nandi's blog

Young Dinosaur Finding Hints At Evolutionary Differences

Monday, October 29, 2018

A species of Diplocodus is on display in the Carnegie Mellon Museum of Natural History. TADEK KURPASKI/CC WIKIMEDIA

U of T researcher involved in study that uncovered rare diplodocid skull remains.

Diplodocids are a group of sauropods that include giants such as Diplodocus and Supersaurus — some of the longest creatures ever to walk the Earth.

Archaeologists have uncovered hundreds of fossils from this dinosaur group, but little is known about their origin or development into adult form.

In a study published in Scientific Reports, researchers including U of T PhD candidate Cary Woodruff analyzed a young diplodocid’s skull remains — unearthed in 2010 in Montana — and found that younger diplodocids may have had different diets than their older counterparts.

The skull remains, dubbed ‘Andrew,’ demonstrate that cranial dimensions did not develop on a fixed scale or at equal measures.

The dental and cranial differences between a mature and immature diplodocid can give the impression that they are of different species, but Andrew reveals that there are implications for cranial ecology as young diplodocids grow.

Woodruff and his team were able to determine specific differences between Andrew and adult skulls discovered earlier, including an extended tooth row, taller jaw bones, and peg tooth formation.

In fact, the authors state that if the fragments of the skull had been discovered separately, they would have likely been misidentified.

This is mostly because these distinct traits were common to other species — taxa — in the same clade as diplodocids, such as Eusauropoda and Macronaria. To a non-expert, it would seem strange that younger dinosaurs may horizontally integrate in taxa.

However, the researchers describe that this may be due to either recapitulation or, most likely, dietary niche partitioning between the young and adults.

Recapitulation theory suggests that an organism takes on forms of its ancestors — forms that were critical for survival in evolutionary past but are no longer needed — as it grows from embryo to adult, reaching the latest derived state during adulthood.

As such, it has been suggested that the skulls of adult diplodocids are taking the same form as their ancestors’.

The researchers in this study outline how dietary levels of specialization are what determined skull sizes, and that this is a form of recapitulation.

The younger diplodocids, like their relatives in the same clade and their common ancestors, ate more plants and lived in forested areas.

But as they got older, they gravitated to open space habitats and developed a more specific diet. Dietary specialization is the latest in the evolutionary timeline of diplodocid behavioural development, and is only found in fully mature individuals.

Woodruff explained why so many diplodocid skeletons have been discovered, but so little is known about their cranial ontogeny.

“The greatest difficulty in studying diplodocid — any sauropod — skulls are their rarity. We have loads of Diplodocus skeletons (well over 100), but fewer than 10 skulls are known. So it’s difficult to even have specimens to study in the first place,” he wrote.

The fragility of these fossils is also a significant limitation. “Dinosaur skulls are made up of dozens of thin, fragile, and delicate bones. The skull could easily get damaged or destroyed long before it’s even buried and begins the fossilisation process,” wrote Woodruff.

Some of Andrew’s bones were missing, “and those that remained were greatly squished” from being underground for millions of years. Bones can also become warped or distorted after long periods.

The work done by Woodruff and his team to draw out the cranial ontogeny and dietary habits of these animals have significant scientific implications. It reveals that diplodocid adults most likely gave birth and then separated from their young early on. It also shows us that herds were mostly segregated according to age.

The work done with Andrew highlights how the fossil record can impart indicators of behaviour and animal sociology. But the questions don’t end here.

“Andrew is not some missing link, nor does it fill in all of the remaining questions — it doesn’t even come close. Each new discovery, finding, and bit of research is like finding a piece to our puzzle. With every piece our picture becomes more and more complete,” wrote Woodruff.

Source: https://thevarsity.ca

What Did Dinosaurs Eat?

Wednesday, October 31, 2018

It's a dino-eat-dino world.  Mikes Photos via Pexels

The Tyrannosaurus rex was a nightmarish lizard, a menacing meat-eater that chomped down on other dinosaurs like the Triceratops and Edmontosaurus with a bone-crushing bite. They likely even cannibalized members of their own species.

But what about the more than 700 other species of dinosaur that existed millions of years ago? For many of them, meat wasn’t on the menu. They ate salad instead. That’s according to Jordan Mallon, a paleontologist at the Canadian Museum of Nature, who says the vast majority of dinosaurs were actually herbivores, munching on plant matter rather than flesh.

“In any ecosystem, you have more herbivores than carnivores,” Mallon says. This applies to the landscapes of today—there are more deer than, say, wolves—and to ancient ecosystems. During his digs, he says, “I probably see six herbivorous dinosaurs to every one carnivore.”

And surprisingly, the bigger the dinosaurs were, the more likely they were to be vegetarian, he says. Take Sauropods, for example. This long-necked group contains the world’s largest dinosaurs—such as Argentinosaurusthe biggest land animal to have ever roamed the Earth, by some estimates—and they munched on little more than ancient plants like cycads, ferns, and ginkgos. A lot of them.

“They would have had to be shoveling in hundreds of pounds of food a day if not more in order to sustain their metabolisms,” Mallon says of Sauropods. “They were just raking in leaves.”

(Some of them also swallowed stones, which may have aided digestion by grinding up the plant material in their stomachs.)

That’s not to say that plenty of species weren’t feasting on flesh. Predators like Majungasaurus and AllosaurusMapusaurus and Giganotosaurus, along with other large carnivores, probably dined on other dinosaurs, Mallon says.

