Tag: fossils

More Than 90 Percent Of All Organisms That Have Ever Lived On Earth Are Extinct

As new species evolve to fit ever changing ecological niches, older species fade away. But the rate of extinction is far from constant.

At least a handful of times in the last 500 million years, 50 to more than 90 percent of all species on Earth have disappeared in a geological blink of the eye.

Though these mass extinctions are deadly events, they open up the planet for new life-forms to emerge.

Dinosaurs appeared after one of the biggest mass extinction events on Earth, the Permian-Triassic extinction about 250 million years ago.

The most studied mass extinction, between the Cretaceous and Paleogene periods about 65 million years ago, killed off the dinosaurs and made room for mammals to rapidly diversify and evolve.




Scientists have narrowed down several of the most likely causes of mass extinction. Flood basalt events (volcano eruptions), asteroid collisions, and sea level falls are the most likely causes of mass extinctions, though several other known events may also contribute.

These include global warming, global cooling, methane eruptions and anoxic events–when the earth’s oceans lose their oxygen.

Both volcano eruptions and asteroid collisions would eject tons of debris into the atmosphere, darkening the skies for at least months on end.

Starved of sunlight, plants and plant-eating creatures would quickly die.

Space rocks and volcanoes could also unleash toxic and heat-trapping gases that—once the dust settled—enable runaway global warming.

An extraterrestrial impact is most closely linked to the Cretaceous-Paleogene extinction event, one of the five largest in the history of the world, and the most recent.

A huge crater off Mexico’s Yucatán Peninsula is dated to about 65 million years ago, coinciding with the extinction.

Global warming fueled by volcanic eruptions at the Deccan Flats in India may also have aggravated the event. Dinosaurs, as well as about half of all species on the planet, went extinct.

Massive floods of lava erupting from the central Atlantic magmatic province about 200 million years ago may explain the Triassic-Jurassic extinction.

About 20 percent of all marine families went extinct, as well as most mammal-like creatures, many large amphibians, and all non-dinosaur archosaurs.

An asteroid impact is another possible cause of the extinction, though a telltale crater has yet to be found.

The Permian-Triassic extinction event was the deadliest: More than 90 percent of all species perished. Many scientists believe an asteroid or comet triggered the massive die-off, but, again, no crater has been found.

Another strong contender is flood volcanism from the Siberian Traps, a large igneous province in Russia. Impact-triggered volcanism is yet another possibility.

Starting about 360 million years ago, a drawn-out event eliminated about 70 percent of all marine species from Earth over a span of perhaps 20 million years.

Pulses, each lasting 100,000 to 300,000 years, are noted within the larger late Devonian extinction.

Insects, plants, and the first proto-amphibians were on land by then, though the extinctions dealt landlubbers a severe setback.

Today, many scientists think the evidence indicates a sixth mass extinction is under way. The blame for this one, perhaps the fastest in Earth’s history, falls firmly on the shoulders of humans.

By the year 2100, human activities such as pollution, land clearing, and overfishing may drive more than half of the world’s marine and land species to extinction.

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‘Siberian Unicorns’ Walked the Earth Alongside Modern Humans

A reconstruction of what a Siberian unicorn might look like, by Heinrich Harder in 1908

Weighing up to 7,700 pounds, Elasmotherium sibiricum—an extinct hairy rhino popularly known as the “Siberian unicorn”—was thought to have disappeared as long as 200,000 years ago.

An updated fossil analysis suggests this formidable species was still around some 39,000 years ago, and that Ice Age conditions, not human hunters, contributed to its demise.

Paleontologists know of around 250 rhino species, of which only five still exist today. Among the most spectacular of these rhinos was Elasmotherium sibiricum—the Siberian unicorn.

For the Neanderthals and modern humans who lived alongside and possibly hunted this massive creature in Eastern Europe and Central Asia, it must’ve been an impressive and deeply intimidating sight.

