Predatory dinosaurs such as T. rex sported lizard-like lips

A new study suggests that predatory dinosaurs, such as Tyrannosaurus rex, did not have permanently exposed teeth as depicted in films such as Jurassic Park, but instead had scaly, lizard-like lips covering and sealing their mouths.

Researchers and artists have debated whether theropod dinosaurs, the group of two-legged dinosaurs that includes carnivores and top predators like T. rex and Velociraptor, as well as birds, had lipless mouths where perpetually visible upper teeth hung over their lower jaws, similar to the mouth of a crocodile.

However, an international team of researchers challenge some of the best-known depictions, and say these dinosaurs had lips similar to those of lizards and their relative, the tuatara -- a rare reptile found only in New Zealand, which are the last survivors of an order of reptiles that thrived in the age of the dinosaurs.

In the most detailed study of this issue yet, the researchers examined the tooth structure, wear patterns and jaw morphology of lipped and lipless reptile groups and found that theropod mouth anatomy and functionality resembles that of lizards more than crocodiles. This implies lizard-like oral tissues, including scaly lips covering their teeth.

These lips were probably not muscular, like they are in mammals. Most reptile lips cover their teeth but cannot be moved independently -- they cannot be curled back into a snarl, or make other sorts of movements we associate with lips in humans or other mammals.

Study co-author Derek Larson, Collections Manager and Researcher in Palaeontology at the Royal BC Museum in Canada, said: "Palaeontologists often like to compare extinct animals to their closest living relatives, but in the case of dinosaurs, their closest relatives have been evolutionarily distinct for hundreds of millions of years and today are incredibly specialised.

"It's quite remarkable how similar theropod teeth are to monitor lizards. From the smallest dwarf monitor to the Komodo dragon, the teeth function in much the same way. So, monitors can be compared quite favourably with extinct animals like theropod dinosaurs based on this similarity of function, even though they are not closely related."

Co-author Dr Mark Witton from the University of Portsmouth said: "Dinosaur artists have gone back and forth on lips since we started restoring dinosaurs during the 19th century, but lipless dinosaurs became more prominent in the 1980s and 1990s. They were then deeply rooted in popular culture through films and documentaries -- Jurassic Park and its sequels, Walking with Dinosaurs and so on.

"Curiously, there was never a dedicated study or discovery instigating this change and, to a large extent, it probably reflected preference for a new, ferocious-looking aesthetic rather than a shift in scientific thinking. We're upending this popular depiction by covering their teeth with lizard-like lips. This means a lot of our favourite dinosaur depictions are incorrect, including the iconic Jurassic Park T. rex."

The results, published in the journal Science, found that tooth wear in lipless animals was markedly different from that seen in carnivorous dinosaurs and that dinosaur teeth were no larger, relative to skull size, than those of modern lizards, implying they were not too big to cover with lips.

Also, the distribution of small holes around the jaws, which supply nerves and blood to the gums and tissues around the mouth, were more lizard-like in dinosaurs than crocodile-like. Furthermore, modelling mouth closure of lipless theropod jaws showed that the lower jaw either had to crush jaw-supporting bones or disarticulate the jaw joint to seal the mouth.

"As any dentist will tell you, saliva is important for maintaining the health of your teeth. Teeth that are not covered by lips risk drying out and can be subject to more damage during feeding or fighting, as we see in crocodiles, but not in dinosaurs," said co-author Kirstin Brink, Assistant Professor of Palaeontology at the University of Manitoba.

She added: "Dinosaur teeth have very thin enamel and mammal teeth have thick enamel (with some exceptions). Crocodile enamel is a bit thicker than dinosaur enamel, but not as thick as mammalian enamel. There are some mammal groups that do have exposed enamel, but their enamel is modified to withstand exposure."

Thomas Cullen, Assistant Professor of Paleobiology at Auburn University and study lead author, said: "Although it's been argued in the past that the teeth of predatory dinosaurs might be too big to be covered by lips, our study shows that, in actuality, their teeth were not atypically large. Even the giant teeth of tyrannosaurs are proportionally similar in size to those of living predatory lizards when compared for skull size, rejecting the idea that their teeth were too big to cover with lips."

The results provide new insights into how we reconstruct the soft-tissues and appearance of dinosaurs and other extinct species. This can give crucial information on how they fed, how they maintained their dental health, and the broader patterns of their evolution and ecology.

Dr Witton said: "Some take the view that we're clueless about the appearance of dinosaurs beyond basic features like the number of fingers and toes. But our study, and others like it, show that we have an increasingly good handle on many aspects of dinosaur appearance. Far from being clueless, we're now at a point where we can say 'oh, that doesn't have lips? Or a certain type of scale or feather?' Then that's as realistic a depiction of that species as a tiger without stripes."

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Researchers solve a 150-year-old mystery: Aetosaur find involves juveniles

Aetosaurs had a small head and a crocodile-like body. The land dwellers were up to six meters long and widely distributed geographically. They died out about 204 million years ago, at the end of the Triassic. In Kaltental near Stuttgart, Germany, an assemblage of 24 Aetosaurus ferratus individuals, only between 20 and 82 centimeters long, was discovered in 1877. Since then, scientists have been puzzling over whether they were juveniles or small adults. A team led by Elżbieta M. Teschner from the University of Bonn has now solved the mystery: Bone examination of two specimens shows that they are juveniles. The results have now been published in the Journal of Vertebrate Paleontology.

Reptiles of the genus Aetosaurus ferratus were discovered in a quarry near Kaltental, now a district of Stuttgart, and were first described nearly 150 years ago. The assemblage of about 24 individuals was dated to be about 215 million years old. "What was striking was that the total body length was only between 20 and 82 centimeters," says Elżbieta M. Teschner, who is pursuing a doctorate in paleontology at the University of Bonn while also conducting research at the University of Opole (Poland). "Interestingly, they were also the only fossils found in the area," she adds.

Oscar Fraas provided the first description of the skeletons in 1877 and suggested that they had washed up together. Sixteen years ago, Rainer R. Schoch of the State Natural History Museum in Stuttgart published a more detailed morphological study. Based on features visible to the naked eye, he determined that they must be juveniles. Together with Julia B. Desojo, an Argentine paleontologist from CONICET at the Museo de La Plata, they later described the skull of a larger skeleton of another aetosaur species (Paratypothorax andressorum). The find, more than 50 kilometers from Kaltental, could potentially be the adult form of the small aetosaur species known from the assemblage, they surmised.

Paleohistology enables age determination

The assumption only recently became certainty: With the help of the science of tissue growth (paleohistology) it has now become possible to examine the bones of the Kaltental find. "Long bones are a good model for calculating the age of animals because they deposit growth rings during their life that can be counted -- similar to the growth rings in tree trunks," says Dorota Konietzko-Meier, paleontologist from the University of Bonn. Based on this method, the relative individual age of the studied specimens could be determined.

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Scientists develop new index based on functional morphology to understand how ancestors of modern birds used their wings

Scientists at Nagoya University in Japan have developed an index to estimate how a bird uses its wings for flight or other locomotion by measuring the strength of the coracoid bone and the animal's body mass. It should improve our understanding of how extinct animals used their wings and the different patterns of wing-propelled locomotion that emerged as birds evolved. Their findings were published in the Journal of Anatomy.

The presence of a wing alone does not tell us whether an animal can fly. For example, penguins evolved wings to propel them through water whereas feathered dinosaurs may have used their wings for other purposes, such as thermoregulation and intraspecific display. Therefore, to better understand how animals evolved the ability to fly, an index must take into account both the presence of wings and the ability to perform powerful wing-beats.

"We wanted to create a new index because people think that if an animal has wings, then it can fly," said the study's second author, Assistant Professor Shin-ichi Fujiwara. "But this is not always true. An animal can also use its wings for other purposes, such as thermal insulation in flightless animals. Our research team focused on how changes in skeletal morphology can lead to changes in locomotion. Subsequently, these changes can lead to major ecological transitions such as a shift in lifestyle from a terrestrial environment to an aerial, aquatic, arboreal, or subterranean environment. The origin of flight in birds has been an important topic in this field. We, therefore, needed to develop an alternative index, based on biomechanics, to determine the flapping ability of birds and which we could also use to measure skeletal remains."

