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Dinosaurs (& other saurs): New Findings & Theories.
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PostPosted: 16-09-2005 09:11    Post subject: Dinosaurs (& other saurs): New Findings & Theories. Reply with quote

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Skull study sheds light on dinosaur diversity


With their long necks and tails, sauropod dinosaurs—famous as the Sinclair gasoline logo and Fred Flintstone's gravel pit tractor—are easy to recognize, in part because they all seem to look alike.

The largest animals known to have walked the earth, sauropods were common in North America during the middle of the dinosaur era but were thought to have been pushed to extinction by more specialized plant-eaters at the end of that era. New discoveries, however, are showing that one lineage of sauropods diversified at the end of the dinosaur era, University of Michigan paleontologist Jeffrey Wilson says.

Wilson's recent restudy and reconstruction of the skull of a Mongolian sauropod adds to a growing body of evidence for sauropod diversity at the end of the dinosaur era. Wilson described the reconstruction and the conclusions he drew from it in a paper published Aug. 24 in the Journal of Systematic Palaeontology.

He based the reconstruction on two nearly complete skulls that were found in the Gobi Desert in the 1950s and 1960s but whose evolutionary relationships have remained enigmatic. In the 1990s and early 2000s, Wilson restudied the skulls and found characteristics identifying them as skulls of titanosaurs, a late surviving sauropod lineage.

"Titanosaurs, which were surprisingly common at the end of the dinosaur era, were really the only sauropod lineage that flourished. All the others went extinct," said Wilson, an assistant professor of geological sciences and an assistant curator at the University of Michigan Museum of Paleontology. But as prevalent as titanosaurs were, they left behind surprisingly few skulls. Paleontologists have found plenty of other titanosaur bones, providing a picture of a group of sauropods with specialized limb bones.

Wilson began to appreciate the finer points of titanosaurs as a graduate student, when he and another student studied fossilized sauropod tracks and titanosaur limb anatomy. From those studies, Wilson concluded that unlike other sauropods, titanosaurs walked with their feet planted far from the middles of their bodies, an unusual style of "wide gauge" locomotion.

"Most animals walk with a narrow gauge, with their feet close to the midline, because it's energetically more efficient to walk that way. But some sauropod trackways tell us that a group of sauropods were walking with a new wide-gauge stance. We can identify characteristics of titanosaurs that would have allowed that stance, and we can tie the appearance of those features with the proliferation of wide gauge tracks everywhere in the fossil record at the end of the dinosaur era." Wilson wonders if the change in locomotion—from typical sauropod narrow-gauge walking to titanosaur wide-gauge walking—corresponded to lifestyle changes, such as different feeding habits. But without skulls to study, it has been hard to draw conclusions about how and what titanosaurs ate.

With his work and that of researchers at the State University of New York, Stony Brook who announced the discovery of a complete titanosaur skeleton in 2001, sauropod specialists finally can start piecing together a clearer picture of the dinosaurs' lives.

One feature of the skulls is particularly intriguing. "They have elongate, sort of horse-like skulls with many openings and grooves on the outer surface of their snouts," said Wilson, who worked closely with U-M Museum of Paleontology artist Bonnie Miljour over the course of a year preparing the paper's many illustrations of the skull reconstruction. "Blood vessels and nerves passed through these holes and may suggest an especially sensitive snout. This probably had some role in feeding, but we haven't investigated it at all."

Oddly, a group of distantly related sauropods evolved a similarly grooved snout. "Apparently, these two different branches of sauropods gravitated toward similar anatomical structures, perhaps because they were specialized for eating certain types of vegetation."

Source: University of Michigan
http://www.physorg.com/news6540.html


Edit to amend title.


Last edited by ramonmercado on 18-02-2009 15:31; edited 2 times in total
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PostPosted: 29-09-2005 11:36    Post subject: Dinosaur eggs fail to reveal life Reply with quote

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Dinosaur eggs fail to reveal life

A medical scan of three fossilised dinosaur eggs by experts hoping to find life in them has proved inconclusive. The eggs were brought to England from China before exports of the rare specimens were banned.

They are encased in one piece of rock and are normally on display at a gem shop in Tunbridge Wells, Kent.

Owner Graham Bell said images from the scan appeared to show parts of the shell, but the Natural History Museum would be investigating further.


It had been hoped that the hadrosaur eggs, which are at least 70 million years old, would yield a glimpse of a dinosaur embryo.

The eggs came from a clutch found in a nesting site in the mongolian desert.

They were spotted in the shop by someone from a local medical centre who offered Mr Bell the chance of putting them through a state-of-the-art scanner usually used for checking out people's heart disease.

Mr Bell said: "As the images emerged so more things became visible and we saw what we first thought were bones... but we think they were probably parts of the shell that had collapsed into the egg before petrification."

He added that the eggs would eventually be sold, which had been always been his original intention.


Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/1/hi/england/kent/4292676.stm

Published: 2005/09/29 08:37:05 GMT

© BBC MMV
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PostPosted: 12-10-2005 11:44    Post subject: Dino reputation 'is exaggerated' Reply with quote

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Dino reputation 'is exaggerated'
The Velociraptor dinosaur made famous by the Hollywood movie Jurassic Park may not have been quite the super-efficient killer we all thought.
Like other dinos in its family, it had a distinctive sickle-shaped claw on the second toe which many have assumed was employed to disembowel victims.

But tests on a mechanical arm suggest this fearsome-looking appendage was probably used just to hang on to prey.

UK scientists report their experiments in the journal Biology Letters.

"This dispels the myth in place for some 40 years that this was a disembowelling claw - this is not the case," says Dr Phil Manning, from the Manchester Museum, University of Manchester.

"I'm saying that the primary function of this claw was to hold on to the predator, effectively like a climber's crampon," the curator of palaeontology told the BBC News website.

Dino kick

Velociraptor belonged to the Dromaeosauridae , a family of small to medium-sized, lightly built and fast-running dinosaurs from the Cretaceous Period (146 million to 65 million years ago) who appear from the fossil record to have been very effective predators.

There is even evidence some, such as Deinonychus , hunted in packs.


It's effectively like a fatal embrace
Dr Phil Manning

They all possessed a large, curved claw on their big toes that could rotate through an arc in excess of 200 degrees.
By kicking and slashing, it has been widely thought these creatures could quickly open up their unfortunate victims, either killing them outright or making them bleed so profusely death followed very quickly.

Dr Manning and his team tested the reputation on a robotic arm fitted with a life-like Dromaeosaur claw. The set-up was based on detailed fossil measurements.

The mechanical limb mimicked the sort kick that might have come from a 2m-long, 40kg Velociraptor . The Kevlar and carbon-fibre-coated aluminium claw was thrust into the flesh from pig and crocodile carcasses.

Skin impact

Instead of producing the expected slashing wounds, the robotic impacts created only small, rounded punctures.


What is more, the way the skin tissue bunched under the impacts prevented the claw from withdrawing easily.
The punctures had a depth of about 30-40mm.

"It seems highly unlikely that wounds of this depth would have posed a danger to the vital organs of a large herbivorous dinosaur, though they would obviously be fatal to small prey," the team writes in Biology Letters.

Dr Manning does not want people to think less of Velociraptor or Deinonychus because of the research.

Its killing efficiency may not have matched their Hollywood image but the creatures would still have presented a terrifying prospect.

Deadly pack

"It's effectively like a fatal embrace," he told the BBC News website.

"These claws were used to hook into the flanks of prey larger than them so the jaws could do the despatching.


"Imagine the scene: it's the Lower Cretaceous, and Tenontosaurs (large, plant-eating dinosaurs) are grazing on ferns or cycads, going about their everyday business," he added.
"Unbeknown to them, you've got a pack of predators stalking them.

"First, [the Dromaeosaurs ] try to separate the animal they wish to kill by running into the pack.

"The lead attacker then jumps on to the flanks of the animal, followed by maybe two or three others, hooking the huge claws in their feet into the animal and holding on with the re-curved claws on their hands.

"And once they're hooked into their prey, the razor sharp teeth of their jaws go to work causing as much blood loss as possible to weaken the animal.

"Eventually, the other animals come over for the kill, probably ripping open the throat and stomach with their teeth - not their claws."

The results of research were first shown on The Truth about Killer Dinosaurs, a BBC television production.

Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/1/hi/sci/tech/4332272.stm

Published: 2005/10/11 23:18:47 GMT

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PostPosted: 17-10-2005 09:24    Post subject: Ichthyosaur bones found off U.K. coast Reply with quote

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Ichthyosaur bones found off U.K. coast

LYME REGIS, England, Oct. 14 (UPI) -- The snout, teeth, vertebrae and ribcage of a 15-foot reptile that lived off the coast of England 190 million years ago have been found.

Geologist Paddy Howe, who is monitoring work on the site in Lyme Regis, says the ichthyosaur looked a bit like a dolphin but was a reptile that swam in the sea at the same time dinosaurs roamed the land, the BBC reported Friday.

The remains were found during work to prevent landslides along the coastline and took months to painstakingly remove.

"Now it's a case of waiting to identify the exact species and how rare the fossil is before deciding whether or not to try and find the rest of it," Howe said. "We hope that the fossil will eventually go on display at Lyme Regis Museum."

Ichthyosaur
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PostPosted: 18-10-2005 12:37    Post subject: Researcher Identifies Tracks Of Swimming Dinosaur In Wyoming Reply with quote

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Researcher Identifies Tracks Of Swimming Dinosaur In Wyoming

The tracks of a previously unknown, two-legged swimming dinosaur have been identified along the shoreline of an ancient inland sea that covered Wyoming 165 million years ago, according to a University of Colorado at Boulder graduate student.