Fossil evidence suggests Elasmotherium weighed over 3.5 tons, was covered in a thick coat of hair, and sported a horn of biblical portions, possibly as long as three feet (1 meter) in length.

Impressive though it may have been, the Siberian unicorns eventually died out. Previous fossil dating suggested an expiry date at some point between 200,000 and 100,000 years ago, long before the large-scale late Quaternary megafaunal extinction, which got rolling around 40,000 years ago.




New research published this week in Nature Ecology & Evolution is now offering a more reliable estimate, dating the demise of Elasmotherium at some point between 39,000 and 35,000 years ago.

The extinction of the Siberian unicorns, therefore, can now be connected to the late Quaternary megafaunal extinction, an event that witnessed the end of the wooly mammoth, Irish elk, and saber-toothed cat.

Siberian unicorns lived alongside anatomically modern humans and Neanderthals. That ancient hominids may have preyed upon these oversized rhinos is not as outrageous a proposition as it may seem.

Early humans, likely a form of Homo erectus, were hunting rhinos in the Philippines around 700,000 years ago.

First published restoration of Elasmotherium sibiricum

But while rhinos were on the hominid menu, this new research suggests climate change, and not hunters, was responsible for Elasmotherium’s demise.

These rhinos, as we now know from the new research, lived during the Ice Age just prior to the Last Glacial Maximum—the stage at which the ice sheets covered their largest area, around 26,500 years ago.

Earth was prone to dramatic climate shifts during this period, producing drought, desertification, a drop in sea levels, and the steady encroachment of glaciers.

These climactic disruptions proved fatal to many species, Elasmotherium among them.

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First Fossil Lungs Found In Dinosaur-Era Bird

For the first time, researchers found the presence of what they believe to be lung tissue in an avian dinosaur fossil.

About 120 million years ago in what’s now northeastern China, a bird met its end during a volcanic eruption.

Ashfall buried the animal so suddenly, its soft tissues didn’t have time to decay, and over millions of years, minerals infiltrated these tissues and preserved their form.

Now, researchers have unveiled this breathtaking specimen, which contains the first fossilized lungs ever found in an early bird.

The species Archaeorhynchus spathula lived alongside the nonavian dinosaurs during the Cretaceous period.

The newfound fossil, which preserves feathers and considerable soft tissue, shows that this primitive bird’s lungs closely resemble those found in living birds.




This suggests that birds’ hyper-efficient lungs, a key adaptation for flight, first emerged earlier than thought, and it underscores how birds—the last living dinosaurs—inherited many iconic traits from their extinct ancestors.

Everything we knew about lungs, about respiration, about evolution of [birds] was just inferring based on skeletal indicators,” says study coauthor Jingmai O’Connor, a paleontologist at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China.

“And now we know that we were inferring less generously than we should have.”

A newly identified Archaeorhynchus specimen showing the preserved plumage and lung tissue.

O’Connor presented the discovery on October 18 at the Society of Vertebrate Paleontology’s annual meeting in Albuquerque, New Mexico, and the finding will be published in the Proceedings of the National Academy of Sciences.

This is an exciting discovery,” says Colleen Farmer, an anatomist and physiologist at the University of Utah who reviewed the study.

Finding bird-like lungs in this group of dinosaurs is to be expected, but it is incredible to uncover hard evidence of this soft structure.

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Investigating The 580-Million-Year-Old Fossil With CT Scan

ediacaran

The Ediacaran biota (flourished 579-541 Mya) forms an important and unresolved episode in the history of life. These organisms arose soon after the end of the major glaciations of the Cryogenian, and persisted until the beginning of the Cambrian.

They are thought to include some of the earliest animals. Understanding the nature and lifestyle of the Ediacaran organisms is therefore important in tracing the potentially long fuse of the Cambrian explosion.

Yet they remain puzzling. This project will use micro-CT to investigate two particularly contentious structures found in rocks of this age, and assess how they fit into the larger picture of the origin of multicellular animals in this age.