“Most meat-eating dinosaurs were eating other dinosaurs because they were the dominant animal in the ecosystem … especially for the bigger dinosaurs, which would have only been able to sustain themselves on dinosaur meat,” he says. “Everything else was too small.”

There were, however, some exceptions. The Spinosaurus, easily recognizable by its sail-like spine, is believed to have been the largest carnivorous dinosaur. Yet it was pescatarian.

“We think there were at least a couple of dinosaurs like Spinosaurus that were fish specialists,” says Mark Norell, chairman of the division of paleontology at the American Museum of Natural History. “They had dolphin-like teeth and snouts,” he says, which are perfect for snatching up prehistoric sea creatures.

So if humans were around 70 million years ago, would we have been on the menu, too? Probably. Though it’s impossible to be sure, barring a real-life Jurassic Park, humans would likely be prey. After all, Norell says, carnivorous dinosaurs were not likely picky eaters.

Source: www.popsci.com

TOP 10 Favorite Paleo-Documentaries

Sunday, October 28, 2018

T.Rex: Ultimate Dino Survivor. 01 by Swordlord3d

This is a modest list of the best paleo-documentaries ever made.

10. T.rex: Ultimate Survivor

This is a rather obscure documentary but a pretty solid one that I recommend. It focuses on how Tyrannosaurus was built to soak up pain, although it's exaggerated at times, like showing it survive impalations from three Triceratops. Still, it's pretty good and it has probably the best T.rex design in any documentary.

9. Ballad of Big Al

This spin-off of one of the best documentaries ever made focuses on the life of a single dinosaur, an Allosaurus named Big Al. The first half focuses on the life of the dinosaur, while the second half explains the science behind the way his life is presented. It's a great blend of science and storytelling.

8. Planet Dinosaur

This one has dropped quite a bit since the last time I made a list like this. The science is really good and exploded with detail. However, the storytelling is pretty mixed. It focuses a bit too much on the violent aspects of the Mesozoic.

7. Dinosaur Planet

This is a very good documentary with great special effects and storytelling. It features some pretty obscure dinosaurs, like Daspletosaurus and Saltasaurus, but also some popular ones like Velociraptor. However, it gets bogged down by the narration being silly at times, and the dinosaurs sometimes being too anthropomorphic. The latter is a sin that was taken to the extreme by Dinosaur Revolution.

6. Prehistoric Park

This documentary makes a pretty silly premise enjoyable and fun. It's about a park where Nigel Marvin goes back in time to save extinct animals, from dinosaurs to the giant insects of the Carboniferous. It makes some interesting speculation and has a fun story.

5. Walking With Beasts

The sequel to Walking With Dinosaurs, this documentary focuses on the mammals, who would go on to dominate the world after the KT Extinction. It features more than just the marketable animals like the Mammoth and Saber-tooth Cats, featuring oddities like carnivorous hoofed pigs and massive predatory whales. It also has great storytelling, but the special effects are noticeably dated.

4. Walking With Monsters

If you thought Beasts was weird, this one takes the weird creatures to the next level, featuring some of the weirdest prehistoric animals of all time. It focuses on the Paleozoic Era, describing events like the Cambrian Explosion and the Great Dying. This entry in the Trilogy of Life changes the formula, being broken up into three episodes, each focusing on two or three time periods. The creature designs are badass, the story is engaging, and of course, that ending is perfection.

3. Last Day of the Dinosaurs

As if the title didn't make it obvious, this program focuses on the extinction of the dinosaurs. It puts the good designs from the terrible Clash of the Dinosaurs to good use. It's sad, tragic, but still educational and enjoyable.

2. Walking With Dinosaurs

Ah, yes, the revolutionary WWD. Its placement on this list speaks for itself, although a lot of you will probably question why it's second place. Well, some parts are horribly outdated despite being enjoyable. Still, it's a timeless legend topped only by one other paleo-documentary...

1. When Dinosaurs Roamed America

This is the American equivalent of WWD. And no, I'm not just saying that as an American citizen. This documentary still holds up for the most part, and it was accurate for its time while still making some big leaps like the inclusion of feathered Dromaeosaurs, granted they didn't belong in New Mexico. The creature designs are gorgeous, as are the environments.

Source: www.scified.com

The Grand Canyon’s Oldest Footprints Are 310 Million Years Old

Saturday, October 27, 2018

The 28 footprints capture an early reptile-like creature's unusual diagonal gait (Courtesy of Stephen Rowland)  Read more: https://www.smithsonianmag.com/smart-news/grand-canyons-oldest-footprints-are-310-million-years-old-180970638/#YS3gjfd49ty6KHgT.99 Give the gift of Smithsonian magazine for only $12! http://bit.ly/1cGUiGv Follow us: @SmithsonianMag on Twitter

Some 310 million years ago, a reptile-like creature with an unusual gait roamed the sandy expanses of the Grand Canyon, leaving a trail of 28 footprints that can still be seen today. As Michael Greshko reports for National Geographic, these unusually well-preserved markers represent the national park’s oldest footfalls—and, if additional analysis links the early reptile to one that left a similar set of prints in Scotland roughly 299 million years ago, the tracks may even earn the distinction of being the oldest of their kind by more than 10 million years.

