Un nuovo dinosauro piumato scoperto in Cina, l’Anchiornis, può aiutare a comprendere meglio la “transizione” da dinosauri ad ucccelli essendo “più basale di Archaeopteryx.
New Feathered Dinosaur Adds to Bird Evolution Theory
January 16, 2009
A fossil of a primitive feathered dinosaur uncovered in China is helping scientists create a better model of how dinosaurs evolved into modern birds.
The winged dinosaur is still in the process of being dated, and might have lived toward the end of the Jurassic period, which lasted from 208 to 144 million years ago.
Anchiornis - A fossil of a primitive feathered dinosaur uncovered in China (above) is helping create a better model of how dinosaurs evolved into modern birds, experts said in January 2009. - Photograph courtesy Xu Xing
In many ways, it is “more basal, or primitive, than Archaeopteryx,” said paleontologist Xu Xing at Beijing’s Institute of Vertebrate Paleontology and Paleoanthropology. Archaeopteryx, the earliest known bird, lived 150 million years ago.
The protobird is “very close to the point of divergence” at which a new branch of winged dinosaurs first took flight, said Xu.
The new species, called Anchiornis huxleyi, was discovered in the ashes of volcanoes that were active during the Jurassic and Cretaceous (144 to 65 million years ago) periods in what is now northeastern China.
(Read about the prehistoric world.)
Anchiornis, which is Greek for “close to bird,” measured just 13 inches (34 centimeters) from head to tail and weighed about 4 ounces (110 grams).
The dinosaur’s body and forelimbs were covered with feathers, and it “might have had some aerial capability,” Xu said.
“Anchiornis is one of the smallest theropod dinosaurs ever uncovered,” Xu explained. Theropods were a group of carnivorous dinosaurs that walked on two legs.
The fossil provides new clues about how feathers, wings, and flight progressively appeared among theropods, along with evidence that certain types of feathered dinosaurs decreased in stature even as their forelimbs became elongated.
The compact structure of Anchiornis “reinforces the deduction that small size evolved early in the history of birds,” Xu explained”[Anchiornis] exhibits some wrist features indicative of high mobility, presaging the wing-folding mechanisms seen in more derived birds,” he said.
“The wrist is a big part of the formation of wings, and pivotal to flight,” Xu added. “During flight, steering and flapping greatly depend on the wrist.”
Despite this protobird’s relatively advanced feathers and wrist, it is unclear if Anchiornis could actually engage in powered flight.
“Behavior and biomechanics are very difficult to determine solely from the fossil record, and perhaps flight is impossible to determine,” said Mark Norell, chairman and curator of the division of paleontology at the American Museum of Natural History in New York.
“Feathers have lots of functions, and probably evolved as thermoregulators,” said Norell, who closely examined the fossil during a trip to Beijing.
“Dinosaurs might have used feathers for sexual display or to make themselves appear bigger, or as camouflage to avoid predators,” he said.
Patterns of spots and bars evident on one species of feathered dinosaur from China might have functioned as a camouflage defense, Norell added.
(Related: “First Dinosaur Feathers for Show, Not Flight?” [October 22, 2008].)
Xu said that the region in northeastern China where most of the world’s feathered dinosaurs, including Anchiornis, have been discovered is a virtual paradise for dinosaur hunting.
“This area has three circles of volcanic activity,” with eruptions that intermittently covered and preserved entire biospheres starting from the early Jurassic.
“Volcanos periodically killed the animals and plants and preserved them perfectly in volcanic ash,” he said.
“Sometimes the volcanic ash even preserves soft tissues, leaving behind an exceptional 3-D fossil.”
Un sopralluogo di altri ricercatori (i paleontologi Brent Breithaupt, Alan Titus e Andrew Milner, e il geologo Rody Cox) afferma che le persunte impronte di dinosauri recentemente descritte (in Vermilion Cliffs National Monumen) non sono altro che forme di erosione. Intanto gli autori dello studio Marjorie Chan and Winston Seiler, sembrano convincersi delle critiche; e in particolare Marjorie Chan si difende affermando che se le tracce sono effettivamente forme di erosione sono diverse da quelle che si ritrovano all’interno della stessa formzione rocciosa.
precedente post: 2008-10-20 – USA: nuovo ritrovamento di impronte di dinosauri, la “sala da ballo”! (dinosaur tracks,”dinosaur dance floor”)
Paleontologists Doubt ‘Dinosaur Dance Floor’
Potholes or Tracks? Both Sides Team for Follow-up Study
Nov. 7, 2008 – A group of paleontologists visited the northern Arizona wilderness site nicknamed a “dinosaur dance floor” and concluded there were no dinosaur tracks there, only a dense collection of unusual potholes eroded in the sandstone.
So the scientist who leads the University of Utah’s geology department says she will team up with the skeptics for a follow-up study.
