Dinosaurs laid blue-green eggs

Scientists have found evidence that dinosaurs laid blue-green eggs, telling us something about the prehistoric creatures’ behaviour and challenging what we know about how coloured eggs evolved.

(A) Pair of oviraptorid Heyuannia eggs (NMNS CYN-2004-DINO-05) from the Chinese province of Jiangxi before
 sampling. Porosity measurements and calculations of water vapour conductance are based on these eggs. Pieces 
of eggshell from each of the four zones depicted in (B) were used in porosity measurements. (B) Egg model 
separated into four zones used for zonal porosity measurements [Credit: PeerJ (2017)]

The team of researchers chemically analyzed eggshells recovered from the Late Cretaceous period, between about 100 million and 66 million years ago, and found two pigments in the makeup, suggesting that the eggshells were originally blue-green. A study in the journal PeerJ says the eggs, which were in a late stage of embryonic development, came from a species of oviraptor, a group of small theropods with feathers that lived in the area of Mongolia, and were collected from river deposits in eastern and southern China. The fact that the eggs were not white suggests that these particular dinosaur parents used open nests and were not constantly brooding over their unborn babies.

In modern birds, colouring on eggshells provides camouflage or diversion so that open-nesting birds can protect their children from potential predators. According to the study, “cryptic colouration evolved to match the predominant shades of colour found in the nesting environment.”

Meanwhile, birds that instead protect their eggs by hovering over them do not have much pigmentation in the shells. Crocodiles, which are close relatives, have unpigmented eggs too; they bury their eggs.

The researchers on this study compared the case of modern birds to those of non-avian dinosaurs that may have had coloured eggs. The blue-green eggs for this oviraptor, a creature that had a beak like a parrot and walked on its hind legs, “support an at least partially open nesting behaviour for oviraptorosaurs,” the authors wrote.

The two pigments found in the eggshells were protoporphyrin and biliverdin. Those two components can be found in the eggshells of many modern birds.

According to the study, scientists have assumed that egg colouration evolved in the last shared ancestor between birds and crocs.

That colouration would have been passed down in the genes even of birds that developed behaviour obviating the need for it. The study gives the example of ostriches, which sit on their eggs. Analysis shows that those eggshells still “contain minor amounts of eggshell pigment.” That lingering amount suggests that evolution gradually reduced the pigment in their eggs because their brooding over their eggs reduced evolutionary pressure on egg-colouring genes.

But this new finding shows a deeper history to the trait than just the last common ancestor of birds and crocodiles. The scientists say it may have evolved when some dinosaurs began building nests that were at least partially exposed, as opposed to burying all their eggs, which was a much more common practice.

“Selection for egg color would only have occurred after the eggs themselves became visible to parents, conspecifics, predators, or parasites,” the authors wrote.

The results of the egg analysis also represent an additional avenue for studying fossils, and the researchers said other fossilized dinosaur eggs could contain evidence of pigmentation.

Initially the scientists thought a bluish colouring on the oviraptor eggs was from mineralization.

“The result has important implications both for the origin of avian biology and the reproductive biology of theropods dinosaurs,” the study says.

Author: Elana Glowatz | Source: International Business Times [September 21, 2017]

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Early trilobites had stomachs, new fossil study finds

Exceptionally preserved trilobite fossils from China, dating back to more than 500 million years ago, have revealed new insights into the extinct marine animal's digestive system. Published in the journal PLOS ONE, the new study shows that at least two trilobite species evolved a stomach structure 20 million years earlier than previously thought.

A specimen of the trilobite Palaeolenus lantenoisi from the Guanshan Biota in southern Yunnan Province, 
China. Rarely are internal organs preserved in fossils, but this specimen shows the digestive system
 preserved as reddish iron oxides. The digestive system is comprised of a crop (inflated region at top 
of specimen), lateral glands, and a central canal that runs along the length of the body; the iron 
oxides that extend beyond the fossil are the remains of gut contents that were 
extruded during preservation [Credit: © F. Chen]

"Trilobites are one of the first types of animals to show up in large numbers in the fossil record," said lead author Melanie Hopkins, an assistant curator in the Division of Paleontology at the American Museum of Natural History. "Their exoskeletons were heavy in minerals, and so they preserved really well. But like all fossils, it's very rare to see the preservation of soft tissues like organs or appendages in trilobites, and because of this, our knowledge of the trilobite digestive system comes from a small number of specimens. The new material in this study really expands our understanding."

Trilobites are a group of extinct marine arthropods -- distantly related to the horseshoe crab -- that lived for almost 300 million years. They were extremely diverse, with about 20,000 species, and their fossil exoskeletons can be found all around the world. Most of the 270 specimens analyzed in the new study were collected from a quarry in southern Kunming, China, during an excavation led by Hopkins' co-author, Zhifei Zhang, from Northwest University in Xi'an.

Previous research suggests that two body plans existed for trilobite digestive systems: a tube that runs down the length of the trilobite's body with lateral digestive glands that would have helped process the food; or an expanded stomach, called a "crop," leading into a simple tube with no lateral glands. Until now, only the first type had been reported from the oldest trilobites. Based on this, researchers had proposed that the evolution of the crop came later in trilobite evolutionary history and represented a distinct type of digestive system.

The Chinese trilobite fossils, about 20 percent of which have soft tissue preservation, are dated to the early Cambrian, about 514 million years ago. Contradictory to the previously proposed body plans, the researchers identified crops in two different species within this material. In addition, they found a single specimen that has both a crop and digestive glands -- suggesting that the evolution of trilobite digestive systems is more complex than originally proposed.

The study backs up an earlier announcement made by a separate research team, which found evidence for the unusual crop and gland pairing in a single juvenile trilobite specimen from Sweden from the late Cambrian. But the Chinese material presents the oldest example of this complex digestive system in a mature trilobite, wiping away doubts that the dual structures might just be part of the animal's early development.

"This is a very rigorous study based on multiple specimens, and it shows that we should start thinking about this aspect of trilobite biology and evolution in a different way," Hopkins said.

Source: American Museum of Natural History [September 21, 2017]

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Big herbivorous dinosaurs ate crustaceans as a side dish

Some big plant-eating dinosaurs roaming present-day Utah some 75 million years ago were slurping up crustaceans on the side, a behavior that may have been tied to reproductive activities, says a new University of Colorado Boulder study.

