Dino killer
Courtesy Donald Davis (for NASA)

How Earth impact kills dinos

As "mdr" explained recently in, astroid found guilty of killing dinosaurs that a panel of scientists, after reviewing all evidence, blame an asteroid impact for the demise of the dinosaurs.

Ozone killed the dinosaurs

A paper has just been published saying that dinosaurs choked on ozone.

A new study in the journal Paleogeography, Paleoclimatology, Paleoecology puts forth the idea that the Chicxulub impact, long blamed for the extinction of the dinosaurs at the end of the Cretaceous era 65 million years ago, could have done them in by flinging huge amounts of ozone precursor chemicals -- nitrogen oxides, methane, and other hydrocarbons -- into the air.

Below the article in Discovery News, this comment by 1sang (Doug) explains why mammals and avians survived.

In order to (survive) all you'd have to do is get on steeper slopes and find enough food to live for a couple of years. Mammals and smaller avian dinosaurs could more easily accomplish this than their massive cousins (in fact, many were probably already in this safety zone away from the many large predators roaming the lowlands).

He also notes that methane release leads to an increase in ozone and that today we have the beginnings of lots of methane being released (I wrote about this here: Methane ice).

Tags : methane, ozone, dinos, dinosaurs, extinction, what killed the dinosaurs, aseroid, earth, collision

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What sent the dinosaurs packing?: The number one suspect, a gigantic asteroid, has finally been convicted of the crime.
Courtesy Mark RyanAfter studying all available evidence and listening to alternative theories (and despite no eyewitnesses), a panel of 45 international scientists has decided it was a huge asteroid that killed all the non-avian dinosaurs some 65 million years ago.

The asteroid, described as a 7 mile-in-diameter chunk of space rock, has been the prime suspect in the ruling reptile’s demise ever since scientists Luis Alvarez and his son Walter first identified a one-inch layer of iridium in Late Cretaceous-age rock exposures throughout the world. The layer was located exactly at the point in the rock record where the Cretaceous period ended, and the Tertiary period began (K-T boundary).
Smoking gun for dinosaurs' demise: K-T Boundary with 1-inch iridium layer (arrow) exposed 10 miles west of Trinidad, Colorado. The element iridium is very rare on Earth but concentrated in meteors and comets. The same iridium layer is found in several exposures around the world, and corresponds in age with the Chicxulub meteor crater in Mexico's Yucatan Peninsula. The layer marks the end of the Cretaceous era, and no non-avian dinosaur remains have ever been found above the boundary. The coal layers above and below the iridium suggests a swampy environment when the layer was laid down in this area of Colorado.
Courtesy Mark RyanThey predicted a meteor impact crater of the same age would be found as the source of the iridium since the element is rare on Earth but common in outer space. Then in 1990 their predictions were verified when the Chicxulub impact crater was discovered in Mexico.

Although the impact site was mostly submerged off the north coast of the Yucatan Peninsula, samples taken from it dated to the end of the Cretaceous period. This and other corroborating evidence helped bolster the killer asteroid hypothesis as the primary theory for the extinction event that wiped out 70-75 percent of life on Earth including non-avian dinosaurs, and other large reptiles. The asteroid is estimated to have slammed into Earth traveling 10 times faster than a rifle bullet, and released the energy of a billion atomic bombs. The impact instantly vaporized a large area of terrain, and sent an explosion of dust and rocky debris up into space, much of which fell back into the atmosphere in a fiery rain. It left a crater 110 miles across, and a cloud of dust circling the planet for weeks. The diminished sunlight would have disrupted the environment severely, including the food chain. Mammals and other smaller creatures were able to survive across the boundary and flourish in later periods.

But not everyone was convinced by the evidence. Other causes for the mass extinction, such as extreme volcanism in India, falling sea levels, disease epidemics, and even fungal infection were all tossed around as possible culprits.

But in the end it seems the evidence implicating the asteroid in the K-T* extinction event was just too strong, and after much deliberation, the impact has been determined as the official cause of death. The panel published its decision in the latest issue of Science.

