Marine fish won an evolutionary lottery 66 million years ago

Why do our oceans contain such a staggering diversity of fish of so many different sizes, shapes and colors? A UCLA-led team of biologists reports that the answer dates back 66 million years, when a six-mile-wide asteroid crashed to Earth, wiping out the dinosaurs and approximately 75 percent of the world’s animal and plant species.

Slightly more than half of today’s fish are “marine fish,” meaning they live in oceans. And most marine fish, including tuna, halibut, grouper, sea horses and mahi-mahi, belong to an extraordinarily diverse group called acanthomorphs. (The study did not analyze the large numbers of other fish that live in lakes, rivers, streams, ponds and tropical rainforests.)

The aftermath of the asteroid crash created an enormous evolutionary void, providing an opportunity for the marine fish that survived it to greatly diversify.

“Today’s rich biodiversity among marine fish shows the fingerprints of the mass extinction at the end of the Cretaceous period,” said Michael Alfaro, a professor of ecology and evolutionary biology in the UCLA College and lead author of the study.

To analyze those fingerprints, the “evolutionary detectives” employed a new genomics research technique developed by one of the authors. Their work is published in the journal Nature Ecology and Evolution.

When they studied the timing of the acanthomorphs’ diversification, Alfaro and his colleagues discovered an intriguing pattern: Although there were many other surviving lineages of acanthomorphs, the six most species-rich groups of acanthomorphs today all showed evidence of substantial evolutionary change and proliferation around the time of the mass extinction. Those six groups have gone on to produce almost all of the marine fish diversity that we see today, Alfaro said.

He added that it’s unclear why the other acanthomorph lineages failed to diversify as much after the mass extinction.

“The mass extinction, we argue, provided an evolutionary opportunity for a select few of the surviving acanthomorphs to greatly diversify, and it left a large imprint on the biodiversity of marine fishes today,” Alfaro said. “It’s like there was a lottery 66 million years ago, and these six major acanthomorph groups were the winners.”

The findings also closely match fossil evidence of acanthomorphs’ evolution, which also shows a sharp rise in their anatomical diversity after the extinction.

The genomic technique used in the study, called sequence capture of DNA ultra-conserved elements, was developed at UCLA by Brant Faircloth, who is now an assistant professor of biological sciences at Louisiana State University. Where previous methods used just 10 to 20 genes to create an evolutionary history, Faircloth’s approach creates a more complete and accurate picture by using more than 1,000 genetic markers. (The markers include genes and other DNA components, such as parts of the DNA that turn proteins on or off, and cellular components that play a role in regulating genes.)

The researchers also extracted DNA from 118 species of marine fish and conducted a computational analysis to determine the relationships among them. Among their findings: It’s not possible to tell which species are genetically related simply by looking at them. Seahorses, for example, look nothing like goatfish, but the two species are evolutionary cousins — a finding that surprised the scientists.

“We demonstrate this approach works, and that it sheds new light on evolutionary history for the most species-rich group of marine vertebrates,” Alfaro said.

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First an alga, then a squid, enigmatic fossil is actually a fish

A fossil slab discovered in Kansas 70 years ago and twice misidentified — first as a green alga and then as a cephalopod — has been reinterpreted as the preserved remains of a large cartilaginous fish, the group that includes sharks and rays. In a study published in the Journal of Paleontology, American Museum of Natural History researchers describe the fishy characteristics of the animal, which lived between 70-85 million years ago.

“There are many examples of temporarily misplaced taxa in paleontological history, including ferns that were once thought to be sponges and lungfish teeth thought to be fungi,” said the lead author, Allison Bronson, a comparative biology Ph.D.-degree student in the Museum’s Richard Gilder Graduate School. “In this case, the misidentification didn’t happen because of a lack of technology at the time — scientists familiar with cartilage structure could easily see this was a chondrichthyan fish. The researchers used reasonable arguments for their interpretations, but didn’t look outside of their own fields.”

The enigmatic specimen, Platylithophycus cretaceum, is roughly 1.5-feet long by 10-inches wide and from the Niobrara Formation in Kansas. The Niobrara Formation is one of the most diverse fish-fossil sites in North America, preserving late Cretaceous animals that lived in and around the Western Interior Seaway, a broad expanse of water that split North America into two land masses.

