Two-faced fish clue that our ancestors ‘weren’t shark-like’
An investigation of a 415 million year-old fish skull strongly suggests that the last common ancestor of all jawed vertebrates, including humans, was not very shark-like. It adds further weight to the growing idea that sharks are not ‘primitive’.
The fossil skull’s external features meant it had always been thought to belong to the bony fishes (osteichthyans), a group which includes familiar fishes such as cod and tuna as well as all land-dwelling creatures with backbones. But when scientists from Oxford University and Imperial College London used X-ray CT scanning to look inside the skull they found the structure surrounding the brain was reminiscent of cartilaginous fishes (chondrichthyans) such as sharks and rays. The fish fossil’s ‘two faces’ led to it being named Janusiscus after the double-faced Roman god Janus.
A report of the research is published in the journal Nature.
‘This 415 million year-old fossil gives us an intriguing glimpse of the ‘Age of Fishes’, when modern groups of vertebrates were really beginning to take off in an evolutionary sense,’ said Dr Matt Friedman of Oxford University’s Department of Earth Sciences, an author of the report. ‘It tells us that the ancestral jawed vertebrate probably doesn’t fit into our existing categories.’
Chondrichthyans have often been viewed as primitive, and treated as proxies for what the ‘ancestral’ jawed vertebrate would have looked like. A key component of this view is the lack of a bony skeleton in cartilaginous fishes.
‘The results from our analysis help to turn this view on its head: the earliest jawed vertebrates would have looked somewhat more like bony fishes, at least externally, with large dermal plates covering their skulls,’ said Sam Giles of Oxford University’s Department of Earth Sciences, first author of the report. ‘In fact, they would have had a mix of what are now viewed as cartilaginous- and bony fish-like features, supporting the idea that both groups became independently specialised later in their separate evolutionary histories.’
Dr Friedman said: ‘This mix of features, some reminiscent of bony fishes and others cartilaginous fishes, suggests that humans may have just as many features that you might call ‘primitive’ as sharks.’
The fossil skull was originally found near the Sida River in Siberia in 1972 and is currently held in the Institute of Geology at the Tallinn University of Technology, Estonia. Study author Martin Brazeau of Imperial College London spotted the specimen in an online catalogue and the team decided it would be worth studying in greater detail using modern investigative techniques.
The team then used X-ray CT (computed tomography) to ‘virtually’ cut through the fossil. Different materials attenuate X-rays to different amounts — just as in a hospital X-ray, bones show up brighter than muscles and skin. This same principle can be applied to fossils, as fossilised bone and rock attenuate X-rays to different degrees. This technique was used to build a 3D virtual model of the fossil, enabling its internal and external features to be examined in great detail. Traces left by networks of blood vessels and nerves, often less than 1/100th of a centimetre in diameter, could then be compared to structure in a variety of jawed vertebrate groups, including sharks and bony fishes.
‘Losing your bony skeleton sounds like a pretty extreme adaptation,’ said Dr Friedman, ‘but with remarkable discoveries from China, Janusiscus strongly suggests that that the ancient ancestors of modern sharks and their kin started out just as ‘bony’ as our own ancestors.’
Ancient fossils reveal rise in parasitic infections due to climate change
When seeking clues about the future effects of possible climate change, sometimes scientists look to the past. Now, a paleobiologist from the University of Missouri has found indications of a greater risk of parasitic infection due to climate change in ancient mollusk fossils. His study of clams from the Holocene Epoch (that began 11,700 years ago) indicates that current sea level rise may mimic the same conditions that led to an upsurge in parasitic trematodes, or flatworms, he found from that time. He cautions that an outbreak in human infections from a related group of parasitic worms could occur and advises that communities use the information to prepare for possible human health risks.
rematodes are internal parasites that affect mollusks and other invertebrates inhabiting estuarine environments, which are the coastal bodies of brackish water that connect rivers and the open sea. John Huntley, assistant professor of geological sciences in the College of Arts and Science at MU, studied prehistoric clam shells collected from the Pearl River Delta in China for clues about how the clams were affected by changes caused from global warming and the resulting surge in parasites.
