The whole of Africa was the cradle of humankind
A team of scientists led by Mohamed Sahnouni, archaeologist at the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), has just published a paper in the journal Science which breaks with the paradigm that the cradle of Humankind lies in East Africa, based on the archaeological remains found at sites in the region of Ain Hanech (Algeria), the oldest currently known in the north of Africa.
For a long time, East Africa has been considered the place of origin of the earliest hominins and lithic technology, because up to now, very little was known about the first hominin occupation and activities in the north of the continent. Two decades of field and laboratory research directed by Dr. Sahnouni have shown that ancestral hominins actually made stone tools in North Africa that are near contemporary with the earliest known stone tools in East Africa dated to 2.6 million years.
These are stone artifacts and animal bones bearing marks of cutting by stone tools, with an estimated chronology of 2.4 and 1.9 million years, respectively, found at two levels at the sites of Ain Boucherit (within the Ain Hanech study area), which were dated using Paleomagnetism, Electron Spin Resonance (ESR), and the Biochronology of large mammals excavated together with the archaeological materials.
Fossils of animals such as pigs, horses and elephants, from very ancient sites, have been used by the paleontologist Jan van der Made, of the Museo Nacional de Ciencias Naturales in Madrid, to corroborate the ages yielded by Paleomagnetism, obtained by the CENIEH geochronologist Josep Parés, and ESR, found by Mathieu Duval, of Griffith University.
Oldowan technology
The artifacts of Ain Boucherit were manufactured of locally available limestone and flint and include faces worked into choppers, polyhedra and subspheroids, as well as sharp-edged cutting tools used to process animal carcasses. These artifacts are typical of the Oldowan stone technology known from 2.6-1.9 million-year-old sites in East Africa, although those from Ain Boucherit show subtle variations.
“The lithic industry of Ain Boucherit, which is technologically similar to that of Gona and Olduvai, shows that our ancestors ventured into all corners of Africa, not just East Africa. The evidence from Algeria changes the earlier view that East Africa was the cradle of Humankind. Actually, the whole of Africa was the cradle of humankind,” states Sahnouni, leader of the Ain Hanech project.
Not mere scavengers
Ain Boucherit is one of the few archaeological sites in Africa which has provided evidence of bones with associated marks of cutting and percussion in situ with stone tools, which shows unmistakably that these ancestral hominins exploited meat and marrow from animals of all sizes and skeletal parts, which implied skinning, evisceration and defleshing of upper and intermediate extremities.
Isabel Cáceres, taphonomist at the IPHES, has commented that “the effective use of sharp-edged tools at Ain Boucherit suggests that our ancestors were not mere scavengers. It is not clear at this moment whether they hunted, but the evidence clearly shows that they were successfully competing with carnivores and enjoyed first access to animal carcasses.”
The tool-makers
At this moment, the most important question is who made the stone tools discovered in Algeria. Hominin remains have still not been found in North Africa which are contemporary with the earliest stone artifacts. As a matter of fact, nor have any hominins yet been documented in direct association with the first stone tools known from East Africa.
Nevertheless, a recent discovery in Ethiopia has shown the presence of early Homo dated to 2.8 million years, most likely the best candidate also for the materials from East and North Africa.
Scientists thought for a long time that the hominins and their material culture originated in the Great Rift Valley in East Africa. Surprisingly, the earliest known hominin, dated to 7.0 million years, and the 3.3 million years Australopithecus bahrelghazali, have been discovered in Chad, in the Sahara, 3000 km from the rift valleys in the east of Africa.
As Sileshi Semaw, scientist at the CENIEH and a co-author of this paper, explains that the hominins contemporary with Lucy (3.2 million years), were probably roamed over the Sahara, and their descendants might have been responsible for leaving these archaeological puzzles now discovered in Algeria, that are near contemporaries of those of East Africa.
“Future research will focus on searching for human fossils in the nearby Miocene and Plio-Pleistocene deposits, looking for the tool-makers and even older stone tools,” concludes Sahnouni.
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Oldest-known ancestor of modern primates may have come from North America, not Asia
About 56 million years ago, on an Earth so warm that palm trees graced the Arctic Circle, a mouse-sized primate known as Teilhardina first curled its fingers around a branch.
The earliest-known ancestor of modern primates, Teilhardina’s close relatives would eventually give rise to today’s monkeys, apes and humans. But one of the persistent mysteries about this distant cousin of ours is where it originated.
Teilhardina (ty-hahr-DEE’-nuh) species quickly spread across the forests of Asia, Europe and North America, a range unparalleled by all other primates except humans. But where did its journey begin?