In 1948, two paleobotanists from the Colorado School of Mines and Princeton University compared the texture of the fossil slab with that of green algae. They described two parts of a plant: surfaces covered with hexagonal plates, which they called “fronds,” and supposedly calcium carbonate-covered thread-like filaments. In 1968, two researchers from Fort Hays Kansas State College studying cephalopods from the Niobrara Formation compared the specimen with a cuttlefish, based primarily on its textural similarities to a cuttlebone — the unique internal shell of cuttlefish. The reclassification made Platylithophycus the oldest sepiid squid then on record.

In both of these earlier studies, the hard tissue was assumed to be composed of calcium carbonate, but no tests were performed. For the new study, Bronson and co-author John Maisey, a curator in the Museum’s Division of Paleontology, applied a small amount of dilute organic acid to the specimen — a method that has been widely used in paleontology since the time of the initial description of Platylithophycus. If there is a reaction, the fossilized material is likely made from calcium carbonate. But if there is no reaction, which was the case when Bronson and Maisey performed the test, it is likely made from calcium phosphate, as are the fossilized skeletons of cartilaginous fish like sharks and rays.

The most obvious clue that Platylithophycus was a cartilaginous fish are the hexagonal plates on the surface of the specimen. After taking a closer look with a scanning electron microscope, Bronson and Maisey reinterpreted that feature as tessellated calcified cartilage, found on both extinct and living sharks and rays. The new study suggests that the “filaments” earlier described are actually part of the gill arches, made up of tessellated cartilage. Gill arches are cartilaginous curved bars along the pharynx, or throat, that support the gills of fish. The “fronds” are reinterpreted as gill rakers, finger-like projections that extend from the gill arches and help with feeding.

“We think this was a rather large cartilaginous fish, possibly related to living filter-feeding rays such as Manta and Mobula,” Maisey said. “This potentially expands the range of diversity in the Niobrara fauna.”

But because this fossil only preserves the animal’s gills and no additional identifying features like teeth, it cannot be given a new name or reunited with an existing species. So until then, this fish will still carry the name of a plant.

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Most primitive kangaroo ancestor rediscovered after 30 years in obscurity

A handful of tiny teeth have led scientists to identify the most distant ancestor of today’s kangaroos. The fossils were found in the desert heart of Australia, and then hidden away, and almost forgotten in a museum collection for over three decades. The findings are published in the Journal of Vertebrate Paleontology.

Kangaroos are icons of Australia’s unique living fauna. However, their earliest ancestry is shrouded in mystery. At the beginning of the 1980’s, a few enigmatic molar teeth were excavated by palaeontologists hunting for fossils around a dry salt lake in northern South Australia. The rare specimens were recognised as an ancient kangaroo ancestor, but had to wait for over 30 years before modern computer-based analyses could confirm the significance of the discovery.

Originally dubbed Palaeopotorous priscus, Latin for ‘[very] ancient’, ‘ancient rat-kangaroo’, by the now eminent Australian palaeontologists Prof. Tim Flannery (University of Melbourne) and Dr Tom Rich (Museums Victoria), the importance of these remains was suggested in their first unveiling to science.

“The teeth of Palaeopotorous were initially described in 1986. Even then they were stated as representing possibly the most primitive relative of the entire modern kangaroo radiation. Yet, nobody ever evaluated this claim, and despite being occasionally mentioned in the scientific literature, they were never again examined in detail,” said Dr Wendy den Boer, who studied the fossils as part of her recently awarded PhD from Uppsala University in Sweden.

“The name Palaeopotorous was established using a single molar tooth, although, eleven other anatomically very similar teeth were recovered during the expedition. None of these fossils were found in association, so it is still unclear whether we are dealing with one, or more species,” said Dr Benjamin Kear, Dr den Boer’s PhD supervisor and co-author on the published article. “This uncertainly means that we have had to use a complex series of analyses to assess its morphological similarity and evolutionary relationships relative to other members of the kangaroo family tree.”