“Because they have soft bodies, trematodes do not leave body fossils,” Huntley said. “However, infected clam shells develop oval-shaped pits where the clam grew around the parasite in order to keep it out; the prevalence of these pits and their makeup provide clues to how the clams adapted to fight trematodes. When compared to documented rises in sea level more than 9,300 years ago, we found that we currently are creating conditions for an increase in trematodes in present-day estuarine environments. This could have harmful implications for both animal and human health, including many of the world’s fisheries.”
Modern-day trematodes will first infest mollusks like clams and snails, which are eaten by shore birds and mammals including humans. Symptoms of infection in humans range from liver and gall bladder inflammation to chest pain, fever, and brain inflammation. The infections can be fatal. At least 56 million people globally suffer from one or more foodborne trematode infections, according to the World Health Organization.
Huntley and his team compared these findings to those from his previous study on clams found in the Adriatic Sea. Using data that includes highly detailed descriptions of climate change and radiocarbon dating Huntley noticed a rising prevalence of pits in the clam shells, indicating a higher prevalence of the parasites during times of sea level rise in both the fossils from China and Italy.
“By comparing the results we have from the Adriatic and our new study in China, we’re able to determine that it perhaps might not be a coincidence, but rather a general phenomenon,” Huntley said. “While predicting the future is a difficult game, we think we can use the correspondence between the parasitic prevalence and past climate change to give us a good road map for the changes we need to make.”
Study casts doubt on mammoth-killing cosmic impact
Rock soil droplets formed by heating most likely came from Stone Age house fires and not from a disastrous cosmic impact 12,900 years ago, according to new research from the University of California, Davis. The study, of soil from Syria, is the latest to discredit the controversial theory that a cosmic impact triggered the Younger Dryas cold period.
The Younger Dryas lasted a thousand years and coincided with the extinction of mammoths and other great beasts and the disappearance of the Paleo-Indian Clovis people. In the 1980s, some researchers put forward the idea that the cool period, which fell between two major glaciations, began when a comet or meteorite struck North America.
In the new study, published online in the Journal of Archaeological Science, scientists analyzed siliceous scoria droplets — porous granules associated with melting — from four sites in northern Syria dating back 10,000 to 13,000 years ago. They compared them to similar scoria droplets previously suggested to be the result of a cosmic impact at the onset of the Younger Dryas.
“For the Syria side, the impact theory is out,” said lead author Peter Thy, a project scientist in the UC Davis Department of Earth and Planetary Sciences. “There’s no way that can be done.”
The findings supporting that conclusion include:
The composition of the scoria droplets was related to the local soil, not to soil from other continents, as one would expect from an intercontinental impact.
The texture of the droplets, thermodynamic modeling and other analyses showed the droplets were formed by short-lived heating events of modest temperatures, and not by the intense, high temperatures expected from a large impact event.
And in a key finding, the samples collected from archaeological sites spanned 3,000 years. “If there was one cosmic impact,” Thy said, “they should be connected by one date and not a period of 3,000 years.”
So if not resulting from a cosmic impact, where did the scoria droplets come from? House fires. The study area of Syria was associated with early agricultural settlements along the Euphrates River. Most of the locations include mud-brick structures, some of which show signs of intense fire and melting. The study concludes that the scoria formed when fires ripped through buildings made of a mix of local soil and straw
First herbivorous ornithischian dinosaur fossil from Malaysia
UMs palaeontologists, Masatoshi Sone and Teng Yu He, reveal that the dinosaur remain is identified to be a tooth of an ornithischian dinosaur, known herbivorous. The new dinosaur tooth (UM10580) is about 13 mm long and 10.5 mm wide in preserved dimension. It is medium to large size for an herbivorous ornithischian tooth.