A paleontologist hiking the Grand Canyon’s Bright Angel Trail with a group of students happened upon the footprints in 2016. The animal’s path, which hardened into sandstone soon after its creator scurried off, had previously been hidden inside of a boulder. When the rock fell and split open, the winding trail was finally exposed, enabling the hikers to spot it as they explored the Arizona canyon.

The scientist reported the find to a fellow paleontologist, Stephen Rowland of the University of Nevada, Las Vegas, and in March of this year, Rowland and geologist Mario Caputo of San Diego State University arrived at the scene to investigate further. The pair announced their preliminary findings, soon to be followed up with a formal scientific study, at this month’s Society of Vertebrate Paleontology’s Annual Meeting.

According to Rowland and Caputo’s presentation abstract, the broken quartz boulder preserved the reptilian creature’s footprints as both impressions and natural casts measuring an overall width of about one meter across. Oddly enough, the tracks appear to represent a diagonal gait, as individual footfalls are angled 40 degrees out from the main pathway.

“Even if it was an ordinary trackway, it would be unusual,” Rowland tells Greshko. “But in this case, it's doing a funny little side-walking step, line-dance kind of thing, which is weird.”

There are a number of potential explanations for the ancient animal’s strange gait. Perhaps a strong wind was blowing from the west, pushing the animal right as it attempted to push forward. Or maybe the creature purposefully angled its walk, hoping to steady itself on the slippery surface of a sand dune.

The creature may have been pushed to the right by strong winds (Courtesy of Stephen Rowland)

It’s unclear what species the animal belonged to, but the scientists write that they “tentatively” assign the tracks to a “basal tetrapod of unknown taxonomic affinity” and the ichnogenus (category of trace fossil) Chelichnuswhich is all basically a very science-y way to say we don't quite know what this is, but we know it had four legs.

As researchers Patrick J. McKeever and Harmut Haubold explained in a 1996 article for the Journal of Paleontology, the Chelichnus classification was first used to describe a set of tracks found in Scotland’s Permian of Dumfries and Galloway during the early 19th century.

Unfortunately, McKeever and Haubold note, “Trackways that represent variations by the same trackmaker due to gait or substrate have been assigned different names. This practice has led to widespread confusion in the area of Permian vertebrate ichnology.”

Still, if Rowland and Caputo’s new identification proves accurate, the Grand Canyon footprints may well be the oldest left by members of the mysterious group.

“With a skeleton with bones and teeth, you get lots of good information, but you don't actually see behavior,” Rowland says to Greshko.

Luckily, he concludes, “we've captured this animal walking.”

Source: www.smithsonianmag.com

Paleontologists Find New Species Of Archaeopteryx, The ‘Missing Link’ Between Dinosaurs And Birds

Saturday, October 27, 2018

Reconstruction of Archaeopteryx albersdoerferi. Image credit: Zhao Chuang / Martin Kundrát.

Archaeopteryx was first described as the ‘missing link’ between reptiles and birds in 1861 — and is now regarded as the link between dinosaurs and birds. Only 12 specimens have ever been found and all are from the late Jurassic of Bavaria, Germany, dating back approximately 150 million years. Now, Dr. Martin Kundrát from the University of Pavol Jozef Šafárik and co-authors have identified a new species of Archaeopteryx — named A. albersdoerferi — that is closer to modern birds in evolutionary terms.

Using synchrotron microtomography, Dr. Kundrát and colleagues examined one of 12 Archaeopteryx specimens, known as ‘specimen number eight.’

“This Archaeopteryx individual is physically much closer to a modern bird than it is to a reptile,” the paleontologists said.

“Therefore, it is evolutionary distinctive and different enough to be described as a new species — Archaeopteryx albersdoerferi.”

Some of the differing skeletal characteristics of Archaeopteryx albersdoerferiinclude the fusion of cranial bones, different pectoral girdle (chest) and wing elements, and a reinforced configuration of carpals and metacarpals (hand) bones.

These characteristics are seen more in modern flying birds and are not found in the older Archaeopteryx lithographica species, which more resembles reptiles and dinosaurs.

Specimen number eight is the youngest of all the 12 known specimens by approximately half a million years. This age difference in comparison to the other specimens is a key factor in describing it as a new species.

“By digitally dissecting the fossil we found that this specimen differed from all of the others,” said co-author Dr. John Nudds, from the School of Earth and Environmental Sciences at the University of Manchester.

“It possessed skeletal adaptations which would have resulted in much more efficient flight.”

“In a nutshell we have discovered what Archaeopteryx lithographica evolved into — i.e. a more advanced bird, better adapted to flying — and we have described this as a new species of Archaeopteryx.”

“This is the first time that numerous bones and teeth of Archaeopteryx were viewed from all aspects including exposure of their inner structure,” Dr. Kundrát said.

“The use of synchrotron microtomography was the only way to study the specimen as it is heavily compressed with many fragmented bones partly or completely hidden in limestone.”

“Whenever a missing link is discovered, this merely creates two further missing links — what came before, and what came after,” Dr. Nudds said.

“What came before was discovered in 1996 with the feathered dinosaurs in China. Our new species is what came after. It confirms Archaeopteryx as the first bird, and not just one of a number of feathered theropod dinosaurs, which some authors have suggested recently. You could say that it puts Archaeopteryxback on its perch as the first bird.”

The discovery is reported in the Historical Biology, an international journal of paleobiology.

