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Ancient Deer-Like Creatures Returned to the Ocean to Become Whales. But Why?

Friday, March 23, 2018

 The evolution of whales. Image: John Klausmeyer/University of Michigan Museum of Natural History

The ocean may be the origin of all life on Earth, but that isn’t to say that all the animals who evolved on land left the water behind forever. In fact, we’re starting to get a pretty good picture of why certain species that returned back to the water decided to do so and how they developed into the marine animals we know today. Paleontologists say creatures began exploring the land during the Silurian period (440-410 million years ago). No one is sure why this occurred. Some scientists say it may have been tight competition for resources in marine environments that pushed species to look for food elsewhere.

 

The first land explorers were arthropods, who started spending just a little bit of time on the surface and then began doing so more and more. They were pre-adapted to land exploration because of their hard shells, which helped retain water. Around 370 million years ago, certain species became permanent land residents. Spiders, mites, and centipedes were the first inhabitants. Then, over the next few million years, amphibians, reptiles, and finally mammals made it onto the scene. But that doesn’t mean they all stayed on land.

During the Early Triassic period (approx. 252-247 million years ago) onward, dozens of terrestrial and freshwater animals returned to the sea. Birds, reptiles, amphibians, and mammals were among them. They evolved and eventually became dominant players in their ecosystems during the Mesozoic and Cenozoic eras. Today, lots of the marine mammals we know and love started out as land-based species.

For instance, a walrus’s ancestor resembles the modern otter, while whales come from a species of ancient deer-like creatures known as Indohyus. They roamed southern Asia about 48 million years ago. An Indohyus was only about the size of a raccoon, and researchers believe that they fed on aquatic plants.

So what coaxed these creatures back into the ocean 100 million years after their ancestors climbed out of it? A duo of researchers contend that this question has received far too little attention, until now. The results of their study has been published in a report in the journal Paleobiology. To date, there have been two prevailing hypotheses.

In one, ecosystem collapse caused mass extinction, pushing animals back toward the sea for food. In another, competition added pressure on species while abundant food sources in the ocean, particularly in areas near the shoreline, pulled species back toward the sea. Geerat Vermeij at the University of California-Davis and his colleague Ryosuke Motani decided to test these theories to see which one was more likely.

The scientists isolated 69 incidents in which a terrestrial species decided to live in or extract sustenance from the ocean after a mass extinction had taken place. In two of the largest such events, one that occurred 201 million years ago at the end of the Triassic and another at the end of the Cretaceous period, there was no grand exodus of land animals back into the sea. A 2014 South African study discovered an increase in species returning to the ocean 66 million years ago, at the tail end of the Cretaceous extinction. What differed in this study was that the previous one only included animals which are still around today.  

Vermeij and Motani’s study supports the idea that terrestrial animals took advantage of food sources in the ocean periodically, not just after mass extinctions, and the trend has only increased over the past 60 million years or so. One reason that may be a pull factor: kelp and seagrass beds developed over this period, allowing for more marine life to sprout and proliferate closer to shore.

To learn more about whale evolution, click here.

Source: http://bigthink.com

Adaptive Radiations in the Mesozoic

Saturday, March 24, 2018

The Ginglymodi Propterus elongatus in the Paleontological Museum Munich. Credit: A. López-Arbarello, LMU

Bony fishes are the most diverse of all extant vertebrate groups. A comprehensive phylogenetic analysis of the group now provides new insights into its 250-million-year evolutionary history.

With some 30,000 currently recognized species, the true bony fishes or teleosts, which belong to the Neopterygii, account for more than half of modern vertebrate diversity. In collaboration with her Argentinian colleague Emilia Sferco, LMU paleontologist Adriana López-Arbarello, who is in the Paleontology and Geobiology Section at the Department of Earth and Environmental Sciences and is also a member of the Geobiocenter, has undertaken a new analysis of the group's family tree. Their results, which shed new light on 250 million years of evolutionary history, appear in the online journal Royal Society Open Science.