*“K-T” stands for Cretaceous-Tertiary, however, use of the term Tertiary is being discouraged now, and the time span it occupied has been replaced with the Paleogene and Neogene periods. So a more proper, up-to-date term would be Cretaceous-Paleogene or K-Pg extinction event.

LINKS AND SOURCES
More about dinosaur extinction
BBC story
Impact theory counterview

Tags : Chicxulub, dinosaur extinction, dinosaurs, extinction, Luis Alvarez, paleontology

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Frozen in time: Unique fossil shows snake coiled among nest of dinosaur eggs and titanosaur hatchling.
Courtesy PLoS Biology
Diagram of fossil
Courtesy PLoS BiologyCheck out this amazing fossil showing the remains of a snake coiled around a nest of dinosaur eggs, including a nearby titanosaur hatchling. The fossil was found 26 years ago in northwestern India, and was originally thought to contain remains of eggs and baby dinosaur bones. But recent re-evalutions revealed some of the bones were actually those of a new species of snake named Sanajeh indicus. The incredible 67 million-year-old fossil is the first of its kind, and suggests that snakes preyed on dinosaurs, just as they prey on birds today. A newly hatched titanosaur would have been easy pickings for the 11.5 foot S. indicus, but an adult titanosaur - which grew to more than 100 feet in length - would have been another story. Scientists think the unique Cretaceous fossil resulted from an ancient landslide that buried the snake just when it was about to go after its next meal. Here's a photo of the incredible fossil and along with a diagram of what it contains. You can read the whole story at PLoS Biology where the research has been published.

Tags : dinosaurs, fossils, paleontology, predator, predator/prey, prey, snake

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Rex in the hen house
Courtesy Mark RyanA new study came out last week that appeared destined to shake up the current line of thought that birds descended from dinosaurs. Birds share common traits with some dinosaurs, including furculas (wishbones), hollow bones, and other skeletal features, which scientists have interpreted to mean the former descended from the latter. But now a new study by researchers at Oregon State University, it may have happened just the opposite way.

"We think the evidence is finally showing that these animals which are usually considered dinosaurs were actually descended from birds, not the other way around," said John Ruben, a professor of zoology at OSU, and the study’s lead author.

The study involved the fossil of a Microraptor, a dromaeosaurid dinosaur with evidence of feathers on both its arms and legs. Studying the skeletal remains, Ruben and his colleagues constructed 3-dimensional models that they tested for flight capabilities. Their study showed Microraptor’s structure better suited to be glider rather than a flyer. From this Ruben extrapolated that it made more sense that Microraptor descendents came down from the trees and eventually evolved into flightless birds we call dromaeosaurs or raptors.

"Raptors look quite a bit like dinosaurs but they have much more in common with birds than they do with other theropod dinosaurs such as Tyrannosaurus," he said. The study appears in the journal for the Proceedings of the National Academy of Science (PNAS).

Sounds good at first, and I have to admit I was smitten with the idea. But not everyone feels the same way.

Over at the Smithsonian’s Dinosaur Tracking blog, freelance science writer Brian Switek has pointed out that Ruben’s proclamation is “actually only a commentary, or the equivalent of an opinion piece.”

He then goes on to point out some of the flaws in Ruben’s argument, particularly the uncertainty surrounding Microraptor’s place in the evolution of flight, and the lack of reasonable evidence that Velociraptor wasn’t a dinosaur. Switek doesn’t think Ruben’s claim stands up to scrutiny.

But what annoys Switek most is how the media inundates the various outlets with this kind of science news, giving it wide distribution and often, undeserved credibility.