_____

Martin Kundrát et al. 2019. The first specimen of Archaeopteryx from the Upper Jurassic Mörnsheim Formation of Germany. Historical Biology 31 (1); doi: 10.1080/08912963.2018.1518443

Source: www.sci-news.com

How The Dinosaur-Killing Asteroid Made Chicxulub Crater?

Friday, October 26, 2018

The impact hit with the energy equivalent to 10 billion Hiroshima bombs. BARCROFT PRODUCTIONS/BBC

It is hard to imagine billions of tonnes of rock suddenly start to splosh about like a liquid - but that is what happened when an asteroid struck the Earth 66 million years ago.

Scientists have now put together a detailed picture of the minutes following the giant impact.

This, remember, is the colossal event that wiped out the dinosaurs.

The analysis of rocks drilled in 2016 from the leftover crater show they underwent a process of fluidisation.

The pulverised material literally began to behave as if it were a substance like water.

Models had predicted what should happen when a 12km-wide stony object from space punched the ground.

Initially, a near-instantaneous bowl would have been created some 30km deep and up to 100km wide.

Then, instabilities would have seen the sides collapse inwards and the base of the hole rebound skyward, briefly reaching higher than the Himalayas.

When everything had settled down, a crater roughly 200km wide and 1km deep would remain.

This is the feature that is now buried under sediments in the Gulf of Mexico, close to the port of Chicxulub.

The impact description - scientists call it the dynamic collapse model of crater formation - is only possible if the hammered rocks can, for a short period, lose their strength and flow in a frictionless way.

And it is the evidence for this fluidisation process that researchers now report after studying the rocks they drilled from something called the "peak ring" - essentially, a circle of hills in the centre of the remnant Chicxulub depression.

The team pulled rock up from more than 1,300m below today's Gulf seafloor. DSMITH@ECORD

"What we found in the drill core is that the rock got fragmented. It was smashed to tiny little pieces that initially are millimetre sized; and that basically causes this fluid-like behaviour that produces in the end the flat crater floor, which characterises Chicxulub and all such large impact structures, including those we also see on the Moon," explains Prof Ulrich Riller, from the University of Hamburg, Germany.

This is not rock being melted; rather, it is rock being broken apart by immense vibrational forces, says Prof Sean Gulick, the drill team co-lead from the University of Texas at Austin, US.

"It is a pressure effect; it's mechanical damage. The amount of energy moving through these rocks is equivalent to Magnitude 10 or 11 earthquakes; the estimate for the whole impact is something like 10 billion Hiroshima bombs."

Ultimately, the rocks will regain their strength. They have to if they are to build the ring of hills.

This return of rigidity, again, is witnessed in the drill core samples.


Chicxulub Crater - The impact that changed life on Earth

The outer rim (white arc) of the crater lies under the Yucatan Peninsula itself, but the inner peak ring is best accessed offshore. copyrightNASA

  • A 12km-wide object dug a hole in Earth's crust 100km across and 30km deep

  • This bowl then collapsed, leaving a crater 200km across and a few km deep

  • The crater's centre rebounded and collapsed again, producing an inner ring

  • Today, much of the crater is buried offshore, under 600m of sediments

  • On land, it is covered by limestone, but its rim is traced by an arc of sinkholes

Mexico's famous sinkholes (cenotes) have formed in weakened limestone overlying the crater. MAX ALEXANDER/B612/ASTEROID DAY

"It is manifested in what we call shear fractures - planar discontinuities where rocks can slide past each other," Prof Riller added. "We see these fractures over-printing the smashed rocks that formed beforehand. These planar structures are evidence that the rock must have regained strength towards the end of crater formation."

As well as bringing new insights into one of the most catastrophic days in Earth history, and the mass extinction that followed - the Chicxulub investigation will also help scientists as they study big impact craters on other planetary bodies.

"We are explaining a fundamental process that will occur on any rocky body," says Prof Gulick.

"For the first time ever, we now have rocks that tell us the kind of deformation they've undergone to temporarily behave like a liquid and then become like a rock again at the end - without melting. It's all done by overlapping deformation mechanisms. This will be a fundamental process that resurfaces planets, not just in our Solar System but presumably in all Solar Systems."

Profs Riller and Gulick were part of the Expedition 364 drilling project, which was conducted in April/May 2016 under the auspices of the European Consortium for Ocean Research Drilling (ECORD) and the International Ocean Discovery Program (IODP).

Their latest findings on "acoustic fluidisation" in the Chicxulub crater are published in the journal Nature.

The Moon's Schrödinger Crater, with its inner ring of hills, was made in the same way. NASA SCIENTIFIC VISUALIZATION STUDIO

Source: www.bbc.com

6 Seriously Science-y Dinosaur Books for Future Paleontologists

Friday, October 26, 2018

Photo illustration by Slate.

For the kid who knows her Diplodocus from her Cryolophosaurus.

Once upon a time, a roaring red dinosaur bubble blower was delivered to a little girl in Texas by the Easter Bunny. She named him “Bob,” forgave him for only blowing bubbles about 12 percent of the time, and added him to her grand dinosaur stage productions.

There was just one detail about Bob she couldn’t accept. “He’s a Triceratops,” she complained, “but he has big, sharp teeth like a meat-eater.”

