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80 precious plant fossils exhibited in Nanjing

Saturday, April 27, 2019

Some fossil specimens of Austrohamia acanthobractea from the Daohugou biota

More than 80 precious plant fossils were exhibited in Nanjing, Jiangsu Province, recently. 

The fossils span from 400 million to 18 million years ago. 

"The Archaefructus liaoningensis in my hand is a representative of the earliest flowers. It's about 125 million years old," said Li Guoxiang, Curator of Nanjing Museum of Paleontology. 

Li said Archaefructus liaoningensis once grew in water. 

Thanks to volcanic ash and other reasons, it slowly evolved into fossils and was preserved forever. 

In the late Jurassic Period, the climate was warm and humid, perfect for these plants' growth.Volcanic ashes preserved the fossils, Li said. 

The fossils were collected by Nanjing Institute of Geology and Paleontology under Chinese Academy of Sciences.

Source: www.ecns.cn

Paleontologists Discover 518 Million-Year-Old Fossil Site in China

Wednesday, March 27, 2019

A reconstruction of early Cambrian ocean life in South China. Image credit: Dongjing Fu.

Animal life exploded in diversity and form during the Cambrian Period about 500 million years ago. An international team of paleontologists has discovered an early Cambrian fossil site in China — the Qingjiang biota — that contains a variety of specimens, more than half of which are previously undescribed. The 518 million-year-old fossil site rivals previously described Cambrian sites, such as the Burgess Shale of British Columbia and the Chengjiang fossil site in China’s Yunnan province, and should help to elucidate biological innovation and diversification during the Cambrian period.

A little more than 500 million years ago, early animal life on Earth exploded in diversity and form in an evolutionary event that would graft the initial branches of most major animal phyla onto the tree of animal life — the Cambrian explosion.

Much of what is known about the Cambrian explosion has been learned from the fossil record at sites where the geological echoes of this early life have been preserved.

Perhaps no other assemblages to date have been more important to our understanding of the Cambrian explosion than the Burgess Shale and Chengjiang localities — both of which contain large and diverse collections of well-preserved fossils, including soft-bodied organisms, which rarely make it into the fossil record.

The discovery of the Qingjiang site — new Burgess Shale-type Lagerstätte (a geologist’s term for a deposit of extraordinarily well-preserved fossils) — was made by Northwest University’s Dr. Dongjing Fu and colleagues from Guizhou University, Northwest University and Pomona College almost by accident.

The paleontologists were working in the mountains and came down to the banks of the Danshui River, located in Hubei Province, when they noticed some rocks had an odd pin-striped pattern — a telltale sign of layers of mud deposited rapidly by ancient storms similar to those found at the famous Chengjiang site.

The arthropod Leanchoilia from the Qingjiang fossil site, China. Image credit: Fu et al, doi: 10.1126/science.aau8800.

In addition to the high taxonomic diversity, Qingjiang fossils are characterized by near-pristine preservation of soft-bodied organisms — including juvenile or larval forms, arthropod and worm cuticles and jellyfishes — and such soft-tissue features as eyes, gills and guts.

More than 4,000 specimens have already been collected, with 101 species identified — of these species, 53 are new to science and names have to yet to be assigned.

“This finding enriches our view of the early animal world and offers us really remarkable views of the simplest animals,” said team member Professor Robert Gaines, from Pomona College.

“One of the most incredible things about this finding is the pristine condition of many of these specimens — fossils that haven’t been substantially affected by impacts of time, and in them you can clearly see soft tissues like eyes, tentacles and gills.”

“The discovery promises to shed light on the evolution of Cambrian ecosystems across space and time. Nowhere do have a more pristine fossil record of early Cambrian life and such a diversity of organisms — and this is just the beginning.”

paper reporting this discovery is published in the journal Science.

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Dongjing Fu et al. 2019. The Qingjiang biota — A Burgess Shale-type fossil Lagerstätte from the early Cambrian of South China. Science 363 (6433): 1338-1342; doi: 10.1126/science.aau8800

Source: www.sci-news.com

Huge T. Rex Fossil Suggests Many Dinosaurs Were Bigger Than We Thought

Tuesday, March 26, 2019

Scotty holds the title of the world’s largest T. rex Amanda Kelley

As if Tyrannosaurus rex wasn’t terrifying enough already. A skeleton in Canada belonged to a T. rex that was comfortably heavier than any other previously found, making it the largest land predator on record. The discovery means we may have underestimated just how large predatory dinosaurs could grow.