“In this increasingly fragmented media landscape, knowledgeable science writers who recognize a fishy story when they see one are getting outnumbered. More often, websites and newspapers simply reprint press releases issued by universities and museums (science writers call this “churnalism”), and this policy sometimes lets questionable science slip through the cracks.” – Brian Switek

One of the reasons for this is the internet. There's just a huge amount of time and space that requires constant feedings of content now. It does make things difficult to sort through. There have been times I’ve begun researching some new science story to post on Science Buzz only to become frustrated with details that don’t seem to add up, confusing statements, info that counters other info, and outright misinformation. Some of it may be due to the writer(s) not being able to properly articulate or distill a particular idea or hypothesis for the general reader (I know I suffer from this occasionally). Sometimes it’s due to the fact that many science writers lack access to the papers themselves (most science journals require paid subscriptions to access anything beyond an abstract of the story), so writers are left with relying on press releases and abstracts or another writer’s thoughts on the subject (like I’m doing here). But other times it ends up being that there’s no real story at all, just a rehash of something from months or years ago that somebody figures needed to be in the headlines again.

To this end, paleontologist Dave Hone over at his Archosaur Musings blog recently posted “A guide for journalists reporting on dinosaur stories” that deals with some of issues raised here. It’s worth reading.

Science Buzz has also covered science writing issues in previous posts.
How to read/write science news
Bad Science Journalism

SOURCE and MORE INFO
ScienceDaily.com story
Microraptor gui: Bird or Dinosaur
Origin and Evolution of Birds

Tags : ancient birds, bird origins, dinosaurs, evolution, paleontology, science journalism, science writing

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Measuring the SMM camptosaurus: SMM paleo lab volunteers Becky Huset (left) and Neva Key consult over their ornithischian limb bone measurements for the Open Dinosaur Project.
Courtesy Mark RyanThe Open Dinosaur Project (ODP) allows anyone with an interest in paleontology, and access to skeletal information, scientific publications, or museum skeletons themselves the opportunity to be part of the compilation of an actual scientific paper. Paleontologists Andy Farke, Matt Wedel, and Mike Taylor make up the core ODP team, but only the core. The rest of the team is made up of individuals around the world. The hope is to put together a comprehensive database of information about the dimensions of limb bones (legs, arms, hands, and feet) of ornithischian (bird-hipped) dinosaurs in museums around the world with a goal of “investigating the evolution of locomotion and limb proportions in this group.”

“The Open Dinosaur Project fits very comfortably into that loose coalition of ideas: we’re trying to democratize science, open up data, blog the process, and make sure that the final publications are freely available to the world,” Mike Taylor said during a recent interview with the Brazilian science publication Ciência Hoje On-line.

Putting tape to toe: SMM volunteer Becky Huset measures the metatarsals and phalanx of the musuem's camptosaurus for the Open Dinosaur Project.
Courtesy Mark RyanTwo volunteers here at the Science Museum of Minnesota got themselves involved with this unique study. Becky Huset and Neva Key both work in the SMM paleo lab, usually hunched over fossils extracting them from rocks or preparing them for display. But recently, the two have spent time out on gallery floor measuring the limbs of some of the museum’s mounted ornithischian dinosaurs.

“We did the Camptosaurus and some cast bones from Stegosaurus from the collections,” Becky said. She added that measurements of the SMM Triceratops were already listed.

Why only ornithischian dinosaurs? Part of the reason was to keep the study somewhat manageable. But ornithischian dinosaurs also have an interesting evolution of locomotion that to date hasn’t been studied in depth. The dinosaur order radiated from a two-legged (biped) form into at least three different four-legged (quadruped) forms including armored dinosaurs (e.g. stegosaurs and ankylosaurs), ceratopsians (e.g. triceratops and chasmosaurus), and various ornithopod types, (e.g. camptosaurs, hadrosaurs, and iguanodontids).

How to measure a scapcoracoid: One of several measuring aids available to project volunteers from the Open Dinosaur Project website.
Courtesy Open Dinosaur ProjectIn order to aid team members in gathering the proper information, instructions, templates, and other documents are available on the Open Dinosaur Project website. Diagrams explaining ornithischian limb osteology – including each bone’s proper name - are also on the site, as are illustrations showing exactly how to properly measure the dimensions of different bones. For those involved who don’t have access to museum specimens or material in other collections, the team leaders provide lists where prior publications with skeletal information can be accessed and mined for the study.