“Science is an evolving process where we seek the truth,” says Marjorie Chan, professor and chair of geology and geophysics, and co-author of a recent study that concluded the pockmarked, three-quarter-acre site in Vermilion Cliffs National Monument was a 190-million-year-old dinosaur “trample surface”.
“We went through the proper scientific process of careful study, comparisons with other published works and peer review” of the study by independent scientists, Chan adds. “We gave the project considerable critical thought and came up with a different interpretation than the paleontologists, but we are open to dialogue and look forward to collaborating to resolve the controversy.”
On Oct. 30 – more than a week after the Utah study was publicized worldwide – four scientists hiked to the remote wilderness-area site: paleontologist Brent Breithaupt, director and curator of the University of Wyoming’s Geological Museum; U.S. Bureau of Land Management paleontologist Alan Titus and geologist Rody Cox; and paleontologist Andrew Milner of the St. George (Utah) Dinosaur Discovery Site at Johnson Farm.
They saw dinosaur tracks en route, but none in the pockmarked “dance floor.”
“There simply are no tracks or real track-like features at this site,” Breithaupt says. “We will be investigating the formation of these features in the upcoming study. Science works best when scientists work together.”
Chan and Winston Seiler, who conducted the research as part of his master’s thesis, say they are not retracting their study, which was published in the October issue of Palaios, an international paleontology journal. But they acknowledge there are strong arguments for the features being potholes rather than dinosaur tracks. The original study cited the possibility that the features were potholes and outlined arguments against it.
Chan says if the features are potholes, they are extremely unusual compared with typical potholes on the Colorado Plateau – and their formation still needs to be explained fully. She will work with Breithaupt and the others to examine the site in greater detail.
“A reinterpretation could emerge, but those conclusions have not yet been written as a scientific paper and need to be submitted to a journal for publication after peer review by other scientists,” she says.
Nevertheless, the University of Utah geologists feel obligated to inform the public of the difference of opinion because of wide publicity about the “dinosaur dance floor.”
“The public interest has been tremendous, and fortunately there are many other fantastic, accessible, documented dinosaur track sites than can be visited in the area,” Breithaput says.
Seiler spent considerable time at the unusual site. He acknowledges that the dinosaur track interpretation is controversial, further study is warranted, and if the paleontologists turn out to be correct, “that’s part of science.”
Chan adds: “This is how science works, and we’ll have to see how it shakes out in the end.”
The original Oct. 20 “dinosaur dance floor” news release and high-resolution photos are at:
previous post: 2008-10-20 – USA: nuovo ritrovamento di impronte di dinosauri, la “sala da ballo”! (dinosaur tracks,”dinosaur dance floor”)
Durante la costruzione di un parco industriale è stato trovato un sito con resti di Conifere risalente a 198 milioni di anni fa. L’area è tra l’altro vicina al Dinosaur Discovery Site dove otto anni fa sono stati scoperte migliaia di impronte di dinosauri. I riceracatori si stanno preparando a raccogliere i reperti che saranno donati a vari musei statali.
vedi pure: 2008-10-26 – Utah, USA: uno dei posti migliori per i dinosauri (world’s best spots for dinosaurs)
Plant fossils found near construction site in S. Utah
They are the only flora fossils ever found from the early Jurassic Period in the Western U.S.
Article Last Updated: 10/29/2008 12:28:53 AM MDT
Plant fossils from the early Jurassic Period were found at a development site in St. George. (Mark Havnes/The Salt Lake Tribune )
ST. GEORGE – Stone fossils of plants that once fueled dinosaurs as they roamed around southern Utah some 198 million years ago were unveiled Tuesday at a ceremony.
They were discovered Friday during construction work on a new industrial park.
The fossils of the prehistoric flora, mainly conifers, are the only ones ever found from the early Jurassic Period in the Western United States.
The site sits next to the Dinosaur Discovery Site at Johnson Farm, where eight years ago thousands of dinosaur tracks were discovered; they are now protected as a city-owned museum.
Now developers will work with scientists to preserve the site.
“This plant site is extremely important to help us examine further the vegetation recovery of plant life during the mass extinction at the end of the Triassic Period,” said Utah State Paleontologist Jim Kirkland.
Kirkland said the area where the plant fossils and tracks are found was once on a vast lake’s northern shore that attracted dinosaurs.
Andrew Milner, paleontologist for St. George, said one of the plant species, Saintgeorgeia jensenii is named after the city and another has been named after him, Milnerites planus.
Trapped in the sedimentary stone, brown juniperlike leaves can be recognized sprouting from stems. Fossilized pine cones also were found.
“They [developers] have been very cooperative,” Kirkland said. “Because it is on private property, they could have told us to get lost and sold everything on eBay.”
Don DeBlieux, a paleontologist with Utah Geological Survey, said several scientists descended on the site Sunday and have been splitting open stones since.