CU Boulder Associate Professor Karen Chin excavating dinosaur coprolites at Grand Staircase-Escalante National 
Monument in Utah. The new study shows herbivorous dinosaurs also were eating crustaceans, likely seasonally 
[Credit: University of Colorado]

The evidence for the crustacean-chowing dinosaurs comes from fossilized feces samples known as coprolites, said Associate Professor Karen Chin, curator of paleontology at CU Boulder's Museum of Natural History. Dating to the late Cretaceous Period, the coprolites were discovered in Grand Staircase-Escalante National Monument in southern Utah by a team from the Denver Museum of Nature & Science who invited Chin out to their dig.

From what we know about dinosaurs, this was a totally unexpected behavior," said Chin. "It was such a surprising discovery we wondered what the motivation could have been."

Chin said the Utah coprolites were similar to those she has examined from Montana -- which likely were from duck-billed dinosaurs known as hadrosaurs -- in that both were similar in size and held jumbled fragments of rotting wood. A closer look at some of the Utah coprolites also turned up thick bits and pieces of fossilized shell, an indication crustaceans were living in the decaying, coniferous wood, she said.

Because crustacean shells turned up in at least 10 coprolite samples in three different stratigraphic layers of the national monument over a distance of about 13 miles, Chin thinks their ingestion by the dinosaurs was purposeful and would have provided valuable protein and calcium sources.

Examples of modern crustaceans, which have hard exoskeletons, include lobsters, crab, shrimp and crayfish. Some of the coprolites examined were probably around two gallons in volume, Chin said.

The size of the crustacean shell bits in the coprolites indicate the crustaceans were at least two inches in length and perhaps larger, said Chin. Individual crustaceans comprised from 20 to 60 percent of the width of a common hadrosaur beak, suggesting it was unlikely the crustaceans were unwittingly swallowed, she said.

"While it is difficult to prove intent regarding feeding strategies, I suspect these dinosaurs targeted rotting wood because it was a great source of protein in the form of insects, crustaceans and other invertebrates," said Chin. "If we take into account the size of the crustaceans and that they were probably wriggling when they were scooped up, the dinosaurs would have likely been aware of them and made a choice to ingest them."

Even though the team is unable to determine what kind of crustaceans they were, fossil crab claws have been found in the same area in a slightly older geologic formation. Present-day Utah appears to have been next to or near a sea during the Cretaceous Period, said Chin.

Chin also suspects the consumption of crustaceans may have been a seasonal dietary shift, perhaps tied to breeding and egg-laying activities of dinosaurs. She notes contemporary bird species -- which are technically avian dinosaurs -- often consume more protein and calcium during the breeding season to support successful reproduction.

"If we found one coprolite with a crustacean fossil in it, that would be a really interesting scientific discovery," Chin said. "But it wouldn't necessarily indicate a recurring feeding behavior. We now have multiple coprolites with crustacean fossils, showing that at least some types of herbivorous dinosaurs occasionally engaged in this unanticipated feeding strategy."

The researchers sliced the coprolite material into thin sections that were then analyzed with an electron microprobe to determine their chemical composition -- in this case they found a preponderance of calcium, said Chin.

Hadrosaurs were one of the most common dinosaur type of the Cretaceous, growing up to 30 feet long and weighing up to three tons. Some species had characteristic crests on their heads. They also had specialized teeth for grinding plant material, and are thought by some paleontologists to have roamed in herds and nurtured their young.

A paper on the subject was published in the journal Scientific Reports.

Source: University of Colorado at Boulder [September 21, 2017]

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Fly away home? Ice Age may have clipped bird migration

The onset of the last ice age may have forced some bird species to abandon their northerly migrations for thousands of years, says new research led by a University of Nebraska-Lincoln ornithologist.

A study led by Nebraska's Robert Zink proposes that many bird species, such as the Canada warbler, may have 
completely stopped migrating during the last ice age [Credit: University of Nebraska-Lincoln]

Published in the journal Science Advances, the study challenges a long-held presumption that birds merely shortened their migratory flights when glaciers advanced south to cover much of North America and northern Europe about 21,000 years ago.

The study concluded that the emergence of glaciers in those regions instead acted as an "adaptive switch" that turned off migratory behavior, transforming the tropics from a cold-weather resort into a long-term residence for certain bird species.

Of the 29 long-distance migrant species examined in the study, 20 likely saw their northern breeding grounds become uninhabitable, according to models developed by the researchers. When the climate again warmed and glaciers retreated back to the Arctic, those species presumably resumed their seasonal migrations.

Lead author Robert Zink said the conclusions could alter how scientists reconstruct the history of bird migration.

"It fundamentally changes the way we study the evolution of migration and think about the migratory behavior of birds," said Zink, professor of natural resources and biological sciences at Nebraska.

Putting Migration On Ice

Researchers generally agree that, millions of years ago, many birds did not migrate from the tropics. But as the global climate began to warm, some species ventured beyond their native habitats to capitalize on better breeding and feeding opportunities afforded by the longer days and insect-rich environments of northern latitudes.

Those species eventually ventured farther and farther from their habitats, finally stopping when they reached environments that could not sustain them during the autumn and winter. They continued to migrate south when seasonal temperatures dropped and food sources waned.

In that context, Zink said his hypothesis suggests that the origin story of bird migration simply underwent multiple reboots, with the "migratory machinery" of birds halting for each of the 20 or so ice ages that have glazed Earth during the past 2.5 million years.

The University of Nebraska-Lincoln's Robert Zink has authored a new study suggesting that the last ice age 
completely halted the northerly migrations of some bird species from about 21,000 to 12,000 years ago 
[Credit: Craig Chandler, University of Nebraska-Lincoln]

"Migrations are costly and risky," said Zink, curator of zoology at the University of Nebraska State Museum. "They're costly in terms of safety, energy -- anything you can think of."

Rather than paying those costs to reach breeding grounds that the encroaching glaciers had shrunk to tiny fractions of their former size, he said, birds instead resorted to their ancestral state: tropical homebodies.

"Some of them were forced so far south that it was no longer a fitness advantage to migrate, because the extra young they could produce south of the glacier wasn't enough to compensate for the cost of migration," Zink said, "and then coming back to the tropics and re-establishing their territory.

"To some people, that's so completely off the wall that they may have trouble wrapping their heads around it -- except that it's the way they would explain to their classes the evolution of migration in the first place. So, in a sense, what I'm proposing is nothing novel. What's novel about it is that (the advent of migration) probably occurred many times."

Redrawing the Map

Zink and his co-author, the University of Minnesota's Aubrey Gardner, conducted their study using a computer model that linked the modern-day distribution of bird species with climate variables -- temperature, precipitation, seasonality -- that characterize their habitats. By comparing those climates with conditions that existed during the last ice age, the model mapped the regions that likely could have supported each of those species from about 21,000 to 12,000 years ago.