By last week, the Open Dinosaur Project had acquired nearly 1600 entries, but the results of all this work remain to be seen. The compiled data will be analyzed over the next couple months, and Farke, Wedel, and Taylor plan to begin writing the paper this spring. When completed the study will be submitted for publication in a peer-reviewed journal. If all goes as planned, after publication, the lead researchers will make all the data available online for future studies.

Now that their data has been entered on the ODP site, SMM volunteers Huset and Key will have their names included as contributors, and eligible to be included in the resulting paper.

"We wanted to get the general public excited about and involved in doing “real” science, working in cooperation with paleontologists. There is a great interest out there in paleontology, particularly dinosaurs. It’s amazing how many non-paleontologists read the technical literature! I thought, “Why not harness this enthusiasm?” There have been many people waiting for this sort of opportunity (even if they didn’t know it), and I think the response speaks for itself." – Andy Farke in Ciência Hoje On-line

Becky Huset enjoyed being involved with the project. “[It] sounded like a good idea,” she said. “I like having knowledge that is freely available to everyone, and it was a good way to contribute to a paper. Do some "real" work."

LINKS

Open Dinosaur Project website
Wedel’s & Taylor’s dino-related blog
More about Ornithischian dinosaurs
Osteology (the scientific study of bones)

Tags : dinosaurs, fossils, ornithischians, osteology, paleontology, scientific method, vertebrate paleontology

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I was surfing around the web the other night and came upon some a series of new videos on YouTube documenting a program originating out of the Paleon Museum in Glenrock, Wyoming. If you want to hunt for dinosaur fossils, Wyoming is the place to go. The series of videos follow a crew of paleo-wannabees led by museum director, Sean Smith, to a couple nearby dig sites. Renowned paleontologist Bob Bakker also gets involved, adding knowledge and background facts, and helping the participants decipher what exactly they find.

The program is well done and contains pretty much what you’d expect on the subject, but what’s cool about this particular series is that one of the participants involved was a volunteer here at the Science Museum of Minnesota a couple years ago. Katie Grace worked with me in the Dinosaur and Fossils gallery, and I remember talking with her about the summer adventure she had with her dad looking for dinosaurs in Wyoming.

Katie appears throughout the videos but most prominently in Pt. 1 where she is interviewed starting at 7:10. Way to go Katie!

By the way, the last video in the series features several watercolor paintings by geologist Arthur Lakes, a subject I wrote about a couple weeks ago.

Tags : Bob Bakker, dinosaur dig, dinosaurs, paleontology

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Arthur Lakes
Courtesy Arthur Lake Library, Colorado School of MinesArthur Lakes, pioneer dinosaur hunter, and chronicler of early American paleontology, was born this day in 1844 in Martock Summerset, England. Educated at Queens College in Oxford, Lakes eventually immigrated to the United States (via Canada) where he worked as a geologist, teacher, artist, and itinerant Episcopalian minister in the area around Golden, Colorado.
Sketch by Arthur Lakes: From a Scientific American article detailing the discovery of dinosaur remains near Morrison, Colorado.
Courtesy Mark Ryan collectionOn March 27, 1877, while out measuring rock units in the foothills of the Rocky Mountains just west of Denver, Lakes and a companion, Captain Henry Beckwith, discovered large exposures of dinosaur remains. Hoping to stir up some interest, money, and perhaps some employment, Lakes sent some of the fossil bones eastward to both Othniel Marsh, and Edward Cope, unintentionally firing up the feud between the two pioneer paleontologists that would soon escalate into the famous Bone Wars of the latter 19th century. Marsh, at Yale’s Peabody Museum, eventually hired Lakes as a field worker, and used the fossils he found to describe a number of new dinosaurs species taken from several productive quarries around the Morrison, Colorado area. These new discoveries all came from the Late Jurassic-aged rocks (named the Morrison formation after the nearby town) and included the first discoveries of the now well known Stegosaurus, Diplodocus and Apatosaurus (Brontosaurus).

When the Colorado quarries were exhausted, Marsh sent Lakes north to Como Bluff in Wyoming Territory. Dinosaur bones had been found there not long after the Colorado discoveries. Arthur Lakes spent the 1879-80 season digging out tons of bones from of the Jurassic-aged sediments around Como Bluff, along with William Reed, a railroad worker who had brought the area’s rich fossil cache to Marsh’s attention. It must have been a strange pairing since the Oxford-trained Lakes was the polar opposite of the self-taught frontiersman Reed.