To create this index, the researchers used the avian coracoid bone. The coracoid bone acts as a strut to prevent the thoracic skeleton from deforming when an animal's powerful flight muscles, which connect the wings to the sternum, contract. Doctoral student Takumi Akeda of the Department of Earth and Planetary Sciences, Graduate School of Environmental Studies, at Nagoya University, and Fujiwara of the Nagoya University Museum, measured the size of a cross section of the coracoid bone in relation to the body mass of 220 bird specimens. Their sample of 209 species included extinct birds such as the dodo and the great auk.

The researchers then divided the birds into four groups based on how they used their wings. These groups were those that used flapping flight (e.g., pigeons); those that used wing-propelled diving (e.g., penguins); those that were flightless with no flapping ability (e.g., ostriches); and those that used thermal and dynamic soaring (e.g., albatrosses and vultures). Based on the strength of the coracoid bone and flapping ability, the researchers could create a new index to analyze flight patterns.

They found that the strength of the coracoid in relation to body mass may reflect the force exerted by the flight muscles, which counteract the lifting force on the wings. This helps to estimate how a bird uses propulsion. Soaring birds had increased coracoid strength, probably to enable them to withstand the greater bending forces caused by the contraction of the flapping muscles. In contrast, non-flapping birds had lower coracoid strength. These findings show that coracoid strength in relation to body mass reflects the lifting force on the wings, therefore, it is a useful tool for reconstructing the type of propulsion used by the animal.

Akeda and Fujiwara's index should allow future researchers to assess the flight styles and flapping abilities of not only extinct birds but also other flying animals, including the Pteranodon and Quetzalcoatlus of "Jurassic World" fame. The index could also allow them to estimate the origin of flight in winged theropods, the ancestors of birds.

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How evolution works

With its powerful digging shovels, the European mole can burrow through the soil with ease. The same applies to the Australian marsupial mole. Although the two animal species live far apart, they have developed similar organs in the course of evolution -- in their case, extremities ideally adapted for digging in the soil.

Science speaks of "convergent evolution" in such cases, when animal, but also plant species independently develop features that have the same shape and function. There are many examples of this: Fish, for example, have fins, as do whales, although they are mammals. Birds and bats have wings, and when it comes to using poisonous substances to defend themselves against attackers, many creatures, from jellyfish to scorpions to insects, have all evolved the same instrument: the venomous sting.

Identical characteristics despite lack of relationship

It is clear that scientists around the world are interested in finding out which changes in the genetic material of the respective species are responsible for the fact that identical characteristics have evolved in them, even though there is no relationship between them.

The search for this is proving difficult: "Such traits -- we speak of phenotypes -- are of course always encoded in genome sequences," says plant physiologist Dr. Kenji Fukushima of the Julius-Maximilians-Universität (JMU) Würzburg. Mutations -- changes in the genetic material -- can be the triggers for the development of new traits.

However, genetic changes rarely lead to phenotypic evolution because the underlying mutations are largely random and neutral. Thus, a tremendous amount of mutations accumulate over the extreme time scale at which evolutionary processes occur, making the detection of phenotypically important changes extremely difficult.

Novel metric of molecular evolution.

Now, Fukushima and his colleague David D. Pollock of the University of Colorado (USA) have succeeded in developing a method that achieves significantly better results than previously used methods in the search for the genetic basis of phenotypic traits. They present their approach in the current issue of the journal Nature Ecology & Evolution.

"We have developed a novel metric of molecular evolution that can accurately represent the rate of convergent evolution in protein-coding DNA sequences," says Fukushima, describing the main result of the now-published work. This new method, he says, can reveal which genetic changes are associated with the phenotypes of organisms on an evolutionary time scale of hundreds of millions of years. It thus offers the possibility of expanding our understanding of how changes in DNA lead to phenotypic innovations that give rise to a great diversity of species.

Tremendous treasure trove of data as a basis

A key development in the life sciences forms the basis of Fukushima's and Pollock's work: the fact that in recent years more and more genome sequences of many living organisms across the diversity of species have been decoded and thus made accessible for analysis. "This has made it possible to study the interrelationships of genotypes and phenotypes on a large scale at a macroevolutionary level," Fukushima says.

However, because many molecular changes are nearly neutral and do not affect any traits, there is often a risk of "false-positive convergence" when interpreting the data -- that is, the result predicts a correlation between a mutation and a particular trait that does not actually exist. In addition, methodological biases could also be responsible for such false-positive convergences.

Correlations over millions of years

"To overcome this problem, we expanded the framework and developed a new metric that measures the error-adjusted convergence rate of protein evolution," Fukushima explains. This, he says, makes it possible to distinguish natural selection from genetic noise and phylogenetic errors in simulations and real-world examples. Enhanced with a heuristic algorithm, the approach enables bidirectional searches for genotype-phenotype associations, even in lineages that have diverged over hundreds of millions of years, he says.

The two scientists analyzed more than 20 million branch combinations in vertebrate genes to examine how well the metric they developed works. In a next step, they plan to apply this method to carnivorous plants. The goal is to decipher the genetic basis that is partly responsible for these plants' ability to attract, capture and digest prey.

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525-million-year-old fossil defies textbook explanation for brain evolution

Fossils of a tiny sea creature that died more than half a billion years ago may compel a science textbook rewrite of how brains evolved.

A study published in Science -- led by Nicholas Strausfeld,a Regents Professor in the University of Arizona Department of Neuroscience, and Frank Hirth, a reader of evolutionary neuroscience at King's College London -- provides the first detailed description of Cardiodictyon catenulum, a wormlike animal preserved in rocks in China's southern Yunnan province. Measuring barely half an inch (less than 1.5 centimeters) long and initially discovered in 1984, the fossil had hidden a crucial secret until now: a delicately preserved nervous system, including a brain.

"To our knowledge, this is the oldest fossilized brain we know of, so far," Strausfeld said.

Cardiodictyon belonged to an extinct group of animals known as armored lobopodians, which were abundant early during a period known as the Cambrian, when virtually all major animal lineages appeared over an extremely short time between 540 million and 500 million years ago. Lobopodians likely moved about on the sea floor using multiple pairs of soft, stubby legs that lacked the joints of their descendants, the euarthropods -- Greek for "real jointed foot." Today's closest living relatives of lobopodians are velvet worms that live mainly in Australia, New Zealand and South America.

A debate going back to the 1800s

Fossils of Cardiodictyon reveal an animal with a segmented trunk in which there are repeating arrangements of neural structures known as ganglia. This contrasts starkly with its head and brain, both of which lack any evidence of segmentation.

"This anatomy was completely unexpected because the heads and brains of modern arthropods, and some of their fossilized ancestors, have for over a hundred years been considered as segmented," Strausfeld said.

According to the authors, the finding resolves a long and heated debate about the origin and composition of the head in arthropods, the world's most species-rich group in the animal kingdom. Arthropods include insects, crustaceans, spiders and other arachnids, plus some other lineages such as millipedes and centipedes.

"From the 1880s, biologists noted the clearly segmented appearance of the trunk typical for arthropods, and basically extrapolated that to the head," Hirth said. "That is how the field arrived at supposing the head is an anterior extension of a segmented trunk."

"But Cardiodictyon shows that the early head wasn't segmented, nor was its brain, which suggests the brain and the trunk nervous system likely evolved separately," Strausfeld said.

Brains do fossilize

Cardiodictyon was part of the Chengjiang fauna, a famous deposit of fossils in the Yunnan Province discovered by paleontologist Xianguang Hou. The soft, delicate bodies of lobopodians have preserved well in the fossil record, but other than Cardiodictyon none have been scrutinized for their head and brain, possibly because lobopodians are generally small. The most prominent parts of Cardiodictyon were a series of triangular, saddle-shaped structures that defined each segment and served as attachment points for pairs of legs. Those had been found in even older rocks dating back to the advent of the Cambrian.

"That tells us that armored lobopodians might have been the earliest arthropods," Strausfeld said, predating even trilobites, an iconic and diverse group of marine arthropods that went extinct around 250 million years ago.

"Until very recently, the common understanding was 'brains don't fossilize,'" Hirth said. "So you would not expect to find a fossil with a preserved brain in the first place. And, second, this animal is so small you would not even dare to look at it in hopes of finding a brain."

However, work over the last 10 years, much of it done by Strausfeld, has identified several cases of preserved brains in a variety of fossilized arthropods.

A common genetic ground plan for making a brain

In their new study, the authors not only identified the brain of Cardiodictyon but also compared it with those of known fossils and of living arthropods, including spiders and centipedes. Combining detailed anatomical studies of the lobopodian fossils with analyses of gene expression patterns in their living descendants, they conclude that a shared blueprint of brain organization has been maintained from the Cambrian until today.