New research shows that Teilhardina brandti, a species found in Wyoming, is as old or older than its Asian and European relatives, upending the prevailing hypothesis that Teilhardina first appeared in China.
Teilhardina’s origins, however, remain a riddle.
“The scientific conclusion is ‘We just don’t know,'” said Paul Morse, the study’s lead author and a recent University of Florida doctoral graduate. “While the fossils we’ve found potentially overturn past hypotheses of where Teilhardina came from and where it migrated, they definitely don’t offer a clearer scenario.”
What is clear, Morse said, is that T. brandti had a wide variety of features, some of which are as primitive as those found in Teilhardina asiatica, its Asian cousin, previously thought to be the oldest species in the genus.
To make this determination, Morse studied 163 teeth and jaws in the most comprehensive analysis of T. brandti to date.
Teeth contain a treasure-trove of information and often preserve better than bone, thanks to their tough enamel. They can reveal clues about an animal’s evolutionary past, its size, diet and age as an individual and in geological time.
Primate teeth have particularly distinct structures that are immediately recognizable to the trained eye, said Jonathan Bloch, study co-author and curator of vertebrate paleontology at the Florida Museum of Natural History.
“Identifying differences between primate teeth is not so different from a biker recognizing that a Harley is different from a scooter or an art critic evaluating whether an image was created by Picasso or Banksy,” he said. “In detail, they are very different from each other in specific, predictable ways.”
While Teilhardina bones are very rare in the fossil record, its teeth are more plentiful — if you know how to find them. Bloch’s team of paleontologists, Morse included, have spent years combing the surface of Wyoming’s Bighorn Basin on hands and knees and then packing out 50-pound bags of soil to a river to screen wash. The remaining bits of bones and teeth — which can be smaller than a flea — are examined under a microscope back at the museum.
This painstaking search has built up the dental record of T. brandti from a single molar — used to first describe the species in 1993 — to hundreds of teeth, providing a broad look at the primate’s population-level variation.
Still, Morse and Bloch were unprepared for the peculiar variation exhibited by specimen UF 333700, a jagged piece of jaw with T. brandti teeth.
“Jon and I started arguing about the alveoli” — empty tooth sockets — “and how they didn’t look right at all,” said Morse, now a postdoctoral researcher at Duke University. “By the end of the day, we realized that specimen completely overturned both the species definition of T. asiatica and part of the rationale for why it is the oldest Teilhardina species.”
Studies based on a small number of teeth simply missed the diversity in Teilhardina’s physical characteristics, Morse said.
“There’s likely a tremendous amount of variation in the fossil record, but it’s extremely difficult to capture and measure when you have a small sample size,” he said. “That’s one of the reasons collecting additional fossils is so important.”
The analysis also reshuffled the Teilhardina family tree, reducing the number of described species from nine to six and reclassifying two species as members of a new genus, Bownonomys, named for prominent vertebrate paleontologist Thomas Bown.
But the precise ages of Teilhardina species are still impossible to pinpoint and may remain that way.
Teilhardina appeared during the geological equivalent of a flash in the pan, a brief 200,000-year period known as the Paleocene-Eocene Thermal Maximum, or PETM. This era was characterized by a massive injection of carbon into the Earth’s atmosphere, which sent global temperatures soaring. Sea levels surged by 220 feet, ecosystems were overhauled and the waters at the North Pole warmed to 74 degrees.
Scientists can use the distinct carbon signature of the PETM to locate this period in the rock record, and carbon isotopes in teeth can also be used to identify fossil animals from the era.
But among Teilhardina fossil sites across the globe, only Wyoming has the uninterrupted, neatly demarcated layers of rock that allow paleontologists to hone in on more precise dates.
“The humblest statement would be to say that these species are essentially equivalent in age,” Bloch said. “Determining which came earlier in the PETM probably surpasses the level of resolution we have in the rock record. But what we can say is that the only place where you can really establish where Teilhardina appears in this climate event with confidence is in the Bighorn Basin.”
As the Earth warmed, plants and animals expanded their ranges northward, returning south as temperatures cooled at the end of the PETM.
“This dance of plants and animals with climate change happened over vast landscapes, with forests moving from the Gulf Coast to the Rocky Mountains in just a few thousand years,” Bloch said.
Teilhardina likely tracked the shifts in its forest habitats across the land bridges that then connected North America, Greenland and Eurasia, he said.
“Teilhardina is not throwing its bag over its shoulder and walking,” he said. “Its range is shifting from one generation to the next. Over 1,000 years, you get a lot of movement, and over 2,000-3,000 years, you could easily cover continental distances.”
