[meteorite-list] Forget the Meteorites - It Was Insects That Did For The Dinosaurs

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 8 Jan 2008 13:38:31 -0800 (PST)
Message-ID: <200801082138.NAA05944_at_zagami.jpl.nasa.gov>

http://www.guardian.co.uk/science/2008/jan/07/dinosaurs

Forget the meteorites - it was insects that did for the dinosaurs
James Randerson
The Guardian (United Kingdom)
January 7 2008

They were the most imposing and terrifying creatures that have ever
walked on the surface of the Earth, but according to a new theory the
dinosaurs may have been pushed towards extinction 65m years ago by
humble insects.

During the later part of the dinosaurs' dominion over the land, insects
underwent an explosion in diversity and in the process dealt a double
whammy to the lumbering giants - they spread disease and contributed to
a transformation of vegetation which the plant-eating reptiles failed to
adapt to.

The hypothesis is laid out in a new book by entomologists George and
Roberta Poinar. George Poinar is a professor of zoology at Oregon State
University.

"We can't say for certain that insects are the smoking gun, but we
believe they were an extremely significant force in the decline of the
dinosaurs," said Poinar. "Our research with amber shows that there were
evolving, disease-carrying vectors in the Cretaceous [period], and that
at least some of the pathogens they carried infected reptiles. This
clearly fills in some gaps regarding dinosaur extinctions."

In the gut of one biting insect preserved in amber - fossilised tree sap
- from that era, the team has found the pathogen that causes the
parasitic disease leishmaniasis, and in another they found a type of
malaria parasite that infects birds and lizards. By inspecting
fossilised dinosaur faeces, the team also found parasitic microbes that
are carried by insects.

Apart from spreading disease, the insects were busy pollinating
flowering plants.

These gradually took over from seed ferns, cycads and gingkoes. If
herbivorous dinosaurs could not adapt to this new diet they would have
gone hungry.

Poinar believes that the most popular theory for the dinosaurs' demise -
that a meteorite impact changed the global climate - falls short because
the extinction took too long.

"Other geologic and catastrophic events certainly played a role. But by
themselves, such events do not explain a process that in reality took a
very, very long time, perhaps millions of years. Insects and diseases do
provide that explanation."
Received on Tue 08 Jan 2008 04:38:31 PM PST