In many cases, Zink said, the model either found no habitable regions beyond the tropics or located habitats so miniscule that they would have struggled to support sizable populations of the species.

"Some species were probably just forced (slightly) south of the glaciers, and their habitats were extensive enough that they would maybe maintain some migratory ability," he said. "But for others, I think there was so little predicted habitat that they just ceased migration all together.

"This evolution of migration is a very (variable) thing. Normally, when we think of evolution, we think of singular, unique events in evolutionary history. But in this case, the ability to migrate is entrenched in birds. They have the ability to navigate using the sun, the stars, the (Earth's) magnetic field. They have the ability to put on large amounts of fat and sustain trans-gulf migrations. Birds are (adaptive) enough in their behavior and physiology that this wasn't a reinvention of some incredible phenomenon."

And if some species did transition back and forth from sedentary to migratory states, researchers should consider pruning certain evolutionary trees accordingly, Zink said. Many evolutionary trees currently treat migration as an irreversible trait rather than a variable behavior, he said, and that assumption could be misinforming discussions of when and where it evolved.

"I wanted to point out that this was a real danger and fallacy that's being committed: mapping something onto an evolutionary tree where the feature -- migration or sedentariness -- changes faster than new species evolved," he said. "You would have constructed the history of migration totally differently."

Author: Scott Schrage | Source: University of Nebraska-Lincoln [September 20, 2017]

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Dinosaur evolution: Lumbering giants had agile ancestors

The best known sauropod dinosaurs were huge herbivorous creatures, whose brain structures were markedly different from those of their evolutionary predecessors, for the earliest representatives of the group were small, lithe carnivores.

A couple of predator Mapusaurus try to isolate a herd of sauropods [Credit: Sergey Krasovskiy]

The sauropod group of dinosaurs included the largest animals that have ever walked the Earth -- up to 40 meters long and weighing as much as 90 tons. Evolutionarily speaking, they were obviously very successful, giving rise to a diverse and widely distributed array of plant-eating species. These forms were characterized by a small head, a long and highly flexible neck that allowed them -- like modern giraffes -- to graze the tops of the tallest trees, and a massive body that made mature specimens invulnerable to predators. The sauropods survived for well over 100 million years before succumbing to the meteorite that snuffed out the dinosaurs at the end of the Cretaceous Era.

However, the early representatives of the lineage that led to these lumbering giants were strikingly different in form and habits. For a start, they were carnivores -- like Saturnalia tupiniquim, an early sauropod dinosaur that was about the same size as a modern wolf. Recent work carried out by researchers for Ludwig-Maxilians-Universitaet (LMU) in Munich in collaboration with colleagues in Brazil now confirms this scenario and adds new details to the story. Most of the evidence for the early members of the Sauropodomorpha comes from their type of dentition.

Now paleontologists Mario Bronzati and Oliver Rauhut, who are based at LMU and the Bavarian State Collection for Paleontology and Geology in Munich, have used computer tomography (CT) to analyze fossil skull bones assigned to S. tupiniquim. The high-resolution images of the cranial bones provided by this technique enabled them to deduce the overall surface morphology of the brain. The results suggest that despite being capable of consuming both meat and plants, S. tupiniquim could have followed a purely predatory lifestyle. The new findings appear in Scientific Reports.

The fossil material used in the study was discovered in Brazil over 20 years ago. It comes from a geological formation that dates back to the Triassic Era, and is about 230 million years old. According to the authors of the study, these are the oldest dinosaur bones that have been successfully reassembled with the aid of computer tomography at sufficiently high resolution to permit the reconstruction of the gross anatomy of the brain.

The evolution of the so-called Sauropodomorpha, of which Saturnalia tupiniquim is an early representative, and the Sauropoda sensu stricto, is marked by a clear tendency towards extension of the neck region, which is accompanied by reduction of the size of the skull -- with a corresponding decrease in the volume of the brain -- relative to the skeleton as a whole. Saturnalia tupiniquim stands at the beginning of this process. But the new study reveals that, unlike the case in the true sauropods, a specific area in the cerebellum, which encompasses the two lobes known as the flocculus and paraflocculus, is particularly prominent in the brain of S. tupiniquim. These structures are known to play an important role in controlling voluntary movements of the head and neck, and are involved in regulating the oculomotor system, which stabilizes the animal's field of view.

Bronzati, Rauhut and their co-authors therefore argue that these features enabled S. tupiniquim to adopt a predatory lifestyle. Their findings strongly suggest that, in contrast to the true sauropods, it had a bipedal gait. Moreover, it was nimble enough to hunt, seize and kill its prey -- thanks to its inferred ability to track moving objects with its eyes and to execute rapid movements of its head and neck in a coordinated and precise fashion. With the aid of CT-based reconstruction of the surface anatomy of the brain, the researchers now hope to retrace other stages in the evolution of the sauropodomorphs.

Source: Ludwig-Maximilians-Universität München [September 20, 2017]

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Scientists produce best estimate of Earth's composition

Scientists at ANU have produced the best estimate of Earth's elemental composition which will help them understand how the Earth formed 4.6 billion years ago.

Credit: NASA/JPL

The Solar System began as a dense blob in a molecular cloud of hydrogen gas and dust that collapsed under its own gravity, forming the early Sun, Earth and other planets.

Co-researcher Associate Professor Charley Lineweaver said the Earth's chemical composition was set at that early stage of formation.

"The four most abundant elements - iron, oxygen, silicon and magnesium - make up more than 90 per cent of the Earth's mass, but working out exactly what the Earth is made of is tricky," said Dr Lineweaver from the Research School of Earth Sciences and the Research School of Astronomy and Astrophysics at ANU.

"Seismological studies of earthquakes inform us about the Earth's core, mantle and crust, but it's hard to convert this information into an elemental composition.

"Our deepest drilling has only scratched the surface down to 10 kilometres of our 6,400 kilometre radius planet. Rocks at the surface only come from as deep as the upper mantle."

The research is published in the international journal Icarus and is available here.

Lead author ANU PhD scholar Haiyang Wang said the team made the most comprehensive estimates of the Earth's composition based on a meta-analysis of previous estimates of the mantle and core, and a new estimate of the core's mass.

"Our work focused on getting realistic uncertainties so that our reference model can be used in future comparisons of the Earth with the Sun, or with Mars or with any other body in the Solar System," said Mr Wang from the ANU Research School of Astronomy and Astrophysics.