More than 99% of the species of Neopterygii in the world today belong to a single lineage, the true bony fishes or Teleostei. Relative to the rich diversity of the teleosts, the other two neopterygian lineages are strikingly impoverished. The Ginglymodi are made up of the seven recognized species of gars, and the Halecomorphi ¬now consist of a single species, Amia calva, commonly known as the bowfin. In their heyday in the Mesozoic – the Age of the Dinosaurs – the picture was very different. At that time, the Ginglymodi and the Halecomorphi were highly diverse, and they dominated the oceans and freshwater habitats, while the teleosts were a much more modest presence in the world's waters.

The huge difference in the numbers of extant species assigned to the three groups makes it extremely difficult to unravel the relationships between them. However, fossil specimens can help to correct this imbalance, and thus make it possible to elucidate their 250-million-year history. "In fact," says Adriana López-Arbarello, "our study was motivated by the discovery of one very unusual fossil genus." Specimens of this genus, dated to 240 million years ago, which exhibit traits characteristic of both the Ginglymodi and the Halecomorphi, were recovered by a Swiss team from an important marine fossil Lagerstätte in the Alps. Their discoverers invited López-Arbarello to participate in the anatomical investigation and description of their finds. Later, López-Arbarello und Sferco took up the task of working out how the new genus fits into the neopterygian family tree. To do so, they assembled the largest morphological dataset yet constructed for fossils of this subclass.

Phylogenetic analysis of these data revealed that Ginglymodi and Halecomorphi are more closely related to each other than either is to Teleostei. This confirms what has been regarded by many paleontologists as a controversial notion – namely that the first two taxonomic groups share a common ancestor, and can therefore be subsumed into a single common taxon. In addition, the new study shows that, in the Mesozoic, all three lineages underwent several rapid adaptive radiations, i.e. during which large numbers of novel species evolved over comparatively short periods of time. Not only were Ginglymodi and Halecomorphi represented by enormous numbers of species, these species were characterized by a broad spectrum of morphological and ecological specializations. Indeed, some of the most impressive Mesozoic fossils belong to these lineages. One example is Scheenstia maximus, which grew to a length of nearly 2 meters.

The Teleostei subsequently developed a wide variety of feeding habits, and enhanced their maneuverability and the efficiency of their reproductive strategies, while the diversity of the other two lineages progressively declined. Precisely why this happened is still unclear. "One can perhaps compare this situation with the evolution of the dinosaurs," López-Arbarello remarks. "Many successful and diverse groups of dinosaurs died out at the end of the Mesozoic. Only one survived, and its diversification continues – the birds. We have no really convincing explanation for their success either. – So we still have a lot to learn about the fauna of the Mesozoic and the biological world of which it was a part."

Source: https://phys.org

Early Birds May Have Been Too Hefty To Sit On Their Eggs

Saturday, March 24, 2018

Credit: Jaime Chirinos/SPL

Fossil pelvises suggest brooding might have evolved late in modern birds.

Birds that lived at the time of the dinosaurs might have been too heavy to sit on clutches of eggs without breaking them, according to an analysis of primitive avian fossils. The findings suggest that incubation might be a defining feature of modern birds, evolving only in the past 100 million years.

Some palaeontologists have criticized the study, in part because the idea flies in the face of evidence that some non-avian dinosaurs closely related to birds sat atop nests on the ground. The accepted view by many researchers was that some dinosaurs were already brooding nests to incubate their eggs, which would suggest that the behaviour evolved long before the proliferation of modern groups of birds, following a mass-extinction event 66 million years ago.

Many fossils of early birds have been discovered in the past three decades — particularly in China — but direct evidence of their reproductive behaviour has been elusive, says palaeontologist Charles Deeming at the University of Lincoln, UK, who led the analysis.

Egg extrapolation

Most birds today incubate their eggs by sitting on them. To test whether the behaviour was common in birds living in the Cretaceous and Upper Jurassic periods, Deeming and his collaborator Gerald Mayr estimated the size and load-bearing capacity of the eggs of 21 species of primitive bird, including Confuciusornis and Yanornis and one of the oldest of all birds, Archaeopteryx, which lived about 150 million years ago.

