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Results tagged “fossils” from NatGeo News Watch

'Killer algae' could have taken down the dinosaurs

Posted on October 20, 2009 | 0 Comments

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By James G. Robertson, National Geographic Digital Media

Large algae blooms could have been a major contributing factor to the last five mass extinctions and smaller die-offs throughout history, researchers at Clemson University announced yesterday, challenging the theories that a major cataclysmic event, like an asteroid strike, alone caused the extinctions.

Today, a change in sediment or water temperature can cause large algae blooms, which can remove oxygen from the water and create toxins that suffocate fish and poison other organisms. The toxins created by some types of algae can creep into groundwater and poison plants, too, which causes problems up the food chain.

The researchers found evidence of spikes in fossilized algae, called stromatolites, about the same time the mass extinctions occurred, leading them to believe that algae had a role in disrupting the food chain by killing off fish or poisoning herbivorous creatures. The blooms could have been caused by fallout from volcanoes or asteroid collisions, or simply from climate change.

While it is a theory about the past, the theory could have an impact on the future as well.

"This hypothesis gives us cause for concern and underscores the importance of careful and strategic monitoring as we move into an era of global climate change," wrote James W. Castle and John H. Rodgers, the authors of the study that was presented at the 2009 meeting of the Geological Society of America.

There is evidence that toxic algae has been creeping northward due to climate change, says Castle, potentially causing problems for wildlife and humans as the planet gets warmer.

You can read more about developments in the asteroid extinction theory at National Geographic News.


 

 

 

Air-filled Bones Helped Prehistoric Reptiles Take First Flight

Posted on February 18, 2009 | 0 Comments

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pterosaur-picture-1.jpgThe Cretaceous pterosaur Anhanguera (wingspan 9-13 feet) cutaway above shows lungs (red), air sacs associated with the neck (green) and with the wings (blue). Below: life reconstruction of Anhanguera.

Illustration by Mark Witton, University of Portsmouth

Balloon-like air sacs, which extended from the lungs throughout the body, hollowing out many bones, paved the way for the evolution of pterosaurs to take flight, scientists announced today.

"In the Mesozoic Era, 70 million years before birds first took wing, pterosaurs dominated the skies with sparrow to aeroplane-size wingspans," says a news statement by the University of Leicester, United Kingdom. "Scientists already knew, on the basis of fossil evidence from the wings, that these extinct reptiles were able to power their flight through flapping, but had little understanding of how pterosaurs met the high energetic requirements for flight."

The new research published in the journal PLoS ONE by researchers from the University of Leicester (UK), Ohio University (USA) and College of the Holy Cross (USA) explains how balloon-like air sacs, which extended from the lungs throughout the body, hollowing out many of the bones in the pterosaur skeleton, provide evidence for a remarkably efficient breathing system in the ancient beasts.

"As an important bonus, the pneumatized skeletal system and air sacs reduced the density of pterosaurs, allowing the evolution of the largest vertebrates ever to take flight, some reaching 10 meters in wingspan," the news statement said.

"We have identified the breathing system of a pterosaur. It's a surprisingly efficient mechanism with the same essential structure of a modern bird's lung apparatus -- except 70 million years earlier" said study co author Dave Unwin, a palaeobiologist in the Department of Museum Studies at the University of Leicester.

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Origin of Claws Seen in 390-million-year-old Fossil

Posted on February 6, 2009 | 0 Comments

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A missing link in the evolution of the front claw of living scorpions and horseshoe crabs was identified with the discovery of a 390 million-year-old fossil, according to researchers at Yale University and the University of Bonn, Germany.

The specimen, named Schinderhannes bartelsi, was found fossilized in slate from a quarry near Bundenbach in Germany, a site that yields spectacularly durable pyrite-preserved fossils -- findings collectively known as the Hunsrück Slate, said a news release about the finding.

"With a head like the giant Cambrian aquatic predator Anomalocaris and a body like a modern arthropod, the specimen is the only known example of this unusual creature," said Derek Briggs, director of Yale's Peabody Museum of Natural History and an author of the paper appearing in today's issue of the journal Science.

The fossil's head section has large bulbous eyes, a circular mouth opening and a pair of segmented, opposable appendages with spines projecting inward along their length. The trunk section is made up of 12 segments, each with small appendages, and a long tail spine. Between the head and trunk, there is a pair of large triangular wing-like limbs -- that likely propelled the creature like a swimming penguin, according to Derek Briggs.  

Reconstruction by Elke Groening
Photo courtesy Steinmann Institute/University of Bonn

"Scientists have puzzled over the origins of the paired grasping appendages found on the heads of scorpions and horseshoe crabs," the news statement said. "The researchers suggest that Schinderhannes gives a hint. Their appendages may be an equivalent to those found in the ancient predatory ancestor, Anomalocaris -- even though creatures with those head structures were thought to have become extinct by the middle of the Cambrian Period, 100 million years before Schinderhannes lived."

