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Tip
Sheet: Science & Technology

Tip sheets highlight timely news and events at Washington University in St. Louis. For more information on any of the stories below or for assistance in arranging interviews, please see the contact information listed with each story. For comments on the Science & Technology news tips service, please contact the editor, Tony Fitzpatrick at (314) 935-5272 or tony_fitzpatrick@aismail.wustl.edu.
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Science & Health | Science & Technology
Dinosaur, crab fossils reveal ecosystem secrets

Media assistance:
Tony Fitzpatrick
- (314) 935-5272
Source: Josh
Smith - (314) 935-7033
Source: Ken Lacovara - (215) 895-6456
Related: Schweitzer
Web site
Related: Egyptdinos.org
project Web site
Related: Video documentary
made on the Egyptian project at
carlsagan.com
and www.mphent.com

[St.
Louis, Mo., March 2003] - For
centuries, they wouldn't be caught
dead next to each other.
But now a team of geologists directed
by Joshua Smith, Ph.D., assistant
professor of earth and planetary
sciences at Washington University
in St. Louis, have found a well-preserved
fossil of a crab within inches
of a tail vertebra from a massive
plant-eating dinosaur.
Necrocarcinidae (crab)
meet titanosaurian sauropod
(dinosaur).
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This well-preserved fossil
of a crab was found within
inches of a dinosaur tail
in Egypt's Bahariya Oasis,
the first evidence in literature
of the two found together.
The find helps piece together
what ancient envrionments
might have been like. |
The
find, in Egypt's Bahariya Oasis,
is the first instance of a crab
fossil found with a dinosaur fossil.
It reveals much about both species
and the kind of ecosystem where
the fossils were found, thought
to be a predator-rich mangrove
setting dominated by tree ferns
and other coastal plants, similar
to Florida's swampy Everglades.
The rocks containing these fossils
are about 94 million years old,
which means they date back to
the Cretaceous Period, which lasted
from 130-65 million years.
"The two normally don't hang with
each other, or they are at least
not commonly discovered together,"
said Smith, of crabs and dinosaurs.
Smith made international news
in 2001 when he and collaborators
published results of their discovery
of the second most massive dinosaur
ever unearthed, Paralititan
stromeri, in the same part
of the Bahariya Oasis. "There
have been anecdotal mentions of
crabs with dinosaurs, but those
remains turned out to be lobsters
or ghost shrimp. Even if the time
gap between the two is thousands
of years, we have visual proof
of these two coexisting together.
This is a nice surprise. It fills
in more about this kind of ecosystem."
The results are in a paper that
will be published later this year
in the Journal of Paleontology.
Smith and collaborators from the University of Pennsylvania, the Cairo
Geological Museum, and Drexel University discovered the fossils in
2001, on an expedition for dinosaur bones. They found a dinosaur tailbone,
fossil plants and the crab, all within a foot-and-a-half of each other.
Because there have been informal (though never published in peer-review
journals) mentions of crabs being part of ecosystems where dinosaur
bones have been found, and more importantly because he isn't qualified
to describe a crab, Smith wanted to clarify and sought geologist Carrie
E. Schweitzer, Ph.D., of the Kent State University Department of Geology.
"As far as we can tell from the
literature, this is the first
confirmed notice of a crab associated
with a dinosaur," said Schweitzer,
who is the lead author on the
crab paper. "The find is significant
because it permits paleontologists
to frame a very diverse -- and
thus much more accurate -- description
of what these ancient environments
would have looked like.
"The deposits that enclose the
dinosaur and the crab also contain
crocodile-like animals, various
invertebrates, fish, sharks, plesiosaurs,
a kind of reptile, and turtles
as well as plant material. Thus,
we have a very complete idea of
what types of organisms comprised
the ecosystem."
Crabs, "brachyuran decapods" in
technical jargon, from coastal
habitats are uncommon in the fossil
record because their remains rapidly
disintegrate, either from decomposition
or scavenging by other predators.
The geologists think that the
crabs of the Bahariya Formation
probably were scavengers that
fed on vegetation and other organic
material. They were a possible
food source for fish and other
vertebrates and invertebrates
in the ecosystem.
Smith speculates that it is possible
that small or baby dinosaurs might
have fed on the crabs, but said
speculation is the most he can
do.
"This would have been a very productive
place biologically, for crabs,
they would have been very happy
here," Smith said. "Almost everything
we're finding at the site is a
predator. I could see a baby Spinosaurus
picking up mangrove crabs, but
it's all speculation because we
have no solid proof of what dinosaurs
ate."
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