Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Tyrannosaurus rex
#1
Tyrannosaurus rex

[Image: 381px-Stan_the_Trex_at_Manchester_Museum.jpg]

Scientific classification 
Kingdom: Animalia 
Phylum: Chordata 
Class: Reptilia 
Superorder: Dinosauria 
Order: Saurischia 
Suborder: Theropoda 
Superfamily: Tyrannosauroidea 
Family: Tyrannosauridae 
Subfamily: Tyrannosaurinae 
Genus: Tyrannosaurus
Species: Tyrannosaurus rex

It seems the t_rex has the strongest jaws of all dinasau's and some claim it is a slow moving carrin feeder, vice versa.
It is also said in some movies that T-rex females are larger than their male counterparts.
[Image: Trex_edited.jpg]

http://en.wikipedia.org/wiki/Tyrannosaurus
[Image: wildcat10-CougarHuntingDeer.jpg]
Reply
#2
STANFORD -- Was Tyrannosaurus rex a fearsome predator who preyed on fellow dinosaurs? Or was the king of the thunder lizards a lowly carrion-eater? 

This question has been the subject of a recent scientific debate among paleontologists. Now the first measurements of how hard T-rex could bite, published in the Aug. 22 issue of the British journal Nature, appear to support the popular view of the dinosaur as one of the most awesome predators to have walked the Earth. 

The authors report that the ferocious beast could exert between 1,440 and 3,011 pounds of force, greater than the crushing force of any known creature, though close to the maximum force exerted by the American alligator, a dinosaur relative. 

"Their teeth were as strong as those of the alligator, a predator that frequently has to deal with struggling prey. We contend that if T-rex could consistently engage prey with its teeth, it could have exploited a predatory niche," says the paper's first author, Gregory Erickson, a graduate student in biology at the University of California-Berkeley. Collaborating on the study were Dennis R. Carter, Stanford professor of biomechanical engineering and an expert on bone mechanics, and two of his graduate students, Samuel D. Van Kirk and Jinntung Su. 

Erickson and Carter met through the Society of Vertebrate Paleontology at a time when Erickson was a graduate student at Montana State University studying the gnawed bone of a 70-million-year-old victim of Tyrannosaurus rex ­ a vegetarian dinosaur called Triceratops. The bone was found by amateur fossil hunter Kenneth H. Olson in 1991 in the Hell Creek Formation in Montana, which has yielded many T-rex and Triceratops fossils. Erickson had determined that the bite marks in the fossil had been made by a Tyrannosaurus rex and proposed a collaboration with Carter to measure the forces required to make such marks. 

Erickson, who later moved to the University of California-Berkeley, joined forces with the Stanford team to determine the force that T-rex had to apply to create the bite marks seen in the fossil. 

Consulting with Veterans Affairs engineer William E. Caler in Menlo Park and Stanford teaching assistant Marc E. Levenston, the team found a cow pelvis that matched the Triceratops bone in both growth form and microstructure. They then made precise measurements of the amount of force required to make an 11.5 mm (half-inch) deep puncture in the cow bone, duplicating the marks found in the Triceratops bone. The role of the tooth was played by a bronze and aluminum cast of a real Tyrannosaurus maxillary tooth, placed in a hydraulic loading machine. 

Breaking only one bronze tooth in the process, the team determined that the T-rex would have exerted the most force at maximum penetration ­ about 1,440 pounds for the tooth that produced the 11.5 mm deep puncture. This tooth was from the front half of the Tyrannosaurus jaw. 

Greater forces would have been exerted simultaneously by teeth further back in the mouth nearer the jaw hinge. From the data the researchers calculated this force to be 3,011 pounds. By comparison, a human exerts a maximum force of about 175 pounds with the rear teeth, an African lion about 937 pounds, and an alligator slightly less than 3,000 pounds. 

"This is like the weight of a pickup truck behind each tooth," Erickson says. The estimate is for a bite during feeding, which typically is less forceful than higher velocity snapping bites such as those used by alligators to seize prey. "

http://www.stanford.edu/dept/news/pr/96/960827tyrexbite.html
[Image: wildcat10-CougarHuntingDeer.jpg]
Reply
#3
Fused Nasal Bones Helped Tyrannosaurids Dismember Prey

Science Daily — New evidence may help explain the brute strength of the tyrannosaurid, says a University of Alberta researcher whose finding demonstrates how a fused nasal bone helped turn the animal into a "zoological superweapon."

"Fused, arch-like nasal bones are a unique feature of tyrannosaurids," said Dr. Eric Snively, a post doctoral research fellow at the University of Alberta. "This adaptation, for instance, was keeping the T. rexes from breaking their own skull while breaking the bones of their prey."

Snively and co-authors, number-crunching physicist Donald Henderson from the Royal Tyrrell Museum of Palaeontology and Doug Phillips from the University of Calgary, compared the skulls and teeth of a number of tyrannosaurids to non-tyrannosaurids. In one of the first studies that looked at the structural mechanics of dinosaur skulls, the scientists used CT scans to investigate such factors as teeth bending strength and nasal and cranium strength. The research is published in the journal Acta Palaeontologica Polonica. 

Tyrannosaurids differ from other dinosaurs in the great robustness of their teeth and skulls, enlarged areas for attachment and expansion of jaw muscles and the consequent ability to bite deeply in the bone. 

Snively's team found that fused tyrannosaurid nasals were stronger than unfused carnosaur nasals. This extensive fusion increased the strength of such dinosaurs as the T. rex and helped them apply powerful bites that could splinter bone. With other carnivorous dinosaurs, says Snively, their skull bones might shear apart slightly when they chomp down on other animals. "With tyrannosaurs, all the bite force was delivered to the prey," he said. "The T. rex especially had a very strong skull and jaw muscles that would turn it into a zoological superweapon. 