Debra Mickelson of CU-Boulder's geological sciences department said the research team identified the tracks of the six-foot-tall, bipedal dinosaur at a number of sites in northern Wyoming, including the Bighorn Canyon National Recreation Area. "It was about the size of an ostrich, and it was a meat-eater," she said. "The tracks suggest it waded along the shoreline and swam offshore, perhaps to feed on fish or carrion."

Mickelson will present her findings at the Geological Society of America's annual meeting Oct. 16-19 in Salt Lake City. She collaborated on the project with researchers from CU-Boulder, Indiana University, Dartmouth College, Tennessee Technological University and the University of Massachusetts.

Mickelson said scientists have previously reported evidence of swimming dinosaurs in other parts of the world and at other times in the geologic record. But the new findings by the team are the only known evidence of any dinosaurs in the Wyoming region during the middle Jurassic, she said.

The dinosaur does not have a name, although Mickelson is continuing to look for bones and other remains that could be used to identify and name the new species. "This dinosaur is similar to a Coelosaur," she said. "It is a dinosaur with bird-like characteristics and is a possible ancestor of birds. It lived in a much earlier time period and was very different from larger dinosaurs like T-Rex or Allosaurus."

The tracks are embedded in a layer of rock known as the Middle Jurassic Bajocian Gypsum Spring Formation, a 165- to 167-million-year-old rock formation that contains fossilized remains of a marine shoreline and tidal flats. Geologists believe an inland sea, called the Sundance Sea, covered Wyoming, Colorado and a large area of the western United States during the Jurassic period from about 165 million years ago to 157 million years ago.

Mickelson said the sea might have been warm and relatively shallow, much like the Gulf of Mexico today.

"The swimming dinosaur had four limbs and it walked on its hind legs, which each had three toes," Mickelson said. "The tracks show how it became more buoyant as it waded into deeper water -- the full footprints gradually become half-footprints and then only claw marks."

Mickelson explained the tracks are found among the traces left by many animals, including ancient crocodiles and marine worms. "The tracks of the ancient crocodiles are very different," she said. "They walk on four legs and have five digits."

Since summarizing preliminary findings last spring, Mickelson and the research group have expanded their study area, which she said contains millions of dinosaur tracks in a number of Gypsum Spring Formation rock outcrops in northern Wyoming.

The tracks are of different sizes and were deposited at about the same time, according to Mickelson, revealing that the dinosaurs likely traveled in packs and exhibited some variation in overall size. "Further research into the geologic record and depositional history of the region supports our conclusion that the dinosaurs were intentionally swimming out to sea, perhaps to feed," she said.

Source: University of Colorado at Boulder


http://www.physorg.com/news7313.html
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PostPosted: 19-10-2005 12:43    Post subject: Wright Brothers Upstaged! Dinos Invented Biplanes Reply with quote

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Wright Brothers Upstaged! Dinos Invented Biplanes

The evolution of airplanes from the Wright Brothers' first biplanes to monoplanes was an inadvertent replay of the much earlier evolution of dinosaur flight, say two dino flight experts.

According to paleontologist Sankar Chatterjee and retired aeronautical engineer R.J. Templin, a small early Chinese dinosaur called Microraptor gui used a two-level, biplane wing configuration to fly from tree to tree in the early Cretaceous.

Among the evidence for the early biplane is that Microraptor had unmistakable flight feathers on its hind limbs as well as on its wings, says Chatterjee, a distinguished professor at Texas Tech University in Lubbock. The Chinese paleontologists who first reconstructed Microraptor had guessed that its four wings were used in tandem, similar to those of dragonfly.

Chatterjee presented the new biplane flight findings Sunday, 16 October, at the Annual Meeting of the Geological Society of America in Salt Lake City.

"The most unusual thing is that they have flight feathers not only on the hand section, but also on foot," said Chatterjee. Flight feathers differ noticeably from other feathers in that they are asymmetrical with interlocking barbules to keep their shape. The leading edge of each long feather was narrower than the trailing edge, which helped streamline the body in flight. The hooked, interlocking barbs gave strength and flexibility to the feather and prevented air from passing through it in flight.

Some present-day birds, especially raptors as well as the earliest Jurassic bird Archaeopteryx, also have (or had) feathers on their legs, Chatterjee says. But these are not flight feathers and appear adapted to streamline the legs during catching and carrying prey so they don't interfere with flight.

Another key element to discovering Microraptor's flight secrets was setting some realistic limitations on how the dinosaur could move its hindlimbs – something that was initially overlooked by Chinese researchers who found the fossil. Chatterjee and Templin studied its anatomy and found that like any dinosaurs, Microraptor held their hindlimbs in erect, vertical plane, permitting forward and backward motion.

"The problem we faced is that the legs of Microraptor, like on any dinosaur, could not be splayed sideways," as the Chinese paleontologists assumed. That means Microraptor could not have extended its rear limbs to form a wing directly behind the front wing. More likely, and more aerodynamically stable, would have been a rear wing that was held lower than the front wing – what from the side would look like a staggered biplane configuration, Chatterjee explains.

