Dinosaur National Monument park officials announced this week that the Split Mountain campground in Utah will remain open throughout the winter, according to AP and other media reports.
Three additional campgrounds at the monument will also be open, but only the hardiest of hikers can attain them due to snowfall levels.
DNM spokesperson Carla Beasley warned that even the Split Mountain campground is particularly cold during the winter months owing to its proximity to the chilly Green River. Cold air tends to settle at the river, which usually remain in the entire area at teeth-chattering temperatures.
However, if you are an experienced camper, the news is good for dinosaur enthusiasts.
The National Park Service states, "Dinosaur fossils can only be noticed on the Utah side of the park. The chief exhibit wall of dinosaur fossils is closed due to significant life, health, and safety issues, but a temporary visitor center is open. Also, few fossils can be seen by hiking 3/4 mile from the temporary visitor center."
Thursday, December 31, 2009
Dinosaur National Monument park officials announced this week that the Split Mountain campground in Utah will remain open throughout the winter, according to AP and other media reports.
Wednesday, December 30, 2009
New research challenges the thought that the asteroid impact that killed the Dinosaurs also sparked a global firestorm.
Scientists modeled the consequence that sand-sized droplets of liquefied rock from the impact had on atmospheric temperature. The asteroid is thought to have gouged away the Chicxulub crater on the Yucatán Peninsula in Mexico.
Formerly it was thought that the falling spherules, as the tiny rocks are called, heated up the atmosphere by several degrees for up to 20 minutes — hot enough and long enough to cause whole forests to spontaneously burst into flames.
As evidence for this, scientists pointed to what appears to be carbon-rich soot from burned trees exposed in the thin band of debris dating back to the impact some 65 million years ago, a shift in geologic time called the K-T boundary.
Tuesday, December 29, 2009
Some dinosaurs, it is identified, were ferocious creatures — using claws, jaws, teeth, horns or even tails to subdue their prey.
But did some make use of poison, too?
A group of paleontologists has found evidence to imply that at least one dinosaur, the birdlike raptor Sinornithosaurus, was venomous. It perhaps used its poison to stun small birds or other prey, the researchers write in The Proceedings of the National Academy of Sciences.
Sinornithosaurus, which was about 3 feet long and lived 125 million years ago, was described in 1999 based on fossils discovered at the Liaoning Quarry in northeastern China. The original description noted some unusual features, with grooves in the teeth and a duct running along the base of the teeth.
David A. Burnham of the University of Kansas and Enpu Gong of Northeastern University in Liaoning and colleagues have now interpreted those features, and a cavity in the skull not previously described, as evidence of a venom delivery system similar to that found in some living lizards.
Monday, December 28, 2009
When Peggy Thompson's husband Larry died in 1965, she was in her early 40s, raising 3 small children and running a Scotts Valley nursery school.
If that weren't enough of a burden to carry from day to day for a new widow, she also had a different role to play.
She was the Queen of the Dinosaurs.
Peggy Thompson, who died Dec. 14 at the age of 86 at her home in Scotts Valley, was the owner and operator of one of the more unusual businesses in the extensive history of Santa Cruz County. It was called Lost World, and it was a Scotts Valley tourist attraction that featured 25 to 30 enormous, realistic, life-sized models of various different Species of Dinosaurs, some of which could be seen by drivers — many of whom were definitely startled out-of-towners — on Highway 17.
The entrance to Lost World was on Scotts Valley Drive, and featured a huge animatronic tree that served as the park's entrance, close to a T-rex looking out over the turret of a castle. The park also featured what was formerly known as the Tree Circus, a grove of trees meticulously grafted into the kinds of whimsical shapes never found in nature. The Thompsons bought the Tree Circus from its creator, Axel Erlandson, renaming it the Enchanted Forest, keeping Erlandson as a hired caretaker.
Thursday, December 24, 2009
If the dinosaurs had dentists to take care of their teeth, they would have been possibly alive today.
At least, this is the picture that is rising out of a new research by scientist of David Varricchio and colleagues.