A medium-sized T. rex had even more skull strength than a larger carnivorous creature, such as the Carcharadontosaurus saharicus, with a head nearly one and a half times as long. T. rex's neck power was similarly staggering. For instance, in a split second, a T. rex could toss its head at a 45 degree angle and throw a 50kg person five metres in the air. And that's with conservative estimates of the creature's muscle force, says Snively. "We kept the muscle numbers down because we thought they couldn't possibly be that powerful, but Tyrrell museum colleagues showed that a T. rex's lower jaw could apply 200,000 newtons of force--that's like lifting a semi-trailer," he said. "All of the T. rex's features came together to give it the strongest bite of any land animal. The T. rex just blows everyone out of the water when it comes to strength.

"The fused nasal bones had been observed before, but no one but us and Emily Rayfield of Bristol hypothesized that the fusion enhanced the skull strength. Now we know it did."

Note: This story has been adapted from a news release issued by University of Alberta.

http://www.sciencedaily.com/releases/2007/05/070518105742.htm
[Image: wildcat10-CougarHuntingDeer.jpg]
Reply
#4
T. Rex Could Outrun Humans


By Jeanna Bryner, LiveScience Staff Writer
posted: 22 August 2007 08:43 am ET

Virtual races between prehistoric beasts reveal that one of the smallest carnivorous dinosaurs would have zipped past the lumbering Tyrannosaurus rex by a long shot. But even so, the "tyrant lizard king" was no slouch. 

Turns out, T. rex could have outrun some of the buffest athletes. 

“The figures we have produced are the best estimate to date as to how fast these prehistoric animals could run,” said Phil Manning, a paleontologist at the University of Manchester in England. 

Manning and his Manchester colleague Bill Sellers, a biomechanics expert, used a supercomputer to calculate the top-running speeds of five meat-eating dinosaurs. 

T. rex would just barely run past a professional soccer player (footballer) in a race, reaching an all-out speed of about 18 mph (8 meters per second), the results showed. However, chicken-sized bipedal competitor Compsognathus could whip around a race track at nearly 40 mph (18 m/s). That's 5 mph quicker than the computer's estimate for an ostrich, the fastest living animal on two legs. 

Based on the computer simulations, here are the estimated race results: 
  • Compsognathus (6.6 pounds, 3 kilograms)—39.8 mph (17.8 m/s) 

  • Ostrich (144 pounds, 65.3 kg)—34.5 mph (15.4 m/s) 

  • Emu (60 pounds, 27.2 kg)—29.8 mph (13.3 m/s) 

  • Velociraptor (44 pounds, 20 kg)—24.2 mph (10.8 m/s) 

  • Dilophosaurus (948 pounds, 430 kg)—23.5 mph (10.5 m/s) 

  • Allosaurus (3,087 pounds, 1,400 kg)—21 mph (9.4 m/s) 

  • Tyrannosaurus (13,230 pounds, 6,000 kg)—17.9 mph (8 m/s) 

  • Human (157 pounds, 71 kg)—17.7 mph (7.9 m/s) 

Game of survival 

The new study downgrades T. rex's running speed somewhat from a previous estimate of 25 mph. 

“While not incredibly fast, this carnivore [T. rex] was certainly capable of running and would have little difficulty in chasing down footballer David Beckham for instance,” Manning said. 

But unlike soccer champs today who get sent off with applause (or in some cases, riots), prehistoric winners got their next meal while the losers lost their lives. 

The running-speed results intrigue paleontologists interested in the predator-prey dynamics of the prehistoric beasts. "Chasing down prey is a vital factor in the lives of extant predators, as is the avoidance of being captured for prey animals," the scientists write in a report of their research to be published online tomorrow by the Proceedings of the Royal Society B. 

Dinosaur gaits 

The scientists say their calculations are the most accurate to date for dinosaur running speeds. 

“Previous research has relied on data from extant bipedal models to provide clues as to how fast dinosaurs could run,” Sellers said. “Such calculations can accurately predict the top speed of a six-ton chicken, but dinosaurs are not built like chickens and nor do they run like them." 

Sellers and Manning instead fed information about the skeletal and muscular structure of each animal, including the extinct dinosaurs, into a 256-processor supercomputer, which calculated the gait and posture needed for top-running speeds. 

The computer spent up to a week mapping out the optimal biomechanics of each animal, ranging from clumsy putterer to smooth runner. 

[Image: 070821_trex_02.jpg]
Tyrannosaurus rex could have reached speeds of 18 miles per hour (8 meters per second). 

http://www.livescience.com/animals/070822_dino_speed.html
[Image: wildcat10-CougarHuntingDeer.jpg]
Reply
#5
Tyrannosaur Footprint Found in Montana


By Jeanna Bryner, LiveScience Staff Writer

posted: 11 October 2007 11:13 am ET

A paleontologist has discovered a giant footprint most likely left by a towering tyrannosaur as it pounded the Earth 65 million years ago. 

The footprint, which measures about 2.5 feet (74 centimeters) in length, was found in rocks in Montana's Hell Creek Formation, a well-known site for Tyrannosaurus rex fossils. 

"We are relatively confident that it's been made by a theropod, or predatory dinosaur," said paleontologist Phillip Manning of the University of Manchester in England, who was part of the team that found the print. 

Based on the footprint's slender toes, toe positions and overall size, Manning and his colleagues have narrowed down the dinosaur's species name to either T. rex or Nanotyrannus, a tyrannosaur whose name means "tiny tyrant." 

"Predatory dinosaurs have much more gracile toes than their dumpy hadrosaur [duck-billed dinosaur] friends that are lolloping around at the end of the Cretaceous," Manning told LiveScience. 

T. rex is thought to have grown to about 40 feet (12 meters) in length, while Nanotyrannus was likely just about 17 feet (5 meters) long. Both dinosaurs lived 67 million to 65 million years ago at the end of the Cretaceous Period. 

Of course there's always the possibility that a species of dinosaur that is new to science left the print, Manning said. 

A future discovery of a more pristine and unweathered footprint at the site, made by the same species, would also help in identifying the dinosaur that made the latest print. 