T. rex was one of the last non-bird dinosaurs to evolve, and it has long been considered a contender for the largest ever predatory dinosaur. That case was made even stronger following the discovery of Sue – a 90 per cent complete T. rex skeleton unearthed in 1990.

Sue was described as the largest animal of its kind in the world, but this title now belongs to the Canadian newcomer: Scotty.

 

Read More: Meet Scotty, World’s Largest Specimen of Tyrannosaurus rex

 

 

“We’re talking about basically a 400-kilogram difference,” says Scott Persons at the University of Alberta, Canada. According to his team’s calculations, Sue weighed an impressive 8460 kilograms, but Scotty tipped the scales at 8870 kilograms. To put it another way, Scotty was a couple of adult male lions heavier than Sue.

Scotty was actually discovered about the same time as Sue, in the early 1990s (it earned its name from a bottle of scotch whisky used by the excavators to toast the find). But because its bones were encased in particularly hard rock, freeing them took decades.

“It wasn’t until now we’ve been able to take a step back and look at the specimen as a whole,” says Persons. “And doing so there’s an oh gosh moment, because the specimen really is enormous.”

Strictly speaking, Scotty is not the longest or tallest T. rex found, but its bones are the heftiest. Persons and his colleagues used a few methods to work out how heavy Scotty would have been, including using the circumference of Scotty’s thigh bones to calculate how much weight the legs were capable of supporting.

Bulking up

The team suspect they know why Scotty was so heavy: its bones suggest it was an exceptionally old individual, probably in its early 30s. T. rex might have reached its maximum body length and height earlier in adulthood, but then bulked up as it became older and mature.

The idea has big implications. Similar meat-eating dinosaurs known as theropods might have followed the same trend, bulking out only after many years.

But given that life for these animals was tough, very few individuals will have reached that full potential, meaning fossils of the oldest and bulkiest theropods will be very rare. In other words, we might be underestimating how big they could grow.

Steve Brusatte at the University of Edinburgh says many palaeontologists have been waiting a long time for a full description of Scotty. “It is probably our best look yet at what one of the largest, oldest, most fully grown adults would have looked like,” he says.

That Scotty seems to be the heaviest T. rex ever found is a reminder that our sample sizes for giant theropods are small, says Brusatte. “New discoveries can reveal even bigger or weirder individuals.”

One mystery is why T. rex could grow to be so large, says Persons. For other gigantic theropods there are mitigating factors that might explain how they survived – for instance, living in water to support their body weight or hunting very slow-moving dinosaurs that weren’t difficult for a heavy predator to catch.

But T. rex lived on dry land and had to hunt relatively fast-moving duck-billed dinosaurs, he says. “So why do tyrannosaurs go down this road of gigantism? We don’t know the answer to that.”

Journal reference: Anatomical RecordDOI: 10.1002/ar.24118

Source: www.newscientist.com

Our Knowledge of Dinosaurs is Evolving. So is the Way we Depict Them

Sunday, March 24, 2019

A dinosaur getting ready for the spotlight. AP PHOTO/BEBETO MATTHEWS

Earlier this month, the American Museum of Natural History in New York opened its latest exhibit (paywall) on everyone’s favorite dinosaur: the iconic Tyrannosaurus rexThrough the summer of 2020, visitors can feast their eyes on the massive predator’s teeth, claws and, oh yes, its bristly feathers.

That’s right, feathers. The curators wanted to make sure that their depictions of T. rex matched the most recent science, which suggests the creature had feathers and maybe honked.

If you’ve noticed that dinosaurs are starting to look less fierce than they did in the era of Jurassic Park, you’re right. But this shift is only the latest in a series of changes in the ways scientific artists have depicted dinosaurs since the 1960s. The more scientists learn about the animals and how they likely lived, the more the artistry of them has evolved, too.

Dinosaurs weren’t of much interest in the middle of the 20th century. Based on evidence from their fossilized skeletons, scientists blamed them for their own extinction. The assumption was that large, lumbering creatures were not cut out to survive. Now we know that a massive asteroid slamming into the planet (paywall) was the source of their demise.