The Hunsrück Slate has previously produced some of the most valuable clues to understanding the evolution of arthropods - including early shrimp-like forms, a scorpion and sea spiders as well as the ancient arthropods trilobites, Yale said.

This finding caps almost 20 years of study by Briggs on the Hunsrück Slate. "Sadly, the quarry from which this fabulous material comes has closed for economic reasons, so the only additional specimens that are going to appear now are items that are already in collectors' hands and that may not have been fully prepared or realized for what they are," Briggs said.

Seven of the Biggest Beasts of All Time

Posted on February 4, 2009 | 4 Comments

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We all know about the size of dinosaurs, of course, but how about a rodent the size of a bull, a sea scorpion bigger than a man, a frog as large as a beach ball, a penguin the size of a small adult human, a 1,000-pound ground-sloth-like marsupial, and a shark that may have grown longer than 50 feet and weighed up to 30 times more than the largest modern great white?

All these titans existed, although not in the same place or period.

Read on for pictures and more about seven of the biggest animals of all time.

1. Biggest Snake Fossil Found in Colombia Coal Mine

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Illustration of Titanoboa cerrejonensis by Jason Bourque/ Released by Nature

The biggest snake that ever lived (that we know about) was a massive anaconda-like beast that slithered through steamy tropical rainforests about 60 million years ago feasting on primitive crocodiles, National Geographic News reported today.

"Fossils discovered in northeastern Colombia's Cerrejon coal mine indicate the reptile was at least 42 feet (13 meters) long and weighed 2,500 pounds (1,135 kilograms)," contributor John Roach reported.

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The snake would have killed its prey by slow suffocation -- wrapping around it and squeezing, just like a modern python or boa. Only this snake was twice the size of today's largest constrictors.

Humans would stand no chance against one of these giant snakes, said Hans-Dieter Sues, paleontologist and associate director for research and collections at the National Museum of Natural History of the Smithsonian Institution in Washington, D.C. "Given the sheer size, the sheer cross section of that snake, it would be probably like one of those devices they use to crush old cars in a junkyard."

 

Precloacal vertebra of an adult Green Anaconda dwarfed by a vertebra of the giant boid snake Titanoboa cerrejonensis (photo credit Kenneth Krysko) and (lower photo) comparison of a vertebra of Titanoboa with the body of a live Python regius (photo credit Jason Head)

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U.S. Designates Four New National Natural Landmarks

Posted on February 4, 2009 | 2 Comments

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Photo of Cave Without a Name courtesy National Park Service

A rare ecosystem in Pennsylvania, the sixth longest cave in Texas, and major fossil sites in Kentucky, New York, and Vermont were recently named National Natural Landmarks (NNL), the National Park Service said yesterday.

"There are now 586 listed sites in the National Natural Landmarks Program, which recognizes significant examples of natural history and supports property owners and managers in conservation efforts," the National Park Service said in a press statement. The program is administered by the National Park Service.

The four new landmarks, announced by acting National Park Service Director Dan Wenk, are Nottingham Park Serpentine Barrens, Cave Without a Name, Big Bone Lick, and Chazy Fossil Reef. "Each of these sites has been identified, evaluated, and designated through a scientific process that formally acknowledges their outstanding biological or geological features," Wenk said in the release.

John Francis is a member of the National Park System Advisory Board  and oversees the reviews and recommendations of NNL listings as Chair of its Science Committee. He is also National Geographic Vice President of Research, Conservation, and Exploration. "The NNL program is a lesser known, but very special part of the park system that should be celebrated," Francis said in an email. "It reflects the true depth of natural wonders in our country and helps people connect to a wealth of treasures sometimes in their own backyards."

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Citizen Support

Students in 3rd grade at the New Haven Elementary School in Union, Kentucky, wrote letters in support of making Big Bone Lick a National Natural Landmark.

"Their letters were really great," said Margi Brooks, National Natural Landmarks Program Manager. "They wrote in during the required 60-day comment period. They told me all the reasons they enjoyed the site, some of the things they do there, and urged me to take good care of our United States of America. 

"I wrote them back right away, thanked them, and sent them all Landmark calendars. They were flabbergasted that someone in the federal government actually WROTE BACK!

"I think, and their teacher pointed this out, that it is so important for kids to feel that we listen to them, and that places they care about can be recognized and conserved if they speak up and state their case. These third graders did an outstanding job of doing that -- and look what they helped accomplish.

"I believe the scientist who evaluated the site will be speaking to this class on Friday -- so they continue to be interested and involved."

Photo of 3rd Grade students courtesy New Haven Elementary School

"We have only had six new Landmarks designated during the past 20 years, so this is exciting for us as well as for the owners and managers of these sites," said National Natural Landmarks Program Manager Margi Brooks. 

"The designation process is really quite rigorous, and ensures that sites chosen are outstanding examples of the resources they represent.

"Designation as a National Natural Landmark allows the National Park Service to act as an advocate for the conservation of the Landmark resources. It also allows us to become partners with the site managers and assist them if they so request. This might include working together on grant applications, site improvements, or educational materials," Brooks said in an email.