“Our results showed that Palaeopotorous was most similar to living rat-kangaroos, as well as some other extinct kangaroo relatives. Using information from fossils, and the DNA of living species, we were able to further determine that at around 24 million years old, Palaeopotorous is not just primitive, but likely represents the most distant forerunner of all known kangaroos, rat-kangaroos and their more ancient ancestors,” said Dr den Boer.

“Palaeopotorous was about the size of a small rabbit, and probably did not hop, but would have bounded on all four legs. Nevertheless, a few bones found at the same site in central Australia indicate that the earliest kangaroos already possessed some key adaptations for hopping gaits,” said Dr Kear.

Palaeopotorous lived at a time when central Australia was much wetter than it is today. Its fossils were buried in clay deposits left by a river, but these earliest kangaroo ancestors would have foraged amongst vegetation growing nearby and along the banks. The teeth of Palaeopotorous were washed into the river after death, along with the remains of many other ancient marsupials.

The dinosaur menu, as revealed by calcium

By studying calcium in fossil remains in deposits in Morocco and Niger, researchers have been able to reconstruct the food chains of the past, thus explaining how so many predators could coexist in the dinosaurs’ time. This study, conducted by the Laboratoire de géologie de Lyon: Terre, planètes et environnement (CNRS/ENS de Lyon/Claude Bernard Lyon 1 University), in partnership with the Centre for Research on Palaeobiodiversity and Palaeoenvironments (CNRS/French National Museum of Natural History/Sorbonne University), is published on April 11, 2018 in the Proceedings of the Royal Society of London B.

A hundred million years ago, in North Africa, terrestrial ecosystems were dominated by large predators — giant theropod dinosaurs, large crocodiles — with comparatively few herbivores. How were so many carnivores able to coexist?

To understand this, French researchers have studied fossils in the Gadoufaoua deposits in Niger (dating from 120 million years ago) and the Kem Kem Beds in Morocco (dating from 100 million years ago). These two sites are characterized by an overabundance of predators compared to the herbivorous dinosaurs found in the locality. More specifically, the researchers measured the proportions of different calcium isotopes(1) in the fossilized remains (tooth enamel and fish scales).

Among vertebrates, calcium is almost exclusively derived from food. By comparing the isotopic composition of potential prey (fish, herbivores) with that of the carnivores’ teeth, it is thus possible to retrace the diet of those carnivores.

The data obtained show similar food preferences at the two deposits: some large carnivorous dinosaurs (abelisaurids and carcharodontosaurids) preferred to hunt terrestrial prey such as herbivorous dinosaurs, while others (the spinosaurids) were piscivorous (fish-eating).(2) The giant crocodile-like Sarcosuchus had a diet somewhere in between, made up of both terrestrial and aquatic prey. Thus, the different predators avoided competition by subtly sharing food resources.

Some exceptional fossils, presenting traces of feeding marks and stomach content, had already provided clues about the diet of dinosaurs. Yet such evidence remains rare. The advantage of the calcium isotope method is that it produces a global panorama of feeding habits at the ecosystem scale. It thus opens avenues for further study of the food chains of the past.

Rare Scottish dinosaur prints give key insight into era lost in time

Dozens of giant footprints discovered on a Scottish island are helping shed light on an important period in dinosaur evolution.

The tracks were made some 170 million years ago, in a muddy, shallow lagoon in what is now the north-east coast of the Isle of Skye.

Most of the prints were made by long-necked sauropods — which stood up to two metres tall — and by similarly sized theropods, which were the older cousins of Tyrannosaurus rex.

The find is globally important as it is rare evidence of the Middle Jurassic period, from which few fossil sites have been found around the world.

Researchers measured, photographed and analysed about 50 footprints in a tidal area at Brothers’ Point — Rubha nam Brathairean — a dramatic headland on Skye’s Trotternish peninsula.

The footprints were difficult to study owing to tidal conditions, the impact of weathering and changes to the landscape. In spite of this, scientists identified two trackways in addition to many isolated foot prints.

Researchers used drone photographs to make a map of the site. Additional images were collected using a paired set of cameras and tailored software to help model the prints.

Analysis of the clearest prints — including the overall shape of the track outline, the shape and orientation of the toes, and the presence of claws — enabled scientists to ascribe them to sauropods and theropods.