Como was one of the prime battlegrounds in the Fossil Feud between Marsh and Cope. The strata there was far richer than that at Morrison, and produced fossils that eventually filled the display halls at many of the world’s great natural history museums, including the Smithsonian in Washington, D. C., the Peabody Museum at Yale, and the American Museum of Natural History in New York.

Original quarry site and dinosaur bone near Morrison: Arthur Lakes first discovered dinosaur bones here in 1877.
Courtesy Mark RyanLakes kept journals and wrote many letters of his activities at both Morrison and Como Bluff describing his explorations and the natural history of both areas (the journals were published in a book in 1997 by the Smithsonian Institute). These, along with his initial discoveries around Morrison, would probably have been enough to keep his name in the annals of paleontology, but his most important contributions to the science were the many sketches and watercolors he made at both locations. These depictions not only preserve a wonderful pictorial record of seminal events in the history of early American paleontology, but have also aided modern researchers in locating historical quarry sites at both locations. Many of Lakes’ original paintings are reposited at the Peabody Museum at Yale in New Haven, Connecticut.

Lakes’ original dinosaur quarry (#1) is preserved today as a historic landmark on the west side of Dinosaur Ridge along Alameda Parkway, overlooking the town of Morrison and the Red Rocks Amphitheater. Some bones, still intact in blocks of hard sandstone, can be seen there, as well as lateral views of some later discovered dinosaur footprints.

Quarry 10 at Morrison, Colorado: Lakes' historic dinosaur quarry was recently re-discovered on the slopes above town by researchers from the Morrison Natural History Museum.
Courtesy Mark RyanThe location of Quarry 10, where the remains of several sauropod species were discovered, was long lost until recently. The quarry was re-discovered and re-opened in 2002 by researchers from the nearby Morrison Natural History Museum. Artifacts of Arthur Lakes’ original diggings, such as nails and campfire charcoal have been recovered from the site. The nails would have come from support beams built to hold up the massive sandstone ledge that capped the softer clay layer from where many of the fossil bones were extracted. Lakes’ journal reported a couple collapses at this quarry in his journal. Luckily no one was working the quarry at the time, otherwise they would no doubt have been crushed to death by several tons of sandstone.

Arthur Lakes artifacts: Bits of charcoal, a support beam nail, and a belt buckle from Arthur Lakes' time recovered from Quarry 10 in Morrison, Colorado.
Courtesy Mark RyanRe-examination of Lakes' quarries has revealed some new secrets, such as the first footprints from a baby Stegosaurus. Yale has also loaned some of Lakes' original finds back to the museum in Morrison, including a toe bone from a baby Apatosaurus, and the articulated leg bones from the Apatosaurus ajax discovered at Quarry 10 in 1877.

Lakes eventually left the fossil trade, and turned his attention to the geology of Colorado, working for the US Geological Survey, and teaching courses in earth science and mining at what is today the Colorado School of Mines. The library at the school is named in his honor. Lakes continued to write, producing books and several articles about mining in Colorado. He and his sons also consulted for mining companies after he retired from teaching, and later moved to British Columbia to live out his days near his family. He died there in 1917.

If you'd like to learn more about Lakes and his life, there's a new book titled The Legacy of Arthur Lakes by Beth Simmons and Katherine Honda, recently published by The Friends of Dinosaur Ridge.

LINKS
Smithsonian article
Friends of Dinosaur Ridge

Tags : Arthur Lakes, dinosaurs, Edward Drinker Cope, fossils, history of paleontology, Othniel C. Marsh, paleontology, vertebrate paleontology

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Tawa hallae: Illustration of the newly discovered theropod dinosaur
Courtesy Jorge GonzalezA new dinosaur found in New Mexico is changing how scientists view the early beginnings of the ruling reptiles. Tawa hallae was a small, carnivorous theropod measuring about 6-13 feet in length that hunted its prey during the late Triassic period not long after dinosaurs first appeared about 230 million years ago. Theropods are a group of mostly carnivorous dinosaurs that include the popular Tyrannosaurus rex. Until now, the record of Triassic theropods in North America has been somewhat lacking. But Tawa is helping change that.