"By comparing known gene expression patterns in living species," Hirth said, "we identified a common signature of all brains and how they are formed."

In Cardiodictyon, three brain domains are each associated with a characteristic pair of head appendages and with one of the three parts of the anterior digestive system.

"We realized that each brain domain and its corresponding features are specified by the same combination genes, irrespective of the species we looked at," added Hirth. "This suggested a common genetic ground plan for making a brain."

Lessons for vertebrate brain evolution

Hirth and Strausfeld say the principles described in their study probably apply to other creatures outside of arthropods and their immediate relatives. This has important implications when comparing the nervous system of arthropods with those of vertebrates, which show a similar distinct architecture in which the forebrain and midbrain are genetically and developmentally distinct from the spinal cord, they said.

Strausfeld said their findings also offer a message of continuity at a time when the planet is changing dramatically under the influence of climatic shifts.

"At a time when major geological and climatic events were reshaping the planet, simple marine animals such as Cardiodictyon gave rise to the world's most diverse group of organisms -- the euarthropods -- that eventually spread to every emergent habitat on Earth, but which are now being threatened by our own ephemeral species."

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A new species of deep-sea fish discovered in the Atacama Trench

A new small blue snailfish is changing our understanding of the world's deepest fishes.

In 2018, an international team of scientists studied the Atacama Trench, an expansive trench that runs along the west coast of South America as a deep underwater valley that mirrors the Andes Mountains. The team, including Newcastle University scientists, deployed free-falling landers to sample the sparse deep-sea creatures around cameras and traps with bait. Two lander systems from Newcastle University recorded three types of hadal snailfish and one of them was not like the others.

The small blue fish, seen from about 6,000 to 7,600 m deep, doesn't look like other hadal snailfish. With large eyes and striking colour, it resembles other species of snailfishes that are found living in much shallower waters. The team used a 3D x-ray technique called microcomputed tomography (micro-CT) and DNA barcoding to see where the new species fit within the snailfish family.

To the team's surprise, the new species appears to be a separate coloniser of the Atacama Trench. The new species belongs is a member of the genus Paraliparis. Species in this genus are particularly abundant in the Southern Ocean of the Antarctic and are rarely found deeper than 2,000 m. Significantly, this is the first time this genus has been found living in the hadal zone.

The team named the new species Paraliparis selti, meaning blue in the Kunza language of the indigenous peoples of the Atacama Desert. The description is published in the journal Marine Biodiversity.

Study lead author, Dr Thom Linley, a visiting researcher at Newcastle University said: "I find this family of fishes absolutely fascinating. They are not at all what we expect from a deep-sea fish and I love to show people that the world's deepest fishes are actually pretty cute.

"For me to get a camera down to where these animals live, it's made of inches thick stainless steel and sapphire glass. It then films these delicate and beautiful animals perfectly adapted to this extreme environment. With engineering-built force we can only clumsily visit these animals for a short time.

"We have been wondering for some time just what makes this type of fish so good at living deep. Maybe it was a series of lucky accidents, a chance fluke, that happened in one lineage. Finding this new species tells us that it's bigger than that. Lightning struck twice and there is something special about this Family.

"Paraliparis selti provides a fantastic opportunity to explore what allows fish to live so deep. If we only had a single lineage to study, we could never be sure which traits were just part of that lineage and which are the deep-sea secret sauce."

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Inside the head of one of Australia's smallest fossil crocs

Approximately 13.5 million years ago, north-west Queensland was home to an unusual and particularly tiny species of crocodile and now scientists are unlocking its secrets.

University of Queensland researchers have used state-of-the-art technology to reveal previously unknown details about the prehistoric Trilophosuchus rackhami's anatomy.

Faculty of Science PhD candidate, Jorgo Ristevski said it is the most detailed examination ever undertaken of the skull anatomy of an extinct croc from Australia.

"By micro-CT scanning the beautifully preserved skull, we were able to digitally separate each bone," Mr Ristevski said.

"We estimated that at adulthood, Trilophosuchus rackhami would have been between 70 and 90 centimetres long and weigh one to two kilograms, which was very small compared to most present-day crocs.

"This was a truly unique looking croc, with a short snout and three distinct ridges on the top of its skull."

Trilophosuchus rackhami means Rackham's three-crested croc, which was named in 1993 in honour of Alan Rackham, who now manages the Riversleigh Fossil Discovery Centre at Mt Isa.

Mr Ristevski said palaeoneurology, a field that studies the brain and nervous system of fossil species, can provide crucial insights into the animal's evolution, morphology and even behaviour.

"For one of the studies, I digitally reconstructed the brain cavity of Trilophosuchus rackhami and found that it resembles that of some distantly related and potentially terrestrial extinct crocs from Africa and South America," Mr Ristevski said.

"We were quite surprised to find this because evolutionarily speaking, Trilophosuchus rackhami is more closely related to today's crocs.

"This may indicate that Trilophosuchus rackhami spent more time on land than most living crocs."

Mr Ristevski said the findings would be useful in interpreting the evolutionary relationships of extinct crocs, something that will be researched in the future.

Associate Professor Steve Salisbury said up until very recently, Australia had an amazing diversity of prehistoric crocs.

"Trilophosuchus rackhami was certainly one of the cutest," he said.

"If we could travel back in time to north Queensland 13 million years ago, not only would you need to watch out for crocodiles at the water's edge, but you'd also have to make sure you didn't step on them in the forest."

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New 3D model shows: Megalodon could eat prey the size of entire killer whales

Megalodon, the largest shark that ever lived, is famous for its huge, human-hand-sized teeth. However, there is little fossil evidence of its whole body. International researchers in collaboration with UZH used an exceptionally preserved specimen to create a 3D computer model of its full body. Their results suggest that the megalodon could fully consume prey the size of today's killer whales and then roam the seas without more food for two months.

The reconstructed megadolon (Otodus megalodon)was 16 meters long and weighed over 61 tons. It was estimated that it could swim at around 1.4 meters per second, require over 98,000 kilo calories every day and have stomach volume of almost 10,000 liters. These results suggest that the megalodon could travel long distances and was capable of eating whole prey of up to 8 meters long. This is notably the size of modern killer whales, today's top ocean predator. An ability to eat large apex predators of comparable size millions of years ago places megalodon at a higher trophic level than modern top predators.

Well-preserved spine enables reconstruction

These are the findings of an international study carried out in collaboration with the University of Zurich. The research was only possible thanks to the 3D modelling of one individual megalodon which was discovered in the 1860s. Against all odds, a sizeable portion of its vertebral column was left behind in the fossil record after the creature died in the Miocene oceans of Belgium at the age of 46 about 18 million years ago.

"Shark teeth are common fossils because of their hard composition which allows them to remain well preserved," says first author Jack Cooper, PhD student at Swansea University. "However, their skeletons are made of cartilage, so they rarely fossilize. The megalodon vertebral column from the Royal Belgian Institute of Natural Sciences is therefore a one-of-a-kind fossil."

From single vertebra to whole body mass

The research team, which includes researchers from Switzerland, UK, USA, Australia and South Africa, first measured and scanned every single vertebra, before reconstructing the entire column. They then attached the column to a 3D scan of a megalodon's dentition from the United States. They completed the model by adding "flesh" around the skeleton using a 3D-scan of the body of a great white shark from South Africa.

"Weight is one of the most important traits of any animal. For extinct animals we can estimate the body mass with modern 3D digital modelling methods and then establish the relationship between mass and other biological properties such as speed and energy usage," says co-author John Hutchinson, professor at the Royal Veterinary College in the UK.

A trans-oceanic super-apex predator

The high energetic demand would have been met by feeding on calorie-rich blubber of whales, in which megalodon bite marks have previously been found in the fossil record. An optimal foraging model of potential megalodon prey encounters found that eating a single 8-meter-long whale may have allowed the shark to swim thousands of miles across oceans without eating again for two months. "These results suggest that this giant shark was a trans-oceanic super-apex predator," says Catalina Pimiento, Professor at the University of Zurich and senior author of the study. "The extinction of this iconic giant shark likely impacted global nutrient transport and released large cetaceans from a strong predatory pressure."

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All the better to better eat you with -- dinosaurs evolved different eye socket shapes to allow stronger bites

Large dinosaur predators, such as Tyrannosaurus rex, evolved different shapes of eye sockets to better deal with high bite forces, new research has shown.