"The only way you'd know whether an animal had left its footprint 65 million years ago in a specific package of rock would be to find the animal dead in its tracks," Manning said.

[Image: 071011-tryann-track-02.jpg]
Phillip Manning helped to discover this dinosaur footprint that could've been made by a meat-eating tyrannosaur 65 million years ago.

http://www.livescience.com/animals/071011-dino-print.html
[Image: wildcat10-CougarHuntingDeer.jpg]
Reply
#6
Molecular Analysis Confirms Tyrannosaurus Rex's Evolutionary Link To Birds

ScienceDaily (Apr. 25, 2008) — Putting more meat on the theory that dinosaurs' closest living relatives are modern-day birds, molecular analysis of a shred of 68-million-year-old Tyrannosaurus rex protein -- along with that of 21 modern species -- confirms that dinosaurs share common ancestry with chickens, ostriches, and to a lesser extent, alligators.

The work, published in the journal Science, represents the first use of molecular data to place a non-avian dinosaur in a phylogenetic tree that traces the evolution of species. The scientists also report that similar analysis of 160,000- to 600,000-year-old collagen protein sequences derived from mastodon bone establishes a close phylogenetic relationship between that extinct species and modern elephants.

"These results match predictions made from skeletal anatomy, providing the first molecular evidence for the evolutionary relationships of a non-avian dinosaur," says co-author Chris Organ, a postdoctoral researcher in organismic and evolutionary biology at Harvard University. "Even though we only had six peptides -- just 89 amino acids -- from T. rex, we were able to establish these relationships with a relatively high degree of support. With more data, we'd likely see the T. rex branch on the phylogenetic tree between alligators and chickens and ostriches, though we can't resolve this position with currently available data."

The current paper builds on work reported in Science last year. In that paper, a team headed by John M. Asara and Lewis C. Cantley, both of Beth Israel Deaconess Medi-cal Center (BIDMC) and Harvard Medical School (HMS), first captured and sequenced tiny pieces of collagen protein from T. rex. For the current work, Organ and Asara and their colleagues used sophisticated algorithms to compare collagen protein from several dozen species. The goal: placing T. rex on the animal kingdom's family tree using molecu-lar evidence.

"Most of the collagen sequence was obtained from protein and genome databases but we also needed to sequence some critical organisms, including modern alligator and modern ostrich, by mass spectrometry," says Asara, director of the mass spectrometry core facility at BIDMC and instructor in pathology at HMS. "We determined that T. rex, in fact, grouped with birds -- ostrich and chicken -- better than any other organism that we studied. We also show that it groups better with birds than modern reptiles, such as alliga-tors and green anole lizards."

While scientists have long suspected that birds, and not more basal reptiles, are di-nosaurs' closest living relatives, for years that hypothesis rested largely on morphological similarities in bird and dinosaur skeletons.

The scraps of dinosaur protein were wrested from a fossil femur discovered in 2003 by John Horner of the Museum of the Rockies in a barren fossil-rich stretch of land that spans Wyoming and Montana. Mary H. Schweitzer of North Carolina State Univer-sity (NCSU) and the North Carolina Museum of Natural Sciences discovered soft-tissue preservation in the T. rex bone in 2005; Asara became involved in analysis of the colla-gen protein because of his expertise in mass spectrometry techniques capable of se-quencing minute amounts of protein from human tumors. While it appears impossible to salvage DNA from the bone, Asara was able to extract precious slivers of protein.

The current work by Organ and Asara suggests that the extracted protein from the fossilized dinosaur tissue is authentic, rather than contamination from a living spe-cies.

"These results support the endogenous origin of the preserved collagen mole-cules," the researchers write.

[Image: 080424140418-large.jpg]
Genetic sequencing show link of T. rex with birds and mastadons with elephants.

Organ, Asara, Schweitzer, and Cantley's co-authors on the Science paper are Wenxia Zheng of NCSU and Lisa M. Freimark of BIDMC. Their research was funded by the National Institutes of Health, the National Science Foundation, the Paul F. Glenn Foundation, and the David and Lucile Packard Foundation.

Adapted from materials provided by Harvard University.

http://www.sciencedaily.com/releases/2008/04/080424140418.htm
[Image: wildcat10-CougarHuntingDeer.jpg]
Reply
#7
T. rex was a stellar smeller

Wednesday, 29 October 2008 Will Dunham
Reuters

When it came to the sense of smell among meat-eating dinosaurs, Tyrannosaurus nosed out the competition, researchers say.

Dr Francois Therrien of the Royal Tyrrell Museum in Alberta, Canada, and colleagues report their findings in the journal Proceedings of the Royal Society B .

Therrien and colleagues compared the size of olfactory bulbs - the part of the brain regulating the sense of smell - in a wide range of carnivorous dinosaurs.

They performed CT scans and measured fossilised skulls of meat-eating dinosaurs, known as theropods, including huge predators, smaller raptors and ostrich-like dinosaurs. They also looked at the primitive bird Archaeopteryx.

Tyrannosaurus was the undisputed king. Its olfactory capabilities surpassed that of the other huge predators the researchers examined, including South American giant Giganotosaurus and African killer Carcharodontosaurus.

"T. rex had a very good sense of smell," says Therrien. "Probably that's how they located prey and patrolled a large territory."

The researchers were not the first to describe T. rex's strong sense of smell, but were the first to rate the beast in comparison to other meat-eating dinosaurs.

Scavenger or hunter?
Other experts have suggested T. rex's sense of smell means it must have been more of a scavenger than an active hunter. Therrien disagrees.

"It has been suggested that the very good sense of smell of T. rex indicated that it was a scavenger because it would have used its sense of smell to locate putrefying carcasses on the landscape," he says.

"But when we look at modern animals, we see that's not the case. Scavengers don't necessarily have a better sense of smell. You have some like the turkey vultures that have a good sense of smell. But you have other scavengers like the Old World vultures that actually have a typical sense of smell because they use sight instead of smell to locate prey."

