important implications regardless of whether this taxon is a dinosaur or the closest relatives of dinosaurs,” Nesbitt said. “It establishes that dinosaurs likely evolved earlier than previously expected and refutes the idea that dinosaur diversity burst onto the scene in the Late Triassic, a burst of diversification unseen in any other groups at that time.”
It now appears that dinosaurs were just part of a large diversification of archosaurs. Archosaurs were among the dominant land animals during the Triassic period 250 million to 200 million years ago and include dinosaurs, crocodiles and their kin.
“Dinosaurs are just part of this archosaur diversification, an explosion of new forms soon after the Permian extinction,” Nesbitt said.
The specimen used to identify the new species is part of the collection at the Natural History Museum, London. Four vertebrae from a second specimen of Nyasasaurus, which were also used in this research, are housed in the South African Museum in Cape Town. The work was funded by the National Science Foundation and the Natural History Museum, London. The fourth co-author on the paper is Christian Sidor, UW professor of biology.
The name Nyasasaurus parringtoni is new, but “Nyasasaurus” — combining the lake name Nyasa with the term “saurus” for lizard — is not. The late paleontologist Alan Charig, included as a co-author on the paper, named the specimen but never documented or published in a way that was formally recognized. “Parringtoni” is in honor of University of Cambridge’s Rex Parrington, who collected the specimens in the 1930s.
“What’s really neat about this specimen is that it has a lot of history. Found in the ’30s, first described in the 1950s but never published, then its name pops up but is never validated. Now 80 years later, we’re putting it all together,” Nesbitt said.
“This work highlights the important role of museums in housing specimens whose scientific importance might be overlooked unless studied and restudied in detail,” Barrett said. “Many of the more important discoveries in paleontology are made in the lab, or museum storerooms, as well as in the field.”
New Ancient Shark Species Gives Insight Into Origin of Great White
ScienceDaily (Nov. 14, 2012) — The great white shark is one of the largest living predatory animals and a magnet for media sensationalism, yet its evolutionary history is as misunderstood as its role as a menace.
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Originally classified as a direct relative of megatooth sharks, the white shark’s evolutionary history has been debated by paleontologists for the last 150 years. In a study appearing in print and online today in the journal Palaeontology, University of Florida researchers name and describe an ancient intermediate form of the white shark, Carcharodon hubbelli, which shows the modern white shark likely descended from broad-toothed mako sharks. The study deviates from the white shark’s original classification as a relative of megatooth sharks such as the extinct Carcharocles megalodon, the largest carnivorous shark that ever lived.
Based on recalibrated dates of the excavation site in Peru, the study also concludes the new species was about 2 million years older than previously believed.
“We can look at white sharks today a little bit differently ecologically if we know that they come from a mako shark ancestor,” said lead author Dana Ehret, a lecturer at Monmouth University in New Jersey who conducted research for the study as a UF graduate student. “That 2-million-year pushback is pretty significant because in the evolutionary history of white sharks, that puts this species in a more appropriate time category to be ancestral or kind of an intermediate form of white shark.”
Most ancient shark species are named using isolated teeth, but analysis of C. hubbelli, also known as Hubbell’s white shark, was based on a complete set of jaws with 222 teeth intact and 45 vertebrae. The species was named for Gainesville resident Gordon Hubbell, a collector who recovered the fossils from a farmer who discovered them in the Pisco Formation of southern Peru in 1988. Hubbell donated the specimens to the Florida Museum of Natural History on the UF campus in December 2009.
“The impetus of this project was really the fact that Gordon Hubbell donated a majority of his fossil shark collection to the Florida Museum,” Ehret said. “Naming the shark in his honor is a small tip of the hat to all the great things he has done to advance paleontology.”
Ehret and co-authors published an initial study describing the shark specimens in the Journal of Vertebrate Paleontology in 2009, but dates for the site reflected information from a 1985 study about the Pisco Formation, he said. With Hubbell’s hand-drawn maps and descriptions of the landscape, researchers returned to the site and found the exact spot the fossils were discovered.
Scientists extracted more accurate age estimates from mollusk shells in the fossil horizon to determine the shark species was from the late Miocene, about 6.5 million years ago, rather than the early Pliocene, about 4.5 million years ago. The new dates will also be useful for better understanding other fossils found in the rich Pisco Formation, which include new whale, marine sloth and terrestrial vertebrate species.
“The thing that was remarkable to me was that these fossils came from right out in the desert and this was before GPS, so Dana had only an approximate notion of where it was,” said Florida Museum of Natural History Director Douglas Jones, a study co-author who conducted strontium isotope dating of the fossils. “But after a few days of looking, we were able to find this deposit and Dana found the rest of the missing shark’s teeth.”