She would revisit the inaccuracy many times, wondering why the person who made Bob would give an herbivore sharp teeth for tearing flesh. That’s when I knew we could no longer get away with any random dinosaur toy or book—our tiny paleontologist would demand scientific plausibility. Is this why Dinosaur Train had fallen out of favor in our house? Anthropomorphized, time-traveling dinos didn’t fit her fascination with the real, gritty, ferocious characters she had created in her mind.

Aptly, National Geographic’s Little Kids First Big Book of Dinosaurs was the first dinosaur book to join our home library. It contains gorgeous illustrations of recognizable favorites like Triceratops, plus plenty of less-famous dinos like Cryolophosaurus. (The book also has very handy pronunciation guides for tongue-tied parents.) Chapters are organized by dinosaur size, giving kids get a sense of how diverse the creatures were. Read all about where they lived and what they ate, or skip the details and dive into surreal illustrations to imagine what it was like to swim with a double-decker-size Pentaceratops.

National Geographic Little Kids First Big Book of Dinosaurs

by Catherine D. Hughes and Franco Tempesta

Here are five more books for kids ages 4 to 9 who are really into dinosaurs and want just the facts, ROOOAARRRR!

The Magnificent Book of Dinosaurs and Other Prehistoric Creatures

by Tom Jackson and Rudolf Farkas

This has the fantastic illustrations and trivia kids love, but the simple formatting will appeal to parents, too. I know encyclopedic science books can make for daunting bedtime reading, but this one is a breeze. I also like that it includes other prehistoric creatures to build further context for what Earth was like before humans.

Dinosaur Tracks

by Kathleen Weidner Zoehfeld and Lucia Washburn

Ask kids how scientists learn about the lives of dinosaurs, and they will likely say “fossils!” While fossilized bones are the diamonds of paleontology, much of what we know about them comes from long tracks of preserved footprints. This book teaches young dinosaur hunters how footsteps were preserved millions of years ago, and what we can deduce from them now. If your child has this level of interest in dino detail, check out other books in the Stage 2 series—Did Dinosaurs Have Feathers? and Dinosaur Babies.

Inside Dinosaurs

by Andra Serlin Abramson and Carl Mehling

What is it with kids and fold-out pages? This book, from the American Museum of Natural History, adeptly uses folding oversized pages to give the reader a sense of dinosaurs’ enormity and where the creatures fit in Earth’s 4-billion-year timeline. This book is written from the paleontologist’s perspective, taking readers along on the discovery process and inspiring further study. Kids will get an idea of how theories have changed and how much more there is to learn about dinosaurs.

Brick by Brick Dinosaurs: More Than 15 Awesome Lego Brick Projects

by Warren Elsmore

How better to imagine and understand dinosaurs than to build them? Brick by Brick Dinosaurs sits perfectly at the intersection of my daughter’s dueling obsessions with dinosaurs and Lego bricks. I expected building instructions for the most popular dinosaurs, but this book goes so much further. Vivid brick models on photorealistic backgrounds give kids another way to connect the facts with the developing dinosaur worlds in their imaginations.

The Dinosaur Expert

by Margaret McNamara and G. Brian Karas

The Dinosaur Expert is a rare narrative picture book in which the dinosaurs are not cutesy characters causing mayhem in implausible scenarios. Instead, the star of the book is a girl who knows everythingabout dinosaurs and gets to share that expertise with her class. “Can girls be paleontologists?” I groan that the question is still posed in a 2018 children’s book, but surely there are classrooms where such gender stereotypes persist. This book helps kids answer confidently: Yes, any kid with a passion for the topic can pursue that passion.

Source: https://slate.com

A New Paleontology Star Is Born As China’s Building Boom 'Uncovers' More Dinosaurs

Friday, October 26, 2018

In this Sept. 12, 2018, photo, a dinosaur model stands near the site of a future dinosaur museum in Yanji, China.  CHRISTINA LARSON/THE ASSOCIATED PRESS

At the end of a street of newly built high-rises in the northern Chinese city of Yanji stands an exposed cliff face, where paleontologists scrape away 100 million-year-old rock in search of prehistoric bones.

Like many fossil excavation sites in China, this one was discovered by accident.

China’s rapid city building has churned up a motherlode of dinosaur fossils. While bulldozers have unearthed prehistoric sites in many countries, the scale and speed of China’s urbanization is unprecedented, according to the United Nations Development Program.

Perhaps no one has seized the scientific opportunity more than Xu Xing, a diligent and unassuming standard-bearer for China’s new prominence in paleontology. The energetic researcher has named more dinosaur species than any living paleontologist, racing between dig sites to collect specimens and further scientists’ understanding of how birds evolved from dinosaurs.

Matthew Lamanna, a curator at the Carnegie Museum of Natural History in Pittsburgh, said Xu is “widely regarded as one of the foremost, if not the foremost, dinosaur paleontologist working in China today.”

“Xu Xing is A-M-A-Z-I-N-G,” Kristina Curry Rogers, a paleontologist at Macalester College in St. Paul, Minnesota, wrote in an email.

Paleontologist Xu Xing stands in front of a dig site in Yanji, China.  CHRISTINA LARSON/THE ASSOCIATED PRESS

Two years ago, Xu’s colleague at the Chinese Academy of Sciences in Beijing, Jin Changzhu, was visiting family in Yanji when he heard talk of fossils uncovered at a construction site. A preliminary inspection yielded what appeared to be a dinosaur shoulder bone.