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Fossil Teeth Reveal Recent Origin Of Human Growth Pattern

fossil

Monash University-led research has shown that the evolution of human teeth is much simpler than previously thought, and that we can predict the sizes of teeth missing from human fossils and those of our extinct close relatives (hominins).

A new study published today in the journal Nature, led by evolutionary biologist Dr. Alistair Evans from Monash University, took a fresh look at the teeth of humans and fossil hominins.




The research confirms that molars, including wisdom teeth, do follow the sizes predicted by what is called ‘the inhibitory cascade’ – a rule that shows how the size of one tooth affects the size of the tooth next to it.

This is important because it indicates that human evolution was a lot simpler than scientists had previously thought. Dr Alistair Evans explains how our fascination with where we come from, and what our fossil ancestors were like, has fuelled our search for new fossils and how we can interpret them.

“Teeth can tell us a lot about the lives of our ancestors, and how they evolved over the last seven million years. What makes modern humans different from our fossil relatives? Palaeontologists have worked for decades to interpret these fossils, and looked for new ways to extract more information from teeth,” Dr Evans said.

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Dr Evans, a research associate at Museum Victoria, discussed how this new research has challenged the accepted view that there was a lot of variation in how teeth evolved in our closest relatives.

“Our new study shows that the pattern is a lot simpler than we first thought – human evolution was much more limited,”Dr Evans said.

Dr Evans led an international team of anthropologists and developmental biologists from Finland, USA, UK and Germany, using a new extensive database on fossil hominins and modern humans collected over several decades, as well as high resolution 3D imaging to see inside the fossil teeth.

teeth

The team then took the research a step further by applying the findings to two main groups of hominins: the species in the genus Homo (like us and Neanderthals), and australopiths, including specimens like Lucy, the famous fossil hominin from Africa.

Dr Evans explained that while it was discovered that both groups follow the inhibitory cascade, they do so slightly differently.

“There seems to be a key difference between the two groups of hominins – perhaps one of the things that defines our genus, Homo,” Dr Evans said.

teeth

Another author on the Nature paper was Professor Grant Townsend from the University of Adelaide’s School of Dentistry. The study examined teeth of modern humans, including those in one of the world’s largest collections of dental casts housed at the Adelaide Dental Hospital.

“These collections of dental casts are critical to finding our place in the hominin evolutionary tree, and advancing knowledge in the oral health of Australians,” said Professor Townsend.

The findings of the study will be very useful in interpreting new hominin fossil finds, and looking at what the real drivers of human evolution were.

As well as shedding new light on our evolutionary past, this simple rule provides clues about how we may evolve into the future.

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The Prehistoric Puzzle Of How Plesiosaurs Swam Through The Oceans

Among the stranger creatures to roam the earth during the time of the dinosaurs was not a dinosaur at all, but a marine reptile — the plesiosaur.

This odd predator navigated Mesozoic Era waters with four flippers — two in the front and two in the back — a design unlike anything seen in modern-day swimmers.

How the plesiosaur actually used its limbs to swim has remained something of a mystery.

But in a study in the journal PLOS Computational Biology, a group of scientists has used computer modeling to pin down what those strokes might have looked like — and it turns out that they probably looked a lot like a penguin’s.




Plesiosaurs were a diverse group of swimming reptiles that thrived for 135 million years, from the Early Jurassic to the Late Cretaceous period (when they were wiped out by the same asteroid that took out the dinosaurs).

Some had long necks, others had short stubby ones, but all of them had this four-flippered body plan, where the animals’ legs had evolved into two pairs of wing-like appendages — “a unique adaptation in the animal Kingdom,” the study authors wrote.

Although plesiosaurs were a key component of Mesozoic marine ecosystems, there are no extant ‘four-winged’ analogues to provide insights into their behavior or ecology, and their locomotion has remained a topic of debate since the first complete plesiosaur skeleton was described in 1824,” the authors wrote.

Without any clear modern comparisons, how theirs flippers worked together has stumped scientists.

