The Great London:
Dinosaurs

The Mesozoic played host to some of the most dangerous predators to ever swim the Earth's oceans. Among these, pliosaurs were lethal hunters, and some of the largest predators ever on this planet. They were the shorter-necked cousins of the plesiosaurs, which are often spoken of in reference to their superficial similarity to the Loch Ness Monster, which we're definitely not going to do here. Together, pliosaurs and plesiosaurs form a group known as Sauropterygia, which existed in the oceans from the Triassic right until the end of the Cretaceous, when they went extinct along with the non-avian dinosaurs and other vertebrate groups. This actually makes sauropterygians the longest living group of marine-adapted tetrapods (animals with four limbs), which is quite an impressive feat!

New discoveries show that perhaps this evolutionary success can be attributed to the ecological diversity that this group possessed, and in particular an ability to adapt to different feeding styles.

Valentin Fischer from the University of Oxford and an international team of researchers have discovered a new pliosaur from western Russia, named Makhaira rossica. The name dreives from the Latinized Ancient Greek word 'mákhaira', which describes a blade with a curved outline, as well as the Latin word 'rossica', which means Russian. The specimen comprises a fragmentary skeleton of a sub-adult animal, found within a series of limestone nodules along the banks of the Volga River.

Makhaira comes from a period in Earth's geological history, known as the earliest part of the Cretaceous, where our knowledge of vertebrate life is relatively poor due to the way in which fossils are differentially preserved through time. Sadly, this lack of knowledge means that our understanding of how faunas changed from the latest part of the Jurassic period into the first part of the Cretaceous is relatively poor compared to other important geological boundaries.

Analysis of the evolutionary placement of this new species places it as the most basal member of a group known as Brachaucheninae, which survived through the Cretaceous. However, the new species is different in being a little smaller than some of its more advanced relatives.

The weirdest feature of the new beasty has to be the teeth. The teeth occur in pairs, and have a trihedral form, meaning they had three peaks on each alveolus, and the edges of the teeth were adorned with wicked serrations. They were also very large, similar even to some teeth from theropod dinosaurs roaming the lands at the time!

The morphology of these teeth suggest that they were equipped just for one thing – devouring other large animals! This form of feeding is known as macrophagy, and was a common form of predation at the time for giant marine crocodyliforms (the ancestors of modern crocodiles) called metriorhynchids. Importantly, this feeding style previously seemed to have been lost in the early evolution of other brachauchenine pliosaurs, but now appears to have been present in at least one species from this group. This shows that Early Cretaceous pliosaurs were still well adapted to hypercarnivory, and retained a high feeding diversity at the beginning of the Cretaceous, and not lost from their Jurassic ancestors.

Recently, Alessandro Chiarenza, a colleague of mine at Imperial College London, reported on what appeared to be the oldest metriorhynchid remains currently known, from a fossil site in Sicily. Based on a single fossilised tooth from a period known as the Aptian, later on in the Cretaceous than when Makhaira was found, these remains extended the duration of metriorhynchids, and their eventual extinction, by several millions of years.

However, the morphology of the teeth of Makhaira wasn't known at the time of publishing the crocodyliform fossils, and it seems that it is actually impossible to distinguish between these and the teeth of some metriorhynchids. This means that the Sicilian tooth cannot be referred unequivocally to either a metriorhynchid or a pliosaur – the teeth of some species is just too similar to say for certain! What does this imply though? Well, it seems that the fate of metriorhynchids is still a mystery concealed by the fossil record, and is only something that future study of these fossils, their other monstrous counterparts, and discovery of new fossils can hope to solve!

The findings are published in the >Royal Society Open Science journal.

Author: Victoria Costello | Source: Public Library of Science [January 16, 2016]

The Australian Age of Dinosaurs Museum today announced the naming of Savannasaurus elliottorum, a new genus and species of dinosaur from western Queensland, Australia. The bones come from the Winton Formation, a geological deposit approximately 95 million years old.

Savannasaurus was discovered by David Elliott, co-founder of the Australian Age of Dinosaurs Museum, while mustering sheep in early 2005. As Elliott recalled yesterday, "I was nearly home with the mob -- only about a kilometre from the yards -- when I spotted a small pile of fossil bone fragments on the ground. I was particularly excited at the time as there were two pieces of a relatively small limb bone and I was hoping it might be a meat-eating theropod dinosaur." Mr Elliott returned to the site later that day to collect the bone fragments with his wife Judy, who 'clicked' two pieces together to reveal a complete toe bone from a plant-eating sauropod. The Elliotts marked the site and made arrangements to hold a dig later that year.