Co-researcher Professor Trevor Ireland from the ANU Research School of Earth Sciences said planetary scientists would find many uses for this new composition record.

"This will have far-reaching importance, not only for planetary bodies in our Solar System but also other star systems in the universe," he said.

Haiyang Wang has received the Prime Minister's Australia Asia Award to support his PhD research at ANU.

Source: The Australian National University [September 18, 2017]

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Ancestor of super predator sea reptile found in Germany

A new species of extinct sea monster from the Early Jurassic has been identified by a team of German and Swedish researchers. The fossilized bones were found in a clay pit near the city of Bielefeld in Germany. The findings will be published in the journal Alcheringa.

Arminisaurus schuberti [Credit: Joschua Knüppe]

The fossilized bones of a plesiosaur, an extinct long-necked marine reptile from the Age of Dinosaurs, have been identified by paleontologists from the Naturkunde-Museum Bielefeld in Germany and Uppsala University in Sweden. The remains are about 190 million years old and were excavated in the early 1980s.

The new find was named Arminisaurus schuberti after the ancient Germanic chieftain Arminius, who defeated the Roman legions at Teutoburg Forest near Bielefeld in 9 AD, and Siegfried Schubert, the amateur paleontologist who secured the specimen for scientific study.

Another extinct sea reptile from Germany was named by the same research team only last month.

‘Only’ 3–4 metres long

“Plesiosaurs were amongst the most successful marine predators from the Age of Dinosaurs. Some, such as the famous Liopleurodon, were colossal predators up to 15 metres long. They were the equivalent of White sharks and Killer whales in the oceans today,” says Sven Sachs, a researcher at the Naturkunde-Museum Bielefeld and author of the study.

By comparison, Arminisaurus was small, only about 3-4 metres long, and probably hunted fish, squid and other small prey in the ancient seas that covered Germany during the Jurassic period.

The preserved bones of Arminisaurus were broken up by mining machinery, but enough was recovered to classify the animal as an early relative of later Jurassic plesiosaur super predators known as pliosaurids. About 40 percent of the skeleton was recovered, including parts of the skull, vertebrae and limb bones.

An important addition

“Arminisaurus is significant because it dates from a timeframe early in the Jurassic, during which we have very few identifiable plesiosaur fossils,” said Benjamin Kear, Curator of Vertebrate Palaeontology at the Museum of Evolution at Uppsala University, and author of the study. “Only two other plesiosaur fossils have ever been named from this mysterious interval in plesiosaurian evolution, making Arminisaurus a very important new addition for the global record of the group”.

The study also showed that Arminisaurus shared features with plesiosaurs that lived 50 million years later, during the Cretaceous period. This information will help unravel the radiation of these bizarre marine reptiles, and shed light on the early diversity of the gigantic pliosaurids.

The paper describing Arminisaurus is published in a forthcoming special issue of the Australasian palaeontology journal Alcheringa, which showcases some of the latest research on ancient marine reptiles. The skeleton will be put on display as a centerpiece in the Naturkunde-Museum Bielefeld in Bielefeld, Germany.

Source: Uppsala University [September 15, 2017]

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Celebrity fossil reveals all for science

With the help of an artist, a geology professor at Lund University in Sweden has figuratively speaking breathed life into one of science's most well-known fossil species; Agnostus pisiformis. The trilobite-like arthropod lived in huge numbers in Scandinavia a half-billion years ago. Today, this extinct species provides important clues for science in several ways.

Agnostus pisiformis [Credit: Esben Horn]

Despite its small size, Agnostus pisiformis is a remarkable and useful fossil. The extinct animal was just one centimetre in size when adult, but has been found exceptionally well-preserved and in large numbers. And it is not only the outer hard shells -- even the animal's soft tissue has been found so well preserved that it is possible to create extremely detailed sculptures that show what the tiny creature looked like.

"The sculptures have been greatly scaled up and show the animal's complete anatomy down to the smallest detail, including all the extremities and antennae," says Mats E. Eriksson, geology professor at Lund University.

Eriksson's research focuses mainly on microscopic fossils and attempts, among other things, to reconstruct ecosystems that are several hundred million years old.

The sculptures were created in connection with a research article he wrote on Agnostus pisiformis. He was assisted by the Danish artist and designer, Esben Horn, whose company, 10 Tons, specialises in producing lifelike sculptures of both extant and extinct organisms for museums and institutions around the world.

Agnostus pisiformis [Credit: Per Ahlberg]

The ancient Agnostus pisiformis is mainly known from Scandinavia, but it has been recorded also elsewhere, for example in England and Russia. Due to the fact that the species only lived for a limited period of time just over 500 million years ago, it is possible to use the fossilto date various rocks, which explains why Agnostus pisiformis is a celebrity within science.

However, the species is not only useful for researchers as a time reference, as it also gives them valuable insights into ancient life on Earth. This fossil is so well-preserved and occursin such large numbers that it is possible to understand its complete development, from juvenile to adult.

"The incredible degree of preservational detail means that we can grasp the entire anatomy of the animal, which in turn reveals a lot about its ecology and mode of life," says Mats E. Eriksson.

He now hopes that the sculptures of Agnostus pisiformis will become part of a travelling exhibition on the long lost faunas that existed in the oceans more than 500 million years ago. He wants to spread the knowledge about early lifeduring what he regards as a very exciting time in Earth history. He also wants to highlight that palaeontology, that is, the study of fossils, is not just about dinosaurs.

"There were actually ecosystems seething with fantastic and bizarre life forms several hundred million years before the dinosaurs even appeared," concludes Mats E. Eriksson.

The findings are published in Earth-Science Reviews.

Source: Lund University [September 15, 2017]

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Changes in Earth's crust caused oxygen to fill the atmosphere

Scientists have long wondered how Earth's atmosphere filled with oxygen. UBC geologist Matthijs Smit and research partner Klaus Mezger may have found the answer in continental rocks that are billions of years old.

Matthijs Smit of the University of British Columbia examines ancient rocks from the 
deep crust in Norway during the summer of 2017 [Credit: Matthijs Smit]

"Oxygenation was waiting to happen," said Smit. "All it may have needed was for the continents to mature."

Earth's early atmosphere and oceans were devoid of free oxygen, even though tiny cyanobacteria were producing the gas as a byproduct of photosynthesis. Free oxygen is oxygen that isn't combined with other elements such as carbon or nitrogen, and aerobic organisms need it to live. A change occurred about three billion years ago, when small regions containing free oxygen began to appear in the oceans. Then, about 2.4 billion years ago, oxygen in the atmosphere suddenly increased by about 10,000 times in just 200 million years. This period, known as the Great Oxidation Event, changed chemical reactions on the surface of the Earth completely.