Less than an hour’s drive from the North Korean border, the midsize city has been erecting residential blocks quickly. Seen from a plane, Yanji looks like a Legoland of new pink- and blue-roofed buildings, but there’s one long empty lot of exposed rocky hillside — the excavation site.

When Xu arrived at Yanji, he recognized the site could fill gaps in the fossil record, noting the relative paucity of bones recovered from the late Cretaceous period, which was around 100 million years ago. An analysis of the layers of volcanic ash revealed the site’s age. Xu is now overseeing a team of scientists using picks, chisels and steel needles to study the exposed hillside, where geologic layers resemble a red and grey layer-cake.

The site has yielded partial skeletons of three ancient crocodiles and one sauropod, the giant plant-eating dinosaurs that included some of the world’s largest land animals.

“This is a major feature of paleontology here in China — lots of construction really helps the scientists to find new fossils,” said Xu as he used a needle to remove debris from a partially exposed crocodile skull.

Born in 1969 in China’s western Xinjiang region, Xu did not choose to study dinosaurs. Like most university students of his era, he was assigned a major. His love for the field grew in graduate school in the 1990s, as feathered dinosaurs recovered from ancient Chinese lakebeds drew global attention.

When Xu and Jin discovered fossils in Yanji in 2016, city authorities halted construction on adjacent high-rise buildings, in accordance with a national law.

“The developer was really not happy with me,” said Xu, but the local government has since embraced its newfound claim to fame.

The city is now facilitating Xu’s work, and even built an on-site police station to guard the fossils from theft. Once the excavation is complete, a museum is planned, to display recovered fossils and photos of Xu’s team at work.

It’s not the first museum to commemorate Xu, whose prodigious fieldwork has taken him across China and resulted in a flurry of articles in top scientific journals.

Toru Sekiyu, a paleontologist from the Fukui Prefectural Dinosaur Museum in Japan who assisted on the Yanji dig, called his Chinese colleague “a superstar paleontologist.”

But Xu is quick to point out the role that good fortune has played in his career.

“To publish papers and discover new species, you need new data — you need new fossils,” he said, adding that finding new species isn’t something a scientist can plan.

Paleontologist Xu Xing leads a dig next to apartments being constructed in Yanji, China, Sept. 12, 2018.  CHRISTINA LARSON/THE CANADIAN PRESS

“My experience tells me that you really need luck, besides your hard work. Then you can make some important discoveries.”

With digs in Inner Mongolia, Liaoning, Yunnan and other Chinese provinces, Xu patiently oversees excavations, sometimes chiseling for years before he knows their ultimate significance.

While his finds are wide-ranging, much of his career has focused on understanding how dinosaurs evolved into modern birds.

China is an ideal location for that study. Two decades ago, rare dinosaur fossils that preserved traces of feathers were found in ancient lakebeds of northeastern China. This discovery, which helped scientists demonstrate that birds descended from dinosaurs, was possible because the mixture of volcanic ash and fine-grained shale in the lakebeds had preserved bits of soft tissue, including feathers — unlike the majority of dinosaur fossils, which contain only bone.

Since then, a flood of new dinosaur bones unearthed in China has helped scientists rewrite their understanding of the tree of life in various ways.

Xu has been at the forefront of research into how dinosaurs evolved feathers and flight. In 2000, he described a curious pigeon-sized dinosaur with four feathered limbs, apparently early wings that allowed the animal to either fly or glide. In 2012, he detailed a carnivorous tyrannosaur , which also had plumage — raising questions about feathers’ original purpose.

Xu now believes that early dinosaur plumage may have played a role in insulation and in mating displays, even before flight feathers evolved. He co-authored a 2010 paper that examined fossilized melanosomes — pigment packets that give rise to colour in modern bird feathers — to deduce the likely colours of dinosaur feathers. Some species likely sported rings of white and brown tail feathers; others had bright red plumage on their heads.

Xu Xing brushes away sediment to examine fossils recovered from a dig site in Yanji, China, Sept. 13, 2018.  CHRISTINA LARSON/THE ASSOCIATED PRESS

Embracing new technology, his team also uses CT scanners to study the interior of fossils and builds 3-D computer simulations to make inferences about what range of motions a dinosaur may have had.

One of the fossils Xu is now examining, found at a construction site in Jiangxi province, will shed light on how modern birds’ reproductive systems evolved from dinosaurs, he says.

In addition to professional accolades, Xu’s work has attracted attention from schoolchildren in multiple countries, who mail him handwritten notes and crayon drawings of dinosaurs, several of which hang in his Beijing office.

Xu replies to every letter, email and text message with a question about dinosaurs. “I feel it would be weird or impolite not to,” he said. But in an era of social media, Xu has refrained from signing up for WeChat, the dominant messaging platform in China, because “I don’t think I could find time for all the new messages.”

Back at the site in Yanji, a colleague brings him a large rock with an exposed sauropod vertebrae to examine.

The bone has a spongey texture, which Xu says is a result of the animal’s respiratory system. Like modern birds, he believes sauropods breathed using both lungs and distributed air sacs, which can leave an impression in the bones.

Xu uses a brush to flick away dirt to inspect the fossil more closely.

“Basically we are reconstructing the evolutionary tree of life,” he said. “If you have more species to study, you have more branches on that tree, more information about the history of life on Earth.”