The site was excavated in September 2005 by a joint Australian Age of Dinosaurs (AAOD) Museum and Queensland Museum team and 17 pallets of bones encased in rock were recovered. After almost ten years of painstaking work by staff and volunteers at the AAOD Museum, the hard siltstone concretion around the bones was finally removed to reveal one of the most complete sauropod dinosaur skeletons ever found in Australia. More excitingly, it belonged to a completely new type of dinosaur.

The new discovery was nicknamed Wade in honour of prominent Australian palaeontologist Dr Mary Wade. "Mary was a very close friend of ours and she passed away while we were digging at the site," said Mr Elliott. "We couldn't think of a better way to honour her than to name the new dinosaur after her."

"Before today we have only been able to refer to this dinosaur by its nickname," said Dr Stephen Poropat, Research Associate at the AAOD Museum and lead author of the study. "Now that our study is published we can refer to Wade by its formal name, Savannasaurus elliottorum," Dr Poropat said. "The name references the savannah country of western Queensland in which it was found, and honours the Elliott family for their ongoing commitment to Australian palaeontology."

In the same publication, Dr Poropat and colleagues announced the first sauropod skull ever found in Australia. This skull, and the partial skeleton with which it was associated, has been assigned to Diamantinasaurus matildae -- a sauropod dinosaur named in 2009 on the basis of its nickname Matilda. "This new Diamantinasaurus specimen has helped to fill several gaps in our knowledge of this dinosaur's skeletal anatomy," said Poropat. "The braincase in particular has allowed us to refine Diamantinasaurus' position on the sauropod family tree."

Dr Poropat collaborated with British sauropod experts Dr Philip Mannion (Imperial College, London) and Professor Paul Upchurch (University College, London), among others, to work out the position of Savannasaurus (and refine that of Diamantinasaurus) on the sauropod family tree. "Both Savannasaurus and Diamantinasaurus belong to a group of sauropods called titanosaurs. This group of sauropods includes the largest land-living animals of all time," said Dr Mannion. "Savannasaurus and the new Diamantinasaurus specimen have helped us to demonstrate that titanosaurs were living worldwide by 100 million years ago."

Poropat and his colleagues suggest that the arrangement of the continents, and the global climate during the middle part of the Cretaceous Period, enabled titanosaurs to spread worldwide.

"Australia and South America were connected to Antarctica throughout much of the Cretaceous," said Professor Upchurch. "Ninety-five million years ago, at the time that Savannasaurus was alive, global average temperatures were warmer than they are today. However, it was quite cool at the poles at certain times, which seems to have restricted the movement of sauropods at polar latitudes. We suspect that the ancestor of Savannasaurus was from South America, but that it could not and did not enter Australia until approximately 105 million years ago. At this time global average temperatures increased allowing sauropods to traverse landmasses at polar latitudes."

Savannasaurus was a medium-sized titanosaur, approximately half the length of a basketball court, with a long neck and a relatively short tail. "With hips at least one metre wide and a huge barrel-like ribcage, Savannasaurus is the most rotund sauropod we have found so far -- even more so than the somewhat hippopotamus-like Diamantinasaurus," said Dr Poropat. "It lived alongside at least two other types of sauropod (Diamantinasaurus and Wintonotitan), as well as other dinosaurs including ornithopods, armoured ankylosaurs, and the carnivorous theropod Australovenator."

Mr Elliott is relieved that Wade can now join "Matilda" and the other new dinosaur species on display in the Museum's Holotype Room. "That this dinosaur specimen can now be displayed for our visitors is a testament to the efforts of numerous volunteers who have worked at the Museum on the fossils over the past decade," he said. Mr Elliott and Dr Poropat agree that the naming of Savannasaurus, the fourth new species published by the AAOD Museum, is just the tip of the iceberg with respect to the potential for new dinosaur species in western Queensland.

"The Australian Age of Dinosaurs Museum has a massive collection of dinosaur fossils awaiting preparation and the number of specimens collected is easily outpacing the number being prepared by volunteers and staff in our Laboratory," Mr Elliott said. "The Museum already has the world's largest collection of bones from Australia's biggest dinosaurs and there is enough new material to keep us working for several decades."

The paper naming the new dinosaur was published in >Scientific Reports.

Source: Australian Age of Dinosaurs Museum of Natural History [October 20, 2016]

A new study published by PeerJ documents injuries inflicted in life and death to a large tyrannosaurine dinosaur. The paper shows that the skull of a genus of tyrannosaur called Daspletosaurus suffered numerous injuries during life, at least some of which were likely inflicted by another Daspletosaurus. It was also bitten after death in an apparent event of scavenging by another tyrannosaur. Thus there's evidence of combat between two large carnivores as well as one feeding on another after death.