Chatterjee and Templin fed Microraptor's flight data into a computer simulation that they have previously used to successfully analyze the flying abilities of pterosaurs and Archaeopteryx. Based on the aeronautical analysis, it appears that Microraptor flights looked rather like those seen today among some "monoplane" forest birds -- something called undulating phugoid gliding, Chatterjee said. In other words, Microraptor launched from a high branch and dove off, falling head-first until it reached a speed that created lift on its wings. With that lift the feathered dino then swooped upwards and landed in the branches of another tree without having to flap its wings and expend muscular energy.

"The biplane wing configuration was probably a very first experiment in nature," says Chatterjee of the early flying technique, which was also used by another feathered dinosaur from China, Pedopenna, he said. Archaeopteryx achieved fully powered flight with monoplane configuration, as its wing became even larger than those of Microraptor, but foot feathers were lost.

"It is intriguing to contemplate that perhaps avian flight, like aircraft evolution, went through a biplane stage before the monoplane was introduced, said Chatterjee. "It seems likely that Microraptor invented the biplane 125 million years before the Wright 1903 Flyer."

The discovery of Microraptor and other small, exquisitely preserved feathered dinosaurs from China also helps to settle a century-old controversy over whether avian flight began in trees (trees-down theory) or on the ground (ground-up theory). These fossils show various transitional stages–from wingless, tree-dwelling theropod dinosaurs to fully winged, active flyers, Chatterjee said.

The central theme of the trees-down theory is that gravity was the source of energy: a small climbing dinosaur first parachuted down, then began to stay aloft longer by gliding, and finally acquired powered flight. As those abilities developed, feathers became larger and more specialized, providing greater lift and thrust. The Chinese feathered dinosaurs show these transitional stages of flight.

In contrast, the ground-up theory has a theropod struggling toward flight directly from the ground, against gravity, without any gliding stage. Such long feathers around the feet would make it hard for Microraptor to run on the ground, says Chatterjee, supporting the idea that it was a tree dweller, thus reinforcing the trees-down theory.

http://www.physorg.com/news7358.html
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PostPosted: 23-10-2005 23:20    Post subject: Reply with quote

A picture of Microraptor gui here
http://www.dinosaurier-interesse.de/web/Bilder/Hille/Microraptor_gui-bunt-h400.gif
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PostPosted: 11-11-2005 11:29    Post subject: Taking A Bite Out Of The Problem: Researchers Devise Dinosau Reply with quote

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Source: Washington University in St. Louis
Date: 2005-11-10
http://www.sciencedaily.com/releases/2005/11/051110084537.htm

--------------------------------------------------------------------------------

Taking A Bite Out Of The Problem: Researchers Devise Dinosaur Classification Method
What do you get when you cross Carcharodontosaurus with Majungatholus? Good luck telling the two apart. Owing to paltry numbers of whole specimens that fail to illuminate a range of intraspecies morphological variation, dinosaur classification can be a task as gargantuan as some of its famed species. But Josh Smith, Ph.D., assistant professor of earth and planetary sciences at Washington University in St. Louis, has concocted a mathematical scheme for identifying dinosaurs based upon measurements of their copious Mesozoic dental droppings. His method could help paleobiologists identify and reconstruct the lives of the creatures that roamed our terra firma many millions of years ago.

Smith, who claims he's "not very good at math," and his coauthors, David R. Vann and Peter Dodson of the University of Pennsylvania, devised a quantitative methodology by which an isolated tooth of a predatory dinosaur — a theropod — can be correlated with a given genus. They used a variety of measurements — some of which had been defined by previous workers — that describe the basic size and general shape of the teeth as well as devised functions that help quantitatively describe the shapes of the curved surfaces possessed by the teeth. The result was a preliminary but rigorous method of classifying theropod teeth with established genera. Smith and his colleagues published their in work in a recent issue of The Anatomical Record (Vol. 285, 2005).

"My whole point was to take an isolated tooth and figure out what dinosaur it belonged to," Smith explained. "The questions I'm interested in are different than 'what did this thing eat?' I'm interested more in teeth as tools for dinosaur identification rather than the teeth as teeth themselves."

Teeth as hardy identifiers

People like teeth. The same mineral that helps us chaw our way to Thanksgiving bliss allows paleontologists like Smith to study a time period so far removed from our own that traces of bones and enamel are among the only clues to the past. Mesozoic-aged dinosaurs, living between 225 and 65 million years ago, are referred to as polyphyodont animals because they continually shed and replaced teeth throughout their lives. Tooth replacement introduces the hardest and most resilient substance in the vertebrate body, enamel, into the local environment many times over as old teeth are lost and fall from the mouths of their owners into streams and onto the forest floor. After countless tooth replacements and millions of years of sedimentation, Smith and his colleagues have uncovered an ample data set of preserved dinosaur enamel: Smith's Rosetta stone of theropod classification.

