Reconstructing how Neanderthals grew, based on an El Sidrón child

How did Neanderthals grow? Does modern man develop in the same way as Homo neanderthalensis did? How does the size of the brain affect the development of the body? A study led by the Spanish National Research Council (CSIC) researcher, Antonio Rosas, has studied the fossil remains of a Neanderthal child's skeleton in order to establish whether there are differences between the growth of Neanderthals and that of sapiens.

Neanderthal children may have grown up as slowly as modern humans 
[Credit: © S.Plailly, E.Daynes/LookatSciences]

According to the results of the article, which are published in Science, both species regulate their growth differently to adapt their energy consumption to their physical characteristics.

"Discerning the differences and similarities in growth patterns between Neanderthals and modern humans helps us better define our own history. Modern humans and Neanderthals emerged from a common recent ancestor, and this is manifested in a similar overall growth rate," explains CSIC researcher, Antonio Rosas, from Spain's National Natural Science Museum (MNCN). As fellow CSIC researcher Luis Ríos highlights, "Applying paediatric growth assessment methods, this Neanderthal child is no different to a modern-day child." The pattern of vertebral maturation and brain growth, as well as energy constraints during development, may have marked the anatomical shape of Neanderthals.

Neanderthals had a greater cranial capacity than today's humans. Neanderthal adults had an intracranial volume of 1,520 cubic centimetres, while that of modern adult man is 1,195 cubic centimetres. That of the Neanderthal child in the study had reached 1,330 cubic centimetres at the time of his death, in other words, 87.5% of the total reached at eight years of age. At that age, the development of a modern-day child's cranial capacity has already been fully completed.

"Developing a large brain involves significant energy expenditure and, consequently, this hinders the growth of other parts of the body. In sapiens, the development of the brain during childhood has a high energetic cost and, as a result, the development of the rest of the body slows down," Rosas explains.

Neanderthals and sapiens

The cost, in terms of energy, of anatomical growth of the modern brain is unusually high, especially during breastfeeding and during infancy, and this seems to require a slowing down of body growth. The growth and development of this juvenile Neanderthal matches the typical characteristics of human ontogeny, where there is a slow anatomical growth between weaning and puberty. This could compensate for the immense energy cost of developing such a large brain.

Skeleton of the Neanderthal boy recovered from the El Sidrón 
cave (Asturias, Spain) [Credit: Paleoanthropology Group 
MNCN-CSIC]

In fact, the skeleton and dentition of this Neanderthal present a physiology which is similar to that of a sapiens of the same age, except for the thorax area, which corresponds to a child between five and six years, in that it is less developed. "The growth of our Neanderthal child was not complete, probably due to energy saving," explains CSIC researcher Antonio Rosas.

The only divergent aspect in the growth of both species is the moment of maturation of the vertebral column. In all hominids, the cartilaginous joints of the middle thoracic vertebrae and the atlas are the last to fuse, but in this Neanderthal, fusion occurred about two years later than in modern humans.

"The delay of this fusion in the vertebral column may indicate that Neanderthals had a decoupling of certain aspects in the transition from infancy to the juvenile phase. Although the implications are unknown, this feature could be related to the characteristic enlarged shape of the Neanderthal torso, or slower brain growth," says Rosas.

The Neanderthal child

The protagonist of this study was 7.7 years old, weighed 26 kilos and measured 111 centimetres at the time of death. Although the genetic analyses failed to confirm the child's sex, the canine teeth and the sturdiness of the bones showed that it to be a male. 138 pieces, 30 of them teeth (including some milk teeth), and part of the skeleton- including some fragments of the skull from the individual- identified as El Sidrón J1, have recovered.

(Left to Right) Antonio García-Tabernero, Antonio Rosas and Luis Ríos beside the Neanderthal child's skeleton 
[Credit: Andrés Díaz-CSIC Communications Department]

The researchers have been able to establish that our protagonist was right-handed and was already performing adult tasks, such as using his teeth as a third hand to handle skins and plant fibres. In addition, they know who his mother was, and that the child protagonist of this investigation had a younger brother in the group. Furthermore, this child was found to have suffered from enamel hypoplasia when he was two or three years old. Hypoplasia (white spots on the teeth, especially visible in the upper incisors), occurs when the teeth have less enamel than normal, the cause usually being malnutrition or disease.

Discovered in 1994, the El Sidrón cave, located in Piloña (in Asturias, northern Spain) has provided the best collection of Neanderthals that exists on the Iberian Peninsula. The team has recovered the remains of 13 individuals from the cave. The group consisted of seven adults (four women and three men), three teenagers and three younger children.

Previous studies have been carried out by a multidisciplinary team led by the paleoanthropologist Antonio Rosas (CSIC's National Museum of Natural Sciences), the geneticist Carles Lalueza-Fox (Institute of Evolutionary Biology, run by CSIC and the Pompeu Fabra University) and by the archaeologist Marco de la Rasilla (University of Oviedo).

Source: Spanish National Research Council (CSIC) [September 22, 2017]

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3-D analysis of dog fossils sheds light on domestication debate

In an effort to settle the debate about the origin of dog domestication, a technique that uses 3-D scans of fossils is helping researchers determine the difference between dogs and wolves.