While it was well-suited to Earth’s hothouse environment, Teilhardina disappeared with the PETM, replaced by new and physically distinct primates. It’s a sobering reminder of what can happen to species — including humans — during periods of swift climatic changes, Bloch said.
“A changing planet has dramatic effects on biology, ecosystems and evolution. It’s part of the process that has produced the diversity of life we see today and mass extinctions of life that have happened periodically in Earth’s history,” Bloch said. “One of the unexpected results of global warming 56 million years ago is that it marks the origin of the group that ultimately led to us. How we will fare under future warming scenarios is less certain.”
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Fossil algae reveal 500 million years of climate change
Earth scientists are able to travel far back in time to reconstruct the geological past and paleoclimate to make better predictions about future climate conditions. Scientists at the Netherlands Institute for Sea Research (NIOZ) and Utrecht University succeeded in developing a new indicator (proxy) of ancient CO2-levels, using the organic molecule phytane, a debris product of chlorophyll. This new organic proxy not only provides the most continuous record of CO2-concentrations ever, it also breaks a record in its time span, covering half a billion years. The data show the present idea that rises in CO2-levels that used to take millions of years, are now happening in a century. These findings are published in Science Advances on November 28th.
As CO2 increases today, it’s vital to understand what impact these changes will have. To better predict the future, we must understand long-term changes in CO2 over geologic history. Direct measurements of past CO2 are available, e.g. bubbles in ice cores containing ancient gases. However, ice cores have a limited time span of one million years. To go farther back in time, earth scientists have developed various indirect measurements of CO2 from proxies e.g. from algae, leaves, ancient soils and chemicals stored in ancient sediments to reconstruct past environmental conditions.
Phytane, a new way to travel in time
A new proxy, using a degradation product of chlorophyll, allows geochemists to infer a continuous record of historic CO2-levels in deep time. Scientists at NIOZ have recently developed phytane as a promising new organic proxy that uncovers half a billion years of CO2-levels in the oceans, from the Cambrian until recent times.
Using the new proxy, they were able to make the most continuous record of ancient carbon dioxide levels ever. “We developed and validated a new way to time travel — going farther back in time and to more places,” says NIOZ-scientist Caitlyn Witkowski. “With phytane, we now have the longest CO2-record with one single marine proxy. This new data is invaluable to modelers who can now more accurately make predictions of the future.”
Witkowski and colleagues selected more than 300 samples of marine sediments from deep sea cores and oils from all over the globe, reflecting the majority of geological periods in the last 500 million years.
Fossil molecules
Past chemical reactions can be ‘stored’ in fossil molecules, and so they may reflect various ancient environmental conditions. Geochemists are able to ‘read’ these conditions, such as seawater temperature, pH, salinity and CO2-levels. Organic matter, such as phytane, reflects the pressure of CO2 in ocean water or the atmosphere (pCO2).
Little green miracles
Although all organic matter has the potential to reflect CO2, phytane is special. Phytane is the pigment responsible for our green world. Anything that uses photosynthesis to absorb sunlight, including plants, algae, and some species of bacteria, has chlorophyll from which phytane comes. Plants and algae take in CO2 and produce oxygen. Without these little green miracles, our world just wouldn’t be the same.
Because chlorophyll is found all around the world, phytane is also everywhere and is a major constituent of decayed and fossilized biomass. “Phytane doesn’t chemically change over the course of time, even if it is millions of years old,” Witkowski says.
Carbon isotope fractionation
CO2 of the past is estimated from organic matter, such as phytane, through the phenomenon of carbon isotope fractionation during photosynthesis. When taking up CO2, plants and algae prefer the light carbon isotope (12C) over the heavy carbon isotope (13C). They only use the heavy carbon isotope when CO2-levels in the surrounding water or atmosphere are low. The proportion between these two isotopes therefore reflects the level of carbon dioxide in the environment at the moment of growth.
This also explains why Witkowski didn’t use terrestrial plants as a source for her research, exclusively using phytane from (fossilized) marine sources. The plant world is divided into so-called C3- and C4-plants, each with their own unique ratio of light-to-heavy carbon. Phytoplankton all have very similar ratios compared to their plant counterparts. Witkowski: “By choosing only marine sources, we could limit uncertainty of the phytane source in the dataset.”
“In our data, we see high levels of carbon dioxide, reaching 1000 ppm as opposed to today’s 410 ppm. In this respect, present day levels are not unique, but the speed of these changes have never been seen before. Changes that typically take millions of years are now happening in a century. This additional CO2-data may help us understand the future of our planet.” In future research, phytane can be used to go even further back in time than the Phanerozoic, the earliest found in two billion-year-old samples.