"The problem is that theropod teeth are simple enough that everyone has ignored them for the last 200 years, " Smith said. He said that the simple shapes of theropod teeth have complicated previous rigorous attempts to use them for classification.

The mathematical tedium Smith claims to have spared while devising the methods was not lost on tooth examination: Smith collected measurements and curvature data from about 2,000 teeth, scrutinizing dinosaur chops as a dentist would a root canal. Thousands of measurements ultimately boiled down into a data set of just under 300 usable teeth. The dataset is comprised of measurements of teeth from genera that are known with certainty; it thus forms a standard of comparison against which unknown teeth can be compared.

Smith then ran statistics on the database to correlate the shapes of unknown teeth with the most similar tooth of known origin. During a test of the methods, most of the time the model worked, correctly identifying known, and even similar-looking teeth as the correct genus.

"I've created the beginnings of a standard of comparison; a data set with teeth that we know where they came from, against which to compare isolated teeth. That's basically all I've done," Smith said.

He said that the model, although functional, isn't without its weaknesses. To properly correlate a tooth with a species, the species that the tooth belongs to must be represented in the data set; otherwise, the analysis will try to match the tooth with the species that most resembles the unknown.

Increasing the data set

"So now I'm working on making the method better and increasing the size of the data set," Smith adds.

Dinosaur identification is critical for paleontologists trying to accurately reconstruct the Mesozoic Period. Teeth can reveal dinosaur eating habits and biology if the tooth is associated with its rightful owner.

"We're taking a potential data set — that is, isolated teeth — that has the potential to be really powerful," Smith said, "Until now, the data have largely been overlooked but we're trying to make use of them. And it looks like it's working. Which is only really significant because everybody said it wouldn't."

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PostPosted: 13-11-2005 22:12    Post subject: First time post - and in anger Reply with quote

I'm a long time lurker, first time poster.

Josh Smith used to supervise my fiancée during the one year she spent as a PhD student at Washington University in St Louis. She was forced to leave the PhD at Wash U due to the behaviour of "Professor" Smith, who, amongst his many other sins (perhaps his wife would care to know about his "field work") assaulted my fiancée and stole research ideas from students and allowed other students to steal research ideas from close friends of my fiancée. As most board members with connections with academia will know, there is no greater professional sin than plagiarism.

Identification of dinosaur species from morphometric analysis of isolated samples of dinosaur teeth was my fiancées proposed PhD dissertation. Josh Smith dismissed this as unworkable and not worth studying. My fiancée countered that there were many isolated specimens and that no-one else was doing this work. Smith said that there was a reason no-one was doing it, because it wouldn't work, and also because it is computers and maths that no-one would understand.

Now I see that Smith has decided to steal her research (no change from his standard behaviour), and still claims he doesn't understand the math, unlike my fiancée, who does. I note the article does not mention the computer programs that would be required to be used for this morphometric analysis. Doubtless Smith has decided to perform the analysis manually with calipers - my fiancée suggested using a powerful suite of computer programs called TPS.

I am sorry if this isn't really in the spirit or purpose of this thread, but I am so damn angry at the moment it's not funny.

Apologies to everyone for this rant. Grrrrrrrrr.
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PostPosted: 13-11-2005 23:35    Post subject: Re: First time post - and in anger Reply with quote

lawofnations wrote:
I'm a long time lurker, first time poster.
I am sorry if this isn't really in the spirit or purpose of this thread, but I am so damn angry at the moment it's not funny.
.................................
Apologies to everyone for this rant. Grrrrrrrrr.

No need to apologise for this interesting insight into the ways of academia.

There are selfish, thieving gits in all fields of human endeavour, sadly.
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PostPosted: 14-11-2005 10:13    Post subject: Reply with quote

lawofnations

This is a far too failiar story. Might I suggest that you or your fiancee contact the editor of Science Daily at:
editor@sciencedaily.com

regards

Ramon
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PostPosted: 17-11-2005 13:39    Post subject: Missing Fossil Link 'Dallasaurus' Found Reply with quote

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Source: Southern Methodist University
Date: 2005-11-16
http://www.sciencedaily.com/releases/2005/11/051116173945.htm

--------------------------------------------------------------------------------

Missing Fossil Link 'Dallasaurus' Found

When amateur fossil finder Van Turner discovered a small vertebra at a construction site near Dallas 16 years ago, he knew the creature was unlike anything in the fossil record. Scientists now know the significance of Turner’s fossil as the origin of an extinct line of lizards with an evolutionary twist: a land-dwelling species that became fully aquatic.

Turner took the remains to paleontologists at the Dallas Museum of Natural History, but it took several years before scientists dubbed the find Dallasaurus turneri. Word of Dallasaurus is now reaching the scientific community with a special issue of the Netherlands Journal of Geosciences, featuring an article by Southern Methodist University paleontologist Michael Polcyn and Gordon Bell Jr. of Guadalupe National Park in Texas.