Previous work had shown that modern birds evolved a more open pelvis, which would have allowed the size of their eggs to increase over time, says Mayr, who is at the Senckenberg Research Institute and Natural History Museum Frankfurt in Germany. In early birds, pelvic bones were fused, creating a canal that limited egg size. Given they had no fossil eggs to measure, the scientists measured the pelvic-canal width to estimate the likely size and mass of each species’ eggs. They then calculated the load mass of each egg — the maximum weight that they could bear without breaking.

The pair found that for every species tested, the load mass of its eggs would have been too low to support the weight of an adult. “If that’s the case, those birds can’t sit on those eggs without real threat of destroying them,” Deeming says. Some species, such as Confuciusornis, had a mass more than three times what the eggs could have supported, according to the study, which was published last month in the Journal of Evolutionary Biology1.

Modern birds, by contrast, lay eggs that can often accommodate three times the body mass of the adult, Deeming says. Based on that, the authors argue that contact incubation — sitting on eggs — evolved late in the history of modern birds, possibly after the emergence of a more open pelvis in the past 100 million years or so.

Deeming says that studies of the few species of dinosaurs whose fossils suggest they brooded their eggs are not definitive. For example, famous fossils of oviraptorids in the Gobi Desert have been found tucked up near their eggs, but they are likely to have been guarding nest mounds, similar to crocodylians, rather than incubating eggs the way modern birds do, he says.

Dinosaur debate

Jingmai O’Connor, an Cretaceous-bird specialist at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, says that the study confirms what she and some other researchers have long inferred about the late development of contact incubation: “I'm sure that early birds were too heavy to incubate in the same manner as living birds.” But the statistical support for the findings is not conclusive, she warns, because it is based on many assumptions and unknown variables, such as the precise shape of these birds’ eggs.

O’Connor agrees that dinosaurs fossilized with nests might have been protecting rather than incubating their eggs. As with many aspects of modern bird behaviour, “derived brooding behaviours evolved in a step-wise fashion, culminating with the full contact incubation observed in living birds”, she says.

Palaeontologist David Varricchio, who studies dinosaur and bird reproduction at Montana State University in Bozeman, says that he likes the study’s approach, but is surprised that the authors calculated egg sizes to be one-tenth to one-fifth of what you would expect for a similar-sized bird today. “There would have to be a huge increase in relative egg size” at the base of the branch of modern birds on the evolutionary tree, he says. “So, something seems out of whack here.”

Luis Chiappe, director of the Dinosaur Institute at the Natural History Museum of Los Angeles County in California, challenges the study’s suggestion that early birds might have nested on the ground rather than in trees. Knowledge of the enantiornithines, one of three groups of primitive birds examined in the study, suggests that they lived in trees, he says. “If you live in a tree, most likely you nest in a tree. And if you nest in a tree, I don't see how these eggs could have been incubated if it's not by contact with a parent.”

Hatchlings might have been found in trees, says Deeming, but that doesn’t mean adults nested in them. He and Mayr believe contact incubation might have been a key innovation that was responsible for the success of modern birds, and might explain why only their ancestors survived, while other early groups of birds perished in the extinction event.

Source: www.nature.com

Lufengosaurus huenei: Jurassic Dinosaur Diagnosed With Bone Disease

Saturday, March 24, 2018

Reconstruction of the bite wound affecting the shoulder of our herbivorous dinosaur. Zongda Zhang/Lida Xing, CC BY-SA

A 200 million year old sauropod has been diagnosed with osteomyelitis, a severe bone disease, according to a scientific paper published on Thursday.

Scientists from China, the United States, Britain and South Africa said study of a Jurassic Lufengosaurus fossil from Lufeng Dinosaur Museum in southwest China's Yunnan Province, suggests it may have had a serious bone infection.

The findings were published on Scientific Reports, an online open-access scientific journal.

Map showing the location of the dinosaur fossil discovery. Lida Xing

 

When the dinosaur was excavated in 1997, there was a pathological abnormality on one of its right ribs. A small hole penetrates almost halfway through the rib, said the museum's Wang Yi.