Daspletosaurus was a large carnivore that lived in Canada and was only a little smaller than its more famous cousin Tyrannosaurus. Like other tyrannosaurs it was most likely both an active predator and scavenger. The individual in question, from Alberta Canada, was not fully grown and would be considered a 'sub-adult' in dinosaur terms (approximately equivalent to an older teenager in human terms). It would have been just under 6 m long and around 500 kg when it died.

Researchers found numerous injuries on the skull that occurred during life. Although not all of them can be attributed to bites, several are close in shape to the teeth of tyrannosaurs. In particular one bite to the back of the head had broken off part of the skull and left a circular tooth-shaped puncture though the bone. The fact that alterations to the bone's surface indicate healing means that these injuries were not fatal and the animal lived for some time after they were inflicted.

Lead author Dr David Hone from Queen Mary, University of London said "This animal clearly had a tough life suffering numerous injuries across the head including some that must have been quite nasty. The most likely candidate to have done this is another member of the same species, suggesting some serious fights between these animals during their lives."

There is no evidence that the animal died at the hands (or mouth) of another tyrannosaur. However, the preservation of the skull and other bones, and damage to the jaw bones show that after the specimen began to decay, a large tyrannosaur (possibly of the same species) bit into the animal and presumably ate at least part of it.

Combat between large carnivorous dinosaurs is already known and there is already evidence for cannibalism in various groups, including tyrannosaurs. This is however an apparently unique record with evidence of both pre- and post-mortem injuries to a single individual.

Source: PeerJ [April 09, 2015]

An international research team is formalizing plans to drill nearly 5,000 feet below the seabed to take core samples from the crater of the asteroid that wiped out the dinosaurs.

The group met last week in Merida, Mexico, a city within the nearly 125-mile-wide impact site, to explain the research plans and put out a call for scientists to join the expedition planned for spring 2016. The roughly $10 million in funding for the expedition has been approved and scheduled by the European Consortium for Ocean Research Drilling (ECORD) — part of the International Ocean Discovery Program (IODP) — and the International Continental Scientific Drilling Program (ICDP).

Dinosaurs and other reptiles ruled the planet for 135 million years. That all changed 65.5 million years ago when a 9-mile-wide asteroid slammed into the Earth, triggering a series of apocalyptic events that killed most large animals and plants, and wiped out the dinosaurs and large marine reptiles. The event set the stage for mammals — and eventually humans — to take over. Yet, we have few geologic samples of the now buried impact crater.

Sean Gulick, a researcher at The University of Texas at Austin Institute for Geophysics (UTIG), and a team of scientists from the U.K. and Mexico are working to change that. The team is planning to take the first offshore core samples from near the center of the impact crater, which is called Chicxulub after the seaside village on the Yucatán Peninsula near the crater’s center.

The team, led by Gulick and Joanna Morgan of Imperial College London, will be sampling the crater’s “peak ring” — an enigmatic ring of topographically elevated rocks that surrounds the crater’s center, rises above its floor and has been buried during the past 65.5 million years by sediments.

A peak ring is a feature that is present in all craters caused by large impacts on rocky planetoids. By sampling the Chicxulub peak ring and analyzing its key features, researchers hope to uncover the impact details that set in motion one of the planet’s most profound extinctions, while also shedding light on the mechanisms of large impacts on Earth and on other rocky planets.

“What are the peaks made of? And what can they tell us about the fundamental processes of impacts, which is this dominant planetary resurfacing phenomena?” said Gulick, who is also a research associate professor at the UT Jackson School of Geosciences. UTIG is a research unit of the Jackson School.

The researchers are also interested in examining traces of life that may have lived inside the peak ring’s rocks. Density readings of the rocks indicate that they probably are heavily broken and porous — features that may have served as protected microenvironments for exotic life that could have thrived in the hot, chemically enriched environment of the crater site after impact. Additionally, the earliest recovery of marine life should be recorded within the sediments that filled in the crater in the millions of years after the impact.

“The sediments that filled in the [crater] should have the record for organisms living on the sea floor and in the water that were there for the first recovery after the mass extinction event,” Gulick said. “The hope is we can watch life come back.”

The expedition will last for two months and involve penetrating nearly 5,000 feet beneath the seabed from an offshore platform. The core will be the first complete sample of the rock layers from near the crater’s center.

Once extracted, the core will be shipped to Germany and split in two. Half will be immediately analyzed by an international team of scientists from the U.S., U.K., Mexico and other nations, and half will be saved at a core repository at Texas A&M University for future research needs by the international community.

The team also includes researchers from the National Autonomous University of Mexico (UNAM) and Centro de Investigación Científica de Yucatán (CICY). Scientists interested in joining the mission must apply by May 8, 2015. For more information on the mission and the application process, see the European Consortium for Ocean Research Drilling’s call for applications.