They describe Dallasaurus, a three-foot long lizard who lived 92 million years ago in the shallow seas and shores of what was then a stretch of Texas mostly under water, and also used the fossil to better understand the mosasaur family tree. Polcyn and Bell painstakingly pieced together an understanding of the anatomy and natural history of Dallasaurus from the bones Turner discovered and from some matching skeletal remains at the Texas Memorial Museum at the University of Texas in Austin.

Dallasaurus represents a missing link in the evolution of a group of creatures called mosasaurs, prehistoric animals that started out on land, but evolved in the seas and dominated the oceans at the same time dinosaurs ruled the land. One aspect of Polcyn and Bell’s research is the revelation that Dallasaurus retained complete limbs, hands and feet suitable for walking on land, whereas later mosasaurs evolved their limbs into flippers.

“This is pretty close to the beginning of the mosasaur family tree,” says Dallas Museum of Natural History Earth Sciences Curator and SMU Adjunct Professor of Paleontology Anthony R. Fiorillo, Ph.D. “It is the most complete mosasaur retaining all of its limbs found in North America.”

Mosasaurs, every bit as prolific, fascinating and nearly as big as some dinosaurs, are becoming more popular for paleontologists to study. Mosasaurs lived and became extinct alongside dinosaurs, but few paleontologists specialize in them. Later mosasaurs grew as large as their dinosaur brethren, reaching up to 45 feet in length. Until the discovery of Dallasaurus, however, only five primitive forms with land-capable limbs were known, all of them found in the Middle East and the eastern Adriatic.

“Lizards had nearly 150 million-year-long history on land; then in the Late Cretaceous, the final stage of the age of dinosaurs, one group moved into the sea and rose to the very top of the food chain,” explains Polcyn, director of SMU’s Visualization Laboratory, part of the university’s geological sciences department. “Starting out as small animals like Dallasaurus, they mastered their new marine environment and rose to become the top predator in their ecosystem, the T. Rex of the ocean.”

The Late Cretaceous period was a time of hot house temperatures and rising sea levels.

“As the earth warmed and the seas rose, small land-dwelling lizards took to the oceans and developed increasing levels of seagoing capabilities, and over 30 million years, eventually evolving into the top predator of their domain before becoming extinct some 65 million years ago” says Polcyn.

The advanced fin-bearing mosasaurs have been grouped into three major lineages. Although a small number of primitive mosasaur have been known to retain land-capable limbs, they were thought to be an ancestral group separate from the later fin-bearing forms. Dallasaurus represents a clear link to one lineage of the later forms and the first time researchers can clearly show mosasaurs evolved fins from limbs within the different lineages of mosasaurs.

With the aid of computer science and SMU’s visualization laboratory, Polcyn has been able to simulate what Dallasaurus looked like, and how, based on his skeletal remains, he would swim and move from land to sea. An artist has taken Polcyn’s visualization work even one step further by creating a life-sized model of Dallasaurus, a work that is soon to be on display at the Museum along with the computer simulation.

When funds become available for reconstructing a suitable exhibit, the bones of Dallasaurus will be displayed at the Dallas Museum of Natural History. The work, however, will take several more years of additional efforts and substantial funding. A nearly 30-foot long mosasaur, some 75 million years old, already is on display at the Dallas Museum.

Major dinosaur finds are frequently the result of creatures dying in groups through flooding or drought, situations that lend themselves fairly well to more complete preservation and conservation of their bones, and much slower deterioration. Mosasaur fossils, in contrast, are rarely found in large groupings, and are only found in areas once covered by seas. Remains were quick to deteriorate under ocean currents; their bodies often fell victim to the ravages of other sea life, such as sharks, who would pick away at carcasses for food. Because of their mostly shallow sea and seaside habitats, the remains of early mosasaurs are even more rare and much harder to find.

But in the last two decades, many new discoveries and significant advances have been made in the understanding of mosasaur evolution and how they lived. Dallasaurus significantly advances that understanding by filling in a long missing piece of mosasaur evolution, specifically a time at which they transition from land to sea.

The importance of Turner’s discovery isn’t lost on the researchers putting together the pieces of the mosasaur puzzle. In fact, they predict the legacy of Turner’s discovery will live on. His contribution was honored by naming the species, “turneri,” after his last name. “Not all major discoveries are made by highly trained paleontologists,” notes Dallas Natural History Museum Curator Fiorillo. “The observant individual, even kids, can still make an important find,” he says. “Once this goes mainstream, and people begin to recognize what mosasaurs are, we’ll be finding more and more.”

# # #

SMU is a private university in Dallas with more than 10,000 students and offers degree programs through seven schools. More information about SMU is available at www.smu.edu.