While in many animals -- and most dinosaurs -- the eye socket is just a circular hole in the skull housing the eyeball, this is very different in large carnivores.

In a new study, published today in Communications Biology, researchers at the University of Birmingham reveal how the unusual elliptical, or oval eye sockets found in the skulls of these predators, could have evolved to help the skull absorb impact as they pounced on prey.

Dr Stephan Lautenschlager, Senior Lecturer for Palaeobiology at the University of Birmingham and author of the new study, analysed the shape of the eye sockets of ca. 500 different dinosaurs and related species.

"The results show that only some dinosaurs had eye sockets that were elliptical or keyhole-shaped," said Dr Stephan Lautenschlager. "However, all of those were large, carnivorous dinosaurs with skull lengths of 1 m or more."

Using computer simulations and stress analysis, Dr Lautenschlager tested what purpose these unusual eye socket shapes could have.

The results demonstrated that a skull with a circular eye socket was more prone to high stresses during biting. However, if these were replaced with other eye socket shapes stresses were considerably reduced allowing top predators, including Tyrannosaurus rex, to evolve high bite forces without compromising skull stability.

The study also showed that most plant-eating species and juvenile individuals retained a circular eye socket. Only large carnivores adopted other morphologies, such as elliptical, keyhole-shaped or figure-of-eight-shaped eye sockets.

Dr Lautenschlager added: "In these species, just the upper part of the eye socket was actually occupied by the eyeball. This also led to a relative reduction of eye size compared with skull size."

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Newly identified fossil insect used 360-degree vision and sticky feet to find and snare its meals

With bulging eyes, an elongated mouth and feet that oozed resin, a fossil insect identified by Oregon State University research is so different from anything alive today that it needed to be placed in its own, extinct family.

George Poinar Jr., professor emeritus in the OSU College of Science, named the insect Palaeotanyrhina exophthalma in a paper published in BioOne Complete. Encased in 100-million-year-old amber from Burma, P. exophthalma is a member of the Hemiptera order -- a "true bug," Poinar said.

"It is a small predator that used its protruding eyes to locate insect prey," said Poinar, an international expert in using plant and animal life forms preserved in amber to learn about the biology and ecology of the distant past.

More than 80,000 species including cicadas, aphids, planthoppers, leafhoppers, bed bugs and shield bugs comprise the order of Hemiptera, an ancient Greek word meaning half-winged. True bugs' size varies widely, from as small as 1 millimeter to as large as 15 centimeters, but they all have a similar arrangement of sucking mouthparts.

P. exophthalma has a body length of just over 5 millimeters. It shares some features with members of the Reduvoidea superfamily, which includes the assassin bug and the kissing bug, but its long labium (lower mouth), its head shape and its forewing veins disqualify it from placement in any modern Reduvoidea family, Poinar said.

Thus he assigned it to a new, extinct family: Palaeotanyrhinidae.

"Its eyes provided a clear, 360-degree view of its habitat so it could see prey that might appear from any side," Poinar said.

It reminded Poinar of the phrase, "Big brother is always watching you," from George Orwell's novel "1984" in which security cameras followed individuals' every movement.

The other strange feature on this fossil is an extended sheath on the final leg segment of the front tarsus, he added.

"That sheath was filled with a resinous substance," Poinar said. "The sticky substance was produced by dermal glands and helped the insect grasp potential prey."

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Prehistoric podiatry: How dinos carried their enormous weight

Scientists have cracked an enduring mystery, discovering how sauropod dinosaurs -- like Brontosaurus and Diplodocus -- supported their gigantic bodies on land.

A University of Queensland and Monash University-led team used 3D modelling and engineering methods to digitally reconstruct and test the function of foot bones of different sauropods.

Dr Andréas Jannel conducted the research during his PhD studies at UQ's Dinosaur Lab and said the team found that the hind feet of sauropod had a soft tissue pad beneath the 'heel', cushioning the foot to absorb their immense weight.

"We've finally confirmed a long-suspected idea and we provide, for the first time, biomechanical evidence that a soft tissue pad -- particularly in their back feet -- would have played a crucial role in reducing locomotor pressures and bone stresses," Dr Jannel said.

"It is mind-blowing to imagine that these giant creatures could have been able to support their own weight on land."

Sauropods were the largest terrestrial animals that roamed the Earth for more than 100 million years.

They were first thought to have been semi-aquatic with water buoyancy supporting their massive weight, a theory disproved by the discovery of sauropod tracks in terrestrial deposits in the mid-twentieth century.

Monash University's Dr Olga Panagiotopoulou said it had also been thought sauropods had feet similar to a modern-day elephant.

"Popular culture -- think Jurassic Park or Walking with Dinosaurs -- often depicts these behemoths with almost-cylindrical, thick, elephant-like feet," Dr Panagiotopoulou said.

"But when it comes to their skeletal structure, elephants are actually 'tip-toed' on all four feet, whereas sauropods have different foot configurations in their front and back feet.

"Sauropod's front feet are more columnar-like, while they present more 'wedge high heels' at the back supported by a large soft tissue pad."

UQ's Associate Professor Steve Salisbury said this was because sauropods and elephants had different evolutionary origins.

"Elephants belong to an ancient order of mammals called proboscideans, which first appeared in Africa roughly 60 million years ago as small, nondescript herbivores, " Associate Professor Salisbury said.

"In contrast, sauropods -- whose ancestors first appeared 230 million years ago -- are more closely related to birds.

"They were agile, two-legged herbivores and it was only later in their evolution that they walked on all fours.

"Crucially, the transition to becoming the largest land animals to walk the earth seems to have involved the adaptation of a heel pad."

The researchers now plan to use the 3D modelling and engineering methods to make further discoveries.

"I'm keen to apply a similar method to an entire limb and to include additional soft tissue such as muscles, which are rarely preserved in fossils," Dr Jannel said.

"We're also excited to study the limbs and feet of other prehistoric animals.

Read more at Science Daily

A new giant dinosaur gives insight into why many prehistoric meat-eaters had such tiny arms

A team co-led by University of Minnesota Twin Cities researcher Peter Makovicky and Argentinean colleagues Juan Canale and Sebastian Apesteguía has discovered a new huge, meat-eating dinosaur, dubbed Meraxes gigas. The new dinosaur provides clues about the evolution and biology of dinosaurs such as the Carcharodontosaurus and Tyrannosaurus rex—specifically, why these animals had such big skulls and tiny arms.

The study is published in Current Biology, a peer-reviewed scientific biology journal.

The researchers initially discovered Meraxes in Patagonia in 2012 and have spent the last several years extracting, preparing, and analyzing the specimen. The dinosaur is part of the Carcharodontosauridae family, a group of giant carnivorous theropods that also includes Giganotosaurus, one of the largest known meat-eating dinosaurs and one of the reptilian stars of the recently released “Jurassic World: Dominion” movie.

Though not the largest among carcharodontosaurids, Meraxes was still an imposing animal measuring around 36 feet from snout to tail tip and weighing approximately 9,000 pounds. The researchers recovered the Meraxes from rocks that are around 90-95 million years old, alongside other dinosaurs including several long-necked sauropod specimens.

Meraxes is among the most complete carcharodontosaurid skeleton paleontologists have found yet in the southern hemisphere and includes nearly the entirety of the animal’s skull, hips, and both left and right arms and legs.

“The neat thing is that we found the body plan is surprisingly similar to tyrannosaurs like T. rex,” said Peter Makovicky, one of the principal authors of the study and a professor in the University of Minnesota N.H. Winchell School of Earth and Environmental Sciences. “But, they’re not particularly closely related to T. rex. They're from very different branches of the meat-eating dinosaur family tree. So, having this new discovery allowed us to probe the question of, ‘Why do these meat-eating dinosaurs get so big and have these dinky little arms?’”

“The discovery of this new carcharodontosaurid, the most complete up to now, gives us an outstanding opportunity to learn about their systematics, paleobiology, and true size like never before,” said Sebastian Apesteguía, a co-author of the study and a researcher at Maimónides University in Argentina.

With the statistical data that Meraxes provided, the researchers found that large, mega-predatory dinosaurs in all three families of therapods grew in similar ways. As they evolved, their skulls grew larger and their arms progressively shortened.

The possible uses of the tiny forelimbs in T. rex and other large carnivorous dinosaurs have been the topic of much speculation and debate.