Early depictions of the creatures were unimaginative. “The way Brontosaurus and Diplodocus (the biggest dinosaurs) were illustrated, they were like giant, gray vacuum cleaners with very, very short legs,” Bob Bakker, a paleontologist and paleo-artist, explained on the 99% Invisible podcast last October.

While Bakker was an undergraduate at Yale studying paleontology in the 1960s, one of his professors took him on a dig for fossils of Deinonychus, a smaller carnivorous dinosaur. The professor, named Jon Ostrom, led him to the idea that dinosaurs likely carried themselves differently than paleontologists had believed. Instead of being more like modern lizards with tails dragging behind them, Bakker and Ostrom started to think that maybe dinosaurs were more like birds, with musculature similar to the animals today.

Although they weren’t the first paleontologists to think of dinosaurs this way, Bakker was one of the first to actually draw dinosaurs as lean, mean, meat-eating machines. His drawings, combined with more evidence of dinosaurs’ high-activity levels, led to more and more ferocious depictions of the ancient creatures through the ’60s and ’70s. By the time Jurassic Park came out in 1993, there was no question of these creatures’ finesse.

But in the two decades since the blockbuster hit came out, dinosaur depictions have changed even more. Artists realized that they were drawing dinosaurs based on skeletons alone. Although their drawings were accurate based on these skeletons, there is so much more to all animals besides their muscles and bones. They have all kinds of soft tissue like skin and fat that can change their appearance—and that don’t preserve well in fossils.

“In order to get the overall picture of dinosaurs right, I think you need a healthy dose of speculation in there,” John Conway, an artist and co-author of the book All Yesterdays: Unique and Speculative Views of Dinosaurs and Other Prehistoric Animalstold the podcast.

In All Yesterdays, Conway and others tried drawing dinosaurs in ways that were scientifically accurate based on the latest studies, but included more speculative information about the creatures’ behavior that could inform how they looked. For example, a Triceratops may have had spines all the way down its back, in addition to the three spiky horns on its head. The goal isn’t necessarily to be perfectly correct, but rather to show that scientists don’t have all the information about how dinosaurs looked.

As paleontologists continue to make discoveries about ancient creatures, the way we see them will also change. While T. rex may have thin, coarse feathers in our depictions now, perhaps later scientists will discover that they were likely fluffier, or even more colorful than we assume today.

Source: https://qz.com

Fossil Treasure Trove of Ancient Animals Unearthed in China

Friday, March 22, 2019

The Cambrian Period was a time of remarkable diversification of life when many of the animal groups that exist today first appear in the fossil record. (Ocean Portal / Smithsonian Institution)

The fossils from the Cambrian Period include dozens of new species and provide a window into life more than 500 million years ago.

The Cambrian was a time of vibrant, wonderful life. Fossil-packed sites like the Burgess Shale in Canada have revealed the unique nature of early animals around 508 million years ago. The strange creatures found in the rock are so delicately preserved that the ancient deposit seemed like a rarity, showing the unusual appendages and body shapes of the time.

In the century since the Burgess Shale discovery, however, other fossil wonderlands of similar age have been uncovered elsewhere on the planet. The latest to be recognized was found in southern China: the Qingjiang Biota.

In a paper published in the journal Science, Paleontologist Dongjing Fu of Xi’an’s Northwest University and colleagues describes the Cambrian Period fossils. At 518 million years old, the collection is about 10 million years older than the Burgess Shale. The way the fossils formed, however, is similar to those in North America. Visible in high contrast as dark fossils on gray stone, the organisms of the Qingjiang Biota are preserved down to the finest details. The fossils include trilobites, jellyfish, shrimp-like arthropods and even tadpole-like animals from the earliest days of the vertebrate family.

Dozens of these species have never been seen before. “What makes the Qingjaing special compared to other Cambrian sites with soft parts preserved, such as the Burgess Shale and Chengjiang Biota [in southern China], is the fact that there is over fifty percent entirely new taxa of animals and algae that are previously unknown to science,” says University of Lausanne paleontologist Allison Daley. Even better, she notes, is that the fossils are of “truly exceptional quality,” preserving the anatomy of the species without some of the natural distortions that sometimes result from the fossilization process.

(A) Leanchoilia sp., showing fine anatomical details, including those of the great appendages. (B) New megacherian preserved with internal soft tissues. (C) A possible kinorhynch scalidophoran, with segmented body armored by scalids. (D) Lobopodian. (E) Priapulid worm. (Dongjing Fu et al., Science 363:1338 (2019))

“It shows how we have these little windows back to the past and how finding another site can change what we know,” says University of Bristol paleontologist Jakob Vinther.