The Dallas Museum of Natural History, a Smithsonian Institution affiliate, is a research and exhibition institution devoted to natural history research and public education. It is funded by public government, companies and by private foundations and individual donations, including the City of Dallas, the state of Texas, the Microsoft Foundation, the Junior League, American Airlines and the Dallas Morning News. With over 280,000 specimens, it is among the largest natural history museums in the country. Located in historic Fair Park in Dallas, the museum is open daily, 362 days annually. The Museum’s website is www.dallasdino.org.

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PostPosted: 19-11-2005 14:44    Post subject: Reply with quote

Quote:

Dinosaurs had appetite for grass
A study of fossil dinosaur dung has for the first time confirmed that the ancient reptiles ate grass.
Grass was previously thought to have become common only after the dinosaurs died out 65 million years ago.

But grasses were probably not a very important part of dinosaur diets - the fossilised faeces show the big beasts ate many different types of plants.

However, the Science journal study suggests grass was possibly an important food for early mammals.

Caroline Strömberg from the Swedish Museum of Natural History and her colleagues studied phytoliths (mineral particles produced by grass and other plants) preserved in fossil dinosaur dung from central India.

Theory dumped

The 65-67 million-year-old dung fossils, or coprolites, are thought to have been made by so-called titanosaur sauropods; large, vegetarian dinosaurs.


"It's difficult to tell how widespread [grass grazing] was," Ms Strömberg told the BBC News website, "Dinosaurs seem to have been indiscriminate feeders."
The study also sheds new light on the evolution of grass. Grasses are thought to have undergone a major diversification and geographic proliferation during the so-called Cenozoic, after the dinosaurs had gone extinct.

But the researchers found at least five different types of grass in the droppings.

This suggests grasses had already undergone substantial diversification in the Late Cretaceous, when the giant beasts still walked the Earth.

Defence mechanism

Many grasses today contain high levels of silica, which makes them tough and hard to chew. One theory proposes that this is an evolutionary defence against being eaten by herbivores.

This defence is traditionally thought to have been a response to large-scale grazing by mammals in the Cenozoic. But, if the theory is correct, it raises the possibility that grasses first began developing this defence in response to grazing by dinosaurs.

However, small mammals living alongside the dinosaurs may also have been grass feeders.

An enigmatic group of extinct mammals known as sudamericid gondwanatherians, which lived during the Late Cretaceous, show possible signs of adaptation to a grassy diet.

Their teeth are ideally suited for handling abrasive materials like grass. But because of grass's patchy presence in the fossil record, these features were interpreted as an adaptation to a semi-aquatic, or burrowing, lifestyle like that of modern beavers.


Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/1/hi/sci/tech/4443696.stm

Published: 2005/11/17 18:55:57 GMT

© BBC MMV
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PostPosted: 02-12-2005 11:12    Post subject: Reply with quote

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Oldest bird had dinosaur feet
19:00 01 December 2005
NewScientist.com news service
Jeff Hecht

Enlarge image
With jagged teeth and raptor-like features, the feathered archaeopteryx is unlike any modern species of bird (Image: G Mayr/Senckenberg)
Enlarge image
Ultraviolet light enhances details of a complete foot, showing that archaeopteryx had an extensible claw on its second toe – a hallmark of raptors – which is absent in all known birds (Image: G Mayr/Senckenberg)The oldest known bird was closer to a dinosaur than previously thought – a discovery that confuses the evolutionary tree as we currently understand it.

An exceptionally well preserved new fossil reveals a foot and skull that more closely resemble those of a group of two-legged predatory dinosaurs called the known as dromeosaurs, than modern birds.

With jagged teeth and a dinosaur-like skeleton, the archaeopteryx is unlike any modern species of bird. But flight feathers on its long front limbs have led palaeontologists to identify the creature as the oldest known species of bird.

Nine previously known specimens of archaeopteryx have led palaeontologists to conclude that birds probably evolved from small meat-eating dinosaurs, and are closely related to the dromeosaurs, a group that includes the velociraptor. Yet precisely how archaeopteryx is related to the raptors has remained unclear – key pieces of these previous specimens are missing.

But the newly revealed fossil appears to fill in many of the gaps. The specimen comes from the private collection of a worker at the Solnhofen limestone quarries in Germany, where the first archaeopteryx fossil was discovered. It has remained unknown to science until its owner's death, when the new owner made it available to scientists at the Wyoming Dinosaur Center in the US.

Computer model
A complete foot reveals that archaeopteryx had an extensible claw on its second toe, which is a hallmark of raptors, but is absent in all known birds. Its first toe, or "hallux", is also at the side of the foot and not reversed as it is in perching birds, which use it to grasp branches.

The skull is also well preserved and shows that the animal had a skull bone known as the "palatine", which is shaped in the same way as in many two-legged dinosaurs.

The new traits were added to a computer model, enabling palaeontologists to analyse the relationship between extinct species. "It's now very difficult to distinguish between [early] birds and [early] dromeosaurs," says Gerald Mayr of the Senckenberg Research Institute in Frankfurt, Germany, who studied the specimen.