Vicious little Velociraptor and its raptor relatives also had an excellent sense of smell, the researchers say. But the ostrich-like dinosaurs like speedy Ornithomimus and the toothless Oviraptor apparently had very poor senses of smell.

Archaeopteryx, the earliest known bird with fossils dating to 150 million years ago, turned out to have a good sense of smell in line with that of the small meat-eating dinosaurs from which palaeontologists believe birds evolved, Therrien and team say.

[Image: r307888_1348512.jpg]
Model of a Tyrannosaur in the Dinosaur Park Münchehagen, Germany. Tyrannosaurus rex had the best nose of all meat-eating dinosaurs. It may have used its sense of smell to strike at night in search of its next victim.

http://www.abc.net.au/science/articles/2008/10/29/2404443.htm?site=science&topic=latest
[Image: wildcat10-CougarHuntingDeer.jpg]
Reply
#8
Dinosaurs Were Airheads


By Jeanna Bryner, Senior Writer

posted: 08 December 2008 02:06 pm ET

The noggins of fierce dinosaurs like T. rex were filled with ... air. The airy skulls would have lightened the load of the head and possibly acted as resonating chambers for communication among some of the dinosaurs, new research reveals. 

"We always knew dinosaurs had relatively small brains, so we might regard them as being airheads, and we can see that's kind of literally true," said researcher Lawrence Witmer of Ohio University. 

The new finding adds to research by Witmer and his colleagues in which they found the air spaces in the skulls of duck-billed dinosaurs helped the animals to vocalize, possibly giving each of them distinct "voices." 

Light-headed 

Witmer and Ohio University colleague Ryan Ridgely used computed tomography to scan the skulls of two predatory dinosaurs, Tyrannosaurus rex and Majungasaurus, as well as two ankylosaurian dinosaurs, Panoplosaurus and Euoplocephalus — both plant-eaters with armored bodies and short snouts. 

The resulting 3-D images revealed large olfactory areas, a curving airway that extended from the nostrils to the throat and several sinus cavities (similar to the pockets that give us sinus headaches). And overall, the amount of air-filled space was much greater than the brain cavity. 

The air spaces probably helped to lighten the load of the T. rex's head, making it about 18 percent lighter than if the head were a solid structure. They estimated a fully fleshed-out T. rex head likely weighed more than 1,100 pounds (500 kg), while the skull of Majungasaurus would have weighed 70 pounds (32 kg). (If T. rex's skull would have been solid bone, it would have weighed a couple hundred pounds more.) 

Neck muscles and other body features could only hold up so much head heft. So if all the other features remained the same, the weight savings from having the air-filled pockets may have allowed T. rex and Majungasaurus to sport other hefty skull features, such as more bone-crushing jaw muscles or the ability to take down larger prey. 

Like hollow beams used in construction, the sinus cavities would have inflated the bones to make them ultra strong yet still relatively light. With light, strong heads, these dinosaurs would have been able to whip their heads around more quickly. 

Dino voices 

The armored dinosaurs were a different story. Unlike the somewhat straight nasal passages found in the predatory dinos, the researchers found airways that were twisted and convoluted, kind of like crazy straws, Witmer said. 

The winding passages were positioned alongside large blood vessels, they found, suggesting heat transfer. So when the armored dinosaurs inhaled, the blood would have warmed that inspired air before it reached the lungs. In addition, some of the heat from the blood vessels may have been transferred into the winding nasal passages, cooling the blood before it reached the brain. 

"These were large-bodied animals generating a lot of heat in their bellies," Witmer told LiveScience. 

The twisty nasal passages also probably acted as resonating chambers, affecting how the ankylosaurs vocalized. The airways may have been slightly different in each animal, Witmer said, giving the animals subtle differences in their voices. 

The findings are published in a recent issue of the journal The Anatomical Record

[Image: 081208-trex-skull-02.jpg?1296073277]
The computed tomography scans of T. rex's skull showed the nasal passageways (yellow) and the sinus cavities, revealing the head was likely full of air when this predator lived. Credit: Lawrence Witmer, Ohio University. 

http://www.livescience.com/animals/081208-dino-airheads.html
[Image: wildcat10-CougarHuntingDeer.jpg]
Reply
#9
How Fat or Fit Were Dinosaurs? Scientists Use Laser Imaging

ScienceDaily (Feb. 20, 2009) — Karl Bates and his colleagues in the palaeontology and biomechanics research group have reconstructed the bodies of five dinosaurs, two T. rex (Stan at the Manchester Museum and the Museum of the Rockies cast MOR555), an Acrocanthosaurus atokensis, a Strutiomimum sedens and an Edmontosaurus annectens.

The team found that the smaller Museum of the Rockies T. rex could have weighed anywhere between 5.5 and 7 tonnes, while the larger specimen (Stan) might have weighed as much as 8 tonnes.

Acrocanthosaurus atokensis was a large predatory dinosaur that looked like T. rex but with large spines on its back and roamed the earth much earlier in the mid Cretaceous period, around 110M years ago. The team suggest Acrocanthosaurus probably weighed in at a similar mass to MOR555 and other medium sized adult T. rex at about 6 tonnes.

The Strutiomimum sedens, whose name means “ostrich mimic”, lived alongside T. rex in the late Cretaceous period and probably weighed somewhere between 0.4 – 0.6 tonnes

The reconstruction of Edmontosaurus annectens, a plant-eating hadrosaur was based on a juvenile specimen, but still weighed in at between 0.8 – 0.95 tonnes. As adults, some hadrosaurs grew as big as T. Rex, again living in the late Cretaceous period.

The team used laser scanning (LiDAR) and computer modelling methods to create a range of 3D models of the specimens, attempting to reconstruct their body sizes and shape as in life. The laser scanner images the full mounted skeleton, resulting in a detailed 3D model in which each bone retains its spatial position and articulation. This provides a high resolution skeletal framework around which the body cavity and internal organs such as stomach, lungs and air sacs can be reconstructed. This has allowed calculation of body segment masses, centres of mass and moments of inertia for each animal – all the information that is needed to analyse body movements.