“What we’re suggesting is that there’s a different take on this,” Makovicky said. “We shouldn’t worry so much about what the arms are being used for, because the arms are actually being reduced as a consequence of the skulls becoming massive. Whatever the arms may or may not have been used for, they’re taking on a secondary function since the skull is being optimized to handle larger prey.”

The researchers also found that carcharodontosaurids including species from Patagonia evolved very quickly, but then disappeared suddenly from the fossil record very soon after.

“Usually when animals are on the verge of extinction, it’s because they’re evolutionary rates are quite slow, meaning they aren’t adapting very quickly to their environment,” explained  Juan Canale, the study’s lead author and a researcher at the National University of Río Negro. “Here, we have evidence that Meraxes and its relatives were evolving quite fast and yet within a few million years of being around, they disappeared, and we don’t know why. It’s one of these finds where you answer some questions, but it generates more questions for the future.”

Read more at Science Daily

New fossil birds discovered near China’s Great Wall – one had a movable, sensitive 'chin'

Approximately 80 miles from the westernmost reach of China's Great Wall, paleontologists found relics of an even more ancient world. Over the last two decades, teams of researchers unearthed more than 100 specimens of fossil birds that lived approximately 120 million years ago, during the time of the dinosaurs. However, many of these fossils have proved difficult to identify: they're incomplete and sometimes badly crushed. In a new paper published in the Journal of Systematics and Evolution, researchers examined six of these fossils and identified two new species. And as a fun side note, one of those new species had a movable bony appendage at the tip of its lower jaw that may have helped the bird root for food.

"It was a long, painstaking process teasing out what these things were," says Jingmai O'Connor, the study's lead author and the associate curator of vertebrate paleontology at Chicago's Field Museum. "But these new specimens include two new species that increase our knowledge of Cretaceous bird faunas, and we found combinations of dental features that we've never seen in any other dinosaurs."

"These fossils come from a site in China that has produced fossils of birds that are pretty darned close to modern birds, but all the bird fossils described thus far haven't had skulls preserved with the bodies," says co-author Jerry Harris of Utah Tech University. "These new skull specimens help fill in that gap in our knowledge of the birds from this site and of bird evolution as a whole."

All birds are dinosaurs, but not all dinosaurs are birds; a small group of dinosaurs evolved into birds that coexisted with other dinosaurs for 90 million years. Modern birds are the descendants of the group of birds that survived the extinction that killed the rest of the dinosaurs, but many prehistoric birds went extinct then too. O'Connor's work focuses on studying different groups of early birds to figure out why some survived while others went extinct.

The fossil site in northwestern China, called Changma, is an important place for researchers like O'Connor studying bird evolution. It's the second-richest Mesozoic (time of the dinosaurs) fossil bird site in the world, but more than half of the fossils found there belong to the same species, Gansus yumenensis.Determining which fossils are Gansus and which ones aren't is tricky; the six specimens that O'Connor and her colleagues examined in this study are primarily just skulls and necks, parts not preserved in known specimens of Gansus. The fossils were also somewhat smushed by their time deep in the Earth, which made analyzing them difficult.

"The Changma site is a special place," says study co-author Matt Lamanna of Pittsburgh's Carnegie Museum of Natural History. "The fossil-bearing rocks there tend to split into thin sheets along ancient bedding planes. So, when you're digging, it's like you're literally turning back the pages of history, layer by layer uncovering animals and plants that haven't seen the light of day in roughly 120 million years."

"Because the specimens were pretty flattened, CT-scanning them and fully segmenting them could take years and might not even give you that much information, because these thin bones are flattened into almost the same plane, and then it just becomes almost impossible to figure out where the boundaries of these bones are," says O'Connor. "So we had to kind of work with what was exposed." Through painstaking work, the researchers were able to identify key features in the birds' jaws that showed that two of the six specimens were unknown to science.

The new species (or, more accurately, new genera -- genus is a step above species in the order scientists use to name organisms) are called Meemannavis ductrix and Brevidentavis zhangi. Meemannavis is named for Meemann Chang, a Chinese paleontologist who became the first woman to lead the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) in Beijing. The name Brevidentavis means "short-toothed bird." Like Gansus, both Meemannavis and Brevidentavis are ornithuromorph birds -- the group that contains modern birds. Like today's birds, Meemannavis was toothless. Brevidentavis, on the other hand, had small, peg-like teeth packed close together in its mouth. Along with those teeth came another strange feature.

"Brevidentavis is an ornithuromorph bird with teeth, and in ornithuromorphs with teeth, there's a little bone at the front of the jaw called the predentary, where its chin would be if birds had chins," explains O'Connor. In a previous study on the predentary in another fossil bird, the authors figured out, by CT-scanning the bone and staining it with chemicals, that the predentary bone underwent stress and also found a kind of cartilage that only forms when there's movement.

"In this earlier study, we were able to tell that the predentary was capable of being moved, and that it would have been innervated -- Brevidentavis wouldn't just have been able to move its predentary, it would have been able to feel through it," says O'Connor. "It could have helped them detect prey. We can hypothesize that these toothed birds had little beaks with some kind of movable pincer at the tip of their jaws in front of the teeth."

Brevidentavis isn't the first fossil bird discovered with a predentary that might have been used in this way, but its existence, along with Meemannavis, helps round out our understanding of the diversity of prehistoric birds, especially in the Changma region.

The study also helps shed light on the most common bird from the site, Gansus, since at least four of the other specimens examined probably belong to this species. "Gansus is the first known true Mesozoic bird in the world, as Archaeopteryx is more dinosaur-like, and now we know what its skull looks like after about 40 years," notes Hai-Lu You of the IVPP.

"These amazing fossils are like a lockpick allowing us to open the door to greater knowledge of the evolutionary history of the skull in close relatives of living birds," says Tom Stidham, a co-author from the IVPP. "At a time when giant dinosaurs still roamed the land, these birds were the products of evolution experimenting with different lifestyles in the water, in the air, and on land, and with different diets as we can see in some species having or lacking teeth. Very few fossils of this geological age provide the level of anatomical detail that we can see in these ancient bird skulls."

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Transparency in butterflies, from A-Z: It’s more of a superpower than we thought

Like invisibility in legends, transparency in nature is a powerful tool. Most transparent animals live in the ocean, where a close visual match with the water renders them almost invisible to predators.

On land, transparency is rare and difficult to achieve, but some butterflies and moths (Lepidoptera) do have transparent wings. And a new study indicates transparency can serve not only to camouflage them, but in other cases to signal and warn predators, "Don't eat me! I'm toxic."

This flexible weapon for self-defense is one of many findings from a multiyear study spanning the physics, biology, ecology, and evolution of transparency in Lepidoptera conducted by several groups, including the lab of Nipam Patel, director of the Marine Biological Laboratory (MBL).

"This is one of those interdisciplinary studies you dream about, where you want to understand [a biological structure] from its physics to its development and ecology," says Patel of the international study, which began as a project in the MBL Embryology course and ended up being funded by the Human Frontier Science Program. Ph.D. candidate Aaron Pomerantz in Patel's lab is also on the team.

Mimicry for Self-Defense

The group's latest paper adds a unique perspective on Lepidoptera self-defense. In some species, vivid wing coloration indicates the presence of chemical defenses that make the butterfly unpalatable or toxic, and predators learn to avoid them. Accordingly, palatable species can evolve to mimic the toxic ones, so predators leave them alone, too. In addition, multiple unpalatable species may converge in their warning colorations, thereby sharing in the benefits of the warning coloration process. Large "mimicry rings" can even form containing both toxic and nontoxic species, all displaying strikingly similar patterns and color combinations.

"The most amazing place to see this is the Amazon," Patel says. "You'll find a group of species that are distantly related to each other, yet they've all converged on a similar wing pattern."

Surprisingly, mimicry rings have also been found among clear-wing species in the Amazon. "So we asked, 'Wait, why would a species be transparent and unpalatable at the same time?'" Patel says. And, structurally, how would a clear-wing species accomplish that trick?

The team looked at the optical and structural properties of transparent butterfly wings within mimicry rings to see if they were convergent, and found in some rings, they were.

"In one transparency ring we studied (see photo 1, middle row), the key unpalatable butterfly doesn't have an anti-glare coating on its transparent wing, so in sunlight, it's really easy to see," Patel says. "It may be signaling a warning pattern to predators when it's in bright sun, and it's camouflaged when in shadows. So it kind of cheats: it has the best of both worlds."