Source: University of Texas at Austin [April 06, 2015]

Large ornamental structures in dinosaurs, such as horns and head crests are likely to have been used in sexual displays and to assert social dominance, according to a new analysis of Protoceratops carried out by scientists at Queen Mary University of London (QMUL). This is the first time scientists have linked the function of anatomy to sexual selection in dinosaurs.

Protoceratops had a large bony frill that extended from the back of the head over the neck. Study of fossils aged from babies to adults revealed the adults to have disproportionately larger frills in relation to their size. The research, published in the journal >Palaeontologia Electronica, shows that the frill was absent in juveniles and suddenly increased in size as the animals reached maturity suggesting that its function is linked to sexual selection.

This suggests the frill might have been used to attract suitable mates by showing off their best attributes or helping them assert the most dominant position in social interactions.

Dr David Hone, lecturer in Zoology from QMUL's School of Biological and Chemical Sciences, said: "Palaeontologists have long suspected that many of the strange features we see in dinosaurs were linked to sexual display and social dominance but this is very hard to show. The growth pattern we see in Protoceratops matches that seen for signalling structures in numerous different living species and forms a coherent pattern from very young animals right through to large adults."

The researchers assessed the change in length and width of the frill over four life stages: hatchling babies, young animals, near-adults, and adults. Not only did the frill change in size but it also changed in shape, becoming proportionally wider as the dinosaur became older.

Dr Rob Knell, Reader in Evolutionary Ecology, also from QMUL's School of Biological and Chemical Sciences, said: "Biologists are increasingly realising that sexual selection is a massively important force in shaping biodiversity both now and in the past. Not only does sexual selection account for most of the stranger, prettier and more impressive features that we see in the animal kingdom, it also seems to play a part in determining how new species arise, and there is increasing evidence that it also has effects on extinction rates and on the ways by which animals are able to adapt to changing environments."

The research formed part of current postgraduate student and QMUL graduate Dylan Wood's undergraduate thesis, which looked at sexual selection in extinct species.

There are numerous, well-preserved specimens of ceratopisian dinosaurs of various sizes and ages making them a good groups to analyse. The researchers analysed 37 specimens of Protoceratops from fossils found in the Djadochta Formation in the Gobi desert and from previous published research. Protoceratops was a small-horned dinosaur that was similar in size to a sheep and was around 2m in total length from snout to tail tip.

Source: Queen Mary, University of London [January 13, 2016]

Researchers have identified the first known example of fossilised brain tissue in a dinosaur from Sussex. The tissues resemble those seen in modern crocodiles and birds.

An unassuming brown pebble, found more than a decade ago by a fossil hunter in Sussex, has been confirmed as the first example of fossilised brain tissue from a dinosaur.

The fossil, most likely from a species closely related to Iguanodon, displays distinct similarities to the brains of modern-day crocodiles and birds. Meninges -- the tough tissues surrounding the actual brain -- as well as tiny capillaries and portions of adjacent cortical tissues have been preserved as mineralised 'ghosts'.

The results are reported in a >Special Publication of the Geological Society of London, published in tribute to Professor Martin Brasier of the University of Oxford, who died in 2014. Brasier and Dr David Norman from the University of Cambridge co-ordinated the research into this particular fossil during the years prior to Brasier's untimely death in a road traffic accident.

The fossilised brain, found by fossil hunter Jamie Hiscocks near Bexhill in Sussex in 2004, is most likely from a species similar to Iguanodon: a large herbivorous dinosaur that lived during the Early Cretaceous Period, about 133 million years ago.

Finding fossilised soft tissue, especially brain tissue, is very rare, which makes understanding the evolutionary history of such tissue difficult. "The chances of preserving brain tissue are incredibly small, so the discovery of this specimen is astonishing," said co-author Dr Alex Liu of Cambridge's Department of Earth Sciences, who was one of Brasier's PhD students in Oxford at the time that studies of the fossil began.

According to the researchers, the reason this particular piece of brain tissue has been so well-preserved is that the dinosaur's brain was essentially 'pickled' in a highly acidic and low-oxygen body of water -- similar to a bog or swamp -- shortly after its death. This allowed the soft tissues to become mineralised before they decayed away completely, so that they could be preserved.

"What we think happened is that this particular dinosaur died in or near a body of water, and its head ended up partially buried in the sediment at the bottom," said Norman. "Since the water had little oxygen and was very acidic, the soft tissues of the brain were likely preserved and cast before the rest of its body was buried in the sediment."

Working with colleagues from the University of Western Australia, the researchers used scanning electron microscope (SEM) techniques in order to identify the tough membranes, or meninges, that surrounded the brain itself, as well as strands of collagen and blood vessels. Structures that could represent tissues from the brain cortex (its outer layer of neural tissue), interwoven with delicate capillaries, also appear to be present. The structure of the fossilised brain, and in particular that of the meninges, shows similarities with the brains of modern-day descendants of dinosaurs, namely birds and crocodiles.