Some of the most beautiful specimens from the site are of soft-bodied creatures that don’t easily enter the geologic record. “The presence of so many stunning cnidarians was an absolute pleasure to see,” Daley says, referring to the jellyfish and sea anemones that thrived in this ancient ecosystem and are some of the key fossils that make the Qingjiang Biota stand out. “The significance of this site is in the way it fills several gaps in knowledge about key animal groups,” including cnidarians, strange invertebrates known as “mud dragons” and comb jellies. Representatives of all these groups are still alive today, making them some of the most ancient and successful animals in the world.

This wealth of squishy-bodied specimens hasn’t been visible at other Cambrian sites. “The diversity of cnidarians and ctenophores and sponges seems unique and therefore may give us a lot of clues to the origin and evolution of these groups that other sites couldn’t,” Vinther says.

The seeming flash fossilization of the Qingjiang Biota preserves an entire community of species, as close as paleontologists can get to time traveling back to 518 million years ago. “The fact that the assemblage of taxa is so different from other sites will also reveal the characteristics that influence what taxa live together in the same place at the same time,” Daley says, “and show us information about their ecological interactions.”

The Qingjiang Biota also adds a new wrinkle to the ongoing fossiliferous debate about the Cambrian explosion. The “explosion” was a dramatic diversification of life during the Cambrian Period, but paleontologists are still discussing whether the evolutionary event was a real, sudden change or if it simply looks that way because of incomplete fossil sampling. While the Qingjiang Biota doesn’t necessarily resolve the debate, Daley says, it adds to the picture of amazing evolutionary radiation during the Cambrian.

The fact that the Qingjiang Biota is about the same age as the nearby Chengjiang Biota, but contains many previously unknown species, indicates that the Cambrian hosted more unusual organisms than paleontologists previously imagined. The diversity of life at the time could be a signal of a much earlier flurry of evolutionary activity that gave rise to many new species preserved at sites like Qingjiang and the Burgess Shale.

The study by Dongjing Fu and colleagues is a preliminary report, announcing the discovery of many species that have yet to be named and intensively studied. There may be more fossils out there as well. The researchers note that the geologic formation in which the Qingjiang Biota resides is found in other places in China and could yield additional fossils.

The identities and interactions of the Qingjiang Biota creatures have yet to fully come into focus. For now, they offer a new window to a time we know little about, and, Daley says, “I can’t wait to see the detailed studies on these amazing fossils in the future.”

Source: www.smithsonianmag.com

Paleontologists Find 110-Million-Year-Old Bird Fossil With Unlaid Egg Still Inside It

Friday, March 22, 2019

Photograph of the holotype of Avimaia schweitzerae. Credit: Barbara Marrs.

A crushed, pancake-like fossil unearthed in northwestern China contains both a bird and its unlaid egg. The fossil also features a medullary bone — a special type of tissue which serves as a readily available store of calcium for the eggshell. This is the first time scientists have found such a bone and an egg together in the same fossil. Ironically, the authors say that the egg is what seems to have killed the mother.

Insight into the reproductive life of ancient birds

The new species, called Avimaia schweitzerae, belongs to a family of ancient birds known as Enantiornithes, which lived alongside their dinosaur cousins for more than 100 million years. Enantiornithine birds were widely distributed across the globe, with remains found in Argentina, North America, Mexico, Mongolia, Australia, Spain, and China. Paleontologists take a special interest in enantiornithines because the species includes both specialized and primitive features, suggesting they represent an evolutionary side branch of early avian evolution.

Paleontologists at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences found bits of eggshell preserved alongside the ancient bird’s fossilized skeleton. These eggshell fragments were detected inside the specimen’s abdomen, showing parts of the egg membrane and cuticle (a protein-covered outer layer that covers the surface of the egg and fills the pores that allow air inside for the growing chick). The researcher also detected small minerals made of calcium phosphate which are typically found among birds who bury their eggs. Previous evidence suggested that Enantiornithes buried their eggs, and these latest findings add more weight to this assumption.

At the same time, this particular eggshell features some unusual characteristics. The shell is too thin and it looks like it had two layers instead of one. This suggests that the mother bird went through egg-binding — when an egg takes longer than usual to pass out of the reproductive tract — and this may have been what ultimately killed her.

