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Mexican dinosaurs



From: Ben Creisler bh480@scn.org

In case this news release has not been mentioned yet:

http://www.unews.utah.edu/p/?r=021208-1
NEW DINOSAUR FROM MEXICO OFFERS INSIGHTS INTO ANCIENT LIFE ON WEST AMERICA

Cretaceous-era duck-billed dinosaur discovery opens new window into time
when much of continent was submerged

Media Contacts

Feb. 12, 2008 - A new species of dinosaur unearthed in Mexico is giving
scientists fresh insights into the ancient history of western North
America, according to an international research team led by scientists from
the Utah Museum of Natural History at the University of Utah.
 
"To date, the dinosaur record from Mexico has been sparse," said Terry
Gates, a paleontologist with the Utah Museum of Natural History, Utah's
designated natural history museum.
 
The new creature - aptly dubbed Velafrons coahuilensis - was a massive
plant-eater belonging to a group of duck-billed dinosaurs, or hadrosaurs.
"Velafrons is a combination of Latin and Spanish meaning "sailed forehead,"
in reference to the large sail-like crest that grew atop the dinosaur's
head," said Rosario Gomez, director of the paleontology program in
Coahuila, Mexico. "The second part of the name honors the state of Coahuila
in north-central Mexico, where the specimen was found," said Gomez. 
 
Utah Museum of Natural History paleontologists teamed up with researchers
from the Utah Geological Survey; Coordinacion de Paleontologia, Secretaria
de Educacion y Cultura de Coahuila the Museo del Desierto, in Saltillo,
Coahuila, Mexico; and the Royal Tyrrell Museum, in Drumheller, Alberta,
Canada, to excavate and study the 72-million-year-old specimen. The species
was announced in the December edition of the Journal of Vertebrate
Paleontology.
 
Mexico's arid climate poses challenges for dinosaur hunters, Gates
explained. With little rainfall, there is minimal erosion, which means
fewer fossils ever see daylight. Yet the fossils emerging from Coahuila
turn out to be a vital part of the North American story for the latter part
of the Age of Dinosaurs. 
 
 
A Different World
 
For most of the Late Cretaceous, high global sea levels resulted in
flooding of the central, low-lying portion of North America. As a result, a
warm, shallow sea extended from the Arctic Ocean to the Gulf of Mexico,
splitting the continent in two. Dinosaurs living on the long, narrow,
peninsula-like western landmass - known as Laramidia, or more simply, "West
America," - occupied only a narrow belt of plains that were sandwiched
between the seaway to the east and rising mountains to the west. Central
America had not formed at the time, which made Mexico the southern tip of
the continent.
 
In many ways, the Late Cretaceous is the best-understood time during the
Age of Dinosaurs, thanks in large part to over 120 years of dinosaur
hunting in Canada, Montana, and the Dakotas. "Yet the dinosaurs from Mexico
have remained a mystery," noted Scott Sampson, a Utah Museum of Natural
History paleontologist and co-author of the study.
 
Gates described the arid, desert terrain where the dinosaur was recovered
as nothing like Mexico during the Late Cretaceous. About 72 million years
ago, this region was a humid estuary near the southernmost tip of West
America, an area where salt water from the ocean mixed with fresh water
from rivers. Many of the dinosaur bones are covered with fossilized snails
and marine clams, indicating that these animals inhabited environments near
the shore.
 
In addition to isolated skeletons, the researchers found large bonebeds of
jumbled duck-bill and horned dinosaur skeletons. These sites appear to
represent mass death events, perhaps associated with powerful storms like
those that are known to occur around the southern tips of Africa and South
America today.
 
"The region was periodically hammered by monstrous storms," Sampson said,
"devastating miles of fertile coastline, apparently killing off entire
herds of dinosaurs."
 

Recovering a Hatchet Head
 
Until recent years, there have been few large-scale paleontological
projects in Mexico focused on the Age of Dinosaurs. Velafrons stands as one
of the first dinosaurs to be named from Mexico.
 
The creature comes from a rock unit known as the Cerro del Pueblo
Formation, which dates to around 71.5 million to 72.5 million years ago.
The skeleton was discovered in the early 1990s on the outskirts of a small
town called Rincon Colorado, about 27 miles west of the city of Saltillo.
 
The skeleton was found by Martha Carolina Aguillon, and excavated over the
course of several seasons by members of the Coordinacion de Paleontologia
de la Secretaria de Educacion y Cultura de Coahuila under the direction of
Jim Kirkland, of the Utah Geological Survey, and Rene Hernandez-Rivera,
Instituto de Geología, Universidad Nacional Autónoma de México. Much of the
excavation work was completed by volunteers as a participant-funded
research project organized by the Dinamation International Society and the
staff of the Museo del Desierto.
 