Having created their ‘best-guess’ reconstruction of each animal, they then varied the volumes of body segments and respiratory organs to find the maximum plausible range of mass for the animals. Even scientists cannot be sure exactly how fat or thin animals like T. rex were in life, and the team were interested in exactly how broad the range of possible values were for body mass. They believe that the lower weight estimates are most likely to be correct as there is no good reason for the dinosaurs to weigh more than they need to as this would affect their speed, energy use and demands on the respiratory system.

The team also measured the body mass of an ostrich, as an existing subject that would show how accurate their technique was, and found the results to be correct.

They will now use the results to further investigate the locomotion of dinosaurs, specifically how they ran.

Karl said: “Our technique allows people to see and decide for themselves how fat or thin the dinosaurs might have been in life. You can see the skeleton with a belly. Anyone from a five-year-old to a Professor can see it and say, ‘I think this reconstruction is too fat or too thin’.

He added: “This study will help us in our research on how dinosaurs ran in 3-D rather than 2-D as in previous studies.

“Reconstructing more dinosaurs in such detail will allow us to examine changes in body mass and particularly centre of mass as they evolved. As we know, dinosaurs evolved into birds. As they did so, the centre of mass moved forward and different walking styles evolved. Although the dinosaurs we have reconstructed are not very close relatives of the birds, we can nevertheless see a small forwards movement in the position of the centre of mass from Acrocanthosaurus atokensis to the T. rex, which lies closer to modern birds on the evolutionary lines.”

[Image: 090220110912-large.jpg]
Best estimate reconstruction of Tyrannosaurus rex BHI 3033 in (A) right lateral, (B) dorsal, © cranial and (D) oblique right craniolateral views (not to scale).

http://www.sciencedaily.com/releases/2009/02/090220110912.htm
[Image: wildcat10-CougarHuntingDeer.jpg]
Reply
#10
Dinosaur Study Backs Controversial Find


By Robert F. Service
ScienceNOW Daily News
31 July 2009

When scientists reported 2 years ago that they had discovered intact protein fragments from a 68-million-year-old Tyrannosaurus rex, the skeptics pounced. They argued that one of the main lines of evidence, signatures of the protein fragments taken by mass spectrometry, was flawed. But now a reanalysis of that mass-spec data from an independent group of researchers backs up the original claim that dinosaur proteins have indeed survived the assault of time. 
In 2005, a team led by Mary Schweitzer of North Carolina State University in Raleigh reported in Science that it had discovered an unusual T. rex fossil, in which some of the soft tissues, including blood vessels and other fibrous tissue, seemed to have been preserved. Two years later, Schweitzer teamed with mass-spec expert John Asara of Harvard Medical School in Boston and colleagues to report that mass-spec studies identified seven peptide fragments that appeared to come from dinosaur collagen and that those sequences were closely related to analogous sequences from the chicken and other modern birds, as would be expected given the many lines of evidence that birds evolved from dinosaurs. But skeptics argued that the mass-spec signals barely hovered above the data's background noise. And Schweitzer and Asara, they argued, couldn't rule out that the signals were caused by contaminants. 

The controversy has continued in letters and follow-up papers. It also prompted Asara to release his complete mass-spec data set to other experts to allow them to judge for themselves. So researchers from the Palo Alto Research Center in California and the University of California, Davis, decided to do just that. They reanalyzed Asara's mass-spec data using a different set of bioinformatics tools and statistical tests. 

In a paper published this month in the Journal of Proteome Research, the California researchers report that three of the peptides are a strong match to what looks to be an ancient form of collagen, whereas others matched with less statistical significance. "In summary, we find nothing obviously wrong with the T. rex mass spectra: the identified peptides seem consistent with a sample containing old, quite possibly very ancient, bird-like bone, contaminated with only fairly explicable proteins," they conclude. 

"That's pretty good news," says Asara. He doubts that the new result will put the entire controversy to rest, because soft tissue from dinosaur is such an extraordinary find. However, he argues, "I think it puts the mass-spectrometry interpretation to rest." The case for T. rex proteins is also helped by the fact that it is no longer a unique discovery. In May, Schweitzer, Asara, and colleagues reported a similar result from an 80-million-year-old dinosaur and raised further hopes that scientists may soon have a window into the molecular makeup of dinosaurs.

http://sciencenow.sciencemag.org/cgi/content/full/2009/731/1?rss=1
[Image: wildcat10-CougarHuntingDeer.jpg]
Reply
#11
Chicken-hearted Tyrants: Predatory Dinosaurs As Baby Killers

ScienceDaily (Aug. 7, 2009) — Two titans fighting a bloody battle – one that often turns fatal for both of them. This is how big predatory dinosaurs like Tyrannosaurus are often depicted while hunting down their supposed prey, even larger herbivorous dinosaurs. The fossils, though, do not account for that kind of hunting behavior but indicate that theropods, the large predatory dinosaurs, were hunting much smaller prey.

Dr. Oliver Rauhut, paleontologist at Ludwig-Maximilians-Universität (LMU) in Munich, and his collegue Dr. David Hone surmise that giant carnivores like Tyrannosaurus preyed mainly on juvenile dinosaurs. "Unlike their adult and well-armed relatives these young animals hardly posed any risk to the predators," says Rauhut. "And their tender bones would have added important minerals to a theropod's diet. Now we hope for more fossils to be found that add new evidence to our hypothesis."

King of tyrants, Tyrannosaurus rex is by far the most famous dinosaur. Not even recent finds of slightly bigger – and maybe even more terrifying – species like Giganotosaurus could dent the aura of "T-Rex". But what would happen if the king turned out a baby killer instead of fearless hunter of much bigger prey? "Animals such as Tyrannosaurus are often seen as the perfect 'killing machines' with extremely powerful bites, which were able to bring down even the largest possible prey," says Rauhut of the Bayerische Staatssammlung für Paläontologie und Geologie and LMU Munich. "But the very few fossils that reflect the hunt of predatory dinosaurs on large herbivores tell a tale of failure – the prey either got away, or both prey and predator were killed."

