Jurassic Isle of Skye

Dinosaur stomping ground in Scotland's Isle of Skye reveals thriving middle Jurassic ecosystem

Dinosaur stomping ground in Scotland reveals thriving middle Jurassic ecosystem

Dozens of footprints expand the list of dinosaurs known to have lived in the region

Jurassic Isle of Skye
Dinosaurs on the Isle of Skye. Credits: Jon Hoad

During the Middle Jurassic Period, the Isle of Skye in Scotland was home to a thriving community of dinosaurs that stomped across the ancient coastline, according to a study published March 11, 2020 in the open-access journal PLOS ONE by Paige dePolo and Stephen Brusatte of the University of Edinburgh, Scotland and colleagues.

The Middle Jurassic Period is a time of major evolutionary diversification in many dinosaur groups, but dinosaur fossils from this time period are generally rare. The Isle of Skye in Scotland is an exception, yielding body and trace fossils of diverse Middle Jurassic ecosystems, serving as a valuable location for paleontological science as well as tourism.

In this paper, dePolo and colleagues describe two recently discovered fossil sites preserving around 50 dinosaur footprints on ancient coastal mudflats. These include the first record on the Isle of Skye of a track type called Deltapodus, most likely created by a stegosaurian (plate-backed) dinosaur. These are the oldest Deltapodus tracks known, and the first strong evidence that stegosaurian dinosaurs were part of the island's Middle Jurassic fauna. Additionally, three-toed footprints represent multiple sizes of early carnivorous theropods and a series of other large tracks are tentatively identified as some of the oldest evidence of large-bodied herbivorous ornithopod dinosaurs.

All tracks considered, these two sites expand the known diversity of what was apparently a thriving ecosystem of Middle Jurassic dinosaurs in Scotland, including at least one type of dinosaur (stegosaurs) not previously known from the region. These findings reflect the importance of footprints as a source of information supplemental to body fossils. Furthermore, the authors stress the importance of revisiting previously explored sites; these new sites were found in an area that has long been popular for fossil prospecting, but the trackways were only recently revealed by storm activity.

Lead author dePolo says: "These new tracksites help us get a better sense of the variety of dinosaurs that lived near the coast of Skye during the Middle Jurassic than what we can glean from the island's body fossil record. In particular, Deltapodus tracks give good evidence that stegosaurs lived on Skye at this time."

Author Brusatte adds: "These new tracksites give us a much clearer picture of the dinosaurs that lived in Scotland 170 million years ago. We knew there were giant long-necked sauropods and jeep-sized carnivores, but we can now add plate-backed stegosaurs to that roster, and maybe even primitive cousins of the duck-billed dinosaurs too. These discoveries are making Skye one of the best places in the world for understanding dinosaur evolution in the Middle Jurassic."

 

Press release from the Public Library of Science.

Citation: dePolo PE, Brusatte SL, Challands TJ, Foffa D, Wilkinson M, Clark NDL, et al. (2020) Novel track morphotypes from new tracksites indicate increased Middle Jurassic dinosaur diversity on the Isle of Skye, Scotland. PLoS ONE 15(3): e0229640. https://doi.org/10.1371/journal.pone.0229640

 


Researchers learn more about teen-age T.Rex

Researchers learn more about teen-age T.Rex

A study of two juvenile T.rex skeletons show how the large predator grew up

Tyrannosaurus Rex T. Rex Nanotyrannus
Skeletal mount of "Jane" the 11 year-old Tyrannosaurus rex, on display at the Burpee Museum of Natural History, Rockford, Illinois. Picture by Zissoudisctrucker, CC BY-SA 4.0

Without a doubt, Tyrannosaurus rex is the most famous dinosaur in the world. The 40-foot-long predator with bone crushing teeth inside a five-foot long head are the stuff of legend. Now, a look within the bones of two mid-sized, immature T. rex allow scientists to learn about the tyrant king's terrible teens as well.

In the early 2000s, the fossil skeletons of two comparatively small T. rex were collected from Carter County, Montana, by Burpee Museum of Natural History in Rockford, Illinois. Nicknamed "Jane" and "Petey," the tyrannosaurs would have been slightly taller than a draft horse and twice as long.

The team led by Holly Woodward, Ph.D., from Oklahoma State University Center for Health Sciences studied Jane and Petey to better understand T. rex life history.

The study "Growing up Tyrannosaurus rex: histology refutes pygmy 'Nanotyrannus' and supports ontogenetic niche partitioning in juvenile Tyrannosaurus" appears in the peer-reviewed journal Science Advances.

Co-authors include Jack Horner, presidential fellow at Chapman University; Nathan Myhrvold, founder and CEO of Intellectual Ventures; Katie Tremaine, graduate student at Montana State University; Scott Williams, paleontology lab and field specialist at Museum of the Rockies; and Lindsay Zanno, division head of paleontology at the North Carolina Museum of Natural Sciences. Supplemental histological work was conducted at the Diane Gabriel Histology Labs at Museum of the Rockies/Montana State University.