3D plot of PC1–3 mandible shape variation. Black: dogs, dark grey: Alaskan wolves, light grey: European wolves, 
dark red: Ivolgin fossils, green: Ust’-Polui fossils, purple: Pleistocene Alaskan wolves, cyan: 1600CE fossil dogs, 
orange: unknown Alaskan fossil canids, pink: 1600CE fossil wolf [Credit: Scientific Reports (2017)]

In the ongoing debate, one camp believes dogs were domesticated in the Paleolithic age (more than 17,000 years ago), when humans were hunter-gatherers. The other camp believes domestication occurred in the Neolithic age (17,000 to 7,000 years ago), when humans first established agriculture and civilizations.

Abby Grace Drake, a senior lecturer in the Department of Ecology and Evolutionary Biology, and her colleagues have been analyzing 3-D scans of ancient fossil canid mandibles to determine whether they belong to dogs or wolves. The answer, they find, is not so simple.

The researchers found that in the early stages of domestication, the skull changed shape but evolution of the mandible lagged behind and did not co-evolve with the skull. Their study is reported in the journal Scientific Reports.

"A lot of the fossil evidence for the date of dog domestication is based on morphological [structural] analysis of mandibles," said Drake, the paper's first author. Robert Losey, an anthropologist at the University of Alberta, Canada, is a senior co-author of the paper. "Our study shows that when you measure modern dog mandibles and wolf mandibles using 3-D measurements you can distinguish them, and yet when we looked at these fossil mandibles, they don't look like dogs or wolves."

Wolves have fairly straight mandibles while dog mandibles are curved, structural features that become evident in a 3-D scan. In a proof of principle, when analyzing the 3-D structures of mandibles of modern dogs, Drake and colleagues correctly classified 99.5 percent of the samples as being dog or wolf.

This video shows how a canid mandible changes shape and curves during its transition from wolf to dog 

[Credit: Abby Grace Drake/Cornell University]

However, 3-D analysis of fossil records from four ancient sites, two from Russia and two from Alaska, found that most of those fossil mandibles could not be classified as either dog or wolf, even though features in canid skulls from the same sites as well as other data proved that the samples were dog remains.

Other evidence also showed that these canids were domesticated: The remains were found within human dwellings, remains at both the Russian sites revealed butchery marks, indicating that they were eaten, and isotope analysis of canid and human remains from one of the sites - Ust'-Polui, in the Russian Arctic - showed canids and humans were both eating fish, and humans were feeding their canids.

Since mandibles do not appear to evolve as rapidly as the skull, the results show they are not reliable for identifying early dog fossils, Drake said.

Four of 26 fossil mandibles from Ust'-Polui, which was occupied from 250 B.C. to 150 B.C., were identified as dogs, while three of the mandibles from the site were identified as wolves.

At another site, Ivolgin, in southern Russia, occupied between 300 B.C. and 200 B.C., none of the 20 mandibles were identified as dogs, though 8 were identified as wolves. All of the skulls found at these sites, 12 from Ivolgin and five from Ust'-Polui, were clearly identified as dogs.

Canid fossils of wolves and dogs from the Alaskan sites from 1600 CE were used as controls and to compare genetic testing against the structural 3-D data.

A 2015 paper by Drake and Michael Coquerelle, an anthropologist at the University Rey Juan Carlos in Alcorcon, Spain, and a co-author on the current paper, used the 3-D technique to refute a claim that dogs existed 30,000 years ago. That claim was based on linear caliper measurements of skulls. Linear measurements are inaccurate because dog and wolf skull sizes overlap, Drake said. On the other hand, 3-D analysis of skulls uses landmarks across the skull to identify differences between dogs and wolves in the angle of the muzzle, or snout, and in the angling of the eye orbits.

"The earliest dogs I've seen in my analysis are from 7,000 to 9,000 years ago," Drake said.

Author: Lindsey Hadlock | Source: Cornell University [September 21, 2017]

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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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Man charged for theft of fossil footprints in Crete

Greek police arrested on Friday a 55-year-old man in connection with the theft of 10 fossilised footprints which were stolen on earlier this week from the site where they were uncovered in Kissamos, Western Crete, authorities said.

The vandalised site, showing fresh sand along the edges of the slab where it has been lifted and the holes left 
by the removal of two blocks in the centre [Credit: Babis Fassoulas]

The suspect faces charges of violating laws on protection of cultural heritage. Authorities were able to locate quickly in regions of Kissamos and Thessaloniki all ten fossils. The objects will be send to Chania to be examined by experts.

The site has been buried in haste to avoid further thefts [Credit: Babis Fassoulas]

Ten of some 40 footprints on the site were cut away and removed from the rock where they were found by a Polish paleontologist in 2002. The 5.7-million-year-old fossils are believed to belong to a hominid ancestor of modern humans and their discovery could upend established theories of human evolution.

The buried site [Credit: Babis Fassoulas]

The theft was reported by a member of the public that visited the site on Tuesday and alerted local police, and was later confirmed by the Natural History Museum of Crete. The investigation of the case is continuing.