On the other hand, the also extremely sparse cases of direct evidence for the diet of predatory dinosaurs – stomach contents and coprolites – show that juveniles or much smaller prey species were ingested and the latter were swallowed whole. Rauhut and Hone, who is now at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China, therefore propose as a hypothesis that large predatory dinosaurs only as an exception attacked other large dinosaurs, but mainly fed on juveniles. "Even modern predators prefer old and sick animals or unexperienced young individuals," states Hone. "These are an easy prey to bring down and the risk of injury for the predator is much lower. This strategy was probably the same in dinosaurs."

Another look at recent predators reveals an additional benefit of young prey: Crocodiles, the closest living relatives of dinosaurs, have extremely strong acids in their stomachs. They can completely dissolve the poorly ossified bones of young animals which adds important nutrients to the reptiles' diet. The fossil finds of juvenile dinosaurs that have been swallowed whole by theropods support the idea that dinosaurs might have profited from this as well.

Missing fossils, though, lend even more plausibility: "Finds of dinosaur nesting sites indicate that they contained large numbers of eggs which should have resulted in a high number of offspring," says Rauhut. "But little of this is reflected in the fossil record: Juvenile dinosaurs are surprisingly rare – maybe because many of them have been eaten by predators. Hopefully there will soon be more evidence to help us really understand the theropods' hunting behavior."

[Image: 090806112357-large.jpg]
Fossil evidence suggests that the large carnivores hunted mainly juvenile dinosaurs instead of giant herbivorous adults.

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

Journal reference:

David W. E. Hone and Oliver W. M. Rauhut. Feeding behaviour and bone utilization by theropod dinosaurs. Lethaia, 2009; DOI: 10.1111/j.1502-3931.2009.00187.x 

http://www.sciencedaily.com/releases/2009/08/090806112357.htm
[Image: wildcat10-CougarHuntingDeer.jpg]
Reply
#12
Mighty T. rex Killed by Lowly Parasite, Study Suggests

By Charles Q. Choi, Special to LiveScience
posted: 29 September 2009 11:19 am ET

The famous dinosaur known as Sue — the largest, most complete and best preserved T. rex specimen ever found — might have been killed by a disease that afflicts birds even today, scientists now suggest. 

The remains of Sue, a star attraction of the Field Museum in Chicago, possess holes in her jaw that some believed were battle scars, the result of bloody combat with another dinosaur, possibly another T. rex. 

Now researchers suggest these scars did not result from a clash of titans, but rather from a lowly parasite. The infection in Sue's throat and mouth may have been so severe that the 42-foot-long, 7-ton dinosaur starved to death. 

The ailment the scientists propose felled Sue and other T. rexes is trichomonosis, also known as trichomoniasis. In birds, the disease is caused by Trichomonas gallinae, a single-celled protozoan. Although some birds, such as pigeons, commonly host the parasite but suffer few ill effects, in birds of prey such as falcons and hawks, the germ causes a pattern of serious lesions in the lower beak that closely matches the holes in the jaws of Sue and occurs in the same anatomical location. 

"It's ironic to think that an animal as mighty as 'Sue' probably died as a result of a parasitic infection. I'll never look at a feral pigeon the same way again," said researcher Steven Salisbury at the University of Queensland in Australia. 

The researchers investigated the jaws of Sue and 60 other tyrannosaur specimens. Nearly 15 percent of them possessed lesions that had previously been attributed to bite wounds or, possibly, a bacterial infection. These holes were roughly 0.2 to more than 1 inch wide (0.5 to more than 2.5 cm), extending through roughly a half-inch (1 cm) of bone. 

The scars of combat among tyrannosaurs and other dinosaurs are not uncommon, but differ notably from trichomonosis lesions, explained researcher Ewan Wolff, a vertebrate paleontologist at the University of Wisconsin in Madison. The holes the parasite makes are often neat and have relatively smooth edges, while bite marks are often messy, scarring and puncturing bone. 

Tyrannosaurs are known to have fought amongst themselves and sometimes even ate one another. The parasite may have been passed through face-biting or cannibalism. 

"We don’t think it is a coincidence that a significant number of adult tyrannosaur specimens show both face-biting marks and evidence of a trichomonosis-like disease," Salisbury said. "Previous studies have shown that up to 60 percent of tyrannosaur specimens display evidence of face-biting." 

Wolff noted there is no known evidence of trichomonosis in other dinosaurs. 

"This leads us to suspect that tyrannosaurs might have been the source of the disease and its transmission in its environment," Wolff explained. 

For the disease to cause such lesions in the jaws of Sue and other tyrannosaurs, it would have had to be at an advanced stage. 

"The lesions we observe on Sue suggest a very advanced stage of the disease and may even have been the cause of her demise," Wolff said. 

The parasite typically concentrates in the back of the throat in birds of prey, where it leads to masses of dying tissue. 

"As the lesions grow, the animal has trouble swallowing food and may eventually starve to death,” Salisbury said. 

These findings strengthen the many connections that research already suggests exist between dinosaurs and birds, with birds inheriting a similar or even the same parasite from their distant ancestors. 

"The discovery gives us an insight into the dinosaur immune system," Wolff said. "The response of tyrannosaurs to this trichomonosis-like disease is almost identical to that found in living birds. These simple holes in tyrannosaur jaws give us a dramatic example of an avian-like defense system in action." 

[Image: 090929-trex-sue-02.jpg?1296087035]
A reconstruction of the Trichomonas-like infection of the T. rex commonly known as "Peck's Rex." Note the yellowing at the back of the mouth and the lesions in the jaw that penetrate the full thickness of the bone. 

http://www.livescience.com/animals/090929-trex-parasite-death.html
[Image: wildcat10-CougarHuntingDeer.jpg]
Reply
#13
Terrible Teens Of T. Rex: Young Tyrannosaurs Did Serious Battle Against Each Other

ScienceDaily (Nov. 2, 2009) — We all know adolescents get testy from time to time. Thank goodness we don't have young tyrannosaurs running around the neighborhood.