"Historically, many museums would collect the biggest, most impressive fossils of a dinosaur species for display and ignore the others," said Woodward. "The problem is that those smaller fossils may be from younger animals. So, for a long while we've had large gaps in our understanding of how dinosaurs grew up, and T. rex is no exception."

The smaller size of Jane and Petey is what make them so incredibly important. Not only can scientists now study how the bones and proportions changed as T. rex matured, but they can also utilize paleohistology-- the study of fossil bone microstructure-- to learn about juvenile growth rates and ages. Woodward and her team removed thin slices from the leg bones of Jane and Petey and examined them at high magnification.

"To me, it's always amazing to find that if you have something like a huge fossilized dinosaur bone, it's fossilized on the microscopic level as well," Woodward said. "And by comparing these fossilized microstructures to similar features found in modern bone, we know they provide clues to metabolism, growth rate, and age."

The team determined that the small T. rex were growing as fast as modern-day warm-blooded animals such as mammals and birds. Woodward and her colleagues also found that by counting the annual rings within the bone, much like counting tree rings, Jane and Petey were teenaged T.rex when they died; 13 and 15 years old, respectively.

There had been speculation that the two small skeletons weren't T. rex at all, but a smaller pygmy relative Nanotyrannus. Study of the bones using histology led the researchers to the conclusion that the skeletons were juvenile T. rex and not a new pygmy species.

Instead, Woodward points out, because it took T. rex up to twenty years to reach adult size, the tyrant king probably underwent drastic changes as it matured. Juveniles such as Jane and Petey were fast, fleet footed, and had knife-like teeth for cutting, whereas adults were lumbering bone crushers. Not only that, but Woodward's team discovered that growing T. rex could do a neat trick: if its food source was scarce during a particular year, it just didn't grow as much. And if food was plentiful, it grew a lot.

"The spacing between annual growth rings record how much an individual grows from one year to the next. The spacing between the rings within Jane, Petey, and even older individuals is inconsistent - some years the spacing is close together, and other years it's spread apart," said Woodward.

The research by Woodward and her team writes a new chapter in the early years of the world's most famous dinosaur, providing evidence that it assumed the crown of tyrant king long before it reached adult size.

 

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giant ostrich Crimean cave

Bird three times larger than ostrich discovered in Crimean cave

Bird three times larger than ostrich discovered in Crimean cave

First evidence that giant ostrich-like birds once roamed Europe

giant ostrich Crimean cave
PaleoArt of the bird discovered in a Crimean cave. It weighed three times the largest living bird, the common ostrich. Credit: Andrey Atuchin

A surprise discovery in a Crimean cave suggests that early Europeans lived alongside some of the largest ever known birds, according to new research published in the Journal of Vertebrate Paleontology.

It was previously thought that such gigantism in birds only ever existed on the islands of Madagascar and New Zealand as well as Australia. The newly-discovered specimen, discovered in the Taurida Cave on the northern coast of the Black Sea, suggests a bird as giant as the Madagascan elephant bird or New Zealand moa. It may have been a source of meat, bones, feathers and eggshell for early humans.

"When I first felt the weight of the bird whose thigh bone I was holding in my hand, I thought it must be a Malagasy elephant bird fossil because no birds of this size have ever been reported from Europe. However, the structure of the bone unexpectedly told a different story," says lead author Dr Nikita Zelenkov from the Russian Academy of Sciences.

"We don't have enough data yet to say whether it was most closely related to ostriches or to other birds, but we estimate it weighed about 450kg. This formidable weight is nearly double the largest moa, three times the largest living bird, the common ostrich, and nearly as much as an adult polar bear."

It is the first time a bird of such size has been reported from anywhere in the northern hemisphere. Although the species was previously known, no one ever tried to calculate the size of this animal. The flightless bird, attributed to the species Pachystruthio dmanisensis, was probably at least 3.5 metres tall and would have towered above early humans. It may have been flightless but it was also fast.

While elephant birds were hampered by their great size when it came to speed, the femur of the current bird was relatively long and slim, suggesting it was a better runner. The femur is comparable to modern ostriches as well as smaller species of moa and terror birds. Speed may have been essential to the bird's survival. Alongside its bones, palaeontologists found fossils of highly-specialised, massive carnivores from the Ice Age. They included giant cheetah, giant hyenas and sabre-toothed cats, which were able to prey on mammoths.

Other fossils discovered alongside the specimen, such as bison, help date it to 1.5 to 2 million years ago. A similar range of fossils was discovered at an archaeological site in the town of Dmanisi in Georgia, the oldest hominin site outside Africa. Although previously neglected by science, this suggests the giant bird may have been typical of the animals found at the time when the first hominins arrived in Europe. The authors suggest it reached the Black Sea region via the Southern Caucasus and Turkey.