The analysis also showed that Avimaia schweitzerae had a reproductive tissue called the medullary bone, making it the only Mesozoic fossil featuring this kind of structure. Previously, scientists had argued that this tissue should to be present in other fossil birds, as well as dinosaurs and pterosaurs, but until now this identification proved ambiguous.

The findings appeared in the journal Nature Communications.

Source: www.zmescience.com

Meet Scotty, World’s Largest Specimen of Tyrannosaurus rex

Monday, March 25, 2019

Scotty is the largest dinosaur skeleton ever found in Canada. Image credit: Amanda Kelley.

The world’s biggest known Tyrannosaurus rex — one of the largest and most fearsome carnivores of all time — lived about 66 million years ago (Cretaceous Period) in what is now Saskatchewan, Canada.

Scotty was 42.7 feet (13 m) long and weighed approximately 8,870 kg.

The large, relatively complete (roughly 65%) skeleton was found in a layer of the Frenchman Formation near Eastend, Saskatchewan, in 1991.

The bones were encased in iron-stained, heavily-cemented sandstone, which took more than a decade to remove.

It’s only recently, after several more years piecing together the specimen like a jigsaw puzzle, that paleontologists have been able to study the specimen.

“This is the rex of rexes,” said Dr. Scott Persons IV, a paleontologist in the Department of Biological Sciences at the University of Alberta.

“There is considerable size variability among Tyrannosaurus. Some individuals were lankier than others and some were more robust.”

“Scotty exemplifies the robust. He comes out a bit heftier than other T. rexspecimens.”

“Scotty is the oldest T. rex known,” said Dr. Persons, first author of a paper published in the journal Anatomical Record.

“By which I mean, it would have had the most candles on its last birthday cake. You can get an idea of how old a dinosaur is by cutting into its bones and studying its growth patterns. Scotty is all old growth.”

But age is relative, and T. rexes grew fast and died young. Scotty was estimated to have been in its early 30s when it died.

“By Tyrannosaurus standards, it had an unusually long life. And it was a violent one,” Dr. Persons said.

“Riddled across the skeleton are pathologies — spots where scarred bone records large injuries.”

Among Scotty’s injuries are broken ribs, an infected jaw and what may be a bite from another T. rex on its tail — battle scars from a long life.

“I think there will always be bigger discoveries to be made. But as of right now, this particular Tyrannosaurus is the largest terrestrial predator known to science,” Dr. Persons said.

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W. Scott Persons IV et al. An Older and Exceptionally Large Adult Specimen ofTyrannosaurus rexAnatomical Record, published online March 21, 2019; doi: 10.1002/ar.24118

Source: www.sci-news.com

15 Discoveries That Will Break Your 'Jurassic Park'-Loving Heart

Thursday, March 21, 2019

If your image of Tyrannosaurus rex is based on the ferocious creature in "Jurassic Park," you've gotten quite a few things wrong about the "king of the dinosaurs."

In recent years, paleontologists have been revising the scientific consensus about how T. rex looked, sounded, and ate.

"Everyone's preconceived ideas of what T. rex acted like and looked like are going to be heavily modified," Mark Norell, a curator at the American Museum of Natural History, told Business Insider. The museum just opened an exhibit devoted to the dino, called "T. rex: The Ultimate Predator."

The exhibit showcases the latest research on the prehistoric animal. And as it turns out, these predators started their lives as fuzzy, turkey-sized hatchlings. They also had excellent vision, with forward-facing eyes like a hawk for superior depth perception. And T. rexes couldn't run — instead, they walked at impressive speeds of up to 25 mph.

But to be fair to Steven Spielberg, only seven or eight T. rex skeletons existed in the fossil record when his classic movie was produced in 1993. Since then, a dozen more skeletons have been discovered, and those bones have changed scientists' understanding of the creatures.

Here's what the T. rex was really like when it hunted 66 million years ago, according to the experts at the AMNH.

1. The first T. rex skeleton was discovered in 1902 by Barnum Brown, a paleontologist with the AMNH.

Today, the institution boasts one of the few original T. rex skeletons on display.

Tyrannosaurus rex — from the Greek words for "tyrant" and "lizard" and the Latin word for "king" — lived between 68 million and 66 million years ago, during the late Cretaceous period (just before the asteroid impact that ended the era of the dinosaurs).