In a new scientific paper, researchers from Northern Illinois University and the Burpee Museum of Natural History in Rockford report that adolescent tyrannosaurs got into some serious scraps with their peers.

The evidence can be found on Jane, the museum's prized juvenile Tyrannosaurus rex, discovered in 2001 in Montana.

Jane's fossils show that she sustained a serious bite that punctured through the bone of the dinosaur's left upper jaw and snout in four places, the researchers report. The injury wasn't life threatening and eventually healed over, according to the scientists. The bite did leave scars, however.

"Jane has what we call a boxer's nose," says Joe Peterson, an NIU Ph.D. candidate in geology and lead author of the study published in the November issue of the journal Palaios. "Her snout bends slightly to the left. It was probably broken and healed back crooked."

The researchers determined that another juvenile tyrannosaur was responsible for the injury.

"Only a few animals could have inflicted the wound," Peterson says, noting that the bite marks were oblong-shaped. A crocodile or an adult T. rex would have left different types of bite marks.

"When we looked at the jaw and teeth of Jane, we realized her bite would have produced a very close match to the injuries on her own face," Peterson says. "That leads us to believe she was attacked by a member of the same species that was about the same age. Because the wound had healed, we think this happened when Jane was possibly a few years younger."

Peterson and Mike Henderson, curator of earth sciences at the Burpee Museum and also a Ph.D. candidate in geology at NIU, were members of the museum group that unearthed the pristine dinosaur skeleton. NIU Presidential Research Professor Reed Scherer, also among the new study's authors, worked as an adviser on the find.

"What's unique about this work is we learn something very, very specific about juvenile dinosaur behavior," Scherer says. "This was an animal about the same size that attacked Jane. Whether it was a sibling or from a rival group, we don't know, but it's fun to speculate."

The sex of Jane, who was named after a museum donor, is unknown. The dinosaur was young when it died, but the Burpee Museum's display leaves no doubt that it was still a creature to be reckoned with. Twenty-two feet long and 7-1/2 feet high at the hip, the young dinosaur tipped the scales at about 1,500 pounds. And it was built to kill, with 71 serrated teeth.

Still, Jane was vastly smaller than an adult T. rex. After much study and consultation with leading U.S. dinosaur experts, Henderson, who led the Montana expeditions, announced in 2006 that Jane was a late juvenile T. rex, about 11 or 12 years old.

"The study of the bite marks on Jane's face demonstrates that even at a young age this dinosaur was engaging in some pretty serious combat," Peterson says. He likened the animal to an adolescent that hadn't quite reached what would have been a huge growth spurt.

The puncture wounds were first noticed several years after the dinosaur was discovered.

"When Jane's skull was found, the bones were disarticulated, or in pieces," Peterson says. "I was examining the casts of the skull bones. I saw that when the left maxilla (upper jawbone) was pieced together, it had more holes in it than the right side. And there was a pattern to the gaps in the side of the face.

"The surface of the face and edges around the puncture marks were smooth, indicating that there hadn't been a fresh break there and the wounds must have healed over while the animal was alive," he adds.

Dr. Christopher Vittore, a Burpee Museum board member and radiologist at Rockford Memorial Hospital, who also contributed to the study in Palaios, took CT scans of the fossils and confirmed Peterson's hypothesis.

"CT scans demonstrated that the holes are most consistent with traumatic puncture injuries that had significant time for healing," Vittore says.

"Complete bone healing requires time for bone remodeling, and CT images show the internal structure of the bone adjacent to the puncture lesions," Vittore adds. "The internal character of the bone showed the injuries occurred significantly earlier in the animal's life, and there was time for healing. It also confirmed that there were no other abnormalities in the bone adjacent to the lesions."

Because the dinosaur had not reached maturity, the researchers concluded that the combat was not likely over sexual conflict or competition but might have been a learning behavior for young dinosaurs prompted by a show of dominance or territorial dispute.

Peterson says other adolescent animals, particularly juvenile crocodiles, exhibit such fighting behavior.

"It's common to find similar puncture marks on young crocodiles," he says. "We can look at the behavior of these modern living ancestors of dinosaurs and get a good idea of what was going on here."

A recent study suggested that, in some dinosaurs, apparent bite marks are actually holes in the skull caused by a parasite. Researchers speculated that such a parasitic infection might have led to the demise of Sue, the famous T. rex at the Field Museum in Chicago.

NIU researchers don't believe a parasite caused Jane's injuries.

"The parasite that has been described causes lesions on the lower jaw," Peterson says. "With Jane, the lesions are on the actual face and are not the same type of structures we see on Sue."

[Image: 091102121454.jpg]
Juvenile T. rexes might have bitten each other in fights, as suggested by this illustration from the researchers who found a bite mark in the left upper jaw and snout in four places on a T. rex fossil. The bite marks were oblong in shape and match up with the tooth shape of other teen tyrannosaurs, but not with the teeth of adults.