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Gigantic mammal ‘cousin’ discovered
During the Triassic period (252-201 million years ago) mammal-like reptiles called therapsids co-existed with ancestors to dinosaurs, crocodiles, mammals, pterosaurs, turtles, frogs, and lizards. One group of therapsids are the dicynodonts. Researchers at Uppsala University in Sweden, together with colleagues in Poland, have discovered fossils from a new genus of gigantic dicynodont. The new species Lisowicia bojani is described in the journal Science.
The earth is about 4.5 billion years old and has gone through many geological periods and dramatic change. During the Triassic period, about 252-201 million years ago, all land on Earth came together and formed the massive continent called Pangea. During this time, the first dinosaurs came into being as well as ancestors to crocodiles, mammals, pterosaurs, turtles, frogs, and lizards. Recently, scientists have become interested in another type of animal, therapsids. Therapsids were “mammal-like” reptiles and are ancestors to the mammals, including humans, found today. One group of therapsids is called dicynodonts. All species of dicynodonts were herbivores (plant eaters) and their sizes ranged from small burrowers to large browsers. Most of them were also toothless. They survived the Permian mass extinction and became the dominant terrestrial herbivores in the Middle and Late Triassic. They were thought to have died out before the dinosaurs became the dominant form of tetrapod on land.
For the first time, researchers in the research programme Evolution and Development at Uppsala University in collaboration with researchers at the Polish Academy of Sciences (Warsaw), have discovered fossils from a new species of dicynodont in the Polish village of Lisowice. The species was named Lisowicia bojani after the village and a German comparative anatomist named Ludwig Heinrich Bojanus who worked in Vilnius and is known for making several important anatomical discoveries. The findings show that the Lisowicia was about the size of a modern-day elephant, about 4.5 metres long, 2.6 metres high and weighed approximately 9 tons, which is 40 percent larger than any previously identified dicynodont. Analysis of the limb bones showed that they had a fast growth, much like a mammal or a dinosaur. It lived during the Late Triassic, about 210-205 million years ago, about 10 million years later than previous findings of dicynodonts.
“The discovery of Lisowicia changes our ideas about the latest history of dicynodonts, mammal Triassic relatives. It also raises far more questions about what really make them and dinosaurs so large,” says Dr Tomasz Sulej, Polish Academy of Sciences.
“Dicynodonts were amazingly successful animals in the Middle and Late Triassic. Lisowicia is the youngest dicynodont and the largest non-dinosaurian terrestrial tetrapod from the Triassic. It’s natural to want to know how dicynodonts became so large. Lisowicia is hugely exciting because it blows holes in many of our classic ideas of Triassic ‘mammal-like reptiles’,” says Dr Grzegorz Niedzwiedzki, Uppsala University.
The first findings of fossils from Lisowice in Poland were made in 2005 by Robert Borz?cki and Piotr Menducki. Since then, more than 1,000 bones and bone fragments have been collected from the area, including fossils from Lisowicia. The area is thought to have been a river deposit during the Late Triassic period.
The discovery of Lisowicia provides the first evidence that mammal-like elephant sized dicynodonts were present at the same time as the more well-known long-necked sauropodomorph dinosaurs, contrary to previous belief. Sauropodomorphs include species like the Diplodocus or Brachiosaurus. It fills a gap in the fossil record of dicynodonts and it shows that some anatomical features of limbs thought to characterize large mammals or dinosaurs evolved also in the non-mammalian synapsid. Finally, these findings from Poland are the first substantial finds of dicynodonts from the Late Triassic in Europe.
“The discovery of such an important new species is a once in a lifetime discovery,” says Dr Tomasz Sulej.
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Rare fossil bird deepens mystery of avian extinctions
During the late Cretaceous period, more than 65 million years ago, birds belonging to hundreds of different species flitted around the dinosaurs and through the forests as abundantly as they flit about our woods and fields today.
But after the cataclysm that wiped out most of the dinosaurs, only one group of birds remained: the ancestors of the birds we see today. Why did only one family survive the mass extinction?
A newly described fossil from one of those extinct bird groups, cousins of today’s birds, deepens that mystery.
The 75-million-year-old fossil, from a bird about the size of a turkey vulture, is the most complete skeleton discovered in North America of what are called enantiornithines (pronounced en-an-tea-or’-neth-eens), or opposite birds. Discovered in the Grand Staircase-Escalante area of Utah in 1992 by University of California, Berkeley, paleontologist Howard Hutchison, the fossil lay relatively untouched in University of California Museum of Paleontology at Berkeley until doctoral student Jessie Atterholt learned about it in 2009 and asked to study it.