Smit, a professor in UBC's department of earth, ocean & atmospheric sciences, and colleague, professor Klaus Mezger of the University of Bern, were aware that the composition of continents also changed during this period. They set out to find a link, looking closely at records detailing the geochemistry of shales and igneous rock types from around the world -- more than 48,000 rocks dating back billions of years.

"It turned out that a staggering change occurred in the composition of continents at the same time free oxygen was starting to accumulate in the oceans," Smit said.

Before oxygenation, continents were composed of rocks rich in magnesium and low in silica -- similar to what can be found today in places like Iceland and the Faroe Islands. But more importantly, those rocks contained a mineral called olivine. When olivine comes into contact with water, it initiates chemical reactions that consume oxygen and lock it up. That is likely what happened to the oxygen produced by cyanobacteria early in Earth's history.

However, as the continental crust evolved to a composition more like today's, olivine virtually disappeared. Without that mineral to react with water and consume oxygen, the gas was finally allowed to accumulate. Oceans eventually became saturated, and oxygen crossed into the atmosphere.

"It really appears to have been the starting point for life diversification as we know it," Smit said. "After that change, the Earth became much more habitable and suitable for the evolution of complex life, but that needed some trigger mechanism, and that's what we may have found."

As for what caused the composition of continents to change, that is the subject of ongoing study. Smit notes that modern plate tectonics began at around the same time, and many scientists theorize that there is a connection.

Smit and Mezger published their findings today in the journal Nature Geoscience. The research was funded by the Natural Sciences and Engineering Research Council.

Source: University of British Columbia [September 18, 2017]

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New Peruvian whale fossil discovery sheds light on whale lineages

A new study led by a Monash biologist has provided fresh information on the origin of one of the major baleen whale lineages, which helps to connect living whales with their deep evolutionary past.

Cranium of Tiucetus rosae (MNHN.F. PPI261, holotype) in (a) oblique anterodorsal and (b) lateral 
view (a, anterior; d, dorsal; l, lateral; p, posterior) [Credit: Felix Marx et al. 
Royal Society Open Science (2017)]

The new whale (Tiucetus rosae) bridges the gap between a family known as cetotheriids – today represented by the living pygmy right whale – and a poorly understood group of ancient whales living 10 to  25 million years ago.

“Tiucetus sheds light on what kind of animal cetotheriids, and thus one of the major modern baleen whale lineages, evolved from,” said lead study author Dr Felix Marx from the Monash School of Biological Sciences.

“We know from DNA and morphological studies how the living baleen whale families relate to each other, but the looks and whereabouts of their earliest ancestors remain largely in the dark.

“Our new whale is starting to change that, by filling in the blanks at the base of Cetotheriidae.”

Phylogenetic position of Tiucetus rosae (shown in red) among other living and extinct baleen whales 
[Credit: Felix Marx et al. Royal Society Open Science (2017)]

The Peruvian whale fossil was found, collected and prepared by the study’s French co-author, Dr Christian de Muizon.  Dr Marx is an expert on baleen whale evolution and was invited to describe and analyse the new specimen. His study, published in Royal Open Society Science, is part of an ongoing research program involving scientists from Peru and several countries in Europe.

There are four families of baleen whale in the modern ocean - 10 to 25 million years ago, the ocean looked rather different, and was dominated by a group of archaic whales scientists still know very little about, according to Dr Marx.

“It is generally thought that these ancient whales belong to one or more of the living families, but they are so different from their modern cousins that no one is quite sure where they fit,” he said.

“Our new fossil superficially looks like an archaic species, but also shares some very clear traits with Cetotheriidae. ­

The research team studied the shape of its bones in detail, and compared it to a broad variety of living and extinct species. Every comparison they made resulted in clear differences with known whales, which meant that the fossil represented a new species.

Source: Monash University [September 14, 2017]

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Ancient amphibian had mouthful of teeth

The idea of being bitten by a nearly toothless modern frog or salamander sounds laughable, but their ancient ancestors had a full array of teeth, large fangs and thousands of tiny hook-like structures called denticles on the roofs of their mouths that would snare prey, according to new research by paleontologists at the University of Toronto.

The Early Permian dissorophid Cacops displays its fearsome dentition as it preys
on the hapless reptile Captorhinus [Credit: Brian Engh]

In research published online in PeerJ, an open access journal, Robert Reisz, distinguished professor of paleontology at University of Toronto Mississauga, explains that the presence of such an extensive field of teeth provides clues to how the intriguing feeding mechanism seen in modern amphibians was also likely used by their ancient ancestors.

The researchers believe that the tooth-bearing plates “were ideally suited for holding on to prey, such as insects or smaller tetrapods, may have facilitated a method of swallowing prey items via retraction of the eyeballs into the mouth, as some amphibians do today."

In many vertebrates, ranging from fish to early synapsids (ancestors of mammals), denticles are commonly found in dense concentrations on the bones of the hard palate (roof of the mouth). However, in one group of tetrapods, temnospondyls (which are thought to be the ancestors of modern amphibians), these denticles were also found on small, bony plates that filled the large soft part of the palate. The entire roof of the mouth was covered with literally thousands of these tiny teeth that they used to grab prey. Since these toothy plates were suspended in soft tissue, they are often lost or scattered during fossilization.

The external morphology of the palatal plates in the sampled specimen (ROM 76838) and Pasawioops. 
(A–C) images of the sampled block of palatal plates (ROM 76838) from various views; (D) an image 
of the dorsal surface of the palatal plates; (E) an enlarged view of the denticulate surface of the plate; 
(F) an individual tooth on the plate, showing fluting; (G) an SEM image of the block from which the plates 
were isolated; (H) enlarged SEM image of the denticulate surface of the plate; (I) an SEM image 
of a single tooth; (J) an image of the palatal view of the holotype of Pasawioops (OMNH 73019); 
(K) An enlarged view of the palatal plates; (L) an enlarged view of the dentition on the palatal 
plates showing the orientation of the dentition [Credit: Bryan M. Gee et al., PeerJ]

Denticles are significantly smaller than the teeth around the margin of the mouth – on the order of dozens to a couple hundred microns in length. They are actually true teeth, rather than just protrusions in the mouths of these tetrapods, says Reisz and his colleagues, Bryan Gee and Yara Haridy, both graduate students in paleontology.