“It’s neat,” DeBlieux said. “We’re finding a lot of things we haven’t seen before.
Scientific museums around the country are interested in the find and have requested some of the fossils.
Kirkland said samples will be shipped to the Smithsonian Institution, the Museum of Natural History in New York City, the University of California Berkeley, the University of Utah and Brigham Young University, among others.
see also: 2008-10-26 – Utah, USA: uno dei posti migliori per i dinosauri (world’s best spots for dinosaurs)
Paleontologists sift Utah soil for plant fossils
The Associated Press - 1 ora fa
The spot is in a bare lot near the Virgin River, not far from the city’s Dinosaur Discovery Site at Johnson Farm, where dinosaur tracks were found eight years ago. Andrew Milner, the city’s paleontologist, said the property’s developers have agreed to …
Plant fossils found near construction site in S. Utah Salt Lake Tribune
Crews sift St. George soil for plant fossils LocalNews8.com
e altri 52 articoli simili »
In Gran Bretagna riscoperto dopo 150 anni un sito che aveva fornito numerosi eccezionali ritrovamenti di pescsi e calamari con resti di parti molli risalenti al Giurassico.
October 24, 2008
Jurassic treasure trove lost by Victorians found by Phil Wilby, fossil sleuth
[Photo: Phil Wilby with a fossilised ammonite found at the site near Christian Malford]
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Phil Wilby, of the British Geological Survey, has now rediscovered the site and led the first dig there in more than 150 years. He hopes that freshly recovered fossils can help to explain why tens of thousands of animals died simultaneously in episodes repeated many times over about a million years.
Fossil hunters and academics flocked to the area in the 1840s and 1850s to dig out extraordinarily well-preserved specimens of fish and squid-like creatures. But despite its importance as an extremely rare source of fossilised soft tissues preserved along with hard bones and shells, the location of the site was lost.
None of the Victorians who visited the site, even leading researchers from universities and museums, recorded the precise place and, when digging ended, the location was forgotten.
Original scientific article:
Geology Today - Volume 24 Issue 3, Pages 95 - 98
Preserving the unpreservable: a lost world rediscovered at Christian Malford, UK
1 British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK. firstname.lastname@example.org; email@example.com 2 Department of Geology, University of Leicester, Bennett Building, University Road, Leicester, LE1 7RH, UK. firstname.lastname@example.org 3 School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK. email@example.com
The small village of Christian Malford, Wiltshire (UK) is known to palaeontologists the world over because of the chance discovery of an astonishing fossil bonanza in the mid-nineteenth century. Pits in the Jurassic Oxford Clay yielded thousands of specimens of exquisitely preserved ammonites, fish and crustaceans, but became most famous for squid-like cephalopods and belemnites (collectively termed coleoids) with fossilized soft-parts. The precise location of the find has remained obscure, until now, and a new attempt is underway to understand the ancient environment that triggered this unusual preservation.
Published Online: 6 May 2008
In Thailandia un contadino scopre nuovo sito con resti fossili di dinosauri (sauropodi e teropodi) datato 150 milioni di anni fa.
Second big fossil site unearthed at Kalasin
A new site rich in dinosaur fossils has been found in Kalasin province, with some of the fossils estimated to be 150 million years old. The new site is the second fossil discovery in the area after the find at Phu Kum Khao.
The new discovery was made in tambon Din Chee in Kham Muang district near the Phu Phan mountain range.
The fossils were found on land owned by Seethan Saengsit, 62, who made the discovery while working on her land.
Thida Saneyamoon, the chief of the geological survey unit of the Mineral Resources Department, said an initial dig had turned up several types of dinosaur fossils – sauropods and theropods – which were estimated to have roamed the area at least 150 million years ago.
There are also a number of fossils of crocodiles and fish, also estimated to be 150 million years old.
The fossils are to undergo a thorough examination by officials from the department. Ms Thida said the newly discovered fossils would be kept at the Sirindhorn Museum in Sahatsakhan district in Kalasin, where a number of rare fossils of crocodiles and replica skeletons of dinosaurs found in the region have been put on display.
Decha Tantiyawarong, the governor of Kalasin, said he had been told by the Mineral Resources Department that more than 100 fossils had been found.
The discovery was the second in the province following the find at Phu Kum Khao, which has some of the largest fossil deposits in Southeast Asia.
The governor said he had ordered the area to be guarded around the clock to prevent people digging up more fossils to supply illegal fossil traders.
The province bans the removal of fossils from the area without permission.
Based on the new Paleontological Research Protection Act of 2008, effective in August, anyone caught exporting rare fossils without permission could be jailed for up to seven years, or face a fine of up to 700,000 baht, and those trading in fossils without a licence face a one-year prison term or a 100,000 baht fine.
Any fossil discoveries have to be reported to the authorities within seven days, and those wanting to trade in fossils need to obtain a licence.
