[meteorite-list] Signs Earth Recovered Quickly From Asteroid Impact

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:01:35 2004
Message-ID: <200206280051.RAA21463_at_zagami.jpl.nasa.gov>

http://www.cnn.com/2002/TECH/science/06/27/ancient.rainforest.ap/index.html

Signs Earth recovered quickly from asteroid
Associated Press
June 27, 2002

CASTLE ROCK, Colorado (AP) -- Scientists digging south of Denver say they
have uncovered evidence of a lush and vibrant rainforest that emerged
surprisingly soon after the asteroid collision that wiped out the dinosaurs
65 million years ago.

The fossils of more than 100 kinds of towering conifer trees, huge ferns and
blooming flowers challenge scientists' long-held assumption that a desolate
Earth took about 10 million years to recover from the catastrophe and
sprouted only a few dreary plant varieties for a long time.

Instead, the finding suggests that plant life -- at least at this now-dry
prairie along Interstate 25 -- was flourishing as early as 1.4 million years
after the impact. Some of the tree fossils measure 6 feet in diameter.

"It not only recovered, it went crazy," said Kirk Johnson, paleontology
curator at the Denver Museum of Nature and Science. He reported the findings
in the latest issue of the journal Science.

In fact, scientists said it might be the earliest example on record of a
true tropical rainforest.

Other plant fossil experts who did not participate in the study said the
discovery was totally unexpected.

While one site cannot explain plant life around the world during that
tumultuous period, experts said the Castle Rock fossils will compel them to
reconsider the period of life immediately following the dinosaurs'
extinction, known as the lower Paleocene.

"I never would've put this so early in the Paleocene," said Leo Hickey,
paleobotany curator at Yale's Peabody Museum. "A flora of this diversity and
richness is really striking."

In their study, Johnson and Denver museum associate Beth Ellis said a
comparison of fossils before and after the apparent asteroid impact indicate
that the forest is not a holdover from the days of the dinosaurs but
something that sprang up later.

Also, Johnson said the plants that grew there are not the same type as those
that grew during the pre-asteroid Cretaceous Period. Instead, they are more
closely related to other plants that typically grew during the Paleocene.

The ancient rainforest was more vibrant than some tropical locations today.
Museum researchers have identified at least 104 plant species at the Castle
Rock site. In contrast, many modern research sites in Brazil contain 40 to
60 plant species, while a location in Peru contains as many as 293.

How a rainforest grew at the site remains unclear.

Johnson believes the Castle Rock rainforest was nourished by humid
Florida-like heat and 100 inches of rain a year, probably delivered by
monsoons that brewed in an older, larger version of today's Gulf of Mexico
and an ancient sea covering what is now the northern Great Plains.

The site was discovered in 1994 by a state highway worker. It is scheduled
to be demolished later this year in a road-widening project.
Received on Thu 27 Jun 2002 08:51:39 PM PDT