Atterholt and Hutchison collaborated with Jingmai O’Conner, the leading expert on enantiornithines, to perform a detailed analysis of the fossil. Based on their study, enantiornithines in the late Cretaceous were the aerodynamic equals of the ancestors of today’s birds, able to fly strongly and agilely.
“We know that birds in the early Cretaceous, about 115 to 130 million years ago, were capable of flight but probably not as well adapted for it as modern birds,” said Atterholt, who is now an assistant professor and human anatomy instructor at the Western University of Health Sciences in Pomona, California. “What this new fossil shows is that enantiornithines, though totally separate from modern birds, evolved some of the same adaptations for highly refined, advanced flight styles.”
The fossil’s breast bone or sternum, where flight muscles attach, is more deeply keeled than other enantiornithines, implying a larger muscle and stronger flight more similar to modern birds. The wishbone is more V-shaped, like the wishbone of modern birds and unlike the U-shaped wishbone of earlier avians and their dinosaur ancestors. The wishbone or furcula is flexible and stores energy released during the wing stroke.
If enantiornithines in the late Cretaceous were just as advanced as modern birds, however, why did they die out with the dinosaurs while the ancestors of modern birds did not?
“This particular bird is about 75 million years old, about 10 million years before the die-off,” Atterholt said. “One of the really interesting and mysterious things about enantiornithines is that we find them throughout the Cretaceous, for roughly 100 million years of existence, and they were very successful. We find their fossils on every continent, all over the world, and their fossils are very, very common, in a lot of areas more common than the group that led to modern birds. And yet modern birds survived the extinction while enantiornithines go extinct.”
One recently proposed hypothesis argues that the enantiornithines were primarily forest dwellers, so that when forests went up in smoke after the asteroid strike that signaled the end of the Cretaceous — and the end of non-avian dinosaurs — the enantiornithines disappeared as well. Many enantiornithines have strong recurved claws ideal for perching and perhaps climbing, she said.
“I think it is a really interesting hypothesis and the best explanation I have heard so far,” Atterholt said. “But we need to do really rigorous studies of enantiornithines’ ecology, because right now that part of the puzzle is a little hand-wavey.”
Atterholt, Hutchison and O’Connor, who is at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China, published an analysis of the fossil today in the open-access journal PeerJ.
Theropod dinosaurs evolved into birds
All birds evolved from feathered theropods — the two-legged dinosaurs like T. rex — beginning about 150 million years ago, and developed into many lineages in the Cretaceous, between 146 and 65 million years ago.
Hutchison said that he came across the fossil eroding out of the ground in the rugged badlands of the Kaiparowits formation in the Grand Staircase-Escalante National Monument in Garfield County, Utah, just inside the boundary of the recently reduced monument. Having found bird fossils before, he recognized it as a late Cretaceous enantiornithine, and a rare one at that. Most birds from the Americas are from the late Cretaceous (100-66 million years ago) and known only from a single foot bone, often the metatarsus. This fossil was almost complete, missing only its head.
“In 1992, I was looking primarily for turtles,” Hutchison said. “But I pick up everything because I am interested in the total fauna. The other animals they occur with tells me more about the habitat.”
According to Hutchison, the area where the fossil was found dates from between 77 and 75 million years ago and was probably a major delta, like the Mississippi River delta, tropical and forested with lots of dinosaurs but also crocodiles, alligators, turtles and fish.
Unlike most bird fossils found outside America, in particular those from China, the fossil was not smashed flat. The classic early Cretaceous bird, Archaeopteryx, was flattened in sandstone, which preserved a beautiful panoply of feathers and the skeletal layout. Chinese enantiornithines, mostly from the early Cretaceous, are equally beautiful and smashed flatter than a pancake.
“On one hand, it’s great — you get the full skeleton most of the time, you get soft tissue preservation, including feathers. But it also means everything is crushed and deformed,” she said. “Not that our fossils have zero deformation, but overall most of the bones have really beautiful three-dimensional preservation, and just really, really great detail. We see places where muscles and tendons were attaching, all kinds of interesting stuff to anatomists.”
Once Hutchison prepared the fossils and placed them in the UC Museum of Paleontology collection, they drew the attention of a few budding and established paleontologists, but no one completed an analysis.
“The stuff is legendary. People in the vertebrate paleontology community have known about this thing forever and ever, and it just happened that everyone who was supposedly working on it got too busy and it fell by the wayside and just never happened,” Atterholt said. “I was honored and incredibly excited when Howard said that I could take on the project. I was over the moon.”