Anyone in possession of fossils needs to inform the Mineral Resources Department, either in writing or verbally within one year – by Aug 9, 2009 – or face a fine of up to 10,000 baht.
Pubblicato sul numeo di Ottobre della rivista Palaios, dai ricercatori dell’università dello Utah Winston M. Seiler e Marjorie A. Chan, uno studio preliminare su un nuovo sito contenente tracce di dinosauri.
L’area è situata al confine tra Arizona e Utah e gli strati contenenti le tracce appartengono alla Navajo Sandstone Formation e risalgono a 190 milioni di anni fa (Giurassico inferiore).
Le tracce sia di piedi che di code presentano un’elevata densità di frequenza, sono state attribuite ad almeno tre ichnogeneri cf. Eubrontes, cf. Anchisauripus, cf. Grallator, e curiosamente fino ad ora erano state ritenute forme di erosione superficiale.
Il rinvenimento di tali impronte è significativo anche perche le aree della Navajo Sandstone Formation erano ritenute un unico immenso deserto, ma il fatto che vi fossero animali con elevate necessità fa ritenere invece dovevano essere presenti anche aree on risorse sufficienti al loro fabbisogno.
Public release date: 20-Oct-2008
Contact: Lee Siegel
University of Utah
‘A dinosaur dance floor’
Numerous tracks at Jurassic oasis on Arizona-Utah border
Geologist Winston Seiler with some of the dinosaur tracks he identified for his thesis as a University of Utah master’s degree student. The impressions once were thought to be potholes…
Click here for more information.
SALT LAKE CITY – University of Utah geologists identified an amazing concentration of dinosaur footprints that they call “a dinosaur dance floor,” located in a wilderness on the Arizona-Utah border where there was a sandy desert oasis 190 million years ago.
The three-quarter-acre site – which includes rare dinosaur tail-drag marks – provides more evidence there were wet intervals during the Early Jurassic Period, when the U.S. Southwest was covered with a field of sand dunes larger than the Sahara Desert.
Located within the Vermilion Cliffs National Monument, the “trample surface” (or “trampled surface”) has more than 1,000 and perhaps thousands of dinosaur tracks, averaging a dozen per square yard in places. The tracks once were thought to be potholes formed by erosion. The site is so dense with dinosaur tracks that it reminds geologists of a popular arcade game in which participants dance on illuminated, moving footprints.
“Get out there and try stepping in their footsteps, and you feel like you are playing the game ‘Dance Dance Revolution’ that teenagers dance on,” says Marjorie Chan, professor and chair of geology and geophysics at the University of Utah. “This kind of reminded me of that – a dinosaur dance floor – because there are so many tracks and a variety of different tracks.”
“There must have been more than one kind of dinosaur there,” she adds. “It was a place that attracted a crowd, kind of like a dance floor.”
A study identifying the dinosaur track site was published in the October issue of the international paleontology journal Palaios. Chan is senior author of the study, which was conducted for a master’s degree thesis by former graduate student Winston Seiler, who now works at Chevron Inc., in Bakersfield, Calif.
University of Utah geologist Winston Seiler walks among hundreds of dinosaur footprints in a “trample surface ” that likely was a watering hole amid desert sand dunes during the Jurassic Period…
Click here for more information.
Seiler says the range of track shapes and sizes reveals at least four dinosaur species gathered at the watering hole, with the animals ranging from adults to youngsters.
“The different size tracks [1 inch to 20 inches long] may tell us that we are seeing mothers walking around with babies,” he says.
The site – a 6-mile roundtrip hike from the nearest road – is in Arizona in the Coyote Buttes North area of the Paria Canyon-Vermilion Cliffs Wilderness, which is part of the U.S. Bureau of Land Management’s (BLM) Vermilion Cliffs National Monument. The track site – about halfway between Kanab, Utah, and Page, Ariz. – is near a popular wind-sculpted sandstone attraction known as the Wave.
A Dense Collection of Dinosaur Footprints – and a Few Tail Drags
Chan says the new study is the first scientific publication to identify the impressions as dinosaur footprints on a trample surface.
As part of the study, Seiler marked off 10 random plots, each of 4 square meters, or roughly 2 yards by 2 yards. He counted 473 tracks within those plots – an average of 12 per square meter. He conservatively estimates the 3,000-square-meter site (about 0.75 acres) has more than 1,000 tracks, but he and Chan believe there perhaps are thousands.
Numerous dinosaur track sites have been found in the western United States, including more than 60 in Navajo Sandstone, where actual dinosaur bones are rare.
“Unlike other trackways that may have several to dozens of footprint impressions, this particular surface has more than 1,000,” Seiler and Chan wrote. And they say the density of tracks is much greater than it is at even larger track sites, such as the one at Coral Pink Sand Dunes State Park in Utah.