Infectious diseases can be transmitted by touching ,sneezing, or biting each other on the face, a habit that may have driven the dinosaurs to extinction through the transmission of a protozoan parasite.
This led the scientists to realize that a protozoan parasite was to blame for the diseased jawbones seen in many tyrannosaurid fossils.
The parasite’s modern-day equivalent, which infects birds, eats away at the jawbone and can cause ulcers so ruthless that the host starves to death.
Living in the jaw, the parasite may have been transfered from one dinosaur to another dinosaur during head biting.
According to Jacqueline Upcroft, a member of f1000 Biology, “This organism generally infects pigeons, doves, turkeys and raptors, causing necrotic ulceration in the upper digestive tract,” and in extreme cases it can fully pierce the bone.
The similarity of the fossilized jawbones and modern-day samples imply that the parasite was deadly enough to kill infected dinosaurs.
“This may not have been an segregated situation but may have occurred en masse and led to the Extinction of the Species,” said Upcroft.
Wednesday, December 23, 2009
Well-preserved fossils of a feathered dinosaur that exist about 124 million years ago — along with certain aspects of its teeth and skull — imply that the turkey-sized creature was venomous.
Sinornithosaurus was unearthed in China and first described by scientists about 10 years ago, but the telling details of the creature’s cranial anatomy are just now being described, says David Burnham, a paleontologist at the University of Kansas in Lawrence.
The majority of the teeth in each side of the creature’s upper jaw have grooves that run from the base of each tooth to the tip, a characteristic seen in some of today’s venomous reptiles. A huge triangular depression on the creature’s upper jawbone — a feature not previously reported in other dinosaurs or their relatives — probably held venom-producing glands, Burnham and his colleagues report online December 21 in the Proceedings of the National Academy of Sciences. Venom curving from those glands probably pooled in reservoirs at the base of each grooved tooth until the dino bit its prey, Burnham says.
Saturday, December 19, 2009
Volunteer Mitch Siegel of Waukegan helps assemble a T-Rex dinosaur skeleton as the Waukegan Public Library gets prepared for the "Dig the Dinosaurs" display, to celebrate the one-year anniversary of the Early Learning Center.
With the scratching sounds of a prehistoric jungle echoing overhead, visitors to the Waukegan Public Library's Early Learning Center are now being welcomed by a smile much toothier than they are accustomed to meeting.
To celebrate the one-year anniversary of opening the ELC, the Waukegan Public Library renovated its ELC facilities for three days and reopened them on November 15 with a new look and feel, gathering dinosaurs into nearly all facet of the space with "Dig the Dinosaurs."
Friday, December 18, 2009
Scientists in the US have unearthed the fossilised bones of a meat-eating dinosaur the size of a large dog which they say could fill in the gaps about the early evolution and global migration of a group of animals that ruled the land for 170 million years.
Tawa hallae lived about 230 million years before and was found in a quarry in northern New Mexico. It owns anatomical features that link it with other dinosaurs living much further south in what is now South America.
Researchers say Tawa bears the idea that the dinosaur lineage evolved in the southern part of the supercontinent Pangea. Successive waves of migration from that region resulted in a diverse variety of dinosaurs spreading to other parts of the giant continent, which later split into numerous separate continents.
Thursday, December 17, 2009
According to Fabio M. Dalla Vecchia, who precede the project, Antonio is noteworthy on many counts. Dalla Vecchia, a researcher at both the the Universitat Autònoma de Barcelona and the Institut Català de Paleontologia told Discovery News that this dinosaur:
• is only the 2nd ever dinosaur species named in Italy
• is the most complete medium to large sized dinosaur ever originate in Europe
• might be one of the most complete dinosaur skeletons in the world
• be evidence for the first time what close relatives to duck-billed dinosaurs looked like in detail
Tethyshodros insularis imply "island dweller hadrosaurid dinosaur of Tethys."
Tethys was an ocean that splited Africa from the Euro-Asia continent during
dinosaur times. The new dinosaur species survived on a small island in the western part of this ocean 70 million years ago. Dalla Vecchia utters that this was an unusual spot for such an animal, comparable to an elephant being found in the Bahamas today.