Researchers determined Hubbell’s white shark was related to ancient broad-toothed mako sharks by comparing the physical shapes of shark teeth to one another. While modern white sharks have serrations on their teeth for consuming marine mammals, mako sharks do not have serrations because they primarily feed on fish. Hubbell’s white shark has coarse serrations indicative of a transition from broad-toothed mako sharks to modern white sharks.
These evolutionary relationships have been hypothesized for decades, and researchers who interpret modern white sharks as being more closely related to megatooth sharks say it is “a friendly disagreement,” according to Michael Gottfried, an associate professor in geological sciences at Michigan State University.
But shark expert David Ward, a research associate at the Natural History Museum, London, said “fewer people believe the big megatooth sharks are related to the great white sharks than believe the Earth is flat.”
“Everyone working within the field will be absolutely delighted to see this relationship formalized,” Ward said.
Study co-authors include Bruce MacFadden of the Florida Museum, Thomas DeVries of the Burke Museum of Natural History and Culture in Seattle, David Foster of UF and Rodolfo Salas-Gismondi of Museo de Historia Natural Javier Prado in Lima.
Oldest Fossil of Giant Panda Family Discovered
ScienceDaily (Nov. 14, 2012) — New fossils found in Spain are thought to be of the oldest recorded ancestor of the giant panda.
The fossils reveal the origins of this unique bear, as described in a paper published Nov. 14 in the open access journal PLOS ONE by Juan Abella and colleagues from the National Museum of Natural Sciences and the Catalan Institute of Paleontology, Spain.
The two 11.6 million-year-old fossil jaws and teeth were discovered in southwest Europe and represent a new genus likely to be the oldest known members of the giant panda family. The fossils bear the characteristics of a bear adapted to eating tough plant material like bamboo. The giant panda, native to certain parts of China, is the only living member of this unique bear family with these dietary habits.
Corresponding author Juan Abella adds: “The new genus we describe in this paper is not only the first bear recorded in the Iberian Peninsula, but also the first of the giant panda’s lineage.”
The Spanish Ministerio de Economı´a y Competitividad (CGL2011-28681, CGL2011-25754, and RYC-2009-04533 to DMA), the research group BSCH-UCM 910607, and the Generalitat de Catalunya (2009 SGR 754 GRC) supported this research. Fieldwork at ACM was funded by CESPA Gestio´n de Residuos, S.A.U.
Date of Earliest Animal Life Reset by 30 Million Years
ScienceDaily (June 28, 2012) — University of Alberta researchers have uncovered physical proof that animals existed 585 million years ago — 30 million years earlier than previous records show.
The discovery was made by U of A geologists Ernesto Pecoits and Natalie Aubet in Uruguay. They found fossilized tracks a centimeter-long, slug-like animal left behind 585 million years ago in silty, shallow-water sediment.
A team of U of A researchers determined that the tracks were made by a primitive animal called a bilaterian, which is distinguished from other non-animal, simple life forms by its symmetry — its top side is distinguishable from its bottom side — and a unique set of “footprints.”
U of A paleontologist Murray Gingras says fossilized tracks indicate that the soft-bodied animal’s musculature enabled it to move through the sediment on the shallow ocean floor. “The pattern of movement indicates an evolutionary adaptation to search for food, which would have been organic material in the sediment,” he said.
There were no fossilized remains of a bilaterian’s body, just its tracks. “Generally when we find tracks of a soft-bodied animal, it means there’s no trace of the body because they fossilize under different conditions,” said Gingras. “It’s usually just the body or just the tracks, not both.”
It took more than two years for the U of A team members to satisfy themselves and a peer review panel of scientists that they had the right age for the bilaterian fossils.
U of A geochronologist Larry Heaman was among a group that returned to Uruguay to collect more fossil samples locked in a layer of sandstone. Heaman says because the depositional age of the sandstone is difficult to determine, they focused their investigation on particles of granitic rock found invading the sandstone samples.
Heaman explains that the granitic rocks were put through the university’s mass spectrometry equipment, a process in which samples are bombarded by laser beams and the resulting atom- to molecule-sized particles are analyzed and dated.
Over the course of his U of A career, Heaman has taken part in a number of breakthrough research projects involving fossils. Last year he got the attention of the paleontology world when he confirmed the surprising date of a fossilized dinosaur bone found in New Mexico. Using U of A equipment, Heaman determined that the bone came from a sauropod, a plant-eating dinosaur that was alive some 700,000 years after the mass-extinction event that many believe wiped out all dinosaur life on Earth.