Source: www.theglobeandmail.com

9 Famous Sauropods: Names And Characteristics

Thursday, October 25, 2018

Different sauropods.

Dinosaurs that have long necks belong to the clade of plant-eating dinosaurs known as sauropods. Sauropods are known for their characteristics like long neck, similarly long tails, thick bodies, and powerful tree trunk-like legs. Some of the largest animals to ever walk the land belong to the sauropods, and well-known sauropods include Diplodocus and Brachiosaurus.

Sauropods appeared in the late Triassic period and existed until the great extinction that occurred after the late Cretaceous period. Let’s take a closer look at some of the long-necked sauropods that existed during the era of the dinosaurs.

Long Neck Dinosaur: Alamosaurus

An Almosaurus skeleton at the Perot Museum. Photo: Dr. Matt Wedel via Wikimedia Commons, CC 4.0

The Alamosaurus is believed to have weighed around 33 tons and measured some 69 feet long. It was initially discovered in the Ojo Alamo Formation, which is a geologic formation that covers the region near Kirtland Shale, New Mexico. It is from the formation that the dinosaur gets its name. The Alamosaurus lived approximately 70 million to 65 million years ago during the late Cretaceous, going extinct during the Cretaceous mass extinction event of the Mesozoic era.

Long Neck Dinosaur: Argentinosaurus

Photo: Slate Weasel via Wikimedia Commons, Public Domain

Argentinosaurus is arguably the longest and heaviest land animal to ever have lived on Earth. It is estimated that the dinosaur weighted between 66 – 97 tons and was around 30 – 35 meters (98 – 118 feet) in length. The creature hatched from an egg that seems impossibly small for its size, the size of a football. The dinosaur was discovered in Argentina and named after the region. The dinosaur lived in the late Cretaceous period some 97 to 93.5 million years ago.

Long Neck Dinosaur: Apatosaurus

Apatosaurus specimen at Carnegie Museum. Photo: Tadek Kurpaski via Wikimedia Commons, CC 2.0

The Apatosaurus is believed to have lived around 150 million years ago during the Late Jurassic era. The dinosaur was discovered in the Morrison Formation, a geological formation that covers what is now parts of Oklahoma, Wyoming, Utah, New Mexico and Colorado in the US. Most estimates of the dinosaur’s size place the dinosaurs somewhere between 21 – 22.8 m (69–75 ft) long with a weight of 16.4 – 22.4 tons. The apatosaurus’ skull is more similar to that of the diplodocus than other sauropods like the Camarasaurus, and it was frequently confused with skulls of other dinosaurs like the Apatosaurus and the Brachiosaurus.

Long Neck Dinosaur: Brachiosaurus

Photo: Nobu Tamura via Wikimedia Commons, CC 4.0

Arguably one of the most famous dinosaurs in the world, the Brachiosaurus lived during the late Jurassic period around 154 to 153 million years ago. Like the Apatosaurus, it was discovered in the Morrison formation. The length of the Brachiosaurus is estimated at around 20 to 21 m or 66 to 69 feet, and it’s weight estimated somewhere between 35 metric tons to 58 metric tons. Part of the uncertainty about the size of the dinosaur comes from the fact that the most complete specimen is likely a juvenile. The neck of the Brachiosaurus is believed to be composed of 13 long cervical vertebrae, and this long neck allowed it to reach vegetation that was possibly as high as 9 meters (30 feet) off the ground.

Long Neck Dinosaur: Camarasaurus

Photo: By Creator:Dmitry Bogdanov – dmitrchel@mail.ru, CC BY 3.0

Camarasaurus roughly translates to “chambered lizard”, which is in reference to the fact that the Camarasaurus’ vertebrae have large holes or chambers in them. The Camarasaurus lived somewhere between 155 to 145 mya, during the Late Jurassic era, and like the Brachiosaurus and Apatosaurus, it was discovered in the Morrison Formation. The Camarasaurus are some of the better preserved sauropod specimens, which enables more accurate estimations. It is estimated that the dinosaurs had a length of somewhere around 23 m or 75, and a weight of around 51 tons (at least for the largest species of the genus, C. supremus).

Long Neck Dinosaur: Diplodocus

By ДиБгд at Russian Wikipedia – Transferred from ru.wikipedia to Commons., Public Domain

Diplodocus translates from neo-Latin as “double beam” and it is in reference to the dinosaur’s double-beamed chevrons (bones located on the bottom of the tail in many reptiles). The dinosaur lived in the late Jurassic era, between 104 million years ago to 152 million years ago. It was found in the Morrison formation alongside dinosaurs like Apatosaurus, Brachiosaurus, and Camarasaurus. The Diplodocus was astonishingly long and is amongst the longest known dinosaurs. Estimates place the total length of the dinosaur at around 24 m or 79 feet in length, with a weight of approximately 12 metric tons. The dinosaurs extremely long tail was made out of caudal vertebrae, around 80 in total and there are speculations as to the function of the spiny, whip-like tail. The tail’s length could have served to counterbalance the weight of the neck, while the spines on it could have served a defensive purpose.