Source: ANA-MPA [September 15, 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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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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Nothing but the tooth: What dental remains from Homo naledi can tell us

Anthropologists just love to sink their teeth into a good mystery, and some recent research from NC State and Vassar College has done just that – by looking at what dental development in Homo naledi fossils can tell us about this human relative and the evolution of our own species, Homo sapiens.

H. naledi teeth in mandible [Credit: Alice Harvey]

In 2013, paleoanthropologists discovered the fossilized remains of at least 15 individual hominins, or human relatives, within the Dinaledi chamber of the Rising Star cave system near Johannesburg, South Africa. The remains were from an entirely new species, dubbed Homo naledi by the researchers. Recently, these fossils were determined to be around 200,000 – 300,000 years old, meaning that H. naledi walked the earth at the same time as other hominins like Neanderthals and possibly the earliest members of H. sapiens.

Chris Walker, assistant professor of anatomy at NC State, and Zach Cofran, a biological anthropologist from Vassar College, were researchers on the original team that studied the H. naledi fossils. Recently the duo had the opportunity to examine the dental remains of the youngest members of H. naledi to see if this extinct species grew more like humans or our extinct relatives.

Humans are unique among primates in how long it takes us to fully develop from child to adult. Chimpanzees, our closest living relatives, develop a bit faster than we do. Tooth formation and eruption patterns – the rate and order in which baby and adult teeth grow and emerge – also differ between humans and chimps. Scientists surmise that this difference may be related to the differences in developmental timing between the two species. Most evidence to date has suggested that the human-like pattern emerged quite recently in our evolutionary history and that our extinct relatives were generally more like chimps than humans with respect to dental development.

Walker and Cofran used CT scans of the mandibles of two H. naledi youngsters – one an infant and one an older child – to determine how the species’ teeth formed and emerged. What they discovered was surprising.

“Overall, we found a mixture of human and chimp patterns, although the eruption sequences in particular were human-like,” Walker says. “Given that H. naledi was alive so recently, similarities to humans aren’t necessarily shocking. But given the numerous primitive anatomical features of H. naledi – including a small brain, which is suggestive of a relatively fast, more chimp-like developmental pace – our findings are somewhat unanticipated. Even Neanderthals, a group that is much more anatomically similar to modern humans than H. naledi, have a more primitive dental eruption sequence.”

The uniqueness of the finding may actually raise more questions than it answers regarding H. naledi, and it potentially affects how anthropologists gauge the development times and life histories of ancient hominin species.

“A prolonged period of growth and development is a defining feature of humans, but we don’t know when this trait evolved,” says Cofran. “We’ve relied on teeth to make inferences about growth and development in extinct species because they preserve well in fossil samples and dental maturation has previously been linked to aspects of life history. But this finding, with the similarities between modern humans and H. naledi, raises questions about the adaptive significance of tooth emergence sequences.”

Walker and first author Cofran published their findings in Biology Letters.

Author: Tracey Peake | Source: North Carolina State University [September 13, 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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First primates were built for leaping, fossil ankle suggests

A 52-million-year-old ankle fossil suggests our prehuman ancestors were high-flying acrobats. These first primates spent most of their time in the trees rather than on the ground, but just how nimble they were as they moved around in the treetops has been a topic of dispute.

This tiny ankle bone belonged to one of the earliest members of the primate family tree. The 52-million-year-old fossil 
suggests that the first primates were expert leapers. Discovered more than 30 years ago by paleontologist 
Marc Godinot, the fossil is now housed at the Muséum National d'Histoire Naturelle in Paris 
[Credit: Douglas Boyer, Duke University]

For years, scientists thought the ancestors of today's humans, monkeys, lemurs and apes were relatively slow and deliberate animals, using their grasping hands and feet to creep along small twigs and branches to stalk insects or find flowers and fruits.

But a fossil study published in the Journal of Human Evolution suggests the first primates were masters at leaping through the trees.

Paleontologists working in a quarry in southeastern France uncovered the quarter-inch-long bone, the lower part of the ankle joint.

The fossil matched up best with a chipmunk-sized creature called Donrussellia provincialis.

Previously only known from jaws and teeth, Donrussellia is thought be one of the earliest members of the primate family tree, on the branch leading to lemurs, lorises and bush babies.

Duke University assistant professor Doug Boyer and colleagues studied scans of Donrussellia's ankle and compared it to other animals, using computer algorithms to analyze the 3-D digital shape of each tiny bone.

They were surprised to find that Donrussellia's ankle was not like those of other primates, but was more similar to those of treeshrews and other nonprimate species.

The team's analyses also suggest the animal didn't just clamber or scurry along small branches. Instead, it may have been able to bound between trunks and branches, using its grasping feet to stick the landing.

The researchers say that -- contrary to what many scientists thought -- the first primates may have evolved their acrobatic leaping skills first, while anatomical changes that allowed them to cling to slender branch tips and creep from tree to tree came later.

"Being able to jump from one tree to another might have been important, especially if there were ground predators around waiting to snag them," Boyer said.

Author: Robin Ann Smith | Source: Duke University [September 11, 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.