"The rim of the penetration is quite smooth, so it is more likely to be caused by some kind of disease, rather than any injury," said paleontologist Xing Lida, lead researcher of the team.

According to Xing, traditional bone pathology involves low powered magnification of the bone, but this only shows the external surface of the fossil.

"In the case of this rib, the lesion penetrates deep into the bone, so we needed to find a way to see the internal structure before diagnosis," Xing said.

The pathological rib of Lufengosaurus, showing the removal of a large area of bone. Lida Xing

 

Now, 20 years after the dinosaur's discovery, X-ray micro-computed tomography (micro-CT) can image the deep structures and reconstruct the cellular structure of the rib.

"From micro-CT scanning and reconstruction, we can tell this Lufengosaurus was attacked by a predator and the bite caused osteomyelitis which took its life. It must have suffered a lot before death," said Ran Hao, researcher at the Chinese Academy of Sciences Kunming institute of zoology.

"This is the first time that China has found such pathological changes in sauropod dinosaurs. This exciting discovery will aid understanding of how osteomyelitis originated and evolved,"said Xing.

Micro-computed tomography allowed us to produce surface renderings of the fossil in 3D (top row) and 2D X-ray slices through the rib (bottom row). These show areas of cellular reorganisation, bone destruction and bone formation indicative of ostemyelitis. Patrick Randolph-Quinney, UCLan

This is only the second case of osteomyelitis in a sauropod in the fossil record. The other case comes from a giant titanosaur from Argentina with a bacterial infection of the spine.

 

Lufengosaurus was a herbivore, with a long neck and a small head. At least 16 Early Jurassic dinosaur species have been named after Lufeng and its neighboring area since paleontologist Yang Zhongjian published a paper on Lufengosaurus huenei in 1941.

The recent work highlights how the use of micro-CT is revolutionizing the study of the fossil record.

"This finding can provide critical insight into palaeo-immunology, behavioral and life history information for dinosaurs, as well as environmental insights into ancient ecosystems," Xing said.

Source: www.xinhuanet.com

 

 

 

Laura Dern to Cameo in Jurassic World: Fallen Kingdom?

Friday, March 23, 2018

Is Laura Dern Returning in Jurassic World 2?

Jeff Goldblum has hinted that Laura Dern could be making a cameo in 'Jurassic World: Fallen Kingdom'.

The 65-year-old actor is reprising his role from the original 1993 movie 'Jurassic Park' as chaos theorist Dr Ian Malcolm in the upcoming dinosaur film.

And Jeff teased Laura, who also starred in the original blockbuster, may be set to join him as paleobotanist Ellie Sattler.

Jeff told 'Entertainment Tonight': "I don't want to pass on gossip like my character, but it would be good news to me and to everyone, [to] millions and billions of people all over the world... all over the universe and cosmos when Ellie Sattler returns."

Laura, 51, has previously admitted she would love to reprise the role.

The 'Big Little Lies' star said: "[It] could be fun. I mean, I love Ellie Sattler. She's a tough feminist! We need her back."

'Jurassic World: Fallen Kingdom' - starring Chris Pratt and Bryce Dallas Howard and directed by J. A. Bayona - is set to open in cinemas this summer.

Universal has already commissioned a third 'Jurassic World' movie for 2021, which would be the sixth film in the franchise.

Laura recently revealed Steven Spielberg, who directed the first 'Jurassic Park' movie, was present at the birth of her children.

The 71-year-old director - who raises seven children with wife Kate Capshaw - formed a close bond with the actress after they were "buddied up" when a hurricane hit the Hawaiian island of Kauai, where they were filming the dinosaur blockbuster, and the experience made them become like "family" to one another.

Laura - who has children Ellery 16, and Jaya, 13, with ex-husband Ben Harper - said: "Going through an experience like that is life-altering. Steven and I were buddies through the hurricane - everyone got buddied up - and by the time the film finished, we were family. He and his wife were at the hospital when I gave birth. We've been at each other's children's celebrations and birthdays. Our friendship has meant the world to me."