Long Neck Dinosaur: Haplocanthosaurus

Photo: By ScottRobertAnselmo – Own work, CC BY-SA 3.0

The Haplocanthosaurus was actually quite small, as far sauropods go. It was discovered in the lowest layer of the Morrison Formation and believed to have lived around 155 million years ago to 152 million years ago. Estimates of the specimens retrieved from the Morrison formation put the dinosaur at around 14.8 m or 50 feet long, and around 12.8 metric tons in weight. Phylogenetic attempts to determine the relationship between Haplocanthosaurus and it’s other sauropod brethren are inconclusive, with some studies finding it to be a primitive macronarian (more primitive than other sauropods), and others suggesting that it could be a primitive diplodocoid and closer to the Diplodocus in nature.

Long Neck Dinosaur: Opisthocoelicaudia

Photo: Adrian Grycuk via Pixabay, CC3.0

Opisthocoelicaudia is a type of sauropod that lived during the late Cretaceous period around 70 million years ago. The dinosaurs were discovered in Mongolia in part of the Gobi desert. The dinosaur could have been closely related to the Alamosaurus, though it is considered a member of the Titanosauria. Opisthocoelicaudia is on the small side for sauropods, weighing in at somewhere between 8.4 to 22 tons and being between 11.4 m (or 37 feet) to 13 m (43 feet) in length. The genus is lacking a skull for the specimens, with the best specimen being a fairly well-preserved skeleton lacking the neck and head.

Long Neck Dinosaur: Saltasaurus

Photo: LadyOfHats via Wikimedia Commons, Public Domain

Saltasaurus is distinct among other sauropods for its stubby limbs and its rather short neck (as far as sauropods go). It lived during the late Cretaceous area around 70 million years ago. The dinosaur was discovered in the Lecho Formation in Argentina. Though still quite large compared to most animals today, the sauropod was small for members of the clade. It is estimated that the dinosaur was somewhere around 12.8 m or 42 feet in length, and weighed approximately seven tons. There is a preserved Saltasau egg displayed for visitors at Utah’s North American Museum of Ancient Life.

DOI:  https://doi.org/10.31988/SciTrends.41341

Source: https://sciencetrends.com

Dinosaur-Killing Asteroid Caused Rock To Flow Like Liquid, Scientists Drilling Into Crater Discover

Thursday, October 25, 2018

The Meteor Crater near Winslow, Arizona, is seen from a plane January 30, 2017. Like Chicxulub, this is the result of an asteroid impact. DANIEL SLIM/AFP/ GETTY IMAGES

Some 66 million years ago, an enormous asteroid struck Earth with the ferocity of millions of atomic bombs. Up to 10 miles wide, the space rock had a cataclysmic impact on our planet, triggering a mass extinction event that claimed three-quarters of all plants and animals and wiped out large dinosaurs.

Today, millions of years worth of sediment obscures the 100-mile-wide impact crater, which slices through Mexico’s Yucatan Peninsula. Vast swathes of trees and ocean coat the pit, named Chicxulub for a local town.

Now, a craggy ring of broken rock within the pit's rim—the only known “peak ring” of any crater on Earth—has revealed the collision caused incredibly strong vibrations that made hard, arid rocks act like liquid, scientists reported Wednesday in Nature.

When the asteroid tore into the planet, it left an incredibly vast pit with deep, rocky walls. When such walls of rock stretch down 20 miles or more, they can become unstable and give way.

"For a while, the broken rock behaves as a fluid," Jay Melosh, a professor of earth, atmospheric and planetary sciences at Purdue University and one of the study authors, said in a statement.

"There have been a lot of theories proposed about what mechanism allows this fluidization to happen, and now we know it's really strong vibrations shaking the rock constantly enough to allow it to flow."

This behavior causes the mountainous ring to jut out inside the pit within minutes, the scientists wrote. It may be the only peak ring on Earth, but similar craters have been observed on other planets, such as Venus and Mercury. "Large impact cratering...is the most fundamental geological process in our solar system. It formed the planets in the first place, continuously re-shapes the surfaces of terrestrial bodies, generates giant ore deposits and is paramount for the evolution of life on Earth," study author Ulrich Riller of the University of Hamburg told Newsweek in an email.

The patterns, cracks and crevices of a mile-long, six-inch-wide rock core harvested from the Chicxulub crater in six-foot chunks revealed the vibration sequence that led to the weird fluid behavior. "Damaged granite revealed a number of deformation structures, which we were able to relate—for the first time—to individual cratering phases and to the mechanisms by which this large crater formed," Riller said.

The culmination of almost a decade's worth of planning, the core revealed the history of the crater, from post-dinosaur surface rocks to those occurring just after impact, to those brought up from the depths by the collapse of the impact crater, Melosh told Newsweek. "It was indeed an uplifting feeling to see these perfectly preserved rocks for the first time when one after the other section of drill core was split in half," Riller added.

Many more research papers on the historic sample will likely be published over the next few years, Melosh added. The results, the team think, will help researchers understand smaller but much more pressing natural disasters.

Rock behaves like fluid in landslides for example, Melosh said in the statement. “Towns have been wiped out by enormous landslides, where people thought they were safe but then discovered that rock will flow like liquid when some disturbance sets a big enough mass in motion."

In other geology news, scientists have been mapping an enormous cave complex discovered under a sinkhole in China. The “world-class” cave hall, they discovered, contains craters, pillars, corridors, and round rocks called cave pearls.

An ancient pit in the permafrost of Siberia continues to yield incredible scientific finds. Researchers recently unearthed a mammoth and even a well-preserved horse from the “Mouth of Hell” crater.

Source: www.newsweek.com

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