The dinosaur tracks and tail marks near the Wave were preserved in the vast Navajo Sandstone Formation. But unlike the dunes that make up much of the Navajo Sandstone, the tracks are within what was a wet, low watering hole between the dunes.
“We’re looking at an area much like the Sahara Desert with blowing sand dunes,” Seiler says. “Areas between these sand dunes could have had ponds – oases.”
The 2.4-inch-wide tail-drag marks – which are up to 24 feet long – are a special discovery because there are fewer than a dozen dinosaur tail-drag sites worldwide, Seiler says. Four tail drags were within the 10 plots he surveyed, and there are others nearby.
“Dinosaurs usually weren’t walking around with their tails dragging,” he says.
This Eubrontes dinosaur footprint — including three toes and a heel — measures roughly 16 inches long. Dinosaur footprints are named by their shape because the species and genus of…
Click here for more information.
Potholes – or Prints from Four Kinds of Dinosaurs?
Chan first visited the site of the dinosaur tracks in 2005 with a BLM ranger who was puzzled by them. Chan initially called them potholes, which are erosion features common in desert sandstone, “but I knew that wasn’t the whole story because of the high concentration and because they weren’t anywhere else nearby but along that one surface.”
Seiler first saw the site in 2006. “At first glance, they look like weathering pits – a field of odd potholes,” he says. “But within about five minutes of wandering around, I realized these were dinosaur footprints.”
One anonymous reviewer of the Palaios study still believes the holes are erosion features. The study argues the impressions are from dinosaurs because:
- They are the correct size for tracks made by big animals, and are limited to a single rock bed.
- Four different kinds of footprint shapes are seen repeatedly in 14 percent of the impressions, and they include obvious claw, toe and heel marks. The other impressions “are clearly similar.”
- One-third of the prints are surrounded by small ridges or mounds. Such features would be expected when animals stepped in wet sand.
- The tracks “are rarely flat and are typically oriented at an angle into the sediment … and indicate a clear direction of travel” to the west-southwest. Seiler says the direction the dinosaurs walked “either was dictated by the large dunes that bounded this wet area, or it could be communal behavior, like walking together as a pack.”
- About one-eighth of the tracks show “overprinting,” in which a dinosaur stepped in the footprint of another or even in its own prints.
“While these impressions may be mistaken for potholes caused by weathering, close examination reveals many footprint features,” Seiler says.
Dinosaur footprints are named by their shape because the animals that made them haven’t been identified. Four kinds of footprints were found on the trample surface:
- Eubrontes footprints measure 10 inches to 16 inches long and have three toes and a heel. Eubrontes tracks are believed to have been made by upright-walking dinosaurs 16 to 20 feet long, or smaller than Tyrannosaurus rex.
- Grallator tracks are about 4 inches to 7 inches long, are three-toed and were left by small dinosaurs only a few feet tall.
- Sauropodomorph dinosaur tracks, which are more circular than the other types, were left by creatures that walked on four legs and were the largest dinosaurs at the site. Their tracks range from 6 inches to 11 inches long. Seiler says the tail-drag marks are associated with these circular footprints, so they likely were made by sauropods.
- Anchisauripus tracks measure 7 inches to 10 inches long and were made by dinosaurs that ranged from 6 feet to 13 feet in length.
An Oasis for Dinosaurs in a Vast Desert of Dunes
When the footprints were made 190 million years ago, “the continents were arranged so this area was in the tropics” and was part of the supercontinent named Pangaea, says Seiler. “It was a desert, like the Sahara but much larger than the Sahara is today,” covering much of Utah, Wyoming, Colorado, New Mexico, Arizona and Nevada.
“Some studies indicate winds probably were much stronger than normal because all the continents were together,” says Chan. “That’s why you had monster dunes.”
“To support large dinosaurs, there probably wasn’t just one watering hole for them to go to, but many,” Seiler says. “They wandered between a network of watering holes for food and water.”
In that sense, the trample surface is not “just a wet pond,” but “it’s possibly a record of global climate change” – a shift from drier to wetter conditions, Chan says.
She says the traditional view is that the Navajo Sandstone represents “a vast, dry uninhabitable desert. But now we are seeing there are a lot of variations, and there were periods when dinosaurs were living there.”
Seiler envisions the dinosaurs were “happy to be at this place, having wandered up and down many a sand dune, exhausted from the heat and the blowing sand, relieved and happy to come to a place where there was water.”
The trample surface “helps paint a picture of what it was like to live back then,” he says. “Tracks tell us what the dinosaurs were doing, what their behavior was, what life was like for them, what they did on a day-to-day basis.”
After the dinosaurs left their prints, the trample surface was covered by shifting dunes, which eventually became Navajo Sandstone. Then, the rock slowly eroded away, exposing the tracks. The tracks eventually will erode too, Seiler says.