The study, carried out by the University of Edinburgh, Staffin Museum and Chinese Academy of Sciences, was published in the Scottish Journal of Geology. It was supported by a grant from the National Geographic Society, and subsidiary funding from the Association of Women Geologists, Derek and Maureen Moss, Edinburgh Zoo and Edinburgh Geological Society.

Paige dePolo, who led the study, conducted the research while an inaugural student in the University’s Research Master’s degree programme in palaeontology and geobiology.

Ms dePolo said: “This tracksite is the second discovery of sauropod footprints on Skye. It was found in rocks that were slightly older than those previously found at Duntulm on the island and demonstrates the presence of sauropods in this part of the world through a longer timescale than previously known. This site is a useful building block for us to continue fleshing out a picture of what dinosaurs were like on Skye in the Middle Jurassic.”

Dr Steve Brusatte of the University of Edinburgh’s School of GeoSciences, who led the field team, said: “The more we look on the Isle of Skye, the more dinosaur footprints we find. This new site records two different types of dinosaurs — long-necked cousins of Brontosaurus and sharp-toothed cousins of T. rex — hanging around a shallow lagoon, back when Scotland was much warmer and dinosaurs were beginning their march to global dominance.”

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127-million-year-old baby bird fossil sheds light on avian evolution

The tiny fossil of a prehistoric baby bird is helping scientists understand how early avians came into the world in the Age of Dinosaurs.

The fossil, which dates back to the Mesozoic Era (250-65 million years ago), is a chick from a group of prehistoric birds called, Enantiornithes. Made up of a nearly complete skeleton, the specimen is amongst the smallest known Mesozoic avian fossils ever discovered.

It measures less than five centimetres — smaller than the little finger on an average human hand — and would have weighed just three ounces when it was alive. What makes this fossil so important and unique is the fact it died not long after its birth. This is a critical stage in a bird’s skeletal formation. That means this bird’s extremely short life has given researchers a rare chance to analyse the species’ bone structure and development.

Studying and analysing ossification — the process of bone development — can explain a lot about a young bird’s life the researchers say. It can help them understand everything from whether it could fly or if it needed to stay with its parents after hatching or could survive on its own.

The lead author of the study, Fabien Knoll, from The University of Manchester’s Interdisciplinary Centre for Ancient Life (ICAL), School of Earth and Environmental Sciences, and the ARAID — Dinopolis in Spain explains: ‘The evolutionary diversification of birds has resulted in a wide range of hatchling developmental strategies and important differences in their growth rates. By analysing bone development we can look at a whole host of evolutionary traits.’

With the fossil being so small the team used synchrotron radiation to picture the tiny specimen at a ‘submicron’ level, observing the bones’ microstructures in extreme detail.

Knoll said: ‘New technologies are offering palaeontologists unprecedented capacities to investigate provocative fossils. Here we made the most of state-of-the-art facilities worldwide including three different synchrotrons in France, the UK and the United States.’

The researchers found the baby bird’s sternum (breastplate bone) was still largely made of cartilage and had not yet developed into hard, solid bone when it died, meaning it wouldn’t have been able to fly.

The patterns of ossification observed in this and the other few very young enantiornithine birds known to date also suggest that the developmental strategies of this particular group of ancient avians may have been more diverse than previously thought.

However, the team say that its lack of bone development doesn’t necessarily mean the hatchling was over reliant on its parents for care and feeding, a trait known as being ‘altricial’. Modern day species like love birds are highly dependent on their parents when born. Others, like chickens, are highly independent, which is known as ‘precocial’. Although, this is not a black-and-white issue, but rather a spectrum, hence the difficulty in clarifying the developmental strategies of long gone bird species.

Luis Chiappe, from the LA Museum of Natural History and study’s co-author added: ‘This new discovery, together with others from around the world, allows us to peek into the world of ancient birds that lived during the age of dinosaurs. It is amazing to realise how many of the features we see among living birds had already been developed more than 100 million years ago.’

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‘Rainbow’ dinosaur had iridescent feathers like a hummingbird

Scientists discovered a dinosaur fossil with feathers so well-preserved that they were able to see the feathers’ microscopic color-bearing structures. By comparing the shapes of those feather structures with the structures in modern bird feathers, they’re able to infer that the new dino, Caihong juji (‘rainbow with the big crest’) had iridescent rainbow feathers like a hummingbird.