Wednesday, December 16, 2009
Infectious diseases can be spreaded by sneezing, touching, or – for Tasmanian devils – biting each other on the face, a habit that may have driven the dinosaurs to extinction through the transmission of a protozoan parasite.
Jacqueline Upcroft, a member of f1000 Biology, draw attention to the 'paleobiological detective work' of David Varricchio and colleagues published in PLoS One. This led them to figure out that a protozoan parasite was to blame for the diseased jaw bones seen in many tyrannosaurid fossils.
The parasite's modern-day equivalent, which infects birds, eats away at the jawbone and can stimulate ulcers so severe that the host starves to death. Living in the jaw, the parasite may have been passed from one dinosaur to another dinosaur during head biting.
Upcroft said, "this organism generally infects pigeons ,doves, turkeys and raptors, causing necrotic ulceration in the upper digestive tract," and in extreme cases it can fully penetrate the bone.
The similarity of the fossilized jawbones and modern-day samples suggest that the parasite was deadly enough to kill infected dinosaurs. Furthermore, as Upcroft notes, "this may not have been an separated situation but may have occurred en masse and led to the extinction of the species."
Tuesday, December 15, 2009
Did four-legged dinosaurs gallop like a horse, run similar to an ostrich or hop like a kangaroo? All three have been suggested, but with only fossils to go on it's a tricky puzzle to solve.
That's why Bill Sellers, a computational zoologist at the University of Manchester, UK, has developed a innovative technique for simulating dinosaur movement and working out which gaits they most likely used.
Sellers and his team used a laser scanner to produce a 3D computer model of the skeleton of an Edmontosaurus, a type of hadrosaur or "duck-billed" dinosaur, and added virtual muscles to make it move. Fossilisation does not safeguard a dinosaur's muscles, but educated guesses about how they worked can be made by studying animals alive today, such as ostriches.
Monday, December 14, 2009
The early evolution of dinosaurs, in the late Triassic period, is fuzzy, to say the least.
Paleontologists recognize that the first dinosaurs emerge about 230 million years ago, but fossil evidence is so spotty that it is unapparent where and when the major lineages — theropods, sauropods and ornithischians — began to diverge.
Some excellent 215-million-year-old fossils unearthed in Ghost Ranch, in northern New Mexico, are aiding to clarify things. The bones, of a theropod that the discoverers have named Tawa hallae, offer strong support for the idea that the major lineages diverged early in dinosaur evolution in the part of the supercontinent Pangea that is now South America.
“What Tawa does is it helps intimate the relationships at the base of dinosauria,” said Sterling J. Nesbitt, a postdoctoral researcher at the University of Texas and lead author of a paper in Science describing the find.
Saturday, December 12, 2009
Bones found out in a New Mexico quarry indicate that the first dinosaurs appeared in what is now South America, with some migrating northward into the US as the continent began to split apart.
The 213-million-year-old fossils of prior unknown carnivorous dinosaur Tawa hallae include several of the best preserved dinosaur skeletons from the Triassic Period.Tawa was about six feet long - the size of a large dog, but with a much longer tail.
"If you have continents splitting separately, you get isolation," said lead author Sterling Nesbit of the University of Texas at Austin. "So when barriers develop, you would anticipate that multiple carnivorous dinosaurs in a region should correspond to a closely related endemic radiation. But that is what we don’t see in early dinosaur evolution."
Friday, December 11, 2009
Scientists have unearthed the fossilised bones of a meat-eating dinosaur the size of a large dog which they believed could fill in the gaps about the early evolution and global migration of a group of animals that take over the land for 170 million years.
The dinosaur, called Tawa hallae, lived about 230 million years ago and was originate in a quarry in northern New Mexico. It hold anatomical features that link it with other dinosaurs living much further south in what is now South America. Researchers said that Tawa bear the idea that the dinosaur lineage evolved in the southern part of the supercontinent Pangea. Successive waves of migration from that region resulted in a diverse variety of dinosaurs spreading to other parts of the giant continent, which later on split into several separate continents.