On becoming Utah's state paleontologist, Kirkland encouraged Scott Sampson
and his students to take over his role on the Coahuila Paleontological
research project.
 
Then, in 2002, Sampson spearheaded the first of two paleontological
expeditions to Coahuila, by securing funds from the University of Utah and
National Geographic Society. The Utah Museum of Natural History crew, along
with other researchers from Mexico, Canada, and the U.S., undertook the
daunting task of completing the hadrosaur excavation, in addition to
locating several other sites that contain new dinosaur species.
 
Armed with a jackhammer and shovels, the crew returned to the Rincon
Colorado dig site, where they labored for two weeks through 12 feet of
overburden, eventually uncovering the ancient skull. Upon its arrival at
the Utah Museum of Natural History, the skull then required another two
years of meticulous preparation by Jerry Golden, a skilled volunteer at the
museum.
 
Based on the development of several bony features on the skull and
skeleton, the scientists believe that this animal was still a youngster at
the time of death. Nevertheless, although not yet fully grown, Velafrons
would have been on the order of 25 feet long, suggesting an impressive
adult size of 30 feet to 35 feet.
 
Gates explained that Velafrons represents the first occurrence of a crested
duck-billed dinosaur in this region of North America. "The crested
duck-billed dinosaurs are an extraordinary example of vertebrate
evolution," he said. Unlike other animals where the nose bone lies in front
of their eyes, these dinosaurs transformed their skulls so that the nose
rested atop their skull. The snout extended backward, up their face, in
order to fill the gap left by the relocated nose bone.
 
Interestingly, breathing was not straight-forward for Velafrons and its
kin. Air flowed through a series of passages from the snout, into their
crest, and finally inserting through a hole above their eyes. Scientists
are uncertain what Velafrons' fan-shaped crest would have been used for,
but a leading hypothesis suggests mate attraction, which explains the
complex nasal passages as a possible musical instrument.
 
 
An Ancient Ecosystem Revealed
 
In addition to Velafrons, the most recent expeditions recovered remains of
a second kind of duck-bill dinosaur, as well as a plant-eating horned
dinosaur. Like its famous cousin, Triceratops, the new Coahuila horned
dinosaur bore a massive horn over each eye and a long bony frill projecting
rearward. The Cerro del Pueblo Formation has also yielded remains of large
and small carnivores, including large tyrannosaurs (though smaller, older
relatives of T. rex), and more diminutive Velociraptor-like predators armed
with sickle-claws on their feet. As well as an abundance of fossilized
bones, researchers discovered the largest assemblage of dinosaur track ways
known from Mexico, a large area crisscrossed with the tracks of different
kinds of dinosaurs. In all, the emerging picture is one of a diverse group
of dinosaurs, perhaps representing an entirely new set of species.
 
Gates noted that this project is about much more than naming new dinosaurs.
Each new species represents another vital piece of the puzzle as we attempt
to comprehend the world of dinosaurs.
 
As might be suspected, paleontologists are excited about the future
paleontological potential of this area.
 
"I am amazed at how prolific this region is," Gates said of the amount of
material waiting to be collected. "Given the large number of fossils, the
high quality preservation, and the great research team that is working this
area, more spectacular discoveries are just around the corner."
 
"Dinosaurs from this particular period are important because this is a time
that is relatively poorly understood," said Don Brinkman, a project
researcher from Canada's Royal Tyrrell Museum of Paleontology, who along
with Aguillon, is studying the non-dinosaur vertebrates found at the site,
including turtles, fish, and lizards. "The locality in Mexico goes a long
way to filling in a gap in our knowledge of the record of changes in
dinosaur assemblages throughout the Late Cretaceous era."
 
Few dinosaurs from this time period are known in North America outside the
Drumheller region of Alberta, which is where the Royal Tyrrell Museum is
located. Brinkman explained that researchers now have two points of
comparison to examine not only different dinosaurs, but also different
ecologies.
 
Research teams want to find examples of plant life and smaller animals that
co-existed with these dinosaurs. This information can be compared with
collections made in other parts of North America to understand north-south
variations in species and entire ecosystems.
 
Sampson added, "Now that we've cracked open this amazing window into the
world of dinosaurs, we look forward to future expeditions that will
undoubtedly reveal more of Mexico's ancient past."
 
In addition to advancing the field of paleontology, the researchers hope
that this project in Coahuila may encourage more tourism to the area and
bring attention to the Museo del Desierto, where the original specimen will
be permanently housed.


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