The tooth has a defined neck and a large expanded crown with a cingulum, a thick ridge round the base of the crown, indicative of an ornithischian tooth. The new material was discovered from a Cretaceous sedimentary rock formation in Pahang, where the carnivorous spinosaurid teeth were reported earlier this year.
In addition to the last carnivorous dinosaur discovery, the present find implies the fact that there was an established vegetated terrestrial ecosystem in Peninsular Malaysia during the Cretaceous period (65–145 million years ago) of late Mesozoic time.
It is plausible that large dinosaur fossil deposits still remain in Malaysia. UM’s research team has currently carried out extensive field investigation around the country that may disclose more significant finds in a near future.
Oldest stone tool ever found in Turkey discovered
Scientists have discovered the oldest recorded stone tool ever to be found in Turkey, revealing that humans passed through the gateway from Asia to Europe much earlier than previously thought, approximately 1.2 million years ago.
According to research published in the journal Quaternary Science Reviews, the chance find of a humanly-worked quartzite flake, in ancient deposits of the river Gediz, in western Turkey, provides a major new insight into when and how early humans dispersed out of Africa and Asia.
Researchers from Royal Holloway, University of London, together with an international team from the UK, Turkey and the Netherlands, used high-precision equipment to date the deposits of the ancient river meander, giving the first accurate timeframe for when humans occupied the area.
Professor Danielle Schreve, from the Department of Geography at Royal Holloway, said: “This discovery is critical for establishing the timing and route of early human dispersal into Europe. Our research suggests that the flake is the earliest securely-dated artefact from Turkey ever recorded and was dropped on the floodplain by an early hominin well over a million years ago.”
The researchers used high-precision radioisotopic dating and palaeomagnetic measurements from lava flows, which both pre-date and post-date the meander, to establish that early humans were present in the area between approximately 1.24 million and 1.17 million years ago. Previously, the oldest hominin fossils in western Turkey were recovered in 2007 at Koçabas, but the dating of these and other stone tool finds were uncertain.
“The flake was an incredibly exciting find,” Professor Schreve said. “I had been studying the sediments in the meander bend and my eye was drawn to a pinkish stone on the surface. When I turned it over for a better look, the features of a humanly-struck artefact were immediately apparent.
“By working together with geologists and dating specialists, we have been able to put a secure chronology to this find and shed new light on the behaviour of our most distant ancestors.”
550-million-year-old fossils provide new clues about fossil formation
A new study from University of Missouri and Virginia Tech researchers is challenging accepted ideas about how ancient soft-bodied organisms become part of the fossil record. Findings suggest that bacteria involved in the decay of those organisms play an active role in how fossils are formed — often in a matter of just a few tens to hundreds of years. Understanding the relationship between decay and fossilization will inform future study and help researchers interpret fossils in a new way.
The vast majority of the fossil record is composed of bones and shells,” said James Schiffbauer, assistant professor of geological sciences in the College of Arts and Science at MU. “Fossils of soft-bodied animals like worms and jellyfish, however, provide our only views onto the early evolution of animal life. Most hypotheses as to the preservation of these soft tissues focus on passive processes, where normal decay is halted or impeded in some way, such as by sealing off the sediments where the animal is buried. Our team is instead detailing a scenario where the actual decay helped ‘feed’ the process turning the organisms into fossils — in this case, the decay of the organisms played an active role in creating fossils.”
Schiffbauer studied a type of fossil animal from the Ediacaran Period called Conotubus, which lived more than 540 million years ago. He noted that these fossils are either replicated by, or associated with, pyrite — commonly called fool’s gold. The tiny fossils are tube-shaped and believed to have been composed of substances similar at least in hardness to human fingernails. These fossilized tubes are all that remain of the soft-bodied animals that inhabited them and most likely resembled worms or sea anemone-like animals.