Thursday, December 10, 2009
The mirrors and smoke model that makes money and pretends waste disappears has now turned full circle, and come up against itself at the Copenhagen climate change conference.
The enduring meeting of 192 parties will be the first time all nations, side-by-side, have had to face the truth that there is nowhere left to pollute - and nowhere else to borrow from.
Until now science has seemed esoteric compared to the pragmatism and rationality of the market. Every time a new disaster occurred, the same mantra was chanted: "markets will adjust".
Well, the markets adjusted dreadfully in September last year, and economists' solution for the US is to print 8 billion $100-paper bills.
Climate change can be a more disastrous market adjustment. Catastrophic geographic situations cannot be papered over with money. That financial accounting has become unhinged from the real economy is already obvious
Wednesday, December 9, 2009
A remote-controlled dinosaur robot worth about 100,000 Australian dollars (£55,600) has been stolen from a Walking With Dinosaurs show in Mexico.
Staff observed the 1.5m tall robot was missing after the show closed on its opening day in Guadalajara on Friday.
The Australian show based on the BBC series has explored worldwide and been seen by more than four million people.
"Only in Mexico! How it occur we don't know," said the show's spokesman, Karla Arroyo.
It is the first instant an exhibit has been stolen from the show, she added.
The theft did not end the show going ahead.
"Everything went on as usual," said Ms Arroyo.
She said the stolen robot was the least expensive from the show - some measure up to 13m and cost up to 1m Australian dollars.
The show originated in Australia, where it first opened in Sydney's Acer Arena in January 2007.
Ten species are symbolized from the 200 million-year reign of the dinosaurs. The show consist of Tyrannosaurus rex and the Stegosaurus.
The UK tour sold more than 500,000 tickets prior this year and has now moved to Europe.
The Walking With Dinosaurs TV series, which used animatronics and computer graphics to portray the prehistoric animals, was broadcast 10 years ago.
The series took two years to make.
Tuesday, December 8, 2009
Flanders noticed the “Age of Dinosaurs” as a time when food was unlimited. The planet was clothed with lush forests providing an all-you-can-eat buffet to herbivores and thus plenty of food on the go for predatory dinosaurs. The herbivores distended themselves with plants and the carnivores kept the populations of herbivores in check, as so the “circle of life” kept cycling on.
But what if something destabilized this cycle? Flanders projected that two factors, working together, utterly changed the dinosaur’s world. The first was the evolution of seed-producing plants. Flanders envisioned the world of the dinosaurs as one carpeted in ferns and archaic plants, and these new variety of plants provided ample food for caterpillars.
As a result of his explore in agricultural science Flanders was well aware of the damage caterpillars could do to plants if their populations were left unchecked. The insatiable hordes could quickly denude an entire forest of its foliage, thus depriving other herbivores of food. This is just what happened at the closing stages of the Cretaceous, Flanders argued. The caterpillars were too numerous and multiplied too quickly, consuming all the plant food before the herbivorous dinosaurs could get any for themselves. And as the herbivorous dinosaurs died out, so did their predators, leaving behind only small reptiles such as crocodiles and turtles that found their food by different means.
Going Where the Dinosaurs Roamed in the United StatesExperts urge 'Westward Ho!' for finding the best dinosaur treasures
The gigantic brachiosaurus, the deadly and fierce tyrannosaurus, the nimble and fast velociraptor.
Millions of years ago, long before humans existed, these creatures - and many others like them -- wander the earth. We visited some of the territory where dinosaurs roamed in what is now the United States.
Morrison Formation, is a group of rock layers that is prime territory for dinosaur fossils. It is centered in the western U.S. states of Wyoming and Colorado. We start our exploration for the dinosaurs of North America at the Wyoming Dinosaur Center.
Malcom Bedell is a investigator at the center. His excavation team is digging up what he is pretty certain is a fossilized diplodocus - a large plant-eating dinosaur -- but it is slow and time-consuming work.