In typical reptiles, the brain has the shape of a sausage, surrounded by a dense region of blood vessels and thin-walled vascular chambers (sinuses) that serve as a blood drainage system. The brain itself only takes up about half of the space within the cranial cavity.

In contrast, the tissue in the fossilised brain appears to have been pressed directly against the skull, raising the possibility that some dinosaurs had large brains which filled much more of the cranial cavity. However, the researchers caution against drawing any conclusions about the intelligence of dinosaurs from this particular fossil, and say that it is most likely that during death and burial the head of this dinosaur became overturned, so that as the brain decayed, gravity caused it to collapse and become pressed against the bony roof of the cavity.

"As we can't see the lobes of the brain itself, we can't say for sure how big this dinosaur's brain was," said Norman. "Of course, it's entirely possible that dinosaurs had bigger brains than we give them credit for, but we can't tell from this specimen alone. What's truly remarkable is that conditions were just right in order to allow preservation of the brain tissue -- hopefully this is the first of many such discoveries."

"I have always believed I had something special. I noticed there was something odd about the preservation, and soft tissue preservation did go through my mind. Martin realised its potential significance right at the beginning, but it wasn't until years later that its true significance came to be realised," said paper co-author Jamie Hiscocks, the man who discovered the specimen. "In his initial email to me, Martin asked if I'd ever heard of dinosaur brain cells being preserved in the fossil record. I knew exactly what he was getting at. I was amazed to hear this coming from a world renowned expert like him."

Source: University of Cambridge [October 27, 2016]

The first detailed study of a Stegosaurus skull shows that the dinosaur had a stronger bite than suspected, enabling it to eat a wider range of plants than other plant-eating dinosaurs with similarly shaped skulls.

A team of scientists from Bristol, London, Manchester and University of Birmingham compared the skull of 'Sophie', the Natural History Museum's new Stegosaurus specimen, with two other dinosaurs, Plateosaurus and Erlikosaurus, which shared similar skull characteristics. Computer modelling at the University of Bristol showed that, despite looking very similar, the dinosaurs had different biting abilities.

Although the three dinosaurs existed in different time periods and locations and had very differently shaped bodies, all three had similar-looking skulls: a large low snout, feeble peg-shaped teeth, and a scissor-like jaw action only capable of moving up and down. All three ate mainly or exclusively plants.

Until now, it has been assumed that the dinosaurs probably had similar biting abilities and therefore ate similar types of plants. But the research reveals that it can be a trap to assume that because a set of dinosaurs shared a set of similar features, they all operated in the same way – function does not necessarily follow form.

As Prof. Paul Barrett, Merit Researcher at The Natural History Museum explains: 'Our key finding really surprised us: we expected that many of these dinosaur herbivores would have skulls that worked in broadly similar ways. Instead we found that even though the skulls were fairly similar to each other in overall shape, the way they worked during biting was substantially different in each case.'

Stegosaurus lived around 150 million years ago and needed to eat a lot of plants to sustain its large size. As grasses did not exist then, it would have fed on plants such as ferns and horsetails. However the research indicates that it had a much higher bite force than anyone had suspected, enabling it to a wider range of plants than previously thought.

As Barrett, leader of the research team, comments: 'Far from being feeble, as usually thought, Stegosaurus actually had a bite force within the range of living herbivorous mammals, such as sheep and cows.'

This wider range of plants means that scientists need to reconsider how Stegosaurus fitted into its ecological niche. For example it may have had a role in spreading the seeds of cycads – woody ever green plants that were abundant in the time of the dinosaurs and whose seeds are contained in large cones.

Dr David Button, from the University of Birmingham's School of Geography, Earth and Environmental Sciences, said: 'The extra information provided by computing modelling is invaluable. Although we can tell roughly what a dinosaur ate from the shape of its teeth and jaws, the differences highlighted by this study indicate that the biology and ecology of these animals is more complex than we previously thought. As we study the lives of dinosaurs in greater detail, they continue to surprise us.'

Lead author Dr Stephan Lautenschlager, a post-doctoral researcher at the University of Bristol's School of Earth Sciences, employed digital models and computer simulations to analyse the dinosaurs' bites, using data from 3D scans of the skulls and lower jaws. He used engineering software to give the skulls the material properties that would match as closely as possible to the real thing, for example, using data on crocodile teeth to model those of the dinosaurs. By attaching muscles to the models, he was able to examine the forces that the jaws could produce and the subsequent stresses on the skulls.