“Most of the animals that had once lived on the Earth — with estimates eclipsing 10 billion species — were never preserved in the fossil record, but in our study we have a spectacular view of a tinier fraction of soft-bodied animals,” said Shuhai Xiao, professor of geobiology at Virginia Tech and a co-author on this study. “We asked the important questions of how, and under what special conditions, these soft-tissued organisms can escape the fate of complete degradation and be preserved in the rock record.”
Schiffbauer and his team performed a sophisticated suite of chemical analyses of these fossils to determine what caused the pyrite to form. They found that the fool’s gold on the organisms’ outer tube formed when bacteria first began consuming the animal’s soft tissues, with the decay actually promoting the formation of pyrite.
“Normally, the Earth is good at cleaning up after itself,” Schiffbauer said. “In this case, the bacteria that helped break down these organisms also are responsible for preserving them as fossils. As the decay occurred, pyrite began replacing and filling in space within the animal’s exoskeleton, preserving them. Additionally, we found that this process happened in the space of a few years, perhaps even as low as 12 to 800. Ultimately, these new findings will help scientists to gain a better grasp of why these fossils are preserved, and what features represent the fossilization process versus original biology, so we can better reconstruct the evolutionary tree of life.”
Asteroid that wiped out dinosaurs may have nearly knocked off mammals, too
The extinction of the dinosaurs 66 million years ago is thought to have paved the way for mammals to dominate, but a new study shows that many mammals died off alongside the dinosaurs.
Metatherian mammals — the extinct relatives of living marsupials (“mammals with pouches,” such as opossums) — thrived in the shadow of the dinosaurs during the Cretaceous period. The new study, by an international team of experts on mammal evolution and mass extinctions, shows that these once-abundant mammals nearly followed the dinosaurs into oblivion.
When a 10-km-wide asteroid struck what is now Mexico at the end of the Cretaceous and unleashed a global cataclysm of environmental destruction, some two-thirds of all metatherians living in North America perished. This includes more than 90% of species living in the northern Great Plains of the USA, the best area in the world for preserving latest Cretaceous mammal fossils.
In the aftermath of the mass extinction, metatherians would never recover their previous diversity, which is why marsupial mammals are rare today and largely restricted to unusual environments in Australia and South America.
Taking advantage of the metatherian demise were the placental mammals: species that give live birth to well-developed young. They are ubiquitous across the globe today and include everything from mice to men.
Dr. Thomas Williamson of the New Mexico Museum of Natural History and Science, lead author on the study, said: “This is a new twist on a classic story. It wasn’t only that dinosaurs died out, providing an opportunity for mammals to reign, but that many types of mammals, such as most metatherians, died out too — this allowed advanced placental mammals to rise to dominance.”
Dr. Steve Brusatte of the University of Edinburgh’s School of GeoSciences, an author on the report, said: “The classic tale is that dinosaurs died out and mammals, which had been waiting in the wings for over 100 million years, then finally had their chance. But our study shows that many mammals came perilously close to extinction. If a few lucky species didn’t make it through, then mammals may have gone the way of the dinosaurs and we wouldn’t be here.”
The new study is published in the open access journal ZooKeys. It reviews the Cretaceous evolutionary history of metatherians and provides the most up-to-date family tree for these mammals based on the latest fossil records, which allowed researchers to study extinction patterns in unprecedented detail.
Dr. Gregory Wilson of the University of Washington also took part in the study.
The work was supported by the US National Science Foundation and the European Commission.
Fossils found in Siberia suggest all dinosaurs could have been feathered
The first ever example of a plant-eating dinosaur with feathers and scales has been discovered in Russia. Previously only flesh-eating dinosaurs were known to have had feathers, so this new find raises the possibility that all dinosaurs could have been feathered.
The new dinosaur, named Kulindadromeus zabaikalicus as it comes from a site called Kulinda on the banks of the Olov River in Siberia, is described in a paper recently published in Science.
Kulindadromeus shows epidermal scales on its tail and shins, and short bristles on its head and back. The most astonishing discovery, however, is that it also has complex, compound feathers associated with its arms and legs.