Wednesday, November 18, 2009
The mammoth brachiosaurus … the fierce and deadly tyrannosaurus … the fast and nimble velociraptor.
There are more than 1,000 known types of dinosaurs, with an expected 2,000 more yet to be discovered, according to paleontologists - dinosaur experts. We visit the nation's capital to learn more about the huge creatures that populated the earth millions of years ago.
The U.S. state of Colorado is an ideal target for anyone interested in hunting for dinosaur fossils. Like Wyoming, its neighbor to the north, Colorado has its own facility devoted to restoring dinosaurs to their original form, the Rocky Mountain Dinosaur Resource Center.
"What we are trying to do is to present an incomplete specimen in a absolute way. Because if you just have random bones lying around, it's hard for someone to come in and look at it and recognize what the animal looked like in its entirety. And, by filling in the blanks, they see the real material that [has] been used in the reconstruction, but they also see what the animal looks similar in its entirety." Anthony Maltese, curator of the center said.
Saturday, October 10, 2009
The asteroid impact that ruined the age of dinosaurs 65 million years ago didn't incinerate life on our planet's surface – it presently broiled it, a new study suggests. The work resolves nagging questions about a theory that the affect triggered deadly wildfires around the world, but it also bring up new questions about just what led to the mass extinction at the end of the Cretaceous period.
The impact of a 10-km asteroid is liable for the extinction of the dinosaurs and most other species on the planet. Early computer models demonstrate that more than half of the debris blasted into space by the impact would fall into the atmosphere within eight hours.
The models predicted the rain of shock-heated debris would radiate heat as intensely as an oven set to "broil" (260 °C) for at least 20 minutes, and maybe a couple of hours. Intense heating for that extend would heat wood to its ignition temperature, causing global wildfires.
Yet some species survived, and the global layer of impact debris doesn't contain as much soot as would be expected from burning the world's forests, raising questions about the scope of post-impact wildfires
Tuesday, September 22, 2009
Princeton geoscientist Gerta Keller has new proof to support her alternative theory that volcanoes, not meteorites, wiped out the dinosaurs. Indeed, the evidence is so convincing that we might be dropping the whole "alternative" part.
Keller is one of several co-authors on a new paper in The Journal of the Geological Society of London that lays out the startling innovative evidence. prior studies of rock formations in India, Mexico, and the United States had first prompted Keller to conclude there was a discernible period between the massive meteorite impact that has been advanced as the killer of the dinosaurs, and their actual final extinction.
This extinction, which is known to have occurred 65 million years back, marked one of the most drastic biological upheavals this planet has ever seen. Signaling the last part of the age of reptiles (the Mesozoic Era) and the beginning of the age of mammals (the Cenozoic Era), this limit between the Cretaceous (abbreviated "K") and Tertiary ("T") periods is known in scientific literature as the K-T Boundary. The K-T Boundary can be observed geologically through the vastly different plant and animal species found on each side of the divide.
Saturday, August 8, 2009
The innovation of a new species of dinosaur from the early Jurassic period (approximately 195 million years old and seven metres long) has been announced and described by Dr Adam Yates, the primary investigator and a palaeontologist from the Bernard Price Institute for Paleontological Research (BPI) from the University of the Witwatersrand, Johannesburg, South Africa.
The vegetarian dinosaur, one of three exposed at the same site, was named Aardonyx celestae -- the genus name (Aardonyx) means "Earth Claw," (Aard -- Afrikaans for Earth) and (Onyx -- Greek for claw) an suitable name, given that the large, earth-encrusted foot claws were some of the first bones to be discovered in the town of Senekal, near Bethlehem in the Northern Free State, in South Africa. The species name (celestae) is specified to acknowledge the occupation of Celeste Yates who prepared much of the fossil.
"This species is vital as the Aardonyx was an animal close to the general ancestor of the huge sauropod dinosaurs," explains Yates. "Sauropods, known widely as "brontosaurs," were the largest backboned animals to walk on land with their long necks, tree-trunk legs and whip-like tails.