“Denticles have all of the features of the large teeth that are found on the margin of the mouth,” says Reisz. “In examining tetrapod specimens dating back (approximately) 289 million years, we discovered that the denticles display essentially all of the main features that are considered to define teeth, including enamel and dentine, pulp cavity and peridontia.”

In reaching these conclusions, the researchers analyzed specimens unearthed from the fossil-rich Dolese Brothers Limestone Quarry near Richards Spur, Okla. They were extraordinarily well preserved, making them ideal candidates for study.

The researchers extracted and isolated the denticle-bearing plates, created thin section slides and examined them under the microscope – no small feat since denticles on this animal were only about 100 microns long.

Reisz and his graduate students suggest that the next big question relates to evolutionary changes to the overall abundance of teeth: If these ancient amphibians had an astonishing number of teeth, why have most modern amphibians reduced or entirely lost their teeth?

Author: Elaine Smith | Source: University of Toronto [September 14, 2017]

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'Mysterious' ancient fossil was definitely an animal, research confirms

It lived well over 550 million years ago, is known only through fossils and has variously been described as looking a bit like a jellyfish, a worm, a fungus and lichen. But was the 'mysterious' Dickinsonia an animal, or was it something else?

A Dickinsonia fossil was first described in 1947 [Credit: Alex Liu]

A new study by researchers at the universities of Oxford, Cambridge, Bristol, and the British Geological Survey provides strong proof that Dickinsonia was an animal, confirming recent findings suggesting that animals evolved millions of years before the so-called Cambrian Explosion of animal life.

Lead author on the paper is Dr Renee Hoekzema, a PhD candidate in Oxford University's Mathematical Institute who carried out this research while completing a previous PhD in Oxford's Department of Earth Sciences. She said: 'Dickinsonia belongs to the Ediacaran biota -- a collection of mostly soft-bodied organisms that lived in the global oceans between roughly 580 and 540 million years ago. They are mysterious because despite there being around 200 different species, very few of them resemble any living or extinct organism, and therefore what they were, and how they relate to modern organisms, has been a long-standing palaeontological mystery.'

In 1947, Dickinsonia became one of the first described Ediacaran fossils and was initially thought to be an organism similar to a jellyfish. Since then, its strange body plan has been compared to that of a worm, a placozoan, a bilaterian and several non-animals including fungi, lichens and even entirely extinct groups.

Co-author Dr Alex Liu, from the Department of Earth Sciences at the University of Cambridge, said: 'Discriminating between these different hypotheses has been difficult, as there are so few morphological features in Dickinsonia to compare to modern organisms. In this study we took the approach of looking at populations of this organism, including assumed juvenile and adult individuals, to assess how it grew and to try to work out how to classify it from a developmental perspective.'

The research was carried out on the basis of a widely held assumption that growth and development are 'conserved' within lineages -- in other words, the way a group of organisms grows today would not have changed significantly from the way its ancestors grew millions of years ago.

Dickinsonia is composed of multiple 'units' that run down the length of its body. The researchers counted the number of these units in multiple specimens, measured their lengths and plotted these against the relative 'age' of the unit, assuming growth from a particular end of the organism. This data produced a plot with a series of curves, each of which tracked how the organism changed in the size and number of units with age, enabling the researchers to produce a computer model to replicate growth in the organism and test previous hypotheses about where and how growth occurred.

Dr Hoekzema said: 'We were able to confirm that Dickinsonia grows by both adding and inflating discrete units to its body along its central axis. But we also recognised that there is a switch in the rate of unit addition versus inflation at a certain point in its life cycle. All previous studies have assumed that it grew from the end where each "unit" is smallest, and was therefore considered to be youngest. We tested this assumption and interpreted our data with growth assumed from both ends, eventually coming to the conclusion that people have been interpreting Dickinsonia as having grown at the wrong end for the past 70 years.

'When we combined this growth data with previously obtained information on how Dickinsonia moved, as well as some of its morphological features, we were able to reject all non-animal possibilities for its original biological affinity and show that it was an early animal, belonging to either the Placozoa or the Eumetazoa.

'This is one of the first times that a member of the Ediacaran biota has been identified as an animal on the basis of positive evidence.'

Dr Liu added: 'This finding demonstrates that animals were present among the Ediacaran biota and importantly confirms a number of recent findings that suggest animals had evolved several million years before the "Cambrian Explosion" that has been the focus of attention for studies into animal evolution for so long.

'It also allows Dickinsonia to be considered in debates surrounding the evolution and development of key animal traits such as bilateral symmetry, segmentation and the development of body axes, which will ultimately improve our knowledge of how the earliest animals made the transition from simple forms to the diverse range of body plans we see today.'

The study is published in the journal Proceedings of the Royal Society B.

Source: University of Oxford [September 14, 2017]

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Tectonic plates 'weaker than previously thought,' say scientists

Experiments carried out at Oxford University have revealed that tectonic plates are weaker than previously thought.

Researchers experimented on olivine crystals to help determine the strength of tectonic plates 
[Credit: Lars Hansen]

The finding explains an ambiguity in lab work that led scientists to believe these rocks were much stronger than they appeared to be in the natural world. This new knowledge will help us understand how tectonic plates can break to form new boundaries.

Study co-author Lars Hansen, Associate Professor of Rock and Mineral Physics in Oxford University's Department of Earth Sciences, said: 'The strength of tectonic plates has been a major target of research for the past four decades. For plate tectonics to work, plates must be able to break to form new plate boundaries. Significant effort has gone into measuring the strength of the key olivine-rich rocks that make up plates using laboratory experiments.

'Unfortunately, those estimates of rock strength have been significantly greater than the apparent strength of plates as observed on Earth. Thus, there is a fundamental lack of understanding of how plates can actually break to form new boundaries. Furthermore, the estimates of rock strength from laboratory experiments exhibit considerable variability, reducing confidence in using experiments to estimate rock properties.'

The new research, published in the journal Science Advances, uses a technique known as 'nanoindentation' to resolve this discrepancy and explain how the rocks that make up tectonic plates can be weak enough to break and form new plate boundaries.

Dr Hansen said: 'We have demonstrated that this variability among previous estimates of strength is a result of a special length-scale within the rocks – that is, the strength depends on the volume of material being tested. To determine this we used nanoindentation experiments in which a microscopic diamond stylus is pressed into the surface of an olivine crystal. These experiments reveal that the strength of the crystal depends on the size of the indentation.