2. The T. rex rocked a mullet of feathers on its head and neck, and some on its tail too.

Feathers are rarely preserved in the fossil record, so they haven't been found on a T. rex specimen. But other dinosaur fossils, including other tyrannosaur species and their relatives, do have preserved feathers.

That means paleontologists can "safely assume" T. rex had feathers as well, Norell said.

Though adult T. rexes were mostly covered in scales, scientists think they had patches of feathers on attention-getting areas like the head and tail.

3. T. rex hatchlings looked more like fluffy turkeys than terrifying predators.

T. rex hatchlings were covered in peach fuzz, much like a duckling. As they aged, they lost most of their feathers, keeping just the ones on the head, neck, and tail.

Most hatchlings didn't survive past infancy. A baby T. rex had a more than 60% chance of succumbing to predators, disease, accidents, or starvation during its first year of life.

4. T. rex had a fairly short lifespan by human standards. No known T. rex lived past the age of 30.

The T. rex was like "the James Dean of the dinosaurs," said Gregory Erickson, a paleontologist from Florida State University who consulted on the museum's new exhibit.

The Hollywood actor, often connected to the famous quote "Live fast, die young, and leave a good-looking corpse," died in a fiery car crash at the age of 24. T. rexes, similarly, were spectacular but died quite young.

Paleontologists can estimate the age that a dinosaur was when it died by analyzing its fossilized bones, which have growth rings that correspond to its age, much like trees. Experts can count the number of rings to determine its age, as well as compare the spaces between rings to find out how fast the dinosaur was growing at different ages.

5. A T. rex grew from a tiny hatchling to a 9-ton predator in about 18 to 20 years, gaining an unbelievable 1,700 pounds per year.

A full-grown Tyrannosaurus rex weighed about 6 to 9 tons. It stood about 12 to 13 feet tall at the hip and was about 40 to 43 feet long.

6. The "king of the dinosaurs" evolved from a larger group of tyrannosaurs that were smaller and faster.

While the T. rex emerged about 68 million years ago, its tyrannosaur ancestors were 100 million years older than that.

The tyrannosauroidea superfamily consists of two dozen species spanning more than 100 million years of evolution.

7. That evolutionary lineage might explain why T. rex had tiny arms.

For earlier tyrannosaur relatives with smaller bodies, these tiny arms were long enough to grasp prey or pull food into their mouth.

"The earliest tyrannosaur species had arms that were perfectly proportioned," Erickson said.

He said he thinks T. rex's puny arms were vestigial — a body part or organ that no longer serves a function but is nevertheless retained (kind of like a human's appendix or wisdom teeth).

8. An adult T. rex didn't need its arms to hunt — its massive jaws, filled with sharp teeth that constantly grew back, were enough.

"T. rex was a head hunter," Norell said. The predator had the rare ability to bite through solid bone and digest it.

Paleontologists know this from the dinosaur's fossilized poop; they've discovered T. rex feces containing tiny chunks of bone eroded by stomach acid.

9. The force of a T. rex bite was stronger than that of any other animal.

T. rex had a bite force of 7,800 pounds, equivalent to the crushing weight of about three Mini Cooper cars. By comparison, the massive saltwater crocodile of northern Australia — which grows to 17 feet and can weigh more than a ton — chomps down with 3,700 pounds of force.

No other known animal could bite with such force, according to museum paleontologists.

10. T. rex was also a cannibal.

Scientists are pretty sure that T. rex ate members of its own species, but they don't know whether the dinosaurs killed one another or just ate ones that were already dead.

Arguments about whether the dinosaur was a hunter or a scavenger have raged over the years, but "a bulk of the evidence points to T. rex being a predator, not a scavenger," Erickson said. "It was a hunter, day in and day out."

11. The predator had a keen sense of smell, acute vision, and excellent hearing, making it hard for prey to avoid detection.

When "Jurassic Park" came out in 1993, scientists knew only that the T. rex was big and carnivorous and had a small brain, Erickson said.

But now paleontologists know that the dinosaur had some of the largest eyes of any land animal ever.

About the size of oranges, T. rex eyes faced forward like a hawk's and were spread farther apart on its face than most other dinosaurs' eyes, giving it superior depth perception during a hunt.