Several high-quality specimens of T. hallae were uncovered, along with the remains of two other early meat-eaters in the spectacularly colorful strata around Ghost Ranch, an area near the town of Abiquiu in northern New Mexico. T, hallae's type specimen – that is the fossil that defines the species – was a nearly complete skeleton of a juvenile. The new study appeared in this month in the journal Science.

Digging out Tawa hallae at Ghost Ranch, NM: Sterling Nesbitt (left) and Michelle Stocker at work in the Hayden Quarry.
Courtesy Randall Irmis, University of UtahThe bones Tawa hallae display similar features found in later dinosaurs (including birds) such as hip structure, hollow bones, and space for air sacs in some vertebrae. But it also contains characteristics found in other early carnivores, such as Herrerasaurus, another Triassic period biped. Herrerasaurus remains have been found in Triassic rocks in South America, alongside the earliest known remains of the two other dinosaur forms: sauropodomorphs (long-necked herbivores such as Diplodocus), and ornithiscians (beaked herbivores such as Stegosaurus). Considered by some paleontologists as one of the earliest dinosaurs. Herrerasaurus displays some theropod features but is missing traits found in others, leading some scientists to speculate whether it was a theropod at all, or even a dinosaur. But according to Sterling Nesbitt, a paleontologist and the study's lead author from the University of Texas in Austin, Tawa hallae has answered some of those questions.

"Tawa pulls Herrerasaurus into the theropod lineage, so that means all three lineages are present in South America pretty much as soon as dinosaurs evolved," said Nesbitt. "Without Tawa, you can guess at that, but Tawa helps shore up that argument."

The remains of two other distinct theropods were also found in the same quarry at Ghost Ranch. One displayed characteristics that made it closely related to Coelophysis (found elsewhere at Ghost Ranch), and the other to Herrerasaurus - indicating the lines diverged before the unified landmass Pangaea split apart into separate continents.

“When we analyzed the evolutionary relationships of these dinosaurs, we discovered that they were only distantly related, and that each species had close relatives in South America,” said Randall Irmis of the University of Utah. “This implies that each carnivorous dinosaur species descended from a separate lineage before arriving in [the part of Pangea that is now] North America, instead of all evolving from a local ancestor.” Irmis co-authored the study, and also works at the Utah Museum of Natural History.

Oddly, no sauropodomorph or ornithischian remains from the Triassic Period have ever been found in North America. Scientists admit that's somewhat perplexing but think it's possible they migrated through the area when it was still part of Pangaea. But thanks to Tawa hallae the evolution of the theropod line is becoming clearer.

"Tawa gives us an unprecedented window into early dinosaur evolution, solidifying the relationships of early dinosaurs, revealing how they spread across the globe, and providing new insights into the evolution of their characteristics," Nesbitt said.

Ghost Ranch, New Mexico: The spectacular rock formations at Ghost Ranch display strata from all three geological periods of the Mesozoic era and have proven rich in Triassic-aged fossils.
Courtesy Mark RyanThe remains of Tawa hallae were found at Ghost Ranch in northern New Mexico about 65 miles north of Santa Fe, the same area where the spectacular Coelophysis remains were discovered in the late 1940s. Both species were found in the Chinle formation (pronounced chin lee), although Tawa’s fossils were found lower in the strata, in the older Petrified Forest member of the formation. The rich bone bed was first discovered in 2004 by amateurs on a week-long paleontology seminar sponsored by the Ruth Hall Museum at Ghost Ranch. Tawa hallae was named for the Hopi word for sun god, and in honor of Ruth Hall, the museum’s founder.

LINKS
National Science Foundation press release
Science Codex story
Science Frontline story

Tags : dinosaurs, paleontology, Tawa hallae, theropods, vertebrate paleontology

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