Question of class
Mayr told New Scientist that there are no unique traits shared by archaeopteryx and other early bird-like fossils that are not present in dinosaurs. This would either mean that archaeopteryx cannot be classed within the same evolutionary group as birds or that this group needs to be redefined.

But Peter Makovicky of the Field Museum of Natural History in Chicago, US, says those results are shaky because Mayr's group considered only three bird-like creatures; archaeopteryx, confuciusornis and a primitive bird called Rahonavis, that lived much later.

In October 2005, Makovicky carried out a separate study that links Rahonavis directly to the dromeosaurs and suggests this species may have evolved flight separately from archaeopteryx and other birds. Makovicky told New Scientist he found no change in the shape of his evolutionary tree when he added the new traits found for archaeopteryx.

Journal reference: Science (Vol 310, p 1483)

http://www.newscientist.com/article.ns?id=dn8408

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Weblinks
Science
http://www.sciencemag.org/
Field Museum of Natural History
http://www.fieldmuseum.org/
Senckenberg Research Institute
http://www.senckenberg.de/
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PostPosted: 16-12-2005 15:31    Post subject: Reply with quote

Quote:
One Size Didn't Fit All for Early Dinosaur, Study Says

James Owen
for National Geographic News

December 15, 2005
One size didn't fit all for the early dinosaur Plateosaurus, a new study suggests.

Fossils show the giant plant-eaters experienced sudden growth spurts, with some adults dwarfing others.


The study team estimates that the biggest individuals measured 33 feet (10 meters) in length and weighed almost 4 tons. Other dinos of the species were twice as small, managing an adult body length of only 15 feet (4.8 meters).

Researchers say the animal, which lived some 200 million years ago, had growth patterns like those seen in living reptiles but unlike those of other, later dinosaurs.

Scientists at the University of Bonn in Germany analyzed growth rings found in the fossilized leg and pelvic bones of Plateosaurus, a long-necked, two-legged dino once common across Europe.

The study, which appears tomorrow in the journal Science, suggests that adults grew at different rates and that their growth occurred either in rapid spurts or slow stretches depending on environmental conditions.

The scientists add that this growth model in such a large dino species means that Plateosaurus possibly marks an initial step in the evolution of genuinely warm-blooded dinosaurs.

Size Range

Mammals grow "in accordance with a genetically programmed blueprint," said Martin Sander, a University of Bonn palaeontologist and lead study author.

Humans, for example, can reach different sizes as adults, but individuals' growth rates will be fairly predictable over time.

Dinosaurs were thought to have had steady growth patterns similar to mammals, but "our findings have thrown this conception into disarray, at least for one dinosaur," Sander said.

Sander and his colleagues say Plateosaurus probably had a similar metabolism to living reptiles. Like today's lizards, crocodiles, and turtles, the dinosaur's growth "was affected by environmental factors such as climate and food availability," the researchers report.

Some individuals hit upon excellent conditions for piling on the pounds, while others fell on lean times.

Dinosaur researcher Paul Barrett, of the Natural History Museum in London, agrees that the study appears to provide "nice evidence of some kind of temporary growth spurt rather than continued, similar rate of growth throughout the animal's lifetime."


This "might correlate with greater instances of food or maybe a warmer summer," Barrett said. "That would make sense in interpreting [Plateosaurus] in a crocodile- or lizardlike model."

Growth spurts and big size differences within a species are characteristic of ectothermic animals—those with a metabolism dependent on external conditions. Lizards, for instance, are active when it's hot but become sluggish in cold weather.

Meanwhile mammals and birds, which have growth rates largely independent of outside factors, are endothermic—they heat and cool their bodies internally.

Which of these two camps dinosaurs belonged to has long been a bone of contention among experts.

Sander says Plateosaurus was probably somewhere between the two, with the animal perhaps representing a first stage in the evolution of endothermic dinosaurs.

Warm-Blooded

Barrett of the Natural History Museum says early large dinosaurs such as Plateosaurus were not endothermic, but likely were warm-blooded.

"They're probably warm-blooded because they're big and they produce a lot of heat through digestion and through muscular action," he said.

"They have a relatively small surface area to their volume ratio, and any excess heat they generated just by accident would mean they have a higher body temperature than the outside environment."

Based on their body structure, some later, smaller dinosaurs also appear to have been endothermic.

"It's a size argument," Barrett said. "Because they are small and active, it looks like they should be warm-blooded to fuel their active lifestyle."

"Some of these little dinosaurs are now known to have had an insulating covering—feathers or fuzz of some kind," he added. "This suggests they were generating heat internally and were trying to retain it."

These small theropod dinosaurs are on the evolutionary line that leads eventually to birds, Barrett says.

"Certainly, by the time you get to birds, [the animals] are generating heat internally," he added.

"Birds are only modified dinosaurs, and at some point in their ancestry you need to switch [endothermy] on. Deciding when that happened is quite difficult, as we can't just go and measure the temperature of an extinct dinosaur."

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