Previously, the team reported on the developmental origins of transparency in a clear-wing species, Greta oto. They also compared wing transparency across 123 Lepidoptera species for its structural basis, optical properties, and biological relevance in relation to concealment, thermoregulation, and protection against UV. Those results showed a wide diversity of solutions to achieve transparency, suggesting that transparency has likely evolved multiple times independently.

Approaching transparency from multiple disciplines brought emergent knowledge and interesting new questions, Patel said. "Now that we've identified different Lepidoptera groups that have found different ways to achieve transparency, we can ask, how did they actually do this? Or, alternatively, if two very distant lineages have come up with the same solution for transparency, did they solve the problem in the same way?"

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Muscular study provides new information about how the largest dinosaurs moved and evolved

New research led by the University of Bristol has revealed how giant 50-tonne sauropod dinosaurs, like Diplodocus, evolved from much smaller ancestors, like the wolf-sized Thecodontosaurus.

In a new study published today in the journal Royal Society Open Science, researchers present a reconstruction of the limb muscles of Thecodontosaurus, detailing the anatomy of the most important muscles involved in movement.

Thecodontosaurus was a small to medium sized two-legged dinosaur that roamed around what today is the United Kingdom during the Triassic period (around 205 million years ago).

This dinosaur was one of the first ever to be discovered and named by scientists, in 1836, but it still surprises scientists with new information about how the earliest dinosaurs lived and evolved.

Antonio Ballell, PhD student in Bristol's School of Earth Sciences and lead author of the study, said: "The University of Bristol houses a huge collection of beautifully preserved Thecodontosaurus fossils that were discovered around Bristol. The amazing thing about these fossilised bones is that many preserve the scars and rugosities that the limb musculature left on them with its attachment."

These features are extremely valuable in scientific terms to infer the shape and direction of the limb muscles. Reconstructing muscles in extinct species requires this kind of exceptional preservation of fossils, but also a good understanding of the muscle anatomy of living, closely related species.

Antonio Ballell added: "In the case of dinosaurs, we have to look at modern crocodilians and birds, that form a group that we call archosaurs, meaning 'ruling reptiles'. Dinosaurs are extinct members of this lineage, and due to evolutionary resemblance, we can compare the muscle anatomy in crocodiles and birds and study the scars that they leave on bones to identify and reconstruct the position of those muscles in dinosaurs."

Professor Emily Rayfield, co-author of the study, said: "These kinds of muscular reconstructions are fundamental to understand functional aspects of the life of extinct organisms. We can use this information to simulate how these animals walked and ran with computational tools."

From the size and orientation of its limb muscles, the authors argue that Thecodontosaurus was quite agile and probably used its forelimbs to grasp objects instead of walking.

This contrasts with its later relatives, the giant sauropods, which partly achieved these huge body sizes by shifting to a quadrupedal posture. The muscular anatomy of Thecodontosaurus seems to indicate that key features of later sauropod-line dinosaurs had already evolved in this early species.

Professor Mike Benton, another co-author, said: "From an evolutionary perspective, our study adds more pieces to the puzzle of how the locomotion and posture changed during the evolution of dinosaurs and in the line to the giant sauropods.

"How were limb muscles modified in the evolution of multi-ton quadrupeds from tiny bipeds? Reconstructing the limb muscles of Thecodontosaurus gives us new information of the early stages of that important evolutionary transition."

Read more at Science Daily

Amazon Rainforest birds’ bodies transform due to climate change

The most pristine parts of the Amazon rainforest devoid of direct human contact are being impacted by human-induced climate change, according to new research by LSU scientists. New analyses of data collected over the past four decades show that not only has the number of sensitive resident birds throughout the Amazon rainforest declined, but the body size and wing length have changed for most studied species. These physical changes in the birds track increasingly hot and dry conditions in the dry season, from June to November.

"Even in the middle of this pristine Amazon rainforest, we are seeing the global effects of climate change caused by people, including us," said Vitek Jirinec, LSU alumnus (Ph.D. '21), associate ecologist at the Integral Ecology Research Center and lead author to this study published in the journal Science Advances.

Birds in the Amazon rainforest have become smaller and their wings have become longer over several generations, indicating a response to the shifting environmental conditions that may include new physiological or nutritional challenges.

This is the first study to discover these changes in non-migratory birds' body size and shape, which eliminates other factors that may have influenced these physiological changes. Jirinec and colleagues studied data collected on more than 15,000 individual birds that were captured, measured, weighed, marked with a leg band and released, over 40 years of field work in the world's largest rainforest. The data reveal that nearly all of the birds' bodies have reduced in mass, or become lighter, since the 1980s. Most of the bird species lost on average about 2 percent of their body weight every decade. For an average bird species that weighed about 30 grams in the 1980s, the population now averages about 27.6 grams. How significant is this?

"These birds don't vary that much in size. They are fairly fine-tuned, so when everyone in the population is a couple of grams smaller, it's significant," said co-author Philip Stouffer, who is the Lee F. Mason Professor in the LSU School of Renewable Natural Resources.

The data set covers a large range of the rainforest so the changes in the birds' bodies and wings across communities are not tied to one specific site, which means that the phenomenon is pervasive.

"This is undoubtedly happening all over and probably not just with birds," Stouffer said. "If you look out your window, and consider what you're seeing out there, the conditions are not what they were 40 years ago and it's very likely plants and animals are responding to those changes as well. We have this idea that the things we see are fixed in time, but if these birds aren't fixed in time, that may not be true."

The scientists investigated 77 species of rainforest birds that live from the cool, dark forest floor to the warmer, sunlit midstory. They discovered that the birds that reside in the highest section of the midstory and are the most exposed to heat and drier conditions, had the most dramatic change in body weight and wing size. These birds also tend to fly more than the birds that live on the forest floor. The idea is that these birds have adapted to a hotter, drier climate by reducing their wing loading therefore becoming more energy efficient in flight. Think of a fighter jet with a heavy body and short wings that requires a lot of energy to fly fast compared to a glider plane with a slim body and long wings that can soar with less energy. If a bird has a higher wing loading, it needs to flap its wings faster to stay aloft, which requires more energy and produces more metabolic heat. Reducing body weight and increasing wing length leads to more efficient resource use while also keeping cooler in a warming climate.

LSU alumnus Ryan Burner (Ph.D. '19) conducted much of the analysis that revealed the variation among the groups of birds over the years. Burner, who is now a research wildlife biologist at the U.S. Geological Survey Upper Midwest Environmental Sciences Center, is the second author of this study.

The question of the future capacity of Amazonian birds to deal with increasingly hotter and drier surroundings, especially in the dry season, remains unanswered. The same question can be asked for a lot of places and species that live at the edges of even more environmental extremes.

Read more at Science Daily

These hips don’t lie: 3D imaging of a pelvis suggests social care for saber-tooths

You can't spell 'Smilodon fatalis' without 'fatal', but researchers at La Brea Tar Pits may have found a softer side to saber-toothed cats along with a connection to our own feline and canine companions.

Published in Scientific Reports, a new study led by Dr. Mairin Balisi, Postdoctoral Fellow at La Brea Tar Pits, in collaboration with orthopaedic surgeons at Cedars-Sinai hospital, used 3D image reconstruction of external and internal bone morphology of a deformed Smilodon hip bone to reveal this saber-toothed cat suffered from hip dysplasia, suggesting a social structure that helped members survive to adulthood even when they couldn't hunt for themselves due to this birth defect.

Part of the richness of La Brea Tar Pits' collection are the fossils exhibiting signs of injury and disease-the more than 8,000 specimens that make up the pathology collection. These damaged bones are incredibly valuable for better understanding extinct animals' behavior. For instance, the lower-back trauma found (and reported in an earlier article by Dr. Balisi) in many Smilodon vertebrae points to a hunting style that includes grappling with large Ice Age prey, like bison. For more than a century, paleontologists thought the massive destruction of the pelvis examined in this study was caused by trauma or infection that eventually led to the animal's death, but a look inside the bone using modern medical technology told a different story.

Using computed tomography, the same technology common in hospitals (and veterinarian offices), the pelvis and matching thigh bone were scanned, and the resulting images were used to create 3D models of the inside of the bones. "To quote Roy Moodie in his 1930 study: this pelvis is 'the most strikingly pathological object in the collection of Rancho La Brea fossils'. And so if we were to CT-scan a specimen-with CT being a resource-intensive method- then we had to start with this one," says Dr. Balisi.