Seven additional images relevant to this press release are available:
Dinosaur Footprints and Tail-drag Marks
Grallator Dinosaur Track
Sauropodomorph Dinosaur Track
Extent of the ‘Dinosaur Dance Floor’
Dinosaur Dance Floor Locator Map
Geologist Winston Seiler
Note: Access to Area is Limited, Permits Required
The dinosaur trample surface and a nearby feature known as the Wave are in the Coyote Buttes North Special Permit Area of the Paria Canyon-Vermilion Cliffs Wilderness Area. A permit and $7 per person fee are required to enter the area.
There is now a four-month wait for the 10 permits issued daily by phone or online. For permits by phone, call the U.S. Bureau of Land Management in St. George, Utah, at (435) 688-3246. For information and permits online, go to
, and then click on “Coyote Buttes.” (If Coyote Buttes page doesn’t open, follow instructions to enable TLS security.)
An additional 10 permits are issued daily – one day in advance of the hike – during a 9 a.m. walk-in lottery March 15-Nov. 14 at the Paria Contact Station, and Nov. 15-March 14 at the BLM’s Kanab (Utah) Field Office.
News media interested in accessing the area should contact Linda Price, Vermilion Cliffs National Monument manager, at (435) 688-3241.
University of Utah Public Relations
201 Presidents Circle, Room 308
Salt Lake City, Utah 84112-9017
(801) 581-6773 fax: (801) 585-3350
|Dancefloor für Dinos
Spiegel Online - 1 ora fa
Hunderte Fußabdrücke von Sauriern glauben Paläontologen im Westen der USA gefunden zu haben. Die Spuren liegen so dicht beieinander, dass die Forscher den …
scinexx | Das Wissensmagazin mit Science-News aus - 5 ore fa
Eine erstaunliche Konzentration von Dinosaurierfußspuren haben Geologen an der Grenze zwischen Arizona und Utah entdeckt. Vor rund 190 Millionen Jahren eine …
Other links: (update on 2008-10-21 11:27 Italy)
|Rock records dino ‘dance floor’
BBC News - 17 ore fa
Scientists have identified an amazing collection of dinosaur footprints on the Arizona-Utah border in the US. There are so many prints – more than 1000 …
Other links in Italiano: (update on 2008-10-21 18:05 Italy)
Volume 23, Issue 10 (October 2008), pag 700
A Wet Interdune Dinosaur Trampled Surface in the Jurassic Navajo Sandstone, Coyote Buttes, Arizona: Rare Preservation of Multiple Track Types and Tail Traces
Abstract . Full Text . PDF (2.29M)
A distinctive, disturbed surface with numerous soft-sediment impressions occurs within a wet interdune interval of Jurassic Navajo Sandstone at the Coyote Buttes along the Arizona-Utah border. These high-density impressions are interpreted as footprints that comprise a dinosaur trampled surface. This surface displays an unusual combination of multiple overlapping track types and sizes, distinct to modified footprint features that include claws and toes and rare tail traces. The trampled surface covers 3000 m2 with an average density of 12 impressions/m2 in its main extent. Although modern water collection and biofilms typical of weathering potholes or pits are superimposed on this surface, the primary origin of the impression features are trace fossil structures formed prior to lithification. Four criteria distinguish the impressions as vertebrate in origin: (1) large—up to several tens of centimeters—repeating identifiable foot morphologies; (2) impression floors surrounded by soft-sediment marginal ridges; (3) impressions that are rarely flat and are typically oriented at an angle into the sediment (media) and indicate a clear direction of travel; and (4) multiple in situ ichnofossils on a moist interdune surface that resulted in soft-sediment deformation. At least three ichnogenera—cf. Eubrontes, cf. Anchisauripus, cf. Grallator— and the tracks attributed to a sauropodomorph appear as regular to asymmetric penetrations into the media with digitate features, commonly accompanied by soft-sediment marginal ridges of displaced sand preserved in the sandstone. The trampled surface provides paleoecologic and paleoclimatologic proxies that suggest a pluvial climate shift likely induced groundwater saturation of an eolian interdune that attracted dinosaurs to the area. The trampled surface provides valuable data for refining ecologic and climatic sensitivities recorded in Early Jurassic eolian deposits.
‘Calamari killing field’ fossils found in sea that covered middle England
By Paul Eccleston
Last Updated: 4:01pm BST 21/08/2008
Complete specimen of the largely soft-bodied squid-like creature Belemnotheutis clasping a fish in its arms; collected in the mid-nineteenth century
In turbulent environmental conditions 160m years ago the waters may have been poisoned by a volcanic eruption or suddenly deprived of oxygen wiping out much of the sea life.
Dramatic and newly discovered fossil images reveal how voracious squid-like creatures were lured to the area to feed on the huge numbers of dead fish. Some held prey in their tentacles at the very moment they also succumbed in the deadly waters.
The scientists believe it developed into a predator-trap in which victims acted as a draw on new shoals entering the area before they were themselves overcome in a perpetual deadly cycle.