Birds arose from dinosaurs over 150 million years ago so it was no surprise when dinosaurs with feathers were found in China in 1996. But all those feathered dinosaurs were theropods, flesh-eating dinosaurs that include the direct ancestors of birds.
Lead author Dr Pascal Godefroit from the Royal Belgian Institute of Natural History in Brussels said: “I was really amazed when I saw this. We knew that some of the plant-eating ornithischian dinosaurs had simple bristles, and we couldn’t be sure whether these were the same kinds of structures as bird and theropod feathers. Our new find clinches it: all dinosaurs had feathers, or at least the potential to sprout feathers.”
The Kulinda site was found in summer 2010 by Professor Dr Sofia Sinitsa from the Institute of Natural Resources, Ecology and Cryology SB RAS in Chita, Russia. In 2013, the Russian-Belgian team excavated many dinosaur fossils, as well as plant and insect fossils.
The feathers were studied by Dr Maria McNamara (University of Bristol and University College, Cork) and Professor Michael Benton (University of Bristol), who has also worked on the feathers of Chinese dinosaurs, and Professor Danielle Dhouailly (Université Joseph Fourier in Grenoble, France) who is a specialist on the development of feathers and scales in modern reptiles and birds.
Dr McNamara said: “These feathers are really very well preserved. We can see each filament and how they are joined together at the base, making a compound structure of six or seven filaments, each up to 15mm long.”
Professor Dhouailly said: “Developmental experiments in modern chickens suggest that avian scales are aborted feathers, an idea that explains why birds have scaly legs. The astonishing discovery is that the molecular mechanisms needed for this switch might have been so clearly related to the appearance of the first feathers in the earliest dinosaurs.”
Kulindadromeus was a small plant-eater, only about 1m long. It had long hind legs and short arms, with five strong fingers. Its snout was short, and its teeth show clear adaptations to plant eating. In evolutionary terms, it sits low in the evolutionary tree of ornithischian dinosaurs. There are six skulls and several hundred partial skeletons of this new dinosaur at the Kulinda locality.
This discovery suggests that feather-like structures were likely widespread in dinosaurs, possibly even in the earliest members of the group. Feathers probably arose during the Triassic, more than 220 million years ago, for purposes of insulation and signalling, and were only later co-opted for flight. Smaller dinosaurs were probably covered in feathers, mostly with colourful patterns, and feathers may have been lost as dinosaurs grew up and became larger.
Decades-old amber collection offers new views of a lost world: Tiny grasshopper encased in amber
Scientists are searching through a massive collection of 20-million-year-old amber found in the Dominican Republic more than 50 years ago, and the effort is yielding fresh insights into ancient tropical insects and the world they inhabited.
When the collection is fully curated, a task that will take many years, it will be the largest unbiased Dominican amber collection in the world, the researchers report.
Perhaps the most striking discovery thus far is that of a pygmy locust, a tiny grasshopper the size of a rose thorn that lived 18- to 20-million years ago and fed on moss, algae and fungi. The specimen is remarkable because it represents an intermediate stage of evolution in the life of its subfamily of locusts (known as the Cladonotinae). The most ancient representatives of this group had wings, while modern counterparts do not. The newly discovered locust has what appear to be vestigial wings — remnant structures that had already lost their primary function.
The discovery is reported in the journal ZooKeys.
“Grasshoppers are very rare in amber and this specimen is extraordinarily well-preserved,” said Sam Heads, a paleontologist at the Illinois Natural History Survey, a division of the Prairie Research Institute at the University of Illinois.
Heads, laboratory technician Jared Thomas and study co-author Yinan Wang found the new specimen a few months after the start of their project to screen more than 160 pounds of Dominican amber collected in the late 1950s by former INHS entomologist Milton Sanderson. Sanderson described several specimens from the collection in a paper in Science in 1960, a report that inspired a generation of scientists to seek out and study Dominican amber, Heads said.
The bulk of the Sanderson amber collection remained in storage, however, until Heads uncovered it in 2010.