"Understanding the 3D shape of a skeleton is fascinating to me," says co-author Dr. Robert Klapper, orthopaedic surgeon and sculptor. Seeing the sheer amount of skulls on the Tar Pits' dire wolf wall over a decade ago led to talking his way into the collection. "When I saw the incredible display of bones at La Brea Tar Pits, I immediately asked to meet (then Collections Manager and study co-author) Chris Shaw. I asked him where were the abnormal joints that I knew must have existed. Chris took me to the stacks and showed me the three pelvises and one femur that he was studying. That's when we decided to collaborate and began the analysis of the etiology of the end-stage degeneration of the saber-tooth hips."

This scanned cat's CAT scan upended the previous interpretation of its hip bones. After careful analysis of the bones' internal structure, the team concluded that the damage wasn't the result of an injury suffered on the hunt, but congenital hip dysplasia.

"Computed tomography (CT) was utilized by our research group to test hypothesized etiologies of hip degeneration in the Smilodon pelvis and femur bone specimens, as it allowed us to observe the anatomical distortions at a more granular level and create three-dimensional reconstructions to use in determining how well the pathology corresponded to that typically seen in bones subjected to many years of chronic remodeling," says Dr. Abhinav Sharma, co-lead author and physician. "Additionally, from a medical standpoint, I am incredibly excited to share this study's findings because it helps illuminate the utility of 3D reconstruction for the characterization of pathology in human bone specimens and highlights its potential for use in creation of patient-specific surgical implants and prostheses tailored for each individual's unique anatomy."

Common in pet dogs and cats, the malformation of the hip bone's ball and socket joints called hip dysplasia would have been extremely problematic for Smilodon. Smilodon's impressive size meant that it needed to prey on megaherbivores like bison and camels to survive. Like living big cats, Smilodon needed strong hind limbs for speed, and from the initial leap to the subsequent grappling required to take down large prey, healthy hips would have been critical to their hunting strategy.

"In this case, our animal sustained a developmental condition (not an injury) and was able to live to adulthood-suggesting that it must have received support, perhaps by food-sharing with its family," says Dr. Balisi.

Hobbled since it was a kitten, this individual could never have hunted or defended territory on its own. While a beloved Labrador retriever might receive a hip replacement or careful pampering by human owners, a Smilodon would have been left to nature -- and their saber-toothed family. This big cat's survival to adulthood suggests that saber-toothed cats took care of one another.

"Social behavior is difficult to infer in fossils. Smilodon in particular is only distantly related to big cats today (like the distance between our house-cats and the African lion, if not greater)," says Dr. Balisi. "So we can't reconstruct Smilodon's socialitybased on, say, living lions and tigers. Living big cats range in social structure anyway: the lion is the only one that's truly social, while tigers and jaguars tend to be solitary or even vary in sociality within a single species."

"In Smilodon's case, we are lucky to have multiple lines of evidence-a lot of them from La Brea Tar Pits-suggesting that it was social," Dr. Balisi says. "Thousands of individuals are preserved here, which is more likely if Smilodon had been social than solitary." This isn't the first sign of saber-tooth social behavior. In other Smilodon fossils, researchers have found signs of healing from grievous injuries that likely would've meant starving without support. Dr. Balisi adds, "evidence from tooth and bone development also support Smilodon having had delayed weaning and extended family care-not just from here but also from other asphalt seeps globally, like Corralito in Ecuador."

Read more at Science Daily

The physics behind a tardigrade's lumbering gait

Plump and ponderous, tardigrades earned the nickname "water bears" when scientists first observed the 0.02-inch-long animals' distinctive lumbering gaits in the 18th century. Their dumpy plod, however, raises the question of why tardigrades evolved to walk at all.

Animals as small and soft as tardigrades seldom have legs and almost never bother walking. For example, round worms of similar size and body type thrash about, slithering their doughy forms over unpredictable substrates. Yet the water bear, a micro-animal so distinct that scientists were forced to assign it to its own phylum, uses eight stubby legs to improbably propel itself through marine and freshwater sediment, across desert dunes, and beneath the soil.

Now, a new study in PNAS analyzes tardigrade gaits and finds that water bears walk in a manner most closely resembling that of insects 500,000 times their size. The discovery implies the existence of either a common ancestor or an evolutionary advantage that explains why one of the smallest and squishiest creatures evolved to walk just like larger, hard-bodied insects.

"Tardigrades have a robust and clear way of moving -- they're not these clumsy things stumbling around in the desert or in leaf litter," says Jasmine Nirody, a fellow in Rockefeller's Center for Studies in Physics and Biology. "The similarities between their locomotive strategy and that of much larger insects and arthropods opens up several very interesting evolutionary questions."

Smooth runners

Nirody and colleagues first determined how water bears walk and run. "If you watch tardigrades under a light microscope for long enough, you can capture a wide range of behavior," Nirody says. "We didn't force them to do anything. Sometimes they would be really chill and just want to stroll around the substrate. Other times, they'd see something they like and run towards it."

Nirody found that, at their most leisurely, water bears lumber about half a body length per second. At full throttle, their loping strides carried them two body lengths in the same amount of time. But the surprise came when she observed how a water bear's feet contact the ground as it gains momentum. Unlike vertebrates, which have distinct gaits for each speed -- picture a horse's hooves as it transitions from a walk to a gallop -- tardigrades run more like insects, scurrying at increasing speeds without ever changing their basic stepping patterns.

"When vertebrates switch from walking to running, there is a discontinuity," Nirody says. "With arthropods, all stepping patterns exist along the same continuum."

Ancient coordination

Why do tardigrades share a locomotive strategy with much larger, hard-bodied insects?

One possible explanation is that tardigrades, long assumed to fit neatly into no existing taxonomy, may share common ancestors -- and even a common neural circuit -- with insects such as fruit flies, ants, and other segmented scurrying creatures. In fact, some scientists advocate classifying tardigrades within the proposed panarthropod clade, a catchall group that would assign common shelf space to insects, crustaceans, velvet worms, and water bears.

Another possibility is that there is no ancestral connection between tardigrades and arthropods, but that the unrelated groups of organisms independently arrived at the same walking and running strategies because they were evolutionarily advantageous. Perhaps the best way to navigate unpredictable terrain with a microscopic body is to plod like a water bear.

Nirody is equally fascinated by both possibilities. "If there is some ancestral neural system that controls all of panarthropod walking, we have a lot to learn," she says. "On the other hand, if arthropods and tardigrades converged upon this strategy independently, then there's much to be said about what makes this strategy so palatable for species in different environments."

Beyond the implications for evolutionary biology and the study of animal locomotion, the findings may have ramifications for the burgeoning fields of soft and microscale robotics.

By studying how small animals evolved to move across challenging environments, scientists may be able to design robots that can more efficiently squeeze into small spaces or operate at the microscale. "We don't know much about what happens at the extremes of locomotion -- how to make an efficient small walker, or how soft-bodied things should move," Nirody says.

Read more at Science Daily

Young T. rexes had a powerful bite, capable of exerting one-sixth the force of an adult

Jack Tseng loves bone-crunching animals -- hyenas are his favorite -- so when paleontologist Joseph Peterson discovered fossilized dinosaur bones that had teeth marks from a juvenile Tyrannosaurus rex, Tseng decided to try to replicate the bite marks and measure how hard those kids could actually chomp down.

Last year, he and Peterson made a metal replica of a scimitar-shaped tooth of a 13-year-old juvie T. rex, mounted it on a mechanical testing frame commonly used in engineering and materials science, and tried to crack a cow legbone with it.

Based on 17 successful attempts to match the depth and shape of the bite marks on the fossils -- he had to toss out some trials because the fresh bone slid around too much -- he determined that a juvenile could have exerted up to 5,641 newtons of force, somewhere between the jaw forces exerted by a hyena and a crocodile.

Compare that to the bite force of an adult T. rex -- about 35,000 newtons -- or to the puny biting power of humans: 300 newtons.

Previous bite force estimates for juvenile T. rexes -- based on reconstruction of the jaw muscles or from mathematically scaling down the bite force of adult T. rexes -- were considerably less, about 4,000 newtons.

Why does it matter? Bite force measurements can help paleontologists understand the ecosystem in which dinosaurs -- or any extinct animal -- lived, which predators were powerful enough to eat which prey, and what other predators they competed with.