Another part of the program's role is information exchange and outreach, Brooks said -- "making the public aware of our country's incredible natural heritage is an important part of this program."

For a site, designation as a National Natural Landmark recognizes that they have one of the best examples of a particular resource, "and this is something they can be very proud of," Brooks added.

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The National Park Service provided the following descriptions of the four new National Natural Landmarks:

The Nottingham Park Serpentine Barrens in Chester County, Pennsylvania support unique vegetation communities that contain many rare and endemic species, including one of the northernmost occurrences of fame flower.The site also has one of the state's largest stands of pitch pine forest.

Nottingham Park Serpentine Barrens photo courtesy National Park Service

Cave Without a Name in Kendall County, Texas contains exceptional cave formations, a rare and threatened salamander, and significant paleontological deposits.

Big Bone Lick in Boone County, Kentucky is unique for its combination of salt springs and associated Late Pleistocene bone beds. The site has been referred to as the birthplace of vertebrate paleontology in North America.

The Big Bone fossils played a very important role in the development of scientific thought regarding the idea of extinction and the relationship of geology and paleontology.

The Chazy Fossil Reef in Grand Isle County, Vermont and Clinton County, New York contains surface exposures of an Ordovician fossil reef. The reef recounts the tropical, marine environment that existed approximately 450 million years ago on the continental shelf of North America.

This paleontological treasure represents the oldest known occurrence of a biologically diverse fossil reef in the world, the earliest appearance of fossil coral in a reef environment, and the first documented example of the ecological principle of faunal succession.

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The Fisk Quarry Preserve on Isle La Motte, Vermont is one site of several sites exposing the  Chazy Fossil Reef. This ancient fossil reef was formed 480-450 million years ago in a shallow tropical sea straddling the equator. It is the oldest known biologically diverse fossil reef in the history of life on earth. Fossils called stromotoporoids can be found in the quarry walls. The Fisk Quarry Preserve along with the nearby Goodsell Ridge Preserve, is owned and managed by the Isle La Motte Preservation Trust.

Photo and caption courtesy Isle La Motte Preservation Trust

National Natural Landmarks Frequently Asked Questions

Related National Geographic News story:
Fossil "Pompeii" of Prehistoric Animals Named U.S. Landmark

Giant Prehistoric Bird With Teeth Found Near London

Posted on September 28, 2008 | 0 Comments

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Image courtesy of Senckenberg Research Institute and Natural History Museum

An ancient relative of modern ducks and geese that skimmed the swampy wetlands of what is today England had a 16-foot wingspan and a beak full of crocodile-like teeth, scientists said on Friday.

Announced in the journal Palaeontology, the findings were based on a skull that belonged to Dasornis, a bony-toothed bird, or pelagornithid. It was discovered in the London Clay, a marine geological formation that lies under much of  of southeast England.

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"America's Smallest Dinosaur" Uncovered in Canada

Posted on September 24, 2008 | 0 Comments

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Illustration by Nick Longrich/Courtesy University of Calgary

A bizarre, chicken-size dinosaur that had tweezer-like jaws and stumpy but powerful forearms has been found in Alberta, Canada. It is the smallest dinosaur species ever found in North America. Researchers believe it may have preyed on insects.

It looked "like an animal created by Dr. Seuss," said Nick Longrich, a paleontology research associate in the department of biological sciences at the University of Calgary.

The remains of the Cretaceous "anteater" were found during a dig for Albertosaurus fossils in 2002.

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Neanderthal Model Is First Replica of Extinct Human Species Based on DNA

Posted on September 17, 2008 | 0 Comments

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Reconstruction by Kennis & Kennis/Photo by Joe McNally/NGS

Meet Wilma, the first reconstruction of a Neanderthal created using evidence from fossil anatomy and ancient DNA.

Neanderthals were a species of human that became extinct 28,000 years ago. The lifesize model was created to illustrate "The Last of the Neanderthals," the cover article in the October 2008 issue of National Geographic magazine.

The article, written by Steve Hall and photographed by David Liittschwager and Joe McNally, explores what caused Neanderthals, who dominated Eurasia for more than 200,000 years, to vanish in the Ice Age, while our modern human ancestors survived.

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Neanderthal Brain Size at Birth Sheds Light on Human Evolution

Posted on September 9, 2008 | 0 Comments

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Three-dimensional computer-assisted reconstructions of Neanderthal infants based on fossils found in Russia and Syria (left) suggests that our closest human relatives had brains as large as ours at birth and larger than ours as adults.

The finding indicates that we and the Neanderthals inherited the pattern of early brain size and development from a yet unknown common human ancestor, researchers who did the reconstruction say. Still largely unknown is how this pattern of brain development arose during evolution.

The research also sheds light on the similarities and differences in the life histories of modern humans and Neanderthals: the timing of major events in an individual's life, such as gestation time, age at sexual maturity, and age at death. The differences could have given modern humans an evolutionary advantage, the study indicates.

Image courtesy of M. Ponce de León and C. Zollikofer, University of Zurich

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