Heaman says the challenge in dating the bilaterian fossil makes it stand out from his other work. “This was the top research accomplishment because it has more direct relevance to the evolution of life as we know it,” he said. “It was such a team effort; any one of us on our own couldn’t have done this.”
Before the U of A bilaterian find, the oldest sign of animal life was dated at 555 million years ago, from a find made in Russia.
Kurt Konhauser, a U of A geomicrobiologist, says the team’s discovery will prompt new questions about the timing of animal evolution and the environmental conditions under which they evolved.
“This research was a huge interdisciplinary effort and shows the depth of the research capabilities here at the U of A,” said Konhauser. “The challenge brought the sciences of geology, paleontology, geomicrobiology and geochronology together to nail down the age of the fossils.”
Konhauser explains that in the past, research into the earliest signs of animal life would typically shift the date back by a few million years, but the U of A’s finding of 30 million years is a real breakthrough.
The U of A’s research team includes Ernesto Pecoits, Natalie Aubet, Kurt Konhauser, Larry Heaman, Richard Stern and Murray Gingras. The research was published June 28 in the journal Science.
Newly Discovered Dinosaur Implies Greater Prevalence of Feathers; Megalosaur Fossil Represents First Feathered Dinosaur Not Closely Related to Birds
ScienceDaily (July 2, 2012) — A new species of feathered dinosaur discovered in southern Germany is further changing the perception of how predatory dinosaurs looked. The fossil of Sciurumimus albersdoerferi,which lived about 150 million years ago, provides the first evidence of feathered theropod dinosaurs that are not closely related to birds.
The fossil is described in a paper published in the Proceedings of the National Academy of Sciences on July 2.
“This is a surprising find from the cradle of feathered dinosaur work, the very formation where the first feathered dinosaur Archaeopteryx was collected over 150 years ago,” said Mark Norell, chair of the Division of Palaeontology at the American Museum of Natural History and an author on the new paper along with researchers from Bayerische Staatssammlung für Paläontologie und Geologie and the Ludwig Maximilians University.
Theropods are bipedal, mostly carnivorous dinosaurs. In recent years, scientists have discovered that many extinct theropods had feathers. But this feathering has only been found in theropods that are classified as coelurosaurs, a diverse group including animals likeT. rexand birds. Sciurumimus — identified as a megalosaur, nota coelurosaur — is the first exception to this rule. The new species also sits deep within the evolutionary tree of theropods, much more so than coelurosaurs, meaning that the species that stem from Sciurumimus are likely to have similar characteristics.
“All of the feathered predatory dinosaurs known so far represent close relatives of birds,” said palaeontologist Oliver Rauhut, of the Bayerische Staatssammlung für Paläontologie und Geologie. “Sciurumimus is much more basal within the dinosaur family tree and thus indicates that all predatory dinosaurs had feathers.”
The fossil, which is of a baby Sciurumimus, was found in the limestones of northern Bavaria and preserves remains of a filamentous plumage, indicating that the whole body was covered with feathers. The genus name ofSciurumimus albersdoerferirefers to the scientific name of the tree squirrels,Sciurus, and means “squirrel-mimic”-referring to the especially bushy tail of the animal. The species name honours the private collector who made the specimen available for scientific study.
“Under ultraviolet light, remains of the skin and feathers show up as luminous patches around the skeleton,” said co-author Helmut Tischlinger, from the Jura Museum Eichstatt.
Sciurumimusis not only remarkable for its feathers. The skeleton, which represents the most complete predatory dinosaur ever found in Europe, allows a rare glimpse at a young dinosaur. Apart from other known juvenile features, such as large eyes, the new find also confirmed other hypotheses.
“It has been suggested for some time that the lifestyle of predatory dinosaurs changed considerably during their growth,” Rauhut said. “Sciurumimus shows a remarkable difference to adult megalosaurs in the dentition, which clearly indicates that it had a different diet.”
Adult megalosaurs reached about 20 feet in length and often weighed more than a ton. They were active predators, which probably also hunted other large dinosaurs. The juvenile specimen of Sciurumimus, which was only about 28 inches in length, probably hunted insects and other small prey, as evidenced by the slender, pointed teeth in the tip of the jaws.
“Everything we find these days shows just how deep in the family tree many characteristics of modern birds go, and just how bird-like these animals were,” Norell said. “At this point it will surprise no one if feather like structures were present in the ancestors of all dinosaurs.