Thursday, July 16, 2009
Visualize a large stream with abundant tributary and torrent fluid through the valley. Galleries of foliage, ferns, and gigantic horsetails grew in large quantities along the river, providing food and shelter for many insects, amphibians, reptiles, and other creatures. In the faintly dryer areas a short remoteness from the water there were cycads, bennettitaleans, ginkgoes, and coniferous trees soaring almost two-hundred feet into the sky.
During the Triassic Period, the type of weather was very different from that of today. Located near the equator, this area was moist and steamy, the landscape dominated by a watercourse system larger than anything on Earth today. Gigantic reptiles and amphibians, early dinosaurs, fish, and many invertebrates lived among the opaque vegetation and in the winding waterways. New fossils draw closer to light as paleontologists continue to study the Triassic treasure trove of Petrified Forest National Park.
Monday, July 13, 2009
Lecturer can download a whole term's work from a new Queensland Museum online science education resource, Biodiscovery and the huge Barrier Reef.
Subject such as
II) Animal physiology
III) Genetics and human impact on the environment
These are explored in the online resource that contains a 52 page downloadable booklet of student activities.
Biodiscovery and the huge obstruction Reef showcases the work of Queensland Museum's Head of Biodiversity and Geosciences Dr John Hooper, who is identifying marine sponges that fabricate bioactive chemicals with important pharmaceutical reimbursement in collaboration with Griffith University's Eskitis Institute.
Queensland Museum's Senior Biodiversity Project Officer Adriana Bauer, a former senior biology and mathematics teacher, said the resource has information and activities suitable for Middle and Senior school students.
"Biodiscovery and the Great Barrier Reef allows teachers and students to explore current topics such as
I) Reefs under threat
II) Ecotourism and the impact of climate change in a relevant and meaningful way using current research and case studies that are underway right now," Ms Bauer said.
"The resource approves national curriculum thesis and could easily form the source of a unit for the Biology, Science 21 or Marine Studies curricula."
The source includes magnificent visual imagery of reef organisms too, a set project for middle school students, and comprehensive response job for those at superior school level, and an interactive game and quiz to connect students at all levels.
Queensland Museum has shaped other award-winning online knowledge resources for middle and senior school students. These include Wild Backyards, Mangrove Challenge and Disease Detectives.
Tuesday, June 30, 2009
British scientists who are trying to solve the mystery behind eating habits of herbivorous Dinosaurs have found that the species had a peculiar way of chewing their food unlike anything alive today.
The scientists at the University of Leicester, who researched the microscopic scratches on the teeth of hadrosaurs - herbivorous duck-billed dinosaurs - discovered that rather than having a flexible lower jaw joint, the creatures had a hinge between the upper jaws and the rest of the skull.
"The Hadrosaurs did chew, but in a totally different way to anything alive today. Rather than a flexible lower jaw joint, they had a hinge between the upper jaws and the rest of the skull," said Paul Barrett, a palaeontologist at the UK-based Natural History Museum.
"As they chew down on their food the upper jaws were forced outwards, flexing along this hinge so that the tooth surfaces slid sideways across each other, grinding and shredding food in the process," he said.
Palaeontologist Mark Purnell of the University of Leicester Department of Geology, who held the research, said, "Our study uses a new approach based on analysis of the microscopic scratches that formed on hadrosaur's teeth as they fed, tens of millions of years ago. The scratches have been preserved intact since the animals died."
Friday, February 6, 2009
Early palaeontologists thought dinosaurs must have been slow and sluggish to have lost the "evolutionary race" to birds and mammals. Modern studies find no sign that they were laggards, lazily dragging their tails behind them.
Most dinosaurs were probably as mobile as large, modern mammals. Like lions, meat-eating dinosaurs were active predators that probably lay down and rested after eating their fill.
One study in 2000 of an exceptionally well-preserved hadrosaur fossil, found in a South Dakota riverbed, suggested that dinosaurs had powerful hearts more like those of birds or mammals than modern reptiles. Researchers argue that the fossilised, four-chambered heart points to an active, bird-like metabolism.