Heads has named the new pygmy locust Electrotettix attenboroughi, the genus name a combination of electrum (Latin from Greek, meaning “amber”) and tettix (Greek, meaning “grasshopper”). The species is named for Sir David Attenborough, a British naturalist and filmmaker (not to be confused with Richard Attenborough, David’s actor brother who appeared in the movie “Jurassic Park”).
“Sir David has a personal interest in amber, and also he was one of my childhood heroes and still is one of my heroes and so I decided to name the species in his honor — with his permission of course,” Heads said. (Attenborough narrates and appears in a new video about the Sanderson collection and the specimen that bears his name.)
The process of screening the amber is slow and painstaking. Much of the amber is clouded with oxidation, and the researchers must carefully cut and polish “windows” in it to get a good look at what’s inside. In addition to the pygmy locust, Heads and his colleagues have found mating flies, stingless bees, gall midges, Azteca ants, wasps, bark beetles, mites, spiders, plant parts and even a mammal hair.
The pygmy locust was found in a fragment that also contained wasps, ants, midges, plant remnants and fungi. Such associations are rich in information, Heads said, offering clues about the creatures’ physiological needs and the nature of their habitat.
“Fossil insects can provide lots of insight into the evolution of specific traits and behaviors, and they also tell us about the history of the time period,” Heads said. “They’re a tremendous resource for understanding the ancient world, ancient ecosystems and the ancient climate — better even, perhaps, than dinosaur bones.”
The National Science Foundation supports this work. Heads and his colleagues are digitizing the best specimens, and will upload the images onto a publicly available website.
Unique images bring fossil insects back to life
A groundbreaking new book that brings together two of the major disciplines behind Jurassic Park is aiming to raise the profile of insect fossils through stunning photographs and unique illustrations.
Fossil Insects, by Dr David Penney and James E Jepson, details the incredible preservation and diversity of fossilised insects from around the world, setting the scene for what these remarkable fossils can tell us about the ancient and modern worlds, and even the future of our planet. Like the mosquito in Jurassic Park, many of the hundreds of thousands of specimens of ancient insect have been preserved in amber.
Using pioneering scientific methods and state of the art technology Dr David Penney from The University of Manchester has drawn on his knowledge of both entomology and palaeontology to discover some astonishing things about these fossilized creatures during the course of his research.
He says: “Insects are the most diverse group of creatures on the planet today. Many of them were around even before the time of the dinosaurs. Bringing together entomology and palaeontology through the study of insect fossils has great potential for revolutionising what we know about both subjects.”
The ancient insects have been brought to life in the book through illustrations that for the first time depict long vanished arthropods living among the flora and fauna during the age of the dinosaurs. In a unique collaboration the artist Richard Bizley has created seven reconstructions of each of the major periods from the Devonian through to the Tertiary.
To make the animals in his paintings look realistic, Richard created models using scientific drawings and pictures of fossils. He then photographed them to see how the light behaves.
Richard says: “When reconstructing fossil insect species, special attention needs to be paid to important diagnostic features, such as the wing venation patterns and the relative lengths of appendage segments. The fact that many fossil insect species are known only from isolated wings posed additional problems. This is where the collaboration with experts became very useful and I worked closely with Dr Penney to produce an accurate reconstruction based on the comparative study of both fossil and living insects.”
He continues: “Plants can be difficult, especially as we are unsure how some of them looked. It is rare to get a fossil of a whole plant, so I had to paint according to the best estimation of how they looked, using the evidence available. Fortunately, scientists have learnt enough to provide some good ideas and many living plants are closely related to those that have become extinct.”
Whilst Jurassic Park remains a fantasy for now Dr Penney says the book and the film did result in an increase in research on fossil insects. He’s now hoping that his book, Fossil Insects, will open up the research to even more people.
He says: “This is the first book to merge these two disciplines in an accessible way, using plain and simple language. It is a book for anyone with a passion for palaeontology and/or entomology.”