The body mass of the bird was reconstructed using calculations from several formulae, based on measurements from the femur bone. Applying these formulae, the body mass of the bird was estimated to be around 450kg. Such gigantism may have originally evolved in response to the environment, which was increasingly arid as the Pleistocene epoch approached. Animals with a larger body mass have lower metabolic demands and can therefore make use of less nutritious food growing in open steppes.

"The Taurida cave network was only discovered last summer when a new motorway was being built. Last year, mammoth remains were unearthed and there may be much more to that the site will teach us about Europe's distant past," says Zelenkov.

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Alcmonavis poeschli

First birds: Archaeopteryx gets company

First birds: Archaeopteryx gets company

Researchers at LMU Munich describe a hitherto unknown bird from the late Jurassic period. It is the second bird capable of flight, after the famous Archaeopteryx, to be identified from this era.

Alcmonavis poeschli
The illustration shows the wing of Alcmonavis poeschli as it was found in the limestone slab. Alcmonavis poeschli is the second known specimen of a volant bird from the Jurassic period. Copyright: O. Rauhut, LMU/SNSB

Archaeopteryx's throne is tottering. Since the discovery of the first fossil of the primal bird in 1861, it had been considered the only bird from the Jurassic geological period. Today's birds are thought to be direct descendants of carnivorous dinosaurs, with Archaeopteryx representing the oldest known flying representative of this lineage. All of the specimens that have been found up to now come from the region of the Solnhofen Archipelago, which during the Jurassic era spanned across what is today the Altmühl Valley, in the area between Pappenheim and Regensburg. Archaeopteryx lived here in a landscape of reef islands about 150 million years ago. A team led by Professor Oliver Rauhut has taxonomically identified a bird unknown until now: Alcmonavis poeschli, the second bird from the era identified as capable of flight. "This suggests that the diversity of birds in the late Jurassic era was greater than previously thought," says Rauhut, paleontologist at the Department of Earth and Environmental Sciences as well as the Bavarian State Collection of Paleontology and Geology.

Only a wing of Alcmonavis poeschli was discovered. "At first, we assumed that this was another specimen of Archaeopteryx. There are similarities, but after detailed comparisons with Archaeopteryx and other, geologically younger birds, its fossil remains suggested that we were dealing with a somewhat more derived bird," says Rauhut. According to the team's taxonomic studies, which are currently featured in the scientific journal eLifeAlcmonavis poeschli was not merely somewhat larger than Archaeopteryx; apparently it could also fly better. "The wing muscles indicate a greater capacity for flying," says Rauhut. Alcmonavis poeschli exhibits numerous traits lacking in Archaeopteryx but present in more recent birds. This suggests that it was adapted better to active, flapping flight.

The discovery of Alcmonavis poeschli has implications for the debate over whether active flapping birds arose from gliding birds. "Its adaptation shows that the evolution of flight must have progressed relatively quickly," says Dr. Christian Foth from the University of Fribourg (Switzerland), one of the co-authors of the study.

The bird now being described for the first time derives its name from the old Celtic word for the river Altmühl, Alcmona, and its discoverer Roland Pöschl, who leads the excavation at the Schaudiberg quarry close to Mörnsheim. A fossil of Archaeopteryx was also discovered in the same unit of limestones. The two primal birds thus apparently lived at the same time in what was then a subtropical lagoon landscape in southern Germany.

 

Press release from the Ludwig-Maximilians-Universität München


ammonite amber

Coastal organisms trapped in 99-million-year-old amber

Coastal organisms trapped in 99-million-year-old amber

ammonite amber
Amber piece showing most large inclusions. Credit: NIGPAS

Most amber inclusions are organisms that lived in the forest. It is very rare to find sea life trapped in amber. However, an international research group led by Prof. WANG Bo from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) reported the first known ammonite trapped in amber in a study in PNAS published on May 13.

The ammonite, a kind of sea animal, was trapped in 99-million-year-old amber from northern Myanmar. The amber is 33 mm long, 9.5 mm wide, 29 mm high and weighs 6.08 g. Besides the ammonite, the amber also encases a diverse assemblage of organisms that today live on land or in the sea, including at least 40 individual animals.

Of the terrestrial fauna found in the amber, mites are the most abundant. Also present are spiders, millipedes, cockroaches, beetles, flies and wasps, most of which would have lived on the forest floor.

Of the marine fauna, in addition to the ammonite itself, sea snails and sea slaters are present. The slaters are like those living on the seashore today.

The researchers used X-ray micro-computed tomography (micro-CT) to obtain high-resolution three-dimensional images of the ammonite including its convoluted sutures, which are important for identifying ammonites.

They found that the ammonite is a juvenile Puzosia (Bhimaites) and its presence in the amber supports a late Albian-early Cenomanian age for the amber deposit. This discovery represents a rare example of dating using amber inclusions.

But how on earth did the ammonite, an extinct sea-dwelling relative of squid, get preserved in a piece of amber that also contains land-based animals? The ammonite and sea snail shells offer possible clues.