Her analysis showed that by the late Cretaceous, enantiornithines had evolved advanced adaptations for flying independent of today’s birds. In fact, they looked quite similar to modern birds: they were fully feathered and flew by flapping their wings like modern birds. The fossilized bird probably had teeth in the front of its beak and claws on its wings as well as feet. Some enantiornithines had prominent tail feathers that may have differed between male and female and been used for sexual display.
“It is quite likely that, if you saw one in real life and just glanced at it, you wouldn’t be able to distinguish it from a modern bird,” Atterholt said.
This fossil bird is also among the largest North American birds from the Cretaceous; most were the size of chickadees or crows.
“What is most exciting, however, are large patches on the forearm bones. These rough patches are quill knobs, and in modern birds they anchor the wing feathers to the skeleton to help strengthen them for active flight. This is the first discovery of quill knobs in any enantiornithine bird, which tells us that it was a very strong flier.”
Atterholt and her colleagues named the species Mirarce eatoni (meer-ark’-ee ee-tow’-nee). Mirarce combines the Latin word for wonderful, which pays homage to “the incredible, detailed, three-dimensional preservation of the fossil,” she said, with the mythical Greek character Arce, the winged messenger of the Titans. The species name honors Jeffrey Eaton, a paleontologist who for decades has worked on fossils from the Kaiparowits Formation. Eaton first enticed Hutchison to the area in search of turtles, and they were the first to report fossils from the area some 30 years ago.
Thousands of such fossils from the rocks of the Kaiparowits Formation, many of them dinosaurs, contributed to the establishment of the Grand Staircase-Escalante National Monument in 1996.
“This area contains one of the best Cretaceous fossil records in the entire world, underscoring the critical importance of protecting and preserving these parts of our natural heritage,” Atterholt said. “Reducing the size of the protected area puts some of our nation’s most valuable natural and scientific resources at risk.”
Hutchison’s field work was supported by the Annie M. Alexander endowment to the UCMP.
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Tiny footprints, big discovery: Reptile tracks oldest ever found in Grand Canyon
A geology professor at the University of Nevada, Las Vegas, has discovered that a set of 28 footprints left behind by a reptile-like creature 310 million years ago, are the oldest ever to be found in Grand Canyon National Park.
The fossil trackway covers a fallen boulder that now rests along the Bright Angel Trail in the national park. Rowland presented his findings at the recent annual meeting of the Society of Vertebrate Paleontology.
“It’s the oldest trackway ever discovered in the Grand Canyon in an interval of rocks that nobody thought would have trackways in it, and they’re among the earliest reptile tracks on earth,” said Rowland.
Rowland said he’s not prepared to say that they’re the oldest tracks of their kind ever discovered, but it’s a possibility, as he’s still researching the discovery.
“In terms of reptile tracks, this is really old,” he said, adding that the tracks were created as the supercontinent Pangaea was beginning to form.
Rowland was first alerted to the tracks in spring 2016 by a colleague who was hiking the trail with a group of students. The boulder ended up along the trail after the collapse of a cliff.
A year later, Rowland studied the footprints up close.
“My first impression was that it looked very bizarre because of the sideways motion,” Rowland said. “It appeared that two animals were walking side-by-side. But you wouldn’t expect two lizard-like animals to be walking side-by-side. It didn’t make any sense.”
When he arrived home, he made detailed drawings, and began hypothesizing about the “peculiar, line-dancing gait” left behind by the creature.
“One reason I’ve proposed is that the animal was walking in a very strong wind, and the wind was blowing it sideways,” he said.
Another possibility is that the slope was too steep, and the animal sidestepped as it climbed the sand dune. Or, Rowland said, the animal was fighting with another creature, or engaged in a mating ritual.
“I don’t know if we’ll be able to rigorously choose between those possibilities,” he said.
He plans to publish his findings along with geologist Mario Caputo of San Diego State University in January. Rowland also hopes that the boulder is soon placed in the geology museum at the Grand Canyon National Park for both scientific and interpretive purposes.
Meanwhile, Rowland said that the footprints could belong to a reptile species that has never yet been discovered.
“It absolutely could be that whoever was the trackmaker, his or her bones have never been recorded,” Rowland said.
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The teeth of Changchunsaurus: Rare insight into ornithopod dinosaur tooth evolution
The teeth of Changchunsaurus parvus, a small herbivorous dinosaur from the Cretaceous of China, represent an important and poorly-known stage in the evolution of ornithopod dentition, according to a study released November 7, 2018 in the open-access journal PLOS ONE by Jun Chen of Jilin University in China and colleagues.