The Jurassic Oxford Clay provided almost unique conditions for the preservation of ammonites, fish and crustaceans but became world famous for squid-like cephalopods and belemnites with fossilized soft-parts.
There are only a handful of areas in the world where creatures have been preserved in this way.
Soft-bodied creatures such as worms and jellyfish probably dominated marine ecosystems at the time but they rarely show up in the fossil record because they decompose and vanish. Much more is known about creatures with decay-resistant hard-parts, such as bones, teeth or shells.
But in some areas – such as the rediscovered site in Wiltshire which the ancient sea once covered – the normal process of decay didn’t happen and outlines of anatomy – even soft flesh areas such as gut, muscle and eye – were perfectly preserved partly because of the chemical make-up of the sediment.
The areas are known as Fossil Lagerstätten and provide a much more accurate picture of ancient ecosystems.
The site – discovered by chance as the Great Western Railway was constructed in the 1840s – provided a fossil bonanza for palaeontologists.
Many of the best fossils were removed and taken to London for safety but ironically were destroyed in German air raids a century later.
Because of its rich resources the location of the site was jealously guarded by a local carpenter who was an amateur fossil hunter. He collected many of the samples but provided misleading information about the exact location of the site and took his secret to the grave.
Over time the railways cuttings became overgrown and flooded and were eventually lost.
But now they have been rediscovered by scientists from the British Geological Society (BGS) and their work will form part of The Fossil Detectives an eight-part series for BBC FOUR, funded by The Open University (OU) and produced by the BBC’s Natural History Unit, BBC TV series.
In the programmes Dr Hermione Cockburn, an associate lecturer with the OU, leads a team of fossil experts and geologists around Britain looking for the best fossil treasures and mysteries.
Celebrity fossil hunters such as Sir David Attenborough, musician and writer Alex James, and singer/songwriter Billy Bragg also make appearances.
Prior to the new excavation it was unknown whether all of the fossil squid collected in the 1840s had come from one or more level but it showed for the first time that the squid were concentrated at several different levels proving that mass mortality events repeatedly hit the area killing vast numbers of the squid and fish.
The prehistoric shallow sea covered an area from Lincolnshire to Dorset and was bordered by coastal swamps where dinosaurs would have roamed.
Dr Phil Wilby of the BGS described the area as ‘a calamari killing field’.
He said it would have been an unstable environment in which the bottom waters continually switched from being able to support life to becoming hostile to life with fluctuations in oxygen level a constant threat.
“As a preservation site for soft-bodied creatures it is as good as it comes and is recognised by palaeontologists the world over. What we don’t yet know what triggered the preservation. It may be that there was a build up of phosphorous in the sediment and when the creatures died and sank into it the chemical structure was changed,” he said.
The Fossil Detectives is being shown on BBC Four beginning on Thursday August 21.
Dal sito del National geographic (link)
“Amazing” Dinosaur Trove Discovered in Utah
June 17, 2008
Crowded with dinosaurs, petrified trees, and other prehistoric treasures, an ancient riverbed in Utah
is surprising scientists.
The discovery sheds new light on a Jurassic landscape dominated by dinosaur giants that lived 145 to 150 million years ago (prehistoric time line).
In just three weeks of work on federal land near Hanksville, Utah, paleontologists say they unearthed at least two meat-eating dinosaurs, a probable Stegosaurus, and four sauropods—long necked, long-tailed plant-eaters that could reach 130 feet (40 meters) long, making them the largest animals ever to have walked the Earth.
“So far [the paleontologists] have found not only scattered bones but partial and complete skeletons. It’s really amazing,” said Scott Foss, a paleontologist in the Bureau of Land Management’s (BLM’s) Salt Lake City office.
Big Sexy Dinosaurs
Some BLM employees and many locals had known that there were dinosaur bones to be found near Hanksville. But the recent dig led by scientists from the Burpee Museum of Natural History in Rockford, Illinois, was still a shocker.
“Nobody anticipated the scale or the scope of what was there. Once they started excavating, they realized that the magnitude was far more than they had expected,” Foss said.
“About two weeks ago they notified us that this was pretty big and we’d better come and take a look.”
The site, now known as the Hanksville-Burpee Quarry, is part of the Morrison formation. “[The formation is] where all the big sexy dinosaurs that we grew up learning about are most commonly found,” Foss said.
Matthew Bonnan, of Western Illinois University, said, “In the late Jurassic you had the largest animals that ever walked the Earth.
“The sauropods sort of reached their zenith of size at this point,” added Bonnan, who had just returned from the dig site.
(Related: “Giant Duck-Billed Dino Unearthed in Utah” [October 3, 2007].)
Riverbed Graveyard Uncovered
Though the Hanksville-Burpee Quarry today is high and dry, it appears to have once been at a bend in a large, long-gone river.