The shells are all empty with no soft-tissue, so the organisms were long dead by the time they were engulfed by resin. The outer shell of the ammonite is broken away and the entrance of the shell is full of sand. The amber also contains additional sand.

ammonite amber
(A) Lateral view under light microscopy. (B) Flattened sutures reconstructed by microtomography. (C) Microtomographic reconstruction, apparent view. (D) Microtomographic reconstruction, surface rendering; (E) Microtomographic reconstruction, virtual section. Credit: NIGPAS

The most likely explanation for the appearance of both marine and terrestrial organisms within the amber is that a sandy beach covered with shells was located close to resin-producing trees. The flying insects were trapped in the resin while it was still on the tree. As the resin flowed down the tree trunk, it trapped organisms that lived near the foot of the tree. Reaching the beach, it entombed shells and trapped the slaters living there.

 

Press release from the Chinese Academy of Sciences


New Jurassic non-avian theropod dinosaur sheds light on origin of flight in Dinosauria

New Jurassic non-avian theropod dinosaur sheds light on origin of flight in Dinosauria

origin of flight Ambopteryx longibrachium
a. Fossil; b. restoration, scale bar equal 10 mm; c. melanosomes of the membranous wing (mw); d. histology of the bony stomach content (bn). st, styliform element; gs, gastroliths. Credit: WANG Min

A new Jurassic non-avian theropod dinosaur from 163 million-year-old fossil deposits in northeastern China provides new information regarding the incredible richness of evolutionary experimentation that characterized the origin of flight in the Dinosauria.

Drs. WANG Min, Jingmai K. O'Connor, XU Xing, and ZHOU Zhonghe from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences described and analyzed the well-preserved skeleton of a new species of Jurassic scansoriopterygid dinosaur with associated feathers and membranous tissues. Their findings were published in Nature.

The new species, named Ambopteryx longibrachium, belongs to the Scansoriopterygidae, one of the most bizarre groups of non-avian theropods. The Scansoriopterygidae differ from other theropods in their body proportions, particularly in the proportions of the forelimb, which supports a bizarre wing structure first recognized in a close relative of Ambopteryx, Yi qi.

Unlike other flying dinosaurs, namely birds, these two species have membranous wings supported by a rod-like wrist bone that is not found in any other dinosaur (but is present in pterosaurs and flying squirrels).

Until the discovery of Yi qi in 2015, such a flight apparatus was completely unknown among theropod dinosaurs. Due to incomplete preservation in the holotype and only known specimen of Yi qi, the veracity of these structures and their exact function remained hotly debated.

As the most completely preserved specimen to date, Ambopteryx preserves membranous wings and the rod-like wrist, supporting the widespread existence of these wing structures in the Scansoriopterygidae.

WANG and his colleagues investigated the ecomorphospace disparity of Ambopteryx relative to other non-avian coelurosaurians and Mesozoic birds. The results showed dramatic changes in wing architecture evolution between the Scansoriopterygidae and the avian lineage, as the two clades diverged and underwent very different evolutionary paths to achieving flight.

Interestingly, forelimb elongation, an important characteristic of flying dinosaurs, was achieved in scansoriopterygids primarily through elongation of the humerus and ulna, whereas the metacarpals were elongated in non-scansoriopterygid dinosaurs including Microraptor and birds.

In scansoriopterygids, the presence of an elongated manual digit III and the rod-like wrist probably compensated for the relatively short metacarpals and provided the main support for the membranous wings. In contrast, selection for relatively elongated metacarpals in most birdlike dinosaurs was likely driven by the need for increased area for the attachment of the flight feathers, which created the wing surface in Microraptor and birds.

The co-occurrence of short metacarpals with membranous wings, versus long metacarpals and feathered wings, exhibits how the evolution of these two significantly different flight strategies affected the overall forelimb structure. So far, all known scansoriopterygids are from the Late Jurassic and their unique membranous wing structure did not survive into the Cretaceous.

This suggests that this wing structure represents a short-lived and unsuccessful attempt to fly. In contrast, feathered wings, first documented in Late Jurassic non-avian dinosaurs, were further refined through the evolution of numerous skeletal and soft tissue modifications, giving rise to at least two additional independent origins of dinosaur flight and ultimately leading to the current success of modern birds.

Life reconstruction of the bizarre membranous-winged Ambopteryx longibrachium. Credit: Chung-Tat Cheung

Press release from the Chinese Academy of Sciences


Cambrian explosion oxygen

Oxygen variation behind evolutionary surges and extinctions during the Cambrian explosion

Oxygen variation controls episodic pattern of Cambrian explosion: study

Early Cambrian sections of the Lena River in Siberia. Credit: ZHU Maoyan

The Cambrian Explosion around 540 million years ago was a key event in the evolutionary history of life. But what exactly controlled the Cambrian Explosion has been a subject of scientific debate since Darwin's time.