This article originally ran on celebretainment.com.

Scientists Are Studying Rotting Animal Carcasses To Understand Why Complete Dinosaur Fossils Are So Rare

Friday, March 23, 2018

Zombie fossil? This is an artist's impression of an undead T. rex. The missing parts are the result of degradation of the body after death. BY HERSCHEL HOFFMEYER

Paleontologists rarely find a complete skeleton from a prehistoric beast. Sometimes, they find only a skull, a tooth or a vertebra and have to make guesses about the creature based on minimal evidence. Where did the rest of the remains go?

It’s not as if part of the beast died in one place and the rest died elsewhere. Scientists usually find only some of the remains because decomposition and scavenging can partially destroy them before they have a chance to fossilize.

New research from the University of Leicester and the University College Cork published in the journal Paleontology will help paleontologists understand the environmental factors that affected dinosaur carcasses before they left the fossils that scientists see and study today. Since you can’t watch a dead nonbird dinosaur decompose anymore, the researchers observed the next best thing—modern animal carcasses.

"As soon as an organism dies, it starts to decay, and this process of decomposition inevitably involves changes in how features or body parts look,” Sarah Gabbott from the University of Leicester said in a statement. “They may collapse, alter their shape or position; all too soon they liquefy and are eaten by bacteria until nothing remains."

The researchers obtained dead insects, hagfish, lampreys and other animals to watch them wither away. This research is similar to that done at “body farms,” where anthropologists study dead human bodies under different conditions to compare with human bodies undergoing autopsies, so they can better determine what happened when they died.

For example, dry conditions and moisture-absorbing materials can help mummify a carcass, including the skin. Scavengers can tear at bodies they find, bringing a leg with them to chew on and leaving the rest behind. However, fossilization is a comparatively rare event, and often animals decompose completely before nature has a chance to preserve them.

Source: www.newsweek.com

HORNY TRICERATOPS: Frills And Horns Did Not Evolve For Species Recognition But To Woo a Mate

Thursday, March 22, 2018

Triceratops Artwork by Zhao Chuang

 

The elaborate frills and horns of a group of dinosaurs including Triceratops and Styracosaurus did not evolve to help species recognise each other, according to researchers at Queen Mary University of London.

It has been suggested that different species that live in the same location may evolve features in order to distinguish one another to help avoid problems such as hybridisation, where two individuals of different species produce infertile or unfit offspring.

To test this hypothesis the researchers examined patterns of diversity in the ornamentation of 46 species of ceratopsians, the horned dinosaurs, but found no difference between species that lived together and those that lived separately.

A previous research paper from Queen Mary found that the frill in one ceratopsian species, Protoceratops, may have evolved under sexual selection. These new findings appear to add evidence to this across the entire group.

The researchers also found evidence that ornamental traits seemed to evolve at a much faster rate than other traits. As these structures are costly to grow and maintain, this finding similarly points to a strong selective pressure on these traits.

The study was published in Proceedings of the Royal Society B.

The Protoceratops in the Horniman Museum, London. Credit: Horniman Museum, London

Andrew Knapp, PhD candidate from the School of Biological and Chemical Sciences and lead author of the study, said: "This resolves a long-standing and hitherto untested hypothesis concerning the origin and function of ornamental traits in ceratopsian dinosaurs. Many general discussions of ceratopsian ornaments in museum signage and popular literature often include examples of what they might have been for, but these tend to be rather speculative.

"We have shown that species recognition, one of the commonest explanations, is unlikely to be responsible for the diversity or origin of ornamentation in this group."

Graphic on dinosaurs with horns on their heads.

The researchers believe the implications extend beyond the scope of ceratopsians and have consequences for the study of evolutionary theory over vast stretches of time.

The fossil record offers an opportunity to see evolution in action over much longer time periods than can be achieved with living organisms, but it is difficult to assign explanations to unusual features such as ceratopsian ornaments with the limited information that fossils provide.

