A meteorite strikes Yucatan, worldwide havoc ensues and 65% of
every living species in the world dies off, including the
Dinosaurs. These are the core elements of the most widely-accepted
theory of dinosaur die off and they are now being challenged as the
cause. It wasn't a single meteorite and all roads do not lead
to the Chicxclub crater.
In a new paper published in the Journal of Geological
Society, a team of scientists led by Princeton University's
Gerta Keller and Theirry Adatte of the University of Lausanne
Switzerland report the meteorite thought to have done the damage --
predates the accepted date of the massive die-off.
The team studied the stratigraphic information at sites
around the 112 mile diamater Chicxulub crater in the northern
Yucatan and concluded the meteorite struck earth as much as 300,000
years before the die off.
H. Richard Lane, program director in the National Science
Foundation (NSF)'s Division of Earth Sciences, which funded the
research. "The two may not be linked after all."
According toe ScienceDaily online:
Advocates of the Chicxulub impact theory suggest that the
impact crater and the mass extinction event only appear far apart
in the sedimentary record because of earthquake or tsunami
disturbance that resulted from the impact of the asteroid.
"The problem with the tsunami interpretation," says
Keller, "is that this sandstone complex was not deposited over
hours or days by a tsunami. Deposition occurred over a very long
time period."
The study found that the sediments separating the two events
were characteristic of normal sedimentation, with burrows formed by
creatures colonizing the ocean floor, erosion and transportation of
sediments, and no evidence of structural disturbance.
The scientists also found evidence that the Chicxulub impact
didn't have the dramatic impact on species diversity that has
been suggested.
At one site at El Penon, the researchers found 52 species
present in sediments below the impact spherule layer, and counted
all 52 still present in layers above the spherules.
"We found that not a single species went extinct as a
result of the Chicxulub impact," says Keller.
This conclusion should not come as too great a surprise, she
says. None of the other great mass extinctions are associated with
an impact, [See TheoryPedia's 'Medea Theory'] and no
other large craters are known to have caused a significant
extinction event.
Keller suggests that the massive volcanic eruptions at the
Deccan Traps in India may be responsible for the extinction,
releasing huge amounts of dust and gases that could have blocked
out sunlight and brought about a significant greenhouse effect.
Get More...
Get a
great overview of Dinosaur impact theory from this
Columbia University series of lecture notes.
http://rainbow.ldeo.columbia.edu/courses/v1001/impact23.html
And rest your brain with Gary Larson's personal, cartoon theory of dinosaur extinction.