A multidisciplinary study, published on May 6 in Nature Geoscience by a joint China-UK-Russia research team, gives strong support to the hypothesis that the oxygen content of the atmosphere and ocean was the principal controlling factor in early animal evolution.

In past decades, important fossil discoveries revealed a puzzling pattern of episodic radiations and extinctions in early animal evolution. This pattern coincides with dramatic fluctuations in the carbon isotopic composition of seawater, according to study co-author ZHU Maoyan from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences.

Lower Cambrian strata along the Aldan and Lena rivers in Siberia consist of continuous sequences of limestone with abundant fossils and reliable age constraints, making these rocks ideal for analysing ancient seawater chemistry. The isotopic signatures of the rocks correlate with the global production of oxygen, allowing the team to determine oxygen levels in shallow sea water and the atmosphere during the Cambrian Period.

The study is the first to show that the pattern of episodic radiations and extinctions in early animal evolution closely matches extreme changes in atmospheric and oceanic oxygen levels. This result strongly suggests that oxygen played a fundamental role in the Cambrian Explosion of animals.

"The complex creatures that came about during the Cambrian Explosion were the precursors to many of the modern animals we see today. By analysing carbon and sulphur isotopes found in ancient rocks, we are able to trace oxygen variations in Earth's atmosphere and shallow oceans during the Cambrian Explosion. We found that evolutionary radiations follow a pattern of 'boom and bust' in tandem with the oxygen levels," said Dr. HE Tianchen, study lead author and postdoctoral researcher at the University of Leeds.

According to Prof. Graham Shields, study co-author from UCL Earth Sciences, this is the first study to show clearly that our earliest animal ancestors experienced a series of evolutionary radiations and bottlenecks caused by extreme changes in atmospheric oxygen levels. The result was a veritable explosion of new animal forms during more than 13 million years of the Cambrian Period.

Study co-author Dr. Benjamin Mills, from the School of Earth and Environment at Leeds, said, "The Siberian Platform gives us a unique window into early marine ecosystems. This area contains over half of all currently known fossilised diversity from the Cambrian Explosion."

"This has been an incredibly successful and exciting joint study. The question of the Cambrian Explosion trigger has puzzled scientists for years. Now, the results give us convincing evidence to link the rapid appearance of animals as well as mass extinction during the early Cambrian with oxygen," said co-author Andrey Yu Zhuravlev from Lomonosov Moscow State University.

Study co-author YANG Aihua from Nanjing University said, "In the last decade, progress has been made in the Cambrian Explosion; this study shows the interactions between the biodiversity of animal and environment during the early Cambrian."

Press release from the Chinese Academy of Sciences

Oxygen linked with the boom and bust of early animal evolution

Cambrian explosion oxygen
This is a fossilized trilobite Aldonaia from the Cambrian Period. Credit: Andrey Zhuravlev, Lomonosov Moscow State University

Extreme fluctuations in atmospheric oxygen levels corresponded with evolutionary surges and extinctions in animal biodiversity during the Cambrian explosion, finds new study led by UCL and the University of Leeds.

The Cambrian explosion was a crucial period of rapid evolution in complex animals that began roughly 540 million years ago. The trigger for this fundamental phase in the early history of animal life is a subject of ongoing biological debate.

The study, published today in Nature Geoscience by scientists from the UK, China and Russia, gives strong support to the theory that oxygen content in the atmosphere was a major controlling factor in animal evolution.

The study is the first to show that during the Cambrian explosion there was significant correlation between surges in oxygen levels and bursts in animal evolution and biodiversity, as well as extinction events during periods of low oxygen.

Dr Tianchen He, study lead author and postdoctoral researcher at the University of Leeds, began this research while at UCL. He said: "The complex creatures that came about during the Cambrian explosion were the precursors to many of the modern animals we see today. But because there is no direct record of atmospheric oxygen during this time period it has been difficult to determine what factors might have kick started this crucial point in evolution.

"By analysing the carbon and sulphur isotopes found in ancient rocks, we are able to trace oxygen variations in Earth's atmosphere and shallow oceans during the Cambrian Explosion. When compared to fossilised animals from the same time we can clearly see that evolutionary radiations follow a pattern of 'boom and bust' in tandem with the oxygen levels.

"This strongly suggests oxygen played a vital role in the emergence of early animal life."

Study co-author Professor Graham Shields from UCL Earth Sciences, said: "This is the first study to show clearly that our earliest animal ancestors experienced a series of evolutionary radiations and bottlenecks caused by extreme changes in atmospheric oxygen levels.

"The result was a veritable explosion of new animal forms during more than 13 million years of the Cambrian Period. In that time, Earth went from being populated by simple, single-celled and immobile organisms to hosting the wonderful variety of intricate, energetic life forms we see today."

Cambrian explosion oxygen
This is a fossilized giant arthropod Phytophilaspis from the Cambrian Period. Credit: Andrey Zhuravlev, Lomonosov Moscow State University

The team analysed the carbon and sulphur isotopes from marine carbonate samples collected from sections along the Aldan and Lena rivers in Siberia. During the time of the Cambrian explosion this area would have been a shallow sea and the home for the majority of animal life on Earth.