A bar or other river feature likely collected the corpses of dinosaurs and other animals that died upstream and were washed down during high-water events over several centuries. The result is a logjam of fossilized bones.
The site’s sandstone also encases freshwater clams, petrified trees, and other preserved matter. “There is potential that there could be burrows that contain fossil mammals. We have petrified logs—a whole group of things that I think are going to tell us something very detailed about this environment,” Bonnan said.
(Related: “Ancient Mammal Relative Dug Burrows in Antarctica?” [June 9, 2008].)
The late Jurassic has been studied intensively for more than a century, yet some key questions linger.
“The big open question that remains is the environment in which the Morrison fauna and flora existed,” said Hans-Dieter Sues, associate director for research and collections at the Smithsonian’s National Museum of Natural History in Washington, D.C.
Sues has received funding from the National Geographic Society’s Committee for Research and Exploration.
Early geologists imagined the Morrison-formation region as a vast swamp, the imagined prime real estate for all those sauropods.
“But later geologists argued that the Morrison was deposited in a dry environment with just some large bodies of water,” said Sues, who is not involved with the Hanksville-Burpee dig.
New Look at Familiar Dinos?
Whatever mysteries the new site may hold, it is unlikely to produce any new dinosaur species, Sues said.
“Except for some really small dinosaurs—including possible bird relatives/precursors—or a good skeleton of the giant Brachiosaurus, there is going to be little that is newsworthy regarding Morrison dinosaurs,” he said.
“The big discoveries to be made lie with other groups of Morrison animals, such as flying reptiles and mammals, which are still mostly known from very fragmentary remains.”
But team member Bonnan hopes the Hanksville-Burpee will eventually rival Utah’s other major Jurassic fossil troves—Dinosaur National Monument and the Cleveland-Lloyd Dinosaur Quarry.
“Even if we don’t find anything new in terms of species, we’re looking at old bones with new eyes and new technologies,” he said.
“In the old days it was more about finding the ‘biggest, baddest, bestest’ dinosaurs, and a museum might have just cherry-picked those best specimens.
“Now there is more interest in the fossil assemblage—what does it tell you about the environment?”
The site will close for the season on Friday. But scientists are already anxiously awaiting the resumption of excavations next summer.
“It will take years to understand the real potential, or how big this site really is,” BLM’s Foss said. “But there is something there worth taking a really good look at.”
Sicuramente non è la prima impronta di Anchilosauro tovata nel mondo, come annunciato nell’articolo, tuttavia essendo esse molto rare la scoperta è da ritenersi sicuramente molto significativa.
Articolo tratto da KJTC8.COM
Exclusive: KJCT hunts for dinosaur tracks
Posted: June 2, 2008 12:19 AM
Updated: June 2, 2008 05:45 PM
CACTUS PARK (KJCT)- A Colorado high school teacher says he discovered the first known Ankylosaur dinosaur footprint in the world near Grand Junction about a week ago.
This weekend he headed back to Cactus Park to look for more dinosaur tracks and bones. KJCT News 8′s Sara Goldenberg joined him on a dinosaur expedition.
”It’s about 150 millions years old… the only one in the world.”
The five-toed Ankylosaur dinosaur track measures nine inches long and 12 inches wide– larger than any known Jurassic foot skeletons.
Kent Hups, a science teacher at Manuel High School and a paleontologist, discovered the track in Cactus Park.
”It’s fun to find something really unique, really fascinating, really fantastic to science, because it motivates you and it motivates the other scientists around to really start looking,” he said.
Ankylosaurs were armored dinosaurs related to Stegosaurs. Hups says it’s the only known track of it’s kind in the world, and it can help tell us what these dinosaurs look like.
”When you start realizing that there’s big Ankylosaurs walking around in the Jurassic, it is fun to go look again. It is fun to go look at bones and go see if you can find remains of these animals,” Hups said.
He found the dinosaur track in a sandstone rock. Hups says he noticed unusual holes in the rock, and when he flipped it over, he found the track.
”I started jumping up and down, and yelled at my friend Mike, and he came over and was like, ‘What?’ I was like, we got something really good here.”
Hups says the Morrison Formation is one of the most well-known locations in the world for dinosaur discoveries. And the geology of the area in Western Colorado exposes the fossils.
”I think it’s really good for looking for dinosaurs in this area because things are exposed and you’re able to see,” he said.
He says this huge find means they can start looking for bigger Ankylosaur tracks out here. He says he has a permit especially for that from the Bureau of Land Management.
“It’s like digging for buried treasure. You get a chance to find things, and when you find a dinosaur bone and you find a track like we found, you realize you’re the first person in the history of the world to see it. And it is like digging up treasure,” Hups said.
The rare dinosaur track will go to the BLM. Three replicas were made, and soon you can see a copy for yourself at the Dinosaur Journey Museum in Fruita.
1 – VIDEO by KJBT8.com