'This concept translates to large rock samples, for which the measured strength increases as the size of the constituent crystals decreases. Because most previous experiments have used synthetic rocks with crystal sizes much smaller than typically found in nature, they have drastically overestimated the strength of tectonic plates. Our results therefore both explain the wide range of previous estimates of rock strength and provide confirmation that the strength of the rocks that make up tectonic plates is low enough to form new plate boundaries.'

The study was an international collaboration involving scientists from Stanford University, the University of Pennsylvania, Oxford University and the University of Delaware.

Dr Hansen added: 'This result has implications beyond forming tectonic plate boundaries. Better predictions of the strength of rocks under these conditions will help inform us on many dynamic processes in plates. For instance, we now know that the evolution of stresses on earthquake-generating faults likely depends on the size of the individual crystals that make up the rocks involved. In addition, flexing of plates under the weight of volcanoes or large ice sheets, a process intimately linked to sea level on Earth, will also ultimately depend on crystal size.'

Source: University of Oxford [September 14, 2017]

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New prehistoric crocodile species identified

Around 95 million years ago, a giant relative of modern crocodiles ruled the coastlines and waterways of what would one day become north central Texas.

Dr. Thomas Adams with the skull of Deltasuchus motherali 
[Credit: Arlington Archosaur Site]

A team including UT’s Stephanie Drumheller-Horton has identified this species, Deltasuchus motherali. They found that adults grew up to 20 feet long and, based on the bite marks discovered on the fossilized bones of prey animals, ate whatever they wanted in their environment, from turtles to dinosaurs.

The team found the bones in a place one normally doesn’t think to look for ancient fossils—in the heart of the Dallas-Fort Worth Metroplex.

The findings were recently published in the Journal of Vertebrate Paleontology.

Drumheller-Horton collaborated with Thomas Adams, curator of paleontology and geology at the Witte Museum in San Antonio, Texas, and Chris Noto of the University of Wisconsin–Parkside.

Deltasuchus motherali: A Large Neosuchian Crocodyliform from the Upper Cretaceous (Cenomanian) 
Woodbine Formation of North Texas [Credit: Arlington Archosaur Site]

The site that produced the new species was discovered in Arlington, Texas, in 2003 by amateur fossil hunters Art Sahlstein, Bill Walker, and Phil Kirchoff.

Dubbed the Arlington Archosaur Site, the area is undergoing rapid residential development, and paleontologists have been working with local volunteers and fossil enthusiasts to excavate the site over the past decade.

“We simply don’t have that many North American fossils from the middle of the Cretaceous, the last period of the age of dinosaurs, and the eastern half of the continent is particularly poorly understood,” Drumheller-Horton said. “Fossils from the Arlington Archosaur Site are helping fill in this gap, and Deltasuchus is only the first of several new species to be reported from the locality.”

Deltasuchus motherali is named for one of the site volunteers, Austin Motheral, who first uncovered the fossils of this particular crocodile with a small tractor when he was just 15 years old.

Volunteers working to uncover fossils, including those of Deltasuchus, in 2009 
[Credit: Arlington Archosaur Site]

Work on the site is supported by a grant from the National Geographic Society, which is funding continued excavations and study of this unique fossil area. Fossils from the site, including the Deltasuchus motherali bones, are part of the collections of the Perot Museum of Nature and Science in Dallas.

Deltasuchus is the first of what may prove to be several new species described from this fossil site. The area preserves a complete ancient ecosystem ranging from 95 million to 100 million years old, and its fossils are important in advancing the understanding of ancient North American land and freshwater ecosystems.

While most of Texas was covered by a shallow sea at the time, the Dallas-Fort Worth area was part of a large peninsula that jutted out from the northeast. The peninsula was a lush environment of river deltas and swamps that teemed with wildlife, including dinosaurs, crocodiles, turtles, mammals, amphibians, fish, invertebrates, and plants.

Source: University of Tennessee at Knoxville [September 13, 2017]

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Rapid climate changes across northern hemisphere in the earliest Middle Pleistocene

By studying climate changes that took place thousands of years ago, we can better understand the global climate system and predict Earth's future climate. A multi-organization research team led by Professor HYODO Masayuki (Research Center for Inland Seas, Kobe University) has discovered evidence of rapid climate changes on a millennial-to-centennial scale that occurred 780 to 760 thousand years ago. The findings were published in Scientific Reports.

Figure 1: Sample locations (a) Chiba section, Osaka Bay, North Pacific mid-latitude point (U1313). (b)(c) show
 the Chiba section location. (d) Location of core TB2 near the Chiba section along the Yoro River
[Credit: Kobe University]

During the 2.6 million year Quaternary Period, the climate repeated a glacial and interglacial cycle, caused by changes in the geographical distribution of solar radiation due to orbital changes including those of Earth's orbit and the tilt of its axis. These changes are regarded as "Milankovitch cycles," over 20,000 years in period. But in the Holocene and last glacial periods, a number of millennial-to-centennial scale climate changes have been observed. Such rapid climate changes have scarcely been reported before the last glacial period.

In the interglacial period between 780 and 760 thousand years ago, Earth's orbital patterns were quite similar to the current (Holocene) era, so this interglacial climate could be useful in predicting Earth's future climate.

Figure 2: Records of climate and environment between 790 and 750 thousand years ago in three areas 
[Credit: Kobe University]

The research team focused on the Kazusa Group (Chiba prefecture, Japan), which has the fastest sedimentation rate in the world for strata of that era, and obtained high resolution paleoceanic environmental records every 10 years. When combined with records from Osaka Bay and the North Atlantic, they found evidence of multiple instances of rapid warming and cooling across all three regions at the same time. The data includes the unusual phenomenon of a rapid temperature rise with cyclicity suddenly finishing with a cold event. The cold events occurred at the same time as the great iceberg flow reached mid-latitudes in the North Atlantic, so they are thought to be caused by meltwater that covered the North Atlantic Ocean.

This cyclic warming and rapid cooling repeated twice just after a geomagnetic reversal, a key event for the Early/Middle Pleistocene boundary, and a third time about 10 thousand years later. All occurred after Earth had recovered its geomagnetic strength. This shows that the second half of this interglacial period, namely the earliest stage of the Middle Pleistocene, was a time of extreme climate change when ice sheets expanded and shrunk causing changes of several meters in sea levels, repeating every 500 to 2000 years.

Figure 3: Close-up of events A,B and G,H [Credit: Kobe University]

The phenomenon of rapid temperature rises modulated by bi-centennial cycles ending with a sudden freeze only occurred during a very brief portion of this interglacial period, during the two warmest periods. There is a high possibility that this 200 year period marks the de Vries Cycle (205 years), when the climate was particularly sensitive to solar activity.