As computer power increases and software becomes more available, Lautenschlager thinks that we will see more modelling used in dinosaur research: 'Using computer modelling techniques, we were able to reconstruct muscle and bite forces very accurately for the different dinosaurs in our study. As a result, these methods give us new and detailed insights into dinosaur biology – something that would not have been several years ago.'

The findings are published in >Nature Scientific Reports.

Source: University of Birmingham [May 20, 2016]

Scientists from the University of Liverpool have developed computer models of the bodies of sauropod dinosaurs to examine the evolution of their body shape.

Sauropod dinosaurs include the largest land animals to have ever lived. Some of the more well-known sauropods include Diplodocus, Apatosaurus and Brontosaurus. They are renowned for their extremely long necks, long tails as well as four thick, pillar-like legs and small heads in relation to their body.

To date, however, there have been only limited attempts to examine how this unique body-plan evolved and how it might be related to their gigantic body size. Dr Karl Bates from the University's Department of Musculoskeletal Biology and his colleagues used three-dimensional computer models reconstructing the bodies of sauropod dinosaurs to analyse how their size, shape and weight-distribution evolved over time.

Evolutionary history

Dr Bates found evidence that changes in body shape coincided with major events in sauropod evolutionary history such as the rise of the titanosaurs. The early dinosaurs that sauropods evolved from were small and walked on two legs, with long tails, small chests and small forelimbs. The team estimate that this body shape concentrated their weight close to the hip joint, which would have helped them balance while walking bipedally on their hind legs.

As sauropods evolved they gradually altered both their size and shape from this ancestral template, becoming not only significantly larger and heavier, but also gaining a proportionally larger chest, forelimbs and in particular a dramatically larger neck.

>A Giraffatitan model of a Sauropod showing how the centre of mass is moved by> reconstructing the soft tissues differently using the convex hulling approach >[Credit: Dr Peter L Falkingham/Liverpool John Moores University]
The team's findings show that these changes altered sauropods' weight distribution as they grew in size, gradually shifting from being tail-heavy, two-legged animals to being front-heavy, four-legged animals, such as the large, fully quadrupedal Jurassic sauropods Diplodocus and Apatosaurus.

The team found that these linked trends in size, body shape and weight distribution did not end with the evolution of fully quadrupedal sauropods. In the Cretaceous period - the last of the three ages of the dinosaurs - many earlier sauropod groups dwindled. In their place, a new and extremely large type of sauropod known as titanosaurs evolved, including the truly massive Argentinosaurus and Dreadnoughtus, among the largest known animals ever to have lived.

Front heavy

The team's computer models suggest that in addition to their size, the titanosaurs evolved the most extreme 'front heavy' body shape of all sauropods, as a result of their extremely long necks.

Dr Bates said: "As a result of devising these models we were able to ascertain that the relative size of sauropods' necks increased gradually over time, leading to animals that were increasingly more front-heavy relative to their ancestors."

Dr Philip Mannion from Imperial College London, a collaborator in the research, added: "These innovations in body shape might have been key to the success of titanosaurs, which were the only sauropod dinosaurs to survive until the end-Cretaceous mass extinction, 66 million years ago."

Dr Vivian Allen from the Royal Veterinary College London, who also collaborated in the research, added: "What's important to remember about studies like this is that there is a very high degree of uncertainty about exactly how these animals were put together. While we have good skeletons for many of them, it's difficult to be sure how much meat there was around each of the bones. We have built this uncertainly into our models, ranging each body part from emaciated to borderline obesity, and even using these extremes we still find these solid, trending changes in body proportions over sauropod evolution."

The paper has been published by the Royal Society Open Science journal.

Source: University of Liverpool [March 29, 2016]

An international research partnership is revealing the first mosasaur fossil of its kind to be discovered in Japan. Not only does the 72-million-year-old marine reptile fossil fill a biogeographical gap between the Middle East and the eastern Pacific, but also it holds new revelations because of its superior preservation. This unique swimming lizard, now believed to have hunted on glowing fish and squids at night, is detailed in an article led by Takuya Konishi, a University of Cincinnati assistant professor of biological sciences. The article is published in the Journal of Systematic Palaeontology, a publication of the Natural History Museum in London.

The fossil marine reptile, Phosphorosaurus ponpetelegans (a phosphorus lizard from an elegant creek), existed during the Late Cretaceous Period just before the last of the dinosaurs such as Tyrannosaurus and Triceratops. Compared with some of their mosasaur cousins that could grow as large as 40 feet, this species is relatively small, about 3 meters, or 10 feet long. This unique discovery in a creek in the town of Mukawa in northern Japan reveals that they were able to colonize throughout the northern hemisphere.