Some have argued that the plesiosaur had a rowing stroke, using its fins like boat oars; others argued for a “flight stroke,” rather like those of penguins and turtles, or a modified flight stroke like the ones sea lions use.

The extinct animals’ swimming motion has been equally up for grabs: Some have posited synchronous motion, with all four flippers moving in the same direction at the same time.

Others have favored semi-synchronous or asynchronous motion, where the forelimbs and hindlimbs move out-of-phase relative to each other.

Researchers haven’t even been able to agree on whether it was the forelimbs or the hindlimbs producing most of the animal’s thrust.

Scientists have tried all kinds of ways to model the animals’ swimming behavior, from using experimental robots to testing out human swimmers using paddles.

These studies, although informative, are limited because they do not deal with accurate representations of the plesiosaur form,” the study authors wrote.

There is therefore still no consensus on how plesiosaurs swam, especially how they moved all four limbs relative to each other.”

To get a better handle on plesiosaur physiology, researchers from Georgia Tech decided to build a computer model — far more accurate than, say, a human with some paddles.

They based theirs on Meyerasaurus victor, a Lower Jurassic plesiosaur from what is now Germany that would have stretched about 11 feet (relatively small by plesiosaur standards).

This model also allowed researchers to test thousands of simulations to try to determine which combinations of movement allowed the animal to move most effectively through the water.

In the end, the scientists found that the plesiosaur was swimming mostly with its forelimbs; surprisingly, the hindlimbs didn’t generate much thrust and likely were used for balance and steering.

Within the biologically possible range of limb motion, the simulated plesiosaur swims primarily with its forelimbs using an unmodified underwater flight stroke, essentially the same as turtles and penguins,” the study authors wrote.

Now that the scientists have developed a working model of this plesiosaur, they can use it to further probe exactly how the hindlimbs were used — and to explore the motion of other extinct swimming animals.

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Oldest Fossils Of Homo Sapiens Found in Morocco

jaw

Fossils discovered in Morocco are the oldest known remains of Homo sapiens, scientists reported, a finding that rewrites the story of mankind’s origins and suggests that our species evolved in multiple locations across the African continent.

Until now, the oldest known fossils of our species dated back just 195,000 years. The Moroccan fossils, by contrast, are roughly 300,000 years old.




Remarkably, they indicate that early Homo sapiens had faces much like our own, although their brains differed in fundamental ways.

Today, the closest living relatives to Homo sapiens are chimpanzees and bonobos, with whom we share a common ancestor that lived over six million years ago.

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Tiny Prehistoric Frogs Trapped In Amber Show That Death Comes At You Fast

Four pieces of amber found in Myanmar contain ancient fossilized frogs.

Life’s too short. By the time you’ve figured a few things out, the years have slipped away. All you can do is love others, let yourself be loved, and try to leave the world a better place.

Unfortunately, the same can’t necessarily be said for a group of Cretaceous frogs that got trapped in tree sap and preserved in amber, which a team of scientists described in the journal Scientific Reports on Thursday.

It’s impossible to say whether these 99-million-year-old frogs loved each other, but as the oldest frogs to be found preserved in amber and the oldest evidence of frogs inhabiting wet tropical forests, they definitely died before they got a chance to see the legacy they left the world.

These days, we’re used to picturing frogs in wet, hot climates, but we don’t know for sure when they began to occupy their preferred ecosystem.

Scientists believe that frogs emerged over 200 million years ago, but as with many animals, there exist major gaps in that fossil record, large swaths of evolutionary time for which we have no direct evidence.




In this new paper, researchers write that four small pieces of amber found in Myanmar contain evidence that could help fill in the frog’s evolutionary timeline.

These amber fossils provide direct evidence that frogs inhabited wet tropical forests before the mass extinction event at the end of the Cretaceous,” Lida Xing, an associate professor at China University of Geosciences in Beijing and first author on the paper.

By studying the remains of these four frogs, which are each about 22 millimeters long — as well as the plant, insect, and spider remains trapped in the amber with them — Xing and his colleagues established that about 99 million years ago frogs lived in an environment similar to ones that they currently inhabit.