12. One of the biggest differences between the museum's depiction of T. rex and the images in popular culture is that the real animal appears to be much svelter.

The new model shows a T. rex with even smaller forelimbs than previous ones and more prominent hind limbs.

According to museum paleontologists, an adult T. rex walked with fairly straight legs, much like an elephant. Walking with bent legs would have placed immense stress on its bones and joints, quickly exhausting its leg muscles.

13. So unlike the creature in "Jurassic Park," the real T. rex couldn't run. It just walked quickly.

An adult T. rex had a long stride, helping it reach speeds of 10 to 25 mph. But the dinosaur never reached a suspended gait, since it always had at least one leg on the ground at all times.

Juvenile T. rexes, which weighed less than an adult, could run.

14. There are still a few lingering mysteries about T. rex, including what color it was.

In movies and illustrations, the animal is often depicted in drab colors, similar to those of a crocodile. But the new museum exhibit suggests that, since reptiles come in every color, the T. rex could have been brightly colored.

It's also challenging for experts to determine the sex of the T. rex skeletons they dig up, leaving questions about differences between males and females unanswered as well.

15. Scientists aren't sure what T. rex sounded like, but the best guesses are based on the dinosaur's closest living relatives: crocodiles and birds.

2016 study suggested that T. rex probably didn't roar, but most likely cooed, hooted, and made deep-throated booming sounds like the modern-day emu.

This article originally appeared on Business Insider.

Evidence from Chile Supports Younger Dryas Extraterrestrial Impact Hypothesis

Thursday, March 21, 2019

An artist’s impression of an asteroid hitting the Earth. Image credit: State Farm / CC BY 2.0.

The Younger Dryas impact hypothesis, also known as Clovis comet hypothesis, posits that the hemisphere-wide debris field of a large, disintegrating asteroid (or comet) struck North America, South America, Europe, and western Asia approximately 12,800 years ago. This event triggered extensive biomass burning, brief impact winter, climate change, and contributed to extinctions of late Pleistocene megafauna. Controversial from the time it was proposed, this hypothesis continues to be contested by those who prefer to attribute the end-Pleistocene reversal in warming entirely to terrestrial causes. Now, University of California, Santa Barbara’s Professor James Kennett and co-authors present further geologic and paleontological evidence of the cosmic impact, this time far south of the equator.

“We have identified the Younger Dryas boundary (YDB) layer at high latitudes in the Southern Hemisphere at near 41 degrees south, close to the tip of South America. This is a major expansion of the extent of the YDB event,” Professor James Kennett said.

“The vast majority of evidence to date has been found in the Northern Hemisphere.”

This discovery began several years ago when a group of Chilean scientists studying sediment layers at a well-known Quaternary paleontological and archaeological site, Pilauco Bajo, recognized changes known to be associated with YDB impact event.

They included a ‘black mat’ layer, 12,800 years in age, that coincided with the disappearance of South American Pleistocene megafauna fossils, an abrupt shift in regional vegetation and a disappearance of human artifacts.

The analyses of the Pilauco sediments yielded the presence of microscopic spherules interpreted to have been formed by melting due to the extremely high temperatures associated with impact.

The layer containing these spherules also show peak concentrations of platinum and gold, and native iron particles rarely found in nature.

“Among the most important spherules are those that are chromium-rich,” Professor Kennett said.

The spherules from the Pilauco site contain an unusual level of chromium, an element not found in Northern Hemisphere YDB impact spherules, but in South America.

“It turns out that volcanic rocks in the southern Andes can be rich in chromium, and these rocks provided a local source for this chromium. Thus, the cometary objects must have hit South America as well,” Professor Kennett explained.

“Other evidence, which is consistent with previous and ongoing documentation of the region by Chilean scientists, pointed to a very large environmental disruption at about 40 degrees south.”

“These included a large biomass burning event evidenced by, among other things, micro-charcoal and signs of burning in pollen samples collected at the impact layer.”

“Furthermore, the burning coincides with the timing of major YDB-related burning events in North America and western Europe.”

The sedimentary layers at Pilauco contain a valuable record of pollen and seeds that show change in character of regional vegetation — evidence of a shifting climate. However, in contrast to the Northern Hemisphere, where conditions became colder and wetter at the onset of the Younger Dryas, the opposite occurred in the Southern Hemisphere.