"Previous discoveries of this particular rare mosasaur have occurred along the East Coast of North America, the Pacific Coast of North America, Europe and North Africa, but this is the first to fill the gap between the Middle East and the Eastern Pacific," explains Konishi, a member of the research team that also was represented by the Royal Tyrrell Museum of Palaeontology (Canada), University of Alberta, Brandon University, Hobetsu Museum (Japan), Fukuoka University and the town of Mukawa.

Because the fossil was so well preserved, the creature revealed it had binocular vision -- its eyes were on the front of the face, providing depth perception. This was a new discovery for this fossil species. The discovery reveals that the eye structure of these smaller mosasaurs was different from their larger cousins, whose eyes were on either side of their large heads, such as the eye structure of a horse. The eyes and heads of the larger mosasaurs were shaped to enhance streamlined swimming after prey that included fish, turtles and even small mosasaurs.

"The forward-facing eyes on Phosphorosaurus provide depth perception to vision, and it's common in birds of prey and other predatory mammals that dwell among us today," says Konishi. "But we knew already that most mosasaurs were pursuit predators based on what we know they preyed upon -- swimming animals. Paradoxically, these small mosasaurs like Phosphorosaurus were not as adept swimmers as their larger contemporaries because their flippers and tailfins weren't as well developed."

As a result, Konishi says it's believed these smaller marine reptiles hunted at night, much like the owl does compared with the daytime birds of prey such as eagles. The binocular vision in nocturnal animals doubles the number of photoreceptors to detect light. And, much like owls with their very large eyes to power those light receptors, the smaller mosasaur revealed very large eye sockets.

Also, because fossils of lantern fish and squid-like animals have been found from the Late Cretaceous Period in northern Japan, and because their modern counterparts are bioluminescent, the researchers believe that Phosphorosaurus may have specifically targeted those glowing fish and squids at night while their larger underwater cousins hunted in daytime.

"If this new mosasaur was a sit-and-wait hunter in the darkness of the sea and able to detect the light of these other animals, that would have been the perfect niche to coexist with the more established mosasaurs," says Konishi.

Painstaking Preservation

The fossil, enclosed in a rock matrix, was first discovered in 2009, in a small creek in northern Japan. Revealing what was inside the matrix while protecting the fossil was a painstaking process that took place at the Hobetsu Museum in Mukawa. The calcareous nodule would be dipped at night in a special acid wash, and then carefully rinsed the next day, as the two-year process freed the bones from the matrix. To further protect the fossil, special casts were made of the bones so that the researchers could piece together the remains without damaging the fossil.

"It's so unusually well-preserved that, upon separating jumbled skull bones from one another, we were able to build a perfect skull with the exception of the anterior third of the snout," says Konishi. "This is not a virtual reality reconstruction using computer software. It's a physical reconstruction that came back to life to show astounding detail and beautiful, undistorted condition."

Future Research

Konishi says future research will examine how this new mosasaur fits in the evolutionary family tree of mosasaurs.

Author: Dawn Fuller | Source: University of Cincinnati [December 08, 2015]

An unidentified fossilised bone in a museum has revealed the size of a fearsome abelisaur and may have solved a hundred-year old puzzle.

Alessandro Chiarenza, a PhD student from Imperial College London, last year stumbled across a fossilised femur bone, left forgotten in a drawer, during his visit to the Museum of Geology and Palaeontology in Palermo Italy. He and a colleague Andrea Cau, a researcher from the University of Bologna, got permission from the museum to analyse the femur. They discovered that the bone was from a dinosaur called abelisaur, which roamed the Earth around 95 million years ago during the late Cretaceous period.

Abelisauridae were a group of predatory, carnivorous dinosaurs, characterised by extremely small forelimbs, a short deep face, small razor sharp teeth, and powerful muscular hind limbs. Scientists suspect they were also covered in fluffy feathers. The abelisaur in today's study would have lived in North Africa, which at that time was a lush savannah criss-crossed by rivers and mangrove swamps. This ancient tropical world would have provided the abelisaur with an ideal habitat for hunting aquatic animals like turtles, crocodiles, large fish and other dinosaurs.

By studying the bone, the team deduced that this abelisaur may have been nine metres long and weighed between one and two tonnes, making it potentially one of the largest abelisaurs ever found. This is helping researchers to determine the maximum sizes that these dinosaurs may have reached during their peak.

Alfio Alessandro Chiarenza, co-author of the study from the Department of Earth Science and Engineering at Imperial, said: "Smaller abelisaur fossils have been previously found by palaeontologists, but this find shows how truly huge these flesh eating predators had become. Their appearance may have looked a bit odd as they were probably covered in feathers with tiny, useless forelimbs, but make no mistake they were fearsome killers in their time."