Terrestrial reptiles reached 5 metres in length before the first dinosaurs evolved 230 million years ago. Some - such as sail-backed Dimetrodon, which flourished in North America during the Permian period (290 to 240 million years ago) - were related to dinosaurs, but were not true dinosaurs.
Monday, January 26, 2009
Several types of marine reptiles evolved during the dinosaur age, but all true dinosaurs were terrestrial animals. Marine crocodiles, like other crocodiles, were closely related to the dinosaurs. So were large, extinct marine reptiles called plesiosaurs, pliosaurs, mosasaurs and ichthyosaurs.
Flying reptiles called pterosaurs first appeared just after the dinosaurs, and then died out at the same time as the dinosaurs. The largest grew to the size of a small aeroplane. However, while they were close relatives, they were not true dinosaurs.
Tuesday, January 20, 2009
A layer of iridium-rich rock marks the impact 65 million years ago of a 10-kilometre asteroid in shallow water covering what is now Mexico's Yucatan peninsula. That impact formed the 180 kilometre-wide Chicxulub crater. There is no convincing evidence that any non-avian dinosaurs survived the aftermath of the impact. Yet we are still not totally sure how the dinosaurs died.
The impact itself could only have killed the dinosaurs in the immediate vicinity of the crater. But it also produced devastating after-effects including giant tsunamis, rain that may have been as acidic as battery acid, and clouds of dust that darkened and cooled the globe for months or even decades.
Another theory suggests that before the impact, dinosaurs were already dwindling as falling sea levels and volcanic eruptions took their toll. A combination of those effects probably wiped out the dinosaurs.
Dinosaurs coexisted with mammals for 150 million years. Although dinosaur nests were undoubtedly vulnerable, the most dangerous predators were probably smaller dinosaurs. Most mammals of the time were probably too small to eat the eggs of large dinosaurs.
Sunday, January 18, 2009
It is hard to imagine that one of the largest impact craters on Earth, 180-kilometers (112-mile) wide and 900-meters (3,000-feet) deep, could all but disappear from sight, but it did.
Chicxulub, located on Mexico's Yucatan peninsula, eluded detection for decades because it was hidden (and at the same time preserved) beneath a kilometer of younger rocks and sediments. Size isn't the only thing that makes Chicxulub special. Most scientists now agree it's the "smoking gun" evidence that a huge asteroid or comet indeed crashed into Earth's surface 65 million years ago causing the extinction of more than 70 percent of the living species on the planet, including the dinosaurs. This idea was first proposed by the father and son team of Luis and Walter Alvarez in 1980.
Though the buried giant can't be seen, the impact crater has left subtle clues of its existence on the surface. "When I talk to school children, I describe it like this," says Dr. Gary Kinsland, a geology professor at the University of Louisiana at Lafayette who has been doing research on Chicxulub since 1994. "Put a bowl on your bed, then throw the sheets and blankets over it. All you'll probably see of the bowl now is a subtle depression."
"There is not a big hole anymore," he continues, "but if you look at the rim of the depression on your bed, you'll see that it is still in the same position as the rim of the bowl beneath. That's how surface expression allows us to interpret something about the buried structure."
The view from space lets scientists see some of Chicxulub's surface features that are not nearly so obvious from the ground. Satellite images showing a necklace of sink holes, called cenotes, across the Yucatan's northern tip are what first caught the attention of NASA researchers Drs. Kevin Pope, Adriana Ocampo and Charles Duller in 1990. They were among the first to propose Chicxulub as the impact site linked to the mass extinctions that occurred at the end of the Cretaceous and beginning of the Tertiary geological ages, called the K/T boundary.
For more information : http://www.jpl.nasa.gov/news/features.cfm?feature=8
Tuesday, January 6, 2009
Mammals remained relatively small until 65 million years ago, when the demise of the dinosaurs left a mass of niches for larger mammals to fill. Most of the types of mammals we know today evolved after this time.