Birds are the last remaining dinosaurs. They’re also some of the most vibrantly colored animals on Earth. A new study in Nature Communications reveals that iridescent feathers go way back — a newly discovered species of dinosaur from 161 million years ago had rainbow coloring.

Caihong juji was tiny, about the size of a duck, with a bony crest on its head and long, ribbon-like feathers. And, based on analysis of its fossilized feathers, the feathers on its head, wings, and tail were probably iridescent, with colors that shimmered and shifted in the light. Its name reflects its appearance — in Mandarin, it means, “rainbow with the big crest.” The new species, which was first discovered by a farmer in northeastern China, was described by an international team of scientists led by Dongyu Hu, a professor in the College of Paleontology at the Shenyang Normal University in China.

“When you look at the fossil record, you normally only see hard parts like bone, but every once in a while, soft parts like feathers are preserved, and you get a glimpse into the past,” says Chad Eliason, a postdoctoral researcher at The Field Museum and one of the study’s authors. Eliason, who began work on the project as a postdoctoral fellow at the University of Texas at Austin, added, “The preservation of this dinosaur is incredible, we were really excited when we realized the level of detail we were able to see on the feathers.”

When the scientists examined the feathers under powerful microscopes, they could see the imprints of melanosomes, the parts of cells that contain pigment. For the most part, the pigment that was once present was long gone, but the physical structure of the melanosomes remained. As it turns out, that was enough for scientists to be able to tell what color the feathers were.

That’s because color isn’t only determined by pigment, but by the structure of the melanosomes containing that pigment. Differently shaped melanosomes reflect light in different colors. “Hummingbirds have bright, iridescent feathers, but if you took a hummingbird feather and smashed it into tiny pieces, you’d only see black dust. The pigment in the feathers is black, but the shapes of the melanosomes that produce that pigment are what make the colors in hummingbird feathers that we see,” explains Eliason.

The scientists were able to match the shapes of the pancake-shaped melanosomes in Caihong with the shapes of melanosomes in birds alive today. By finding birds with similarly shaped melanosomes, they were able to determine what kinds of colors Caihong may have flashed. The best matches: hummingbirds.

Colorful plumage is used in modern birds to attract mates — the rainbow feathers of Caihong might be a prehistoric version of a peacock’s iridescent tail. Caihong is the oldest known example of platelet-shaped melanosomes typically found in bright iridescent feathers.

It’s also the earliest known animal with asymmetrical feathers — a feature used by modern birds to steer when flying. Caihong couldn’t fly, though — its feathers were probably primarily used to attract mates and keep warm. While modern birds’ asymmetrical feathers are on their wingtips, Caihong’s were on its tail. “The tail feathers are asymmetrical but wing feathers not, a bizarre feature previously unknown among dinosaurs including birds,” said co-author Xing Xu of the Chinese Academy of Science. “This suggests that controlling [flight] might have been first evolved with tail feathers during some kind of aerial locomotion.”

But while Caihong’s feathers were a first, it had other traits associated with much earlier species of dinosaurs, including the bony crest on its head. “This combination of traits is rather unusual,” says co-author Julia Clarke of the University of Texas at Austin. “It has a velociraptor-type skull on the body of this very avian, fully feathered, fluffy kind of form.”

This combination of old and new traits, says Eliason, is evidence of mosaic evolution, the concept of different traits evolving independently from each other. “This discovery gives us insight into the tempo of how fast these features were evolving,” he adds.

For Eliason, the study also illuminates the value of big data. “To find the color of Caihong’s feathers, we compared its melanosomes with a growing database of thousands of measurements of melanosomes found in modern birds,” he says. It’s also broadened his own research interests.

“I came out of the project with a whole different set of questions that I wanted answers to — when I open up a drawer full of birds in the Field Museum’s collections, now I want to know when those iridescent feathers first developed, and how.”

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Origins of photosynthesis in plants dated to 1.25 billion years ago

The world’s oldest algae fossils are a billion years old, according to a new analysis by earth scientists at McGill University. Based on this finding, the researchers also estimate that the basis for photosynthesis in today’s plants was set in place 1.25 billion years ago.