Ornithischian (“bird-hipped”) dinosaurs developed an incredible diversity of teeth, including the famously complex dental batteries of derived ornithopods, but little is known about how these intricate arrangements arose from the simple tooth arrangements of early dinosaurs. Changchunsaurus parvus belongs to an early branch at or near the origins of the ornithopods, and thus may provideinsight into the ancestral state of ornithopod tooth development. In this study, Chen and colleagues took thin sections from five jaw bones of Changchunsaurus to investigate tooth composition as well as how the teeth are maintained throughout the life of the animal using histological techniques.
Among the notable features of Changchunsaurus dentition is a unique method of tooth replacement that allowed it to recycle teeth without disrupting the continuous shearing surface formed by its tooth rows. The authors also found that the teeth feature wavy enamel, a tissue type formerly thought to have evolved only in more derived ornithopods. The authors suspect these features may have arisen early on as this group of dinosaurs became specialized for herbivory.
Features of the jaws and teeth are often used to assess dinosaur phylogeny. In addition to investigating the evolution of ornithopod dentition, this study also identifies new dental traits that might help sort out ornithischian relationships in future analyses. But the authors note that this is only the first in-depth study at a dinosaur near the base of the ornithopod family tree, and that more studies on more dinosaurs will be needed to fill in the full picture of this group’s evolution.
Professor Chen Jun summarizes: “These tissue-level details of the teeth of Changchunsaurus tell us that their teeth were well-adapted to their abrasive, plant-based diets. Most surprisingly, the wavy enamel described here, presumably to make it more resistant to wear, was previously thought to be exclusive to their giant descendants, the duckbilled dinosaurs.”
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Journal Reference:
Jun Chen, Aaron R. H. LeBlanc, Liyong Jin, Timothy Huang, Robert R. Reisz. Tooth development, histology, and enamel microstructure in Changchunsaurus parvus: Implications for dental evolution in ornithopod dinosaurs. PLOS ONE, 2018; 13 (11): e0205206 DOI: 10.1371/journal.pone.0205206
New species of ‘missing link’ between dinosaurs and birds identified
Known as the ‘Icon of Evolution’ and ‘the missing link’ between dinosaurs and birds, Archaeopteryx has become one of the most famous fossil discoveries in Palaeontology.
Now, as part of an international team of scientists, researchers at The University of Manchester have identified a new species of Archaeopteryx that is closer to modern birds in evolutionary terms.
Dr John Nudds, from the University’s School of Earth and Environmental Sciences, and the team have been re-examining one of the only 12 known specimens by carrying out the first ever synchrotron examination, a form of 3D X-ray analysis, of an Archaeopteryx.
Thanks to this new insight, the team says that this individual Archaeopteryx fossil, known as ‘specimen number eight’, is physically much closer to a modern bird than it is to a reptile. Therefore, it is evolutionary distinctive and different enough to be described as a new species — Archaeopteryx albersdoerferi.
The research, which is being published in journal Historical Biology, says that some of the differing skeletal characteristics of Archaeopteryx albersdoerferi include the fusion of cranial bones, different pectoral girdle (chest) and wing elements, and a reinforced configuration of carpals and metacarpals (hand) bones.
These characteristics are seen more in modern flying birds and are not found in the older Archaeopteryx lithographica species, which more resembles reptiles and dinosaurs.
Specimen number eight is the youngest of all the 12 known specimens by approximately half a million years. This age difference in comparison to the other specimens is a key factor in describing it as a new species.
Dr Nudds explains: “By digitally dissecting the fossil we found that this specimen differed from all of the others. It possessed skeletal adaptations which would have resulted in much more efficient flight. In a nutshell we have discovered what Archaeopteryx lithographica evolved into — i.e. a more advanced bird, better adapted to flying — and we have described this as a new species of Archaeopteryx.”
Archaeopteryx was first described as the ‘missing link’ between reptiles and birds in 1861 — and is now regarded as the link between dinosaurs and birds. Only 12 specimens have ever been found and all are from the late Jurassic of Bavaria, now Germany, dating back approximately 150 million years.
Lead author, Dr Martin Kundrát, from the University of Pavol Jozef Šafárik, Slovakia, said: “This is the first time that numerous bones and teeth of Archaeopteryx were viewed from all aspects including exposure of their inner structure. The use of synchrotron microtomography was the only way to study the specimen as it is heavily compressed with many fragmented bones partly or completely hidden in limestone.”