The researchers have now largely ruled out one explanation, species recognition, and provided some evidence for another, sexual selection.

The Chasmosaurus skeleton in the Royal Tyrrell Museum of Paleontology. Credit: Royal Tyrrell Museum of Paleontology
 

Mr Knapp said: "If sexual selection is indeed the driver of ornament evolution in ceratopsians, as we are increasingly confident it is, demonstrating it through different lines of evidence can provide a crucial window into tracing its effects over potentially huge timescales."

He added: "Modern computer models have suggested that sexual selection can promote rapid speciation, adaptation, and extinction. In our world of increasing pressure on the natural world, these predictions may have important consequences for conservation and the fate of living things everywhere."

To test these predictions the researchers hope to look at changes in the fossil record and gather further evidence to first identify sexual selection in a fossil group.

More information: Patterns of divergence in the morphology of ceratopsian dinosaurs: sympatry is not a driver of ornament evolution, Proceedings of the Royal Society B (2018). http://rspb.royalsocietypublishing.org/content/285/1875/20180312

Journal reference: Proceedings of the Royal Society B

Provided by: Queen Mary, University of London

Source: https://phys.org

Mongolia to Recover Dinosaur Fossils From South Korea, France

Wednesday, March 21, 2018

Mongolia is working to recover dinosaur fossils which were illegally trafficked into South Korea and France, the Department for Economic Crime of the Mongolian General Police Department said Monday.

The competent authorities concerned found out that the dinosaur fossils were smuggled from Mongolia into South Korea and France, the department said in a statement.

A South Korean court has officially ordered returning of the dinosaur fossils, and the French side said the fossils will be returned to its native Mongolia if the country submits a petition for the recovering of the fossils.

The fossils originated from Mongolia's southern Umnugobi Province, which is known for its large numbers of dinosaur findings, according to the Mongolian Paleontological Institute.

Under Mongolian law, significant fossil discoveries cannot be permanently exported or sold to non-Mongolians, even if privately owned.

Source: www.xinhuanet.com

The Arkansaurus Dinosaur is Officially Official

Thursday, March 22, 2018

The Arkansas legislature resolved last year that Arkansaurus Fridayi was the state's official dinosaur and that was good. But now the Journal of Vertebrate Paleontology has announced the newly recognized creature and that is really official.

Arkansaurus (meaning "Arkansas lizard") is an extinct genus of ornithomimid theropod dinosaur. Arkasaurus fridayi, the type and only species, was declared the official Arkansas state dinosaur in 2017. The dinosaur was discovered in Lockesburg, Arkansas, and was a bipedal ornithomimosaur dinosaur. Its nearest relative is the ornithomimosaur Nedcolbertia. It is named for the state of Arkansas and its discoverer J.B. Friday, who found the dinosaur's fossilized foot on his farm in 1972. It is the only dinosaur fossil currently described from Arkansas. The fossil was officially described in 2018 by paleontologists ReBecca Hunt-Foster and James Quinn in the Journal of Vertebrate Paleontology.

Arkansaurus fridayi lived during the Albian and Aptian stages of the Early Cretaceous.

Even Dinosaurs Had Parasites

Thursday, March 22, 2018

Dinosaur Parasites!

Fossilised faeces and holes in ancient jawbones show that dinosaurs, like modern animals, were plagued by parasites.

Even mighty dinosaurs such as Tyrannosaurus rex were not immune from being pestered by parasites.

By examining fossilised dinosaur droppings – known as coprolites – palaeontologists have found evidence of internal parasites including eggs from flatworms and roundworms, and cysts that look like those formed by modern amoebas. A 100-million-year-old fly has also been found preserved in amber that hosted a malaria-like parasite in its own guts, indicating that dinosaurs too may have been prey to the tiny infectious organism. Distinctive holes in T. rex jawbones may also be signs of a parasite that caused invasive ulcers in the mouth and throat.

Parasites

It just goes to show that strength and size are no defence against parasites. For that, you need hygiene and – if all else fails – modern medicine.

Source: https://cosmosmagazine.com

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