The study, published in the journal Geology, could resolve a long-standing mystery over the age of the fossilized algae, Bangiomorpha pubescens, which were first discovered in rocks in Arctic Canada in 1990. The microscopic organism is believed to be the oldest known direct ancestor of modern plants and animals, but its age was only poorly dated, with estimates placing it somewhere between 720 million and 1.2 billion years.

The new findings also add to recent evidence that an interval of Earth’s history often referred to as the Boring Billion may not have been so boring, after all. From 1.8 to 0.8 billion years ago, archaea, bacteria and a handful of complex organisms that have since gone extinct milled about the planet’s oceans, with little biological or environmental change to show for it. Or so it seemed. In fact, that era may have set the stage for the proliferation of more complex life forms that culminated 541 million years ago with the so-called Cambrian Explosion.

“Evidence is beginning to build to suggest that Earth’s biosphere and its environment in the latter portion of the ‘Boring Billion’ may actually have been more dynamic than previously thought,” says McGill PhD student Timothy Gibson, lead author of the new study.

Pinpointing the fossils’ age

To pinpoint the fossils’ age, the researchers pitched camp in a rugged area of remote Baffin Island, where Bangiomorpha pubescens fossils have been found There,despite the occasional August blizzard and tent-collapsing winds, they collected samples of black shale from rock layers that sandwiched the rock unit containing fossils of the alga. Using the Rhenium-Osmium (or Re-Os) dating technique, applied increasingly to sedimentary rocks in recent years, they determined that the rocks are 1.047 billion years old.

“That’s 150 million years younger than commonly held estimates, and confirms that this fossil is spectacular,” says Galen Halverson, senior author of the study and an associate professor in McGill’s Department of Earth and Planetary Sciences. “This will enable scientists to make more precise assessments of the early evolution of eukaryotes,” the celled organisms that include plants and animals.

Because Bangiomorpha pubescens is nearly identical to modern red algae, scientists have previously determined that the ancient alga, like green plants, used sunlight to synthesize nutrients from carbon dioxide and water. Scientists have also established that the chloroplast, the structure in plant cells that is the site of photosynthesis, was created when a eukaryote long ago engulfed a simple bacterium that was photosynthetic. The eukaryote then managed to pass that DNA along to its descendants, including the plants and trees that produce most of the world’s biomass today.

Origins of the chloroplast

Once the researchers had gauged the fossils’ age at 1.047 billion years, they plugged that figure into a “molecular clock,” a computer model used to calculate evolutionary events based on rates of genetic mutations. Their conclusion: the chloroplast must have been incorporated into eukaryotes roughly 1.25 billion years ago.

“We expect and hope that other scientists will plug this age for Bangiomorpha pubescens into their own molecular clocks to calculate the timing of important evolutionary events and test our results,” Gibson says. “If other scientists envision a better way to calculate when the chloroplast emerged, the scientific community will eventually decide which estimate seems more reasonable and find new ways to test it.”

Synchrotron sheds light on the amphibious lifestyle of a new raptorial dinosaur

An exceptionally well-preserved dinosaur skeleton from Mongolia unites an unexpected combination of features that defines a new group of semi-aquatic predators related to Velociraptor. Detailed 3D synchrotron analysis allowed an international team of researchers to present the bizarre 75 million-year-old predator, named Halszkaraptor escuilliei, in Nature. The study not only describes a new genus and species of bird-like dinosaur that lived during the Campanian stage of the Cretaceous in Mongolia but also sheds light on an unexpected amphibious lifestyle for raptorial dinosaurs.

Theropods encompass all carnivorous dinosaurs, including the largest land-living predators in the history of life on Earth, such as Tyrannosaurus, and iconic agile hunters like Velociraptor. During 160 million years of the Mesozoic Era, theropods became the dominant predators on all continents, yet never conquered aquatic environments. Although some theropods reportedly incorporated fish in their diet, proposed indications for aquatic locomotion associated with exclusively aquatic lifestyles remain controversial.