The lower Cambrian strata in Siberia are composed of continuous limestone with rich fossil records and reliable age constraints, providing suitable samples for the geochemical analyses. The isotope signatures in the rocks relate to the global production of oxygen, allowing the team to determine oxygen levels present in the shallow ocean and atmosphere during the Cambrian Period.

This is the Lena River in Sakha (Yakutia), Siberia. Credit: Andrey Zhuravlev, Lomonosov Moscow State University

Study co-author Dr Benjamin Mills, from the School of Earth and Environment at Leeds, said: "The Siberian Platform gives us a unique window into early marine ecosystems. This area contains over half of all currently known fossilised diversity from the Cambrian explosion.

"Combining our isotope measurements with a mathematical model lets us track the pulses of carbon and sulphur entering the sediments in this critical evolutionary cradle. Our model uses this information to estimate the global balance of oxygen production and destruction, giving us new insight into how oxygen shaped the life we have on the planet today."

Study co-author Maoyan Zhu from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, said: "Understanding what triggered the Cambrian explosion requires multidisciplinary study. That's why with Graham Shields we organized together such a multidisciplinary team funded by NERC and NSFC in past years. I am so excited about the results through this collaborative project."

"On the other hand, it took a long time to get this result. We already got samples from Siberia in 2008. The sections in Siberia are difficult to access. It took time for us to organize the expedition and collect the samples there. Without support from Russian colleagues, we could not do the project."

Study co-author Andrey Yu Zhuravlev from Lomonosov Moscow State University said: "This has been an incredibly successful and exciting joint study. The question of the Cambrian Explosion trigger has puzzled scientists for years. Now, the results give us convincing evidence to link the rapid appearance of animals as well as mass extinction during the early Cambrian with oxygen."

###

Further information

The paper Possible links between extreme oxygen perturbations and the Cambrian radiation of animals is published in Nature Geoscience 06 May 2019. (DOI: 10.1038/s41561-019-0357-z)

Full list of authors: Tianchen He, Maoyan Zhu, Benjamin J. W. Mills, Peter M. Wynn, Andrey Yu. Zhuravlev, Rosalie Tostevin, Philip A. E. Pogge von Strandmann, Aihua Yang, Simon W. Poulton and Graham A. Shields

This work was facilitated and supported by a joint Sino-UK-Russia research collaboration.

UK institutes: UCL; University of Leeds; Lancaster University; University of Oxford

Chinese institutes: Nanjing Institute of Geology and Palaeontology, CAS; University of Chinese Academy of Sciences; Nanjing University

Russian institute: Lomonosov Moscow State University

 

Press release from the University of Leeds

 


Suskityrannus hazelae

Suskityrannus hazelae: a new 3-foot-tall relative of Tyrannosaurus rex

New 3-foot-tall relative of Tyrannosaurus rex

A new relative of the Tyrannosaurus rex - much smaller than the huge, ferocious dinosaur made famous in countless books and films, including, yes, "Jurassic Park" - has been discovered and named by a Virginia Tech paleontologist and an international team of scientists.

The newly named tyrannosauroid dinosaur - Suskityrannus hazelae - stood rougly 3 feet tall at the hip and was about 9 feet in length, the entire animal only marginally longer than the just the skull of a fully grown Tyrannosaurus rex, according to Sterling Nesbitt, an assistant professor with Department of Geosciences in the Virginia Tech College of Science. In a wild twist to this discovery, Nesbitt found the fossil at age 16 whilst a high school student participating in a dig expedition in New Mexico in 1998, led by Doug Wolfe, an author on the paper.

In all, Suskityrannus hazelae is believed to have weighed between 45 and 90 pounds. The typical weight for a full-grown Tyrannosaurus rex is roughly 9 tons. Its diet likely consisted of the same as its larger meat-eating counterpart, with Suskityrannus hazelae likely hunting small animals, although what it hunted is unknown. The dinosaur was at least 3 years old at death based on an analysis of its growth from its bones.

Suskityrannus hazelae
Sterling Nesbitt and fossil remains of Suskityrannus hazelae, which he found at age 16 in 1998. Credit: Virginia Tech

The fossil dates back 92 million years to the Cretaceous Period, a time when some of the largest dinosaurs ever found lived.

"Suskityrannus gives us a glimpse into the evolution of tyrannosaurs just before they take over the planet," Nesbitt said. "It also belongs to a dinosaurian fauna that just proceeds the iconic dinosaurian faunas in the latest Cretaceous that include some of the most famous dinosaurs, such as the Triceratops, predators like Tyrannosaurus rex, and duckbill dinosaurs like Edmontosaurus."