The fossil originated from a sedimentary outcrop in Morocco called the Kem Kem Beds, which are well known for the unusual abundance of giant predatory dinosaur fossils. This phenomenon is called Stromer's Riddle, in honour the German palaeontologist Ernst Stromer, who first identified this abundance in 1912. Since then scientists have been asking how abelisaurs and five other groupings of predatory dinosaurs could have co-existed in this region at the same time, without hunting each other into extinction.

Now the researchers in today's study suggest that these predatory dinosaur groups may not have co-existed so closely together. They believe that the harsh and changing geology of the region mixed the fossil fragment records together, destroying its chronological ordering in the Kem Kem beds, and giving the illusion that the abelisaurs and their predatory cousins shared the same terrain at the same time. Similar studies of fossil beds in nearby Tunisia, for example, show that creatures like abelisaurs were inland hunters, while other predators like the fish eating spinosaurs probably lived near mangroves and rivers.

Chiarenza added: "This fossil find, along with the accumulated wealth of previous studies, is helping to solve the question of whether abelisaurs may have co-existed with a range of other predators in the same region. Rather than sharing the same environment, which the jumbled up fossil records may be leading us to believe, we think these creatures probably lived far away from one another in different types of environments."

Fossilised femora are useful for palaeontologists to study because they can determine the overall size of the dinosaur. This is because femora are attached to the thigh and tail muscles and have scars, or bumps, which tell palaeontologists where the ligaments and muscles were attached to the bone and how big those muscles and ligaments would have been.

Andrea Cau, co-author from the University of Bologna, said: "While palaeontologists usually venture to remote and inaccessible locations, like the deserts of Mongolia or the Badlands of Montana, our study shows how museums still play an important role in preserving specimens of primary scientific value, in which sometimes the most unexpected surprises can be discovered. As Stephen Gould, an influential palaeontologist and evolutionary biologist, once said, sometimes the greatest discoveries are made in museum drawers."

The study is published in the journal Peer J. Chiarenza did the underpinning analysis with Cau while at the University of Bologna.

The next step will see the team looking for more complete remains from these predatory dinosaurs trying to better understand their environment and evolutionary history.

Author: Colin Smith | Source: Imperial College London [February 29, 2016]

Our ancestors evolved three times faster in the 10 million years after the extinction of the dinosaurs than in the previous 80 million years, according to UCL researchers.

The team found the speed of evolution of placental mammals -- a group that today includes nearly 5000 species including humans -- was constant before the extinction event but exploded after, resulting in the varied groups of mammals we see today.

Lead researcher, Dr Thomas Halliday (UCL Genetics, Evolution & Environment), said: "Our ancestors -- the early placental mammals - benefitted from the extinction of non-avian dinosaurs and dwindling numbers of competing groups of mammals. Once the pressure was off, placental mammals suddenly evolved rapidly into new forms.

"In particular, we found a group called Laurasiatheria quickly increased their body size and ecological diversity, setting them on a path that would result in a modern group containing mammals as diverse as bats, cats, rhinos, whales, cows, pangolins, shrews and hedgehogs."

The team found that the last common ancestor for all placental mammals lived in the late Cretaceous period, about three million years before the non-avian dinosaurs became extinct 66 million years ago. This date is 20 million years younger than suggestions from previous studies which used molecular data from living mammals and assumed a near-constant rate of evolution.

In this study, funded by the Natural Environment Research Council and published in >Proceedings B of the Royal Society, the researchers analysed fossils from the Cretaceous to the present day, and used the dates of their occurrence in the fossil record to estimate the timing of divergences based on an updated tree of life. The new tree was released by the same team in 2015 and has the largest representation of Paleocene mammals to date.

The scientists measured all the small changes in the bones and teeth of 904 placental fossils and mapped the anatomical differences between species on the tree of life. From measuring the number of character changes over time for each branch, they found the average rate of evolution for early placental mammals both before and after the dinosaur extinction event. They compared the average rate of evolution over the geological stages before the extinction and the geological stages after to see what impact it had.

Senior author, Professor Anjali Goswami (UCL Genetics, Evolution & Environment and UCL Earth Sciences), said: "Our findings refute those of other studies which overlooked the fossils of placental mammals present around the last mass extinction. Using rigorous methods, we've successfully tracked the evolution of early placental mammals and reconstructed how it changed over time. While the rate differed between species, we see a clear and massive spike in the rates of evolution straight after the dinosaurs become extinct, suggesting our ancestors greatly benefitted from the demise of the dinosaurs. The huge impact of the dinosaur extinction on the evolution of our ancestors really shows how important this event was in shaping the modern world."

Professor Paul Upchurch (UCL Earth Sciences), co-author of the study, added: "Our large and refined data set allows us to build a clearer picture of evolutionary history. We plan on using it to study other large-scale evolutionary patterns such as how early placental mammals dispersed across the continents via land bridges that no longer exist today."

Source: University College London [June 28, 2016]