A swan-necked and flipper-forelimbed new dinosaur species that combines an unexpected mix of features now demonstrates that some bird-like dinosaurs did adopt a semi-aquatic lifestyle. The fossil, nicknamed “Halszka” for Halszkaraptor escuilliei, was found at Ukhaa Tolgod. This locality in southern Mongolia has been known by palaeontologists for decades and is often targeted by poachers. “Illicit fossil trade presents a great challenge to modern palaeontology and accounts for a dramatic loss of Mongolian scientific heritage,” says Pascal Godefroit of the Royal Belgian Institute of Natural Sciences in Brussels. “Illegally exported from Mongolia, Halszka resided in private collections around the world before it was acquired in 2015 and offered to palaeontologists for study and to prepare its return to Mongolia.”

Although several important groups of predatory dinosaurs have been discovered in Mongolia, Halszka does not belong to any of them, having a number of strange features that are mostly absent among dinosaurs, but are shared by reptilian and avian groups with aquatic or semiaquatic ecologies. “The first time I examined the specimen, I even questioned whether it was a genuine fossil” says Andrea Cau of the Geological Museum Capellini in Bologna. Although Halszka is unique in many ways, certain parts of the skeleton, including the sickle-shaped “killer claws” on its feet, are shared with well-known dinosaurs such as Velociraptor. “This unexpected mix of traits makes it difficult to place Halszka within traditional classifications,” Cau remarks.

In order to ascertain the integrity of the fossil, the specimen was visualised and reconstructed in three dimensions using synchrotron multi-resolution X-ray microtomography. “This technique is currently the most powerful and sensitive method to image internal details without damaging invaluable fossils. The ESRF has become the worldwide leader for high quality X-ray imaging of such precious specimens,” notes Paul Tafforeau of the ESRF. “We had to mobilise an ESRF team of palaeontologists to study the complete anatomy of Halzka. So far, it’s the specimen for which the greatest number of experiments were made on a single fossil,” adds Tafforeau.

“Our first goal was to demonstrate that this bizarre and unexpected fossil is indeed a genuine animal: multi-resolution scanning confirmed that the skeleton is not a composite assembled from parts of different dinosaurs,” explains Dennis Voeten of the ESRF. “We implemented new methods for the acquisition and optimisation of tomographic scan data, which not only confirmed the integrity of the specimen, but also revealed additional palaeontological information,” Vincent Fernandez of the ESRF clarifies.

The synchrotron was even able to reveal, in astonishing detail, those parts of the skeleton that have remained deep within the rock ever since the dinosaur got buried. “Our analysis demonstrated that numerous teeth, which are not visible externally, are still preserved inside the mouth,” says Vincent Beyrand of the ESRF. “We also identified a neurovascular mesh inside its snout that resembles those of modern crocodiles to a remarkable degree. These aspects suggest that Halszka was an aquatic predator.”

The ESRF data revealed that the fossil represents a new genus and species of amphibious dinosaur that walked on two legs on land, with postural adaptations similar to short-tailed birds (like ducks), but used its flipper-like forelimbs to manoeuvre in water (like penguins and other aquatic birds), relying on its long neck for foraging and ambush hunting.

This new species was named Halszkaraptor escuilliei. Its generic name honours the late palaeontologist Halszka Osmólska. “This important genus is named in recognition of Halszka’s contribution to the study of Mongolian dinosaurs from the Gobi,” comments Rinchen Barsbold of the Mongolian Academy of Sciences. “The specific name refers to François Escuillié and thereby acknowledges his role in the first recognition and in the return of this specimen to Mongolia,” adds Khishigjav Tsogtbaatar of the Institute of Paleontology and Geology in Ulaanbaatar.

Halszkaraptor is not the only strange dinosaur recovered from the Gobi. Several previously described enigmatic Mongolian theropods were closely related to the new species, the study found. United in a new group, named Halszkaraptorinae, “is an unexpected subfamily of dromaeosaurs — the group colloquially known as raptors. This bizarre subfamily appears to have evolved a lifestyle different from all other predatory dinosaurs,” says Philip Currie of the University of Alberta.