Researchers will now verify whether the same phenomenon can be observed in other regions. Evidence from the southern hemisphere will be the key to showing whether it was a global phenomenon. This discovery is very unusual among the climate warming that occurred in the past, as well as being an important key to learning about the diversity of temperature rises and understanding current global warming.

Additionally, this discovery was made in the Chiba Section (Japan), a candidate section for the Early/Middle Pleistocene era global boundary stratotype sections and points (GSSP), currently under review by the International Union of Geological Sciences. These findings provide further evidence for the academic value of the Chiba Section.

Source: Kobe University [September 12, 2017]

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Ancient tree reveals cause of spike in Arctic temperature

A kauri tree preserved in a New Zealand peat swamp for 30,000 years has revealed a new mechanism that may explain how temperatures in the Northern Hemisphere spiked several degrees centigrade in just a few decades during the last global ice age.

It's only when a human stands beside the tree stump of an ancient kauri, that you can get 
a clear sense of the size of these ancient trees [Credit: www.ancientkauriproject.com]

Unexpectedly, according to new research led by scientists from UNSW Sydney and published in Nature Communications, it looks like the origin of this warming may lie half-a-world away, in Antarctica.

Rapid warming spikes of this kind during glacial periods, called Dansgaard-Oeschger events, are well known to climate researchers. They are linked to a phenomenon known as the "bipolar seesaw," where increasing temperatures in the Arctic happen at the same time as cooling over the Antarctic, and vice versa.

Until now, these divergences in temperature at the opposite ends of Earth were believed to have been driven by changes in the North Atlantic, causing deep ocean currents, often referred to as the ocean "conveyor belt," to shut down. This led to warming in the Northern Hemisphere and cooling in the south.

But the study, which examines a specific Dansgaard-Oeschger event that occurred around 30,000 years ago, suggests Antarctica plays a role too.

The paper describes how the researchers used a detailed sequence of radiocarbon dates from an ancient New Zealand kauri tree to precisely align ice, marine and sediment records across a period of greatly changing climate.

"Intriguingly, we found that the spike in temperature preserved in the Greenland ice core corresponded with a 400-year-long surface cooling period in the Southern Ocean and a major retreat of Antarctic ice," said lead author and UNSW scientist Professor Chris Turney.

Summary of CSIRO Mk3L ensemble simulations showing the impact of a 338-year duration freshwater flux 
of 0.54 Sv into the Weddell and Ross Seas [Credit: Keele University]

"As we looked more closely for the cause of this opposite response we found that there were no changes to the global ocean circulation during the Antarctic cooling event that could explain the warming in the North Atlantic. There had to be another cause."

A clue to what might be going on if the oceans weren't involved appeared in lake sediments from the Atherton Tableland, Queensland. The sediments showed a simultaneous collapse of rain-bearing trade winds over tropical northeast Australia.

It was a curious change, so the researchers turned to climate models to see if these climate events might somehow be linked.

They started by modelling the release of large volumes of freshwater into the Southern Ocean, exactly as would happen with rapid ice retreat around the Antarctic.

Consistent with the data, they found that there was cooling in the Southern Ocean but no change in the global ocean circulation.

They also found that the freshwater pulse caused rapid warming in the tropical Pacific. This in turn led to changes to the atmospheric circulation that went on to trigger sharply higher temperatures over the North Atlantic and the collapse of rain-bearing winds over tropical Australia.

Essentially, the model showed the formation of a 20,000 km long "atmospheric bridge" that linked melting ice in Antarctica to rapid atmospheric warming in the North Atlantic.

"Our study shows just how important Antarctica's ice is to the climate of the rest of the world and reveals how rapid melting of the ice here can affect us all. This is something we need to be acutely aware of in a warming world," Professor Turney said.

It also showed how deeply the climate was linked across great distances said fellow author and climate modeller from the University of Tasmania, Dr Steven Phipps.

"Our research has revealed yet another remarkable example of the interconnections that are so much a part of our climate system," Dr Phipps said.

"By combining past records of past events with climate modelling, we see how a change in one region can have major climatic impacts at the opposite ends of Earth."

Source: University of New South Wales [September 12, 2017]

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Half-a-billion-year-old fossils shed light animal evolution on Earth

Scientists have discovered traces of life more than half-a-billion years old that could change the way we think about how all animals evolved on earth.

X-ray microtomography image of trace fossil in sediment [Credit: Luke Parry, University of Bristol]

The international team, including palaeontologist from The University of Manchester, found a new set of trace fossils left by some of the first ever organisms capable of active movement. Trace fossils are the tracks and burrows left by living organisms, not physical remains such as bones or body parts.

The fossils were discovered in sediment in the Corumbá region of western Brazil, near the border with Bolivia. The burrows measure from under 50 to 600 micrometres or microns (?m) in diameter, meaning the creatures that made them were similar in size to a human hair which can range from 40 to 300 microns in width. One micrometre is just one thousandth of a millimetre.

Dr Russell Garwood, from Manchester's School of Earth and Environmental Sciences, said: 'This is an especially exciting find due to the age of the rocks -- these fossils are found in rock layers which actually pre-date the oldest fossils of complex animals -- at least that is what all current fossil records would suggest.'

A 3-D X-ray image of trace fossil in sediment [Credit: Luke Parry, University of Bristol]

The fossils found date back to a geological and evolutionary period known as the Ediacaran-Cambrian transition. This was when the Ediacaran Period, which spanned 94 million years from the end of the Cryogenian Period, 635 million years ago, moved into the Cambrian Period around 541 million years ago. To put that into context, dinosaurs lived between 230 and 65 million years ago in the Mesozoic Era.

The Ediacaran-Cambrian transition is seen as extremely important period in evolutionary science and theory. Dr Garwood explains: 'The evolutionary events during the Ediacaran-Cambrian transition are unparalleled in Earth history. That's because current fossil records suggests that many animal groups alive today appeared in a really short time interval.'

However, the team suggest these burrows were created by 'nematoid-like organisms', similar to a modern-day roundworm, that used an undulating locomotion to move through the sediment, leaving these trace fossils behind. This is important because current DNA studies, known as 'molecular clocks', which are used to estimate how long ago a group animals originated, suggests the first animals appeared before these burrows. But this research, which has been published in Nature Ecology and Evolution, shows these trace fossils pre-date similar animals currently found in the fossil record.