Dr Nudds added: “Whenever a missing link is discovered, this merely creates two further missing links — what came before, and what came after! What came before was discovered in 1996 with the feathered dinosaurs in China. Our new species is what came after. It confirms Archaeopteryx as the first bird, and not just one of a number of feathered theropod dinosaurs, which some authors have suggested recently. You could say that it puts Archaeopteryx back on its perch as the first bird!”
Story Source:
Materials provided by The University of Manchester. Note: Content may be edited for style and length.
Journal Reference:
Martin Kundrát, John Nudds, Benjamin P. Kear, Junchang Lü, Per Ahlberg. The first specimen of Archaeopteryx from the Upper Jurassic Mörnsheim Formation of Germany. Historical Biology, 2018; 31 (1): 3 DOI: 10.1080/08912963.2018.1518443
Newly described fossils could help reveal why some dinos got so big
By the time non-avian dinosaurs went extinct, plant-eating sauropods like the Brontosaurus had grown to gargantuan proportions. Weighing in as much as 100 tons, the long-neck behemoths are the largest land animals to ever walk the earth.
How they grew so large from ancestors that were small enough to be found in a modern-day petting zoo has remained a mystery. A new, in-depth anatomical description of the best preserved specimens of a car-sized sauropod relative from North America could help paleontologists with unraveling the mystery.
Adam Marsh, a paleontologist at Petrified Forest National Park, led the description of the dinosaur while earning his master’s degree from The University of Texas at Austin Jackson School of Geosciences. The findings were published on Oct. 10 in the journal PLOS ONE. Marsh co-authored the paper with his advisor, Jackson School Professor Timothy Rowe.
The dinosaur — called Sarahsaurus aurifontanalis — lived about 185 million years ago during the Early Jurassic. It could hold important clues about sauropods’ size because it belonged to the dinosaur grouping that preceded them. Its evolutionary placement combined with the exquisite preservation of the specimens is giving researchers a detailed look into its anatomy and how it relates to its larger cousins.
“Sarahsaurus preserves in its anatomy the anatomical changes that were happening in the Late Triassic and Early Jurassic that were occurring in the evolutionary lineage,” Marsh said. “It can help tell us how getting big happens.”
The description is based on two skeletons discovered in Arizona by Rowe in 1997. The bones belong to the Navajo Nation, which owns the land where the fossils were discovered, and are curated by the Jackson School Museum of Earth History Vertebrate Paleontology Collections. The bones are slightly crushed, and in some cases still linked together into body parts such as the hand and tail. The only major missing part is the skull.
“The specimens are well preserved in three dimensions and remarkably complete, which is very rare in the fossil record,” said collections Director Matthew Brown. “Such complete specimens help paleontologists better understand the fragmentary and incomplete fossils remains we typically find.”
Marsh describes Sarahsaurus as a “ground sloth-like” dinosaur. It stood upright, walked on its hind-legs and had powerful forelimbs with a large, curved claw capping the first finger of each hand. It had a lot in common with the earliest sauropod ancestors — like walking on two legs — but it was also starting to show features that would foreshadow how its massive relatives would evolve — such as an increase in body size and a lengthening of the neck vertebrae.
“It’s starting to gain the characters of getting large compared to the earliest members of the group,” Marsh said.
Size and neck-length are features that sauropods would take to extremes as they evolved. By studying these traits and others in Sarahsaurus, and seeing how they compare to those of other dinosaurs, scientists can help reveal how these changes occurred across evolutionary history and how different dinosaurs relate to one another.
For example, the anatomical review helped clarify the relationship between Sarahsaurus and two other sauropod relatives that lived in North America during the Early Jurassic. The researchers found that the three don’t have a common North American ancestor — instead they evolved from dinosaur lineages that came to North America independently.
Marsh is currently working on another study that could shed more light on how sauropods evolved. Led by Sterling Nesbitt, an assistant professor at Virginia Tech and research associate at the Jackson School’s vertebrate collections, the project involves tracking anatomical differences in dinosaur limb bones to determine which features relate to evolution and which relate to the age of an animal. Marsh said that the two Sarahsaurus skeletons examined for this paper are a great addition to the project.
“We’ve got two individuals from basically the same hole in the ground with different bumps and grooves on their femora,” Marsh said. “It lends itself really well to this comprehensive anatomical description and it’s going to be really important for comparisons of early dinosaur anatomy.”
The research was funded by the Jackson School of Geosciences and the National Science Foundation. The Sarahsaurus specimens were collected under permit from the Navajo Nation Minerals Department.
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Materials provided by University of Texas at Austin. Note: Content may be edited for style and length.