“When we look beyond fossil dinosaurs, we find most of Halszkaraptor’s unusual features among aquatic reptiles and swimming birds,” concludes lead author Andrea Cau. “The peculiar morphology of Halszkaraptor fits best with that of an amphibious predator that was adapted to a combined terrestrial and aquatic ecology: a peculiar lifestyle that was previously unreported in these dinosaurs. Thanks to synchrotron tomography, we now demonstrate that raptorial dinosaurs not only ran and flew, but also swam!”

Early avian evolution: The Archaeopteryx that wasn‘t

Paleontologists at Ludwig-Maximilians-Universitaet (LMU) in Munich correct a case of misinterpretation: The first fossil “Archaeopteryx” to be discovered is actually a predatory dinosaur belonging to the anchiornithid family, which was previously known only from finds made in China.

Even 150 million years after its first appearance on our planet, Archaeopteryx is still good for surprises. The so-called Urvogel has attained an iconic status well beyond the world of paleontology, and it is one of the most famous fossils ever recovered. In all, a dozen fossil specimens have been assigned to the genus. Archaeopteryx remains the oldest known bird fossil, not only documenting the evolutionary transition from reptiles to birds, but also confirming that modern birds are the direct descendants of carnivorous dinosaurs. LMU paleontologist Oliver Rauhut and Christian Foth from the Staatliches Museum für Naturkunde in Stuttgart have re-examined the so-called Haarlem specimen of Archaeopteryx, which is kept in Teylers Museum in that Dutch city and has gone down in history as the first member of this genus to be discovered.

In the journal BMC Evolutionary Biology, Foth and Rauhut now report that this fossil differs in several important respects from the other known representatives of the genus Archaeopteryx. In fact, their taxonomic analysis displaces it from its alleged perch on the phylogenetic tree: “The Haarlem specimen is not a member of the Archaeopteryx clade,” says Rauhut, a paleontologist in the Department of Earth and Environmental Sciences at LMU who is also affiliated with the Bavarian State Collections for Paleontology and Geology in Munich.

Instead, the two scientists assign the fossil to a group of bird-like maniraptoran dinosaurs known as anchiornithids, which were first identified only a few years ago based on material found in China. These rather small dinosaurs possessed feathers on all four limbs, and they predate the appearance of Archaeopteryx. “The Haarlem fossil is the first member of this group found outside China. And together with Archaeopteryx, it is only the second species of bird-like dinosaur from the Jurassic discovered outside eastern Asia. This makes it even more of a rarity than the true specimens of Archaeopteryx,” Rauhut says.

Made in China

The Haarlem specimen was found about 10 km to the northeast of the closest Archaeopteryx locality known (Schamhaupten) a full four years before the discovery of the skeleton that would introduce the Urvogel to the scientific world in 1861. Schamhaupten was once part of the so-called Solnhofen archipelago in the Altmühl Valley in southern Bavaria, the area from which all known specimens of the genus Archaeopteryx originated. Its taxonomic reassignment therefore provides new insights into the evolution of the bird-like dinosaurs in the Middle to Late Jurassic. “Our biogeographical analysis demonstrates that the group of dinosaurs that gave rise to birds originated in East Asia — all of the oldest finds have been made in China. As they expanded westward, they also reached the Solnhofen archipelago,” says Christian Foth. Thus, the fossil hitherto incorrectly assigned to the genus Archaeopteryx must have been one of the first members of the group to arrive in Europe.

Around 150 million years ago, the area known today as the Altmühl Valley was dotted with the coral and sponge reefs and lagoons of the Solnhofen archipelago, and the open sea lay to the West and South. The Haarlem fossil was originally recovered from what was then the eastern end of the archipelago, quite close to the mainland. Unlike Archaeopteryx, anchiornithids were unable to fly, and might not have been able to reach areas further offshore. On the other hand, all true fossils of Archaeopteryx found so far were recovered from the lithographic limestone strata further to the west, closer to the open sea. Based on the new findings, Rauhut argues that other known Archaeopteryx fossils may need reassessment: “Not every bird-like fossil that turns up in the fine-grained limestones around Solnhofen need necessarily be a specimen of Archaeopteryx,” he points out.

The authors of the new study have proposed that the Haarlem specimen be assigned to a new genus, for which they suggest the name Ostromia — in honor of the American paleontologist John Ostrom, who first identified the fossil as a theropod dinosaur.

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