The study’s authors dubbed the species Electrorana limoae, from the Latin words for “amber” (electrum) and “frog” (rana), as well as Mrs. Mo Li, “who purchased and provided these specimens for study,” they write.

These four pieces of amber (specimen B and D are each shown from multiple angles) are the oldest amber-preserved frogs ever found.

And while the researchers were fortunate to come into possession of the specimens, the quality of the remains did pose issues.

As you can see, the frog remains are either ripped apart or curled up, and not one of them remained intact.

Fortunately, micro-CT scans allowed the researchers to penetrate the amber to get a better look at the frogs’ anatomies and figure out where they sit in the evolutionary tree.

They determined that E. limoae is likely an ancestor of these existing species, as well as some that have been long extinct.

Living in a wet environment, most frog specimens from E. limoae’s home environment had no chance of being preserved as fossils, so this amber from Myanmar gave scientists a rare opportunity to glimpse into the tree of life and add one more piece to the puzzle of evolution.

I can only hope that there are more spectacular fossils to come,” Blackburn tells National Geographic. “In today’s tropical forests, there is a rich diversity of living frog species.

“So, there might be many more species to discover still in the Cretaceous amber from Myanmar.”

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The First Living Giant Ship Worm Found In The Philippines

ship worm

Mud-dwelling organism that lives head down in a tusk-like tube found alive for first time, although its existence had been known of for centuries.

About three feet long and glistening black with a pink, fleshy appendage, it looks like the entrails of an alien from a bad horror film. In fact, it is a giant ship worm.




Discovered in the mud of a shallow lagoon in the Philippines, a living creature of the species has never been described before.

Even though its existence has been known for more than 200 years thanks to fossils of the baseball bat-sized tubes that encase the creature.


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Oldest known case of dandruff found in 125m-year-old dinosaur

A fossil of a microraptor found in Liaoning province, China. The crow-sized dinosaur lived about 125m years ago.

The oldest known case of dandruff has been identified in a small feathered dinosaur that roamed the Earth about 125m years ago.

Paleontologists found tiny flakes of fossilised skin on a crow-sized microraptor, a meat-eating dinosaur that had wings on all four of its limbs.

Tests on two other feathered dinosaurs, namely beipiaosaurus and sinornithosaurus, and a primitive bird known as confuciusornis, also revealed pieces of fossilised dandruff on the animals’ bodies.

The prehistoric skin flakes are the only evidence scientists have of how dinosaurs shed their skin.

The material shows that rather than losing their outer layer in one piece, or in large sheets, as is common with modern reptiles, the feathered dinosaurs adapted to shed their skin in tiny flakes.




Images of the dandruff taken with a powerful electron microscope show that the material is extremely well-preserved and is almost identical to that found on modern birds.

Like human dandruff, the skin flakes are made of tough cells called corneocytes that are full of the protein keratin.

The work, published in Nature Communications, suggests that dinosaurs who sported feathers evolved skin to cope with their plumage as far back as the middle Jurassic.

Even though they are in the early stages of feather evolution, they have already adapted their skin to this more modern structure,” McNamara said.

Prehistoric dandruff found on the skin of a microraptor dinosaur. Photograph: Maria McNamara at University College Cork

The fossilised remains of all of the animals studied were recovered from rock formations in north-eastern China. At 2m long, beipiaosaurus and sinornithosaurus grew to more than twice the size of microraptor.

Modern birds have very fatty corneocytes that are loosely packed with keratin, a feature which helps the birds lose heat from the exertion of flying.

McNamara found that the dinosaur dandruff cells lacked such fat, suggesting that the animals did not get as warm as modern birds, perhaps because they could not fly far, or failed to get airborne at all.

Many dinosaurs that sported feathers were not competent fliers. Instead, their plumage served other purposes: to keep them warm, provide camouflage, and perhaps attract members of the opposite sex with multicoloured displays.

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