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

Journal reference:

Joseph E. Peterson, Michael D. Henderson, Reed P. Scherer, And Christopher P. Vittore. Face Biting On A Juvenile Tyrannosaurid And Behavioral Implications. Palaios, 2009; 24 (11): 780 DOI: 10.2110/palo.2009.p09-056r 

http://www.sciencedaily.com/releases/2009/11/091102121454.htm
[Image: wildcat10-CougarHuntingDeer.jpg]
Reply
#14
Predation vs. scavenging.
—Perhaps the best
known predatory dinosaur, Tyrannosaurus, has
been suggested to have been an obligate scavenger
(Horner, 1994; Horner and Lessem, 1993; Horner
and Dobb, 1997). Horner (1994) argues that several
morphological features of Tyrannosaurus would
have precluded a predatory lifestyle: 1) relatively
small size of the eye that would have prohibited
spotting prey at a distance; 2) limb proportions
indicative of slow top running speeds, which would
have prevented Tyrannosaurus from chasing and
capturing prey; 3) disproportionately tiny forelimbs
that would have been useless for holding prey; 4)
relatively broad teeth that depart from the expected
blade-like configuration for teeth of a predator.
We do not find these arguments persuasive. The
size of the orbit of Tyrannosaurus relative to its skull
size is in fact rather large for a reptile of its size
(Fig. 3). Furthermore, the dimensions of the orbit
suggest that Tyrannosaurus had a big eye in absolute
terms, which would have increased its lightgathering
capacity and thus its acuity (Walls, 1942;
Dusenberry, 1992). Even though Tyrannosaurus
lacks the cursorial hind limb proportions of smaller
theropods, and was probably not as good a runner
as sometimes portrayed (Farlow et al., 1995b, 2000;
Christiansen, 1999; Hutchinson and Garcia, 2002),
its metatarsus/femur or tibia/femur length ratios
indicate that it was likely as fleet, or faster, than
other big theropods, and certainly faster than the
herbivorous dinosaurs that were its likely prey
(Gatesy, 1991; Holtz, 1995).
Horner’s last two arguments strike us as begging
the question. Without explicitly saying so, he is
hypothesizing that grasping forelimbs are a necessity
for killing prey (which will be news to wolves,
seriemas, and secretary birds), and that animals with
broad-based teeth are unable to kill prey with them
(which orcas and crocodiles will find surprising).
Because the morphology of Tyrannosaurus matches
the predictions of his hypotheses, Horner concludes
that Tyrannosaurus could not have been a predator,
without first testing those hypotheses.
The brain of Tyrannosaurus had respectably
large olfactory bulbs (Brochu, 2000), suggesting
that the sense of smell was quite acute in this
dinosaur. Horner and Dobb (1997) argued that this
would have allowed Tyrannosaurus to detect the
odor of rotting carcasses from afar. This is
unquestionably true, but it is also true that a keen
sense of smell would have been useful for picking
up the scent of live prey, or for behaviors unrelated
to food acquisition (Brochu, 2000).
We agree with Horner that Tyrannosaurus is
unlikely to have engaged in extended, Hollywoodstyle
battles with other large dinosaurs (or huge
apes, for that matter). However, surprise, hit-andrun
attacks on healthy victims (Paul, 1988), or
culling of sick, injured (Carpenter, 2000), or very
young dinosaurs, would seem quite likely. In short,
we suspect that Tyrannosaurus and other
carnivorous theropods were, like most extant
predators, opportunistic carnivores, eagerly
searching for carrion (in which activity the large
body sizes of many theropods may have been an
advantage; Farlow, 1994), but also killing prey
whenever possible.

THE FOSSIL RECORD OF PREDATION IN DINOSAURS
JAMES O. FARLOW1 AND THOMAS R. HOLTZ, JR.
[Image: wildcat10-CougarHuntingDeer.jpg]
Reply
#15
T. Rex Plodded Like an Elephant, Nerve Study Says

Mason Inman
for National Geographic News
Published June 29, 2010

The mighty Tyrannosaurus rex was no quick, agile killing machine—the "tyrant king" dinosaur just didn't have the nerves.

Instead, most times T. rex probably plodded along like an elephant, according to a new study that estimated the "speed limit" of nerve signals running through the dinosaur's body.

When a vertebrate—an animal with a backbone—stubs its toe, electrical signals get carried from the toe to the spinal cord by a nerve, which is made up of bundles of long, fiberlike cells.

Since the researchers couldn't study a T. rex's nerves directly, the team looked at how nerves work in a range of modern animals, from the tiny shrew to midsize dogs and pigs to massive Asian elephants.

The scientists found that, for all body sizes, nerves have a basic speed limit of about 180 feet (55 meters) a second. That's the fastest a signal can travel from an animal's feet to its spinal cord—the kind of signal that's essential for walking and running.

At that speed limit, big animals such as elephants can't run too fast or they're effectively running blind.

Suppose an elephant steps on a pebble, said study leader Max Donelan of Simon Fraser University in Burnaby, Canada. If the pachyderm was running fast, "its foot would be nearly off the ground before it could do something in response to that troublesome pebble."

The same goes for T. rex, said study co-author John Hutchinson, an expert on dinosaur movement at the Royal Veterinary College in London.

"Nerves are nerves—in vertebrates anyway," Hutchinson said. "So the principles will apply generally to dinosaurs, too."

T. rex Would Still Have Been Impressive, Exciting

According to the study, there's a trade-off between the number of nerve cells in a bundle and how fast the nerve can transmit a signal.

For a big animal such as an elephant to be as fast as a shrew and still feel every step, the elephant's nerves would have to be 100 feet (30 meters) thick—clearly impossible.

Instead, elephant nerves can either be relatively slow and sensitive or fast and dulled.

As long as a bus and weighing around 6.5 tons, the average T. rex would also have needed to move slowly to feel with its feet, according to the study, which appears Wednesday in the Proceedings of the Royal Society B.

The idea that T. rex lumbered like an elephant fits with other studies of the dinosaur's body, including one paper that found that T. rex's leg muscles would have to have been heftier than its whole body weight for the dinosaur to have been a speed demon.

"To be agile, Tyrannosaurus would need to be both all muscle and all nerve," Simon Fraser's Donelan said.

Nonetheless, elephants can occasionally get up to a fast clip, sometimes charging fast enough to catch people. Ditto for big dinosaurs, the Royal Veterinary College's Hutchinson said. 

Tyrannosaurus rex were "by no means slow, sluggish, ponderous, clumsy animals. They still would have been impressive and exciting to see, and capable of surprising feats from time to time."

http://news.nationalgeographic.com/news/2010/06/100629-science-dinosaurs-t-rex-nerves-elephants/ 
[Image: wildcat10-CougarHuntingDeer.jpg]
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)