“The plant assemblages indicate that there was an abrupt and major shift in the vegetation from wet, cold conditions at Pilauco to warm, dry conditions. The atmospheric zonal climatic belts shifted ‘like a seesaw,’ with a synergistic mechanism, bringing warming to the Southern Hemisphere even as the Northern Hemisphere experienced cooling and expanding sea ice. The rapidity — within a few years — with which the climate shifted is best attributed to impact-related shifts in atmospheric systems, rather than to the slower oceanic processes,” Professor Kennett said.

“Meanwhile, the impact with its associated major environmental effects, including burning, is thought to have contributed to the extinction of local South American Pleistocene megafauna as well as the termination of the culture similar to the Clovis culture in the north.”

“The amount of bones, artifacts and megafauna-associated fungi that were relatively abundant in the soil at the Pilauco site declined precipitously at the impact layer, indicating a major local disruption.”

The distance of the Pilauco site — 3,728 miles (6,000 km) from the closest well-studied site in South America — and its correlation with the many Northern Hemispheric sites greatly expands the extent of the YD impact event.

“The sedimentary and paleo-vegetative evidence gathered at the site is in line with previous, separate studies conducted by Chilean scientists that indicate a widespread burn and sudden major climate shifts in the region at about YDB onset. This new study further bolsters the hypothesis that a cosmic impact triggered the atmospheric and oceanic conditions of the Younger Dryas,” Professor Kennett said.

The findings appear in the journal Scientific Reports.

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Mario Pino et al. 2019. Sedimentary record from Patagonia, southern Chile supports cosmic-impact triggering of biomass burning, climate change, and megafaunal extinctions at 12.8 ka. Scientific Reports 9, article number: 4413; doi: 10.1038/s41598-018-38089-y

Source: www.sci-news.com

Alligator Study Reveals Insight Into Dinosaur Hearing

Tuesday, March 19, 2019

American alligator. Credit: Ruth Elsey, Louisiana Department of Wildlife and Fisheries

A new study of American alligators found that the reptiles form neural maps of sound in the same way birds do.

To determine where a sound is coming from, animal brains analyze the minute difference in time it takes a sound to reach each ear -- a cue known as interaural time difference. What happens to the cue once the signals get to the brain depends on what kind of animal is doing the hearing.

Scientists have known that birds are exceptionally good at creating neural maps to chart the location of sounds, and that the strategy differs in mammals. Little was known, however, about how alligators process interaural time difference.

A new study of American alligators found that the reptiles form neural maps of sound in the same way birds do. The research by Catherine Carr, a Distinguished University Professor of Biology at the University of Maryland, and her colleague Lutz Kettler from the Technische Universität München, was published in the Journal of Neuroscience on March 18, 2019.

Most research into how animals analyze interaural time difference has focused on physical features such as skull size and shape, but Carr and Kettler believed it was important to look at evolutionary relationships.

Birds have very small head sizes compared with alligators, but the two groups share a common ancestor -- the archosaur -- which predates dinosaurs. Archosaurs began to emerge around 246 million years ago and split into two lineages; one that led to alligators and one that led to dinosaurs. Although most dinosaurs died out during the mass extinction event 66 million years ago, some survived to evolve into modern birds.

Carr and Kettler's findings indicate that the hearing strategy birds and alligators share may have less to do with head size and more to do with common ancestry.

"Our research strongly suggests that this particular hearing strategy first evolved in their common ancestor," Carr said. "The other option, that they independently evolved the same complex strategy, seems very unlikely."

To study how alligators identify where sound comes from, the researchers anesthetized 40 American Alligators and fitted them with earphones. They played tones for the sleepy reptiles and measured the response of a structure in their brain stems called the nucleus laminaris. This structure is the seat of auditory signal processing. Their results showed that alligators create neural maps very similar to those previously measured in barn owls and chickens. The same maps have not been recorded in the equivalent structure in mammal brains.

"We know so little about dinosaurs," Carr said. "Comparative studies such as this one, which identify common traits extending back through evolutionary time add to our understanding of their biology."


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Materials provided by University of MarylandNote: Content may be edited for style and length.


Journal Reference:

  1. Lutz Kettler and Catherine Carr. Neural maps of interaural time difference in the American alligator: a stable feature in modern archosaursJournal of Neuroscience, March 18, 2019 DOI: 10.1523/JNEUROSCI.2989-18.2019

Source: www.sciencedaily.com

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