The findings are published in the latest online issue of Nature Ecology & Evolution. In describing the new find, Nesbitt said, "Suskityrannus has a much more slender skull and foot than its later and larger cousins, the Tyrannosaurus rex. The find also links the older and smaller tyrannosauroids from North America and China with the much larger tyrannosaurids that lasted until the final extinction of non-avian dinosaurs.

(Tyrannosaurus rex small arm jokes abund. So, if you're wondering how small the arms of Suskityrannus were, Nesbitt and his team are not exactly sure. No arm fossils of either specimen were found, but partial hand claws were found. And, they are quite small. Also not known: If Suskityrannus had two or three fingers.)

Two partial skeletons were found. The first included a partial skull that was found in 1997 by Robert Denton, now a senior geologist with Terracon Consultants, and others in the Zuni Basin of western New Mexico during an expedition organized by Zuni Paleontological Project leader Doug Wolfe.

The second, more complete specimen was found in 1998 by Nesbitt, then a high school junior with a burgeoning interest in paleontology, and Wolfe, with assistance in collection by James Kirkland, now of the Utah Geological Survey. "Following Sterling out to see his dinosaur, I was amazed at how complete a skeleton was lying exposed at the site," Kirkland said.

For much of the 20 years since the fossils were uncovered, the science team did not know what they had.

"Essentially, we didn't know we had a cousin of Tyrannosaurus rex for many years," Nesbitt said. He added the team first thought they had the remains of a dromaeosaur, such as Velociraptor. During the late 1990s, close relatives Tyrannosaurus rex simply were not known or not recognized. Since then, more distant cousins of Tyrannosaurus rex, such as Dilong paradoxus, have been found across Asia.

The fossil remains were found near other dinosaurs, along with the remains of fish, turtles, mammals, lizards, and crocodylians. From 1998 until 2006, the fossils remain stored at the Arizona Museum of Natural History in Mesa, Arizona. After 2006, Nesbitt brought the fossils with him through various postings as student and researcher in New York, Texas, Illinois, and now Blacksburg. He credits the find, and his interactions with the team members on the expedition, as the start of his career.

"My discovery of a partial skeleton of Suskityrannus put me onto a scientific journy that has framed my career," said Nesbitt, also a member of the Virginia Tech Global Change Center. "I am now an assistant professor that gets to teach about Earth history."

The name Suskityrannus hazelae is derived from "Suski," the Zuni Native American tribe word for "coyote," and from the Latin word 'tyrannus' meaning king and 'hazelae' for Hazel Wolfe, whose support made possible many successful fossil expeditions in the Zuni Basin. Nesbitt said permission was granted from the Zuni Tribal Council to use the word "Suski."

 

Funding for Nesbitt and his team’s research into Suskityrannus came from the Discovery Channel, the Virginia Tech Department of Geosciences, and the American Museum of Natural History. Additional scientists on the team come from the University of Edinburgh, the Natural History Museum of Los Angeles, the University of Utah, and several more institutions.

Suskityrannus hazelae
An artist's rendering of how Suskityrannus hazelae may have looked. Credit: Virginia Tech, Andrey Atuchin

Press release from Virginia Tech


balena di Matera Balaenoptera cf. musculus di Matera

The largest fossil whale ever found

The largest fossil whale ever found

New fossils shed light on the evolution of extreme gigantism of whales in a study involving palaeontologists from the University of Pisa

 

A new study just published in the international journal Biology Letters, published by the prestigious Royal Society of London, describes the enormous skeleton of a fossil blue whale, discovered in 2006 on the edge of Lake San Giuliano near Matera (southern Italy). This research involved the palaeontologists Giovanni BianucciAlberto CollaretaWalter LandiniCaterina Morigi and Angelo Varola of the Department of Earth Sciences of the University of PisaAgata Di Stefano of the Department of Biological Geological and Environmental Sciences of the University of Catania, and Felix Marx of the Directorate Earth and History of Life of the Royal Belgian Institute of Natural Sciences in Brussels.

balena di Matera Balaenoptera cf. musculus di Matera
Excavation of the fossil skeleton of Balaenoptera cf. musculus on the edge of San Giuliano Lake, Matera, Italy (photo G. Bianucci).

Giovanni Bianucci, who took part in the excavation and coordinated the study of the fossil, explains: "The shape of its bones clearly identifies the Matera fossil as a close relative of the living blue whale (Balaenoptera musculus), the largest animal that ever lived. This idea also fits with the estimated length of the new specimen, which at 26 meters is the largest whale fossil ever described, and perhaps the largest whale that ever swam in the Mediterranean Sea. This finding is important not just because it is a world record, but above all because of its implications for the evolution of extreme size".

balena di Matera Balaenoptera cf. musculus di Matera
Comparison between the ear bones of the extant blue whale and the fossil from Matera, highlighting similar features (photo and composition by F. Marx and G. Bianucci).