"If you are up to almost 6,000 newtons of bite force, that places them in a slightly different weight class," said Tseng, UC Berkeley assistant professor of integrative biology. "By really refining our estimates of juvenile bite force, we can more succinctly place them in a part of the food web and think about how they may have played the role of a different kind of predator from their larger, adult parents."

The study reveals that juvenile T. rexes, while not yet able to crush bones like their 30- or 40-year-old parents, were developing their biting techniques and strengthening their jaw muscles to be able do so once their adult teeth came in.

"This actually gives us a little bit of a metric to help us gauge how quickly the bite force is changing from juvenile to adulthood, and something to compare with how the body is changing during that same period of time," said Peterson, a professor at the University of Wisconsin in Oshkosh and a paleopathologist -- a specialist on the injuries and deformities visible in fossil skeletons. "Are they already crushing bone? No, but they are puncturing it. It allows us to get a better idea of how they are feeding, what they are eating. It is just adding more to that full picture of how animals like tyrannosaurs lived and grew and the roles that they played in that ecosystem."

Tseng, Peterson and graduate student Shannon Brink of East Carolina University in Greenville, North Carolina, will publish their findings this week in the journal PeerJ.

Teeth marks galore, but who was the biter?

Experiments using metal casts of dinosaur teeth to match observed bite marks are rare, not because bite marks on dinosaur fossils are rare, but because the identity of the biter is seldom clear.

Two dinosaur fossils that Peterson excavated years earlier from the Hell Creek Formation of eastern Montana, however, proved ideal for such an experiment. One, the skull of a juvenile T. rex, had a healed bite mark on its face. "What, other than another T. rex, would be able to chomp another T. rex and puncture its skull?" he reasoned. Tyrannosaurs, like crocodiles today, played rough, and the wound was likely from a fight over food or territory.

In addition, the puncture holes in the skull, which had healed, were the size and shape of juvenile T. rex teeth, and the spacing fit a juvenile's tooth gap. Juvenile T. rexes have teeth that are oval in cross section: more knife-like, presumably to cut and tear flesh. Adult T. rexes have teeth with round cross sections: more like posts, to crush bone. Both juveniles and adults could replace lost or broken teeth from spares buried in the jaw that emerged once the socket was empty.

Because skull bone is harder than other bone, Peterson said, matching these holes with punctures made by the metal tooth in a cow bone provided an upper limit to the bite force.

The other fossil was a tail vertebra from a plant-eating, duckbilled dinosaur, an Edmontosaurus. It had two puncture marks from teeth that matched those of a juvenile T. rex. Peterson said that T. rex was the only predator around at that time -- the late Cretaceous Period, more than 66 million years ago -- that could have bitten that hard on the tailbone of a duckbill. The juvenile likely punctured the bone when chomping down on a meaty part of the tail of the already dead animal.

Because vertebrae are softer, experimentally creating similar punctures in a cow bone gave the researchers a lower limit on bite force.

Tseng employed a testing technique that was used in 2010 by researchers who measured the bite force of a much older and smaller dinosaur from the early Cretaceous: a Deinonychus, made famous under a different name -- Velociraptor -- in the 1993 movie Jurassic Park. Its bite force was between 4,000 and 8,000 newtons.

Tseng, then at the University at Buffalo in New York, and Peterson made a replica of a juvenile T. rex tooth from the middle of the jaw using a dental-grade cobalt chromium alloy, which is much harder than dinosaur tooth enamel, Tseng said.

They then mounted the metal tooth in a mechanical testing frame and pushed it slowly, at a millimeter per second, into a fresh-frozen and thawed humerus of a cow. Bones are easier to fracture at low speed than with a rapid chomp. Because the middle of the humerus has a thicker cortex than the bone near the joint ends, the middle was used to replicate the facial punctures. The ends were used to simulate the vertebra punctures.

"What we did, an actualistic study, is to say, 'Let's actually stab the thing with a tooth and see what it does,'" Peterson said. "What we are finding is that our estimates are slightly different than other models, but they are within a close enough range -- we are on the same page."

Tseng emphasized that there is no one number describing the bite force of any animal: it depends on how the creature bites and adjusts the prey in its mouth for the best leverage.

"They probably were not just chomping down. If you look at modern predators, even reptilian predators, sometimes there is adjustment. Maybe they are finding the most mechanically advantageous place, or the strongest tooth to make their bite," said Tseng, who is a 2004 graduate of UC Berkeley's Department of Integrative Biology and an assistant curator in the University of California Museum of Paleontology. "Presumably, there is some tuning involved before they make that bite, so they can literally take the best bite forward to make that kill or to damage whatever they are trying to get into."

Nevertheless, the measurements are a start in charting the increase in tyrannosaurs' bite force as they mature, similar to how paleontologists have charted T. rex size and weight with age.

"Just as you can do a growth curve for such an organism, you can also do a strength curve for their bite force -- what was their bite force at 12 or 13 years old, what was it at 30, 35 or 40 years old. And what does that potentially mean about the role that those animals played in that ecosystem at the time?" Peterson said. "What's cool about finding bite marks in bone from a juvenile tyrannosaur is that it is tells us that at 13 years old, they weren't capable of crushing bone yet, but they were already trying, they were puncturing bone, pretty deep. They are probably building up their strength as they get older."

Tseng, whose primary interest is mammals, is eager to resume studies interrupted by the pandemic to measure the bite force of various living and extinct animals in order to infer the ecosystem niches of predators no longer alive. For those creatures, fossils are all that paleontologists have, in order to "interpret behavior and breathe some life into these extinct animals," said Peterson.

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How an elephant's trunk manipulates air to eat and drink

New research from the Georgia Institute of Technology finds that elephants dilate their nostrils in order to create more space in their trunks, allowing them to store up to nine liters of water. They can also suck up three liters per second -- a speed 50 times faster than a human sneeze (150 meters per second/330 mph).

The Georgia Tech College of Engineering study sought to better understand the physics of how elephants use their trunks to move and manipulate air, water, food and other objects. They also sought to learn if the mechanics could inspire the creation of more efficient robots that use air motion to hold and move things.

While octopus use jets of water to move and archer fish shoot water above the surface to catch insects, the Georgia Tech researchers found that elephants are the only animals able to use suction on land and underwater.

The paper, "Suction feeding by elephants," is published in the Journal of the Royal Society Interface.

"An elephant eats about 400 pounds of food a day, but very little is known about how they use their trunks to pick up lightweight food and water for 18 hours, every day," said Georgia Tech mechanical engineering Ph.D. student Andrew Schulz, who led the study. "It turns out their trunks act like suitcases, capable of expanding when necessary."

Schulz and the Georgia Tech team worked with veterinarians at Zoo Atlanta, studying elephants as they ate various foods. For large rutabaga cubes, for example, the animal grabbed and collected them. It sucked up smaller cubes and made a loud vacuuming sound, or the sound of a person slurping noodles, before transferring the vegetables to its mouth.

To learn more about suction, the researchers gave elephants a tortilla chip and measured the applied force. Sometimes the animal pressed down on the chip and breathed in, suspending the chip on the tip of trunk without breaking it. It was similar to a person inhaling a piece of paper onto their mouth. Other times the elephant applied suction from a distance, drawing the chip to the edge of its trunk.

"An elephant uses its trunk like a Swiss Army Knife," said David Hu, Schulz's advisor and a professor in Georgia Tech's George W. Woodruff School of Mechanical Engineering. "It can detect scents and grab things. Other times it blows objects away like a leaf blower or sniffs them in like a vacuum."

By watching elephants inhale liquid from an aquarium, the team was able to time the durations and measure volume. In just 1.5 seconds, the trunk sucked up 3.7 liters, the equivalent of 20 toilets flushing simultaneously.

An ultrasonic probe was used to take trunk wall measurements and see how the trunk's inner muscles work. By contracting those muscles, the animal dilates its nostrils up to 30 percent. This decreases the thickness of the walls and expands nasal volume by 64 percent.

"At first it didn't make sense: an elephant's nasal passage is relatively small and it was inhaling more water than it should," said Schulz. "It wasn't until we saw the ultrasonographic images and watched the nostrils expand that we realized how they did it. Air makes the walls open, and the animal can store far more water than we originally estimated."

Based on the pressures applied, Schulz and the team suggest that elephants inhale at speeds that are comparable to Japan's 300-mph bullet trains.

Schulz said these unique characteristics have applications in soft robotics and conservation efforts.

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