Gigantism is a phenomenon that has emerged, independently and at different times, in many vertebrate lineages. Large body size is thought to confer some form of competitive advantage, but exactly how and why it evolved remains a matter of debate. In recent years, research into vertebrate gigantism has focused especially on baleen whales (Mysticeti), which include the largest animals on Earth. By far the biggest is the blue whale, which can exceed 30 meters in length and reach up to 180 tonnes in weight.

Skull of Balaenoptera cf. musculus from Matera (left), next to an explanatory drawing showing the position of the preserved bones in the complete skull (photo of the skull by Akhet s.r.l.; drawing and composition by G. Bianucci and F. Marx).

Unlike most other mammals, mysticetes lack teeth, and instead use comb-like keratinous plates hanging from their upper jaw to trap tiny prey like krill. Their extremely large size has been interpreted as a way to avoid predation, e.g. by the - now extinct - gigantic sperm whale Livyatan melvillei, or the equally impressive megatooth shark Carcharocles megalodon; or as the result of a recent change in the availability and distribution of prey, which would have forced whales to move between distant feeding and/or breeding grounds.

balena di Matera Balaenoptera cf. musculus di Matera
Artistic reconstruction of the Matera whale (drawing by Alberto Gennari).

"Most fossil whales are much smaller than their living relatives" explains Alberto Collareta, "which has led to the idea that baleen whale gigantism is a relatively recent phenomenon. For example, one recent study modelled the evolution of mysticete body size over time, and found that extremely large whales only arose during the past 2-3 million years. Unfortunately, the mysticete fossil record of this period is rather poor, which means that scientists so far had to rely mainly on data from the living species".

Fossils from the past 2-3 million years are rare, because sea levels during this period were often lower than today. Most of the fossils that formed were drowned when the water rose again, and now lie inaccessible beneath the ocean floor. There are, however, some exceptions, such as the new blue whale from Matera. Agata di Stefano and Caterina Morigi analysed microfossils found with the specimen, which showed that the animal lived sometime between 1.49 and 1.25 million years ago. Its size demonstrates that extremely large whales already existed back then, and likely arose earlier than previously thought. 

"Together, the Matera whale and some other, even older finds from Peru show that large whales evolved earlier, and probably more gradually, than previously thought. These ocean giants play a crucial role as ecosystem engineers, and probably have done so for quite some time." says Felix Marx.

Giovanni Bianucci concludes: "The profound impact of baleen whales on the modern ocean highlights the need to understand their deep-time ecology. Doing so will help us gain a better understanding of the evolutionary dynamics of the marine environment, and the delicate balance of the biological communities within it".

Mysticete body length plotted against time. Red circles indicate the position of the Matera whale and three new fossil mysticetes from Peru (diagram modified by Graham J. Slater et al.; drawing of Balaenoptera cf. musculus by Carl Buell).

 

Press release from the University of Pisa


Egernia gillespieae Australia lizard

Australian blue tongue lizard ancestor was round-in-the-tooth

Australian blue tongue lizard ancestor was round-in-the-tooth

Egernia gillespieae Australia lizard
The reassembled skull bones of Egernia gillespieae, a 15 million year old skink from Riversleigh World Heritage Area of northwestern Queensland. Remarkably similar to modern social skinks (silhouette shown) E. gillespieae instead is equipped with rounded crushing teeth and a deep, thick jaw. Credit: M. Hutchinson, P. Stokes and K. Thorn

Reconstruction of the most complete fossil lizard found in Australia, a 15 million year old relative of our modern blue tongues and social skinks named Egernia gillespieae, reveals the creature was equipped with a robust crushing jaw and was remarkably similar to modern lizards.

A new study lead by Flinders University PHD student Kailah Thorn, published in the journal of Vertebrate Palaeontology, combined the anatomy of of living fossils with DNA data to put a time scale on the family tree of Australia's 'social skinks'.

"This creature looked like something in-between a tree skink and a bluetongue lizard. It would have been about 25 cm long, and unlike any of the living species it was equipped with robust crushing jaws," says Ms Thorn.

The results show that our Australia's bluetongue lizards split from Egernia as early as 25 million years ago.

"The new fossil is unusually well-preserved, with much of the skull, and some limb bones, all from a single individual. It belongs to the genus Egernia, a modern species in this group which are often called 'social skinks' and are known for living in family groups, sharing rocky outcrops and hollow tree stumps."

Remarkably similar to modern social skinks, E. gillespieae instead is equipped with rounded crushing teeth and a deep, thick jaw.

Fossil preparator Dr. Anna Gillespie immersing a large block of Riversleigh Limestone in acid. Credit: Dr. Anna Gillespie

The fossils are from the Riversleigh World Heritage fossil deposits in northwest Queensland, and were named after Dr Anna Gillespie, a UNSW palaeontologist responsible for preparing many of the spectacular fossils from that area.

"I have been preparing the Riversleigh fossil material for quite a few years now and lizard bones are rare elements. When the jaw appeared and was quickly followed by associated skull elements, I had a good feeling it would be a significant addition to the Riversleigh reptile story," says Dr Gillespie.

 

Press release from Flinders University