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Big Bakker article in June Discovery Mag
"And now investigative research paleontologist Bob Bakker at the Wyoming
International Dinosaur Society is pushing us into really uncharted dinosaur
territory - behavior. By studying teeth of allosaurs, the top predators in
North America about 150 Ma, Bakker has concluded that the animals we have long
thought of as robotic eating machines (think land sharks) were nurturing,
protective, and attentive to their young, which they probably raised to early
adulthood."
>From Discover Mag, June 2003: "Dinosaur Family Values".
This looks like an article that is a rehash of Bakker's "Raptor Family Values"
paper from Dinofest in 1997. As with articles like this, it gives a summary of
Bakker's life's work, mentions his distaste for the "pompous, priestly
language" of the academic establishment, etc... Good remarks come from the
likes of John McIntosh... There are tid bits about his "lone wolf" reputation
and such as well, coming from anonymous quotes of other paleontologists... such
as from "A specialist in dinosaur anatomy"... Oh, it also says that "Raptor
Pack", a summary of his research aimed at young readers, will be published this
month.
Bakker talks about ceratosaurs... and how they had low, long body plans with
deep flexible tails... "A really good swimmer"... So, finding their teeth at
surf sites made sense. The article says that these guys probably ate fish by
the water's edge. Bakker says "Ceratosaur teeth are sharp, long, delicate, and
rarely worn. Ceratosaurs were pretty careful in their chewing; they were making
filets. Megalosaurs had thick, coarse teeth, good for crushing stuff. Allosaur
teeth are sort of in the middle." This is part of the ceratosaurs liked
different habitats than allosaurs deal.
The article goes on to explain his findings from 33 sites at Como Bluff... How
the teeth of adult and young allosaurs were basically the same, meaning they
ate the same things (unlike crocodilians which show a different pattern)...
Bones of prey exhibit baby and adult teeth marks... Baby teeth are found shed
with adult teeth, meaning they were eating in the same place, feeding
together... which leads to his "lairs", being not dens or nests, but just a
communal feeding area. Meaty parts of prey (rumps, thigh, upper tail) were
dragged to the lairs, and were buried by slow moving water (fined grained
sediments), showing that they didn't just wash in. These lairs also contain no
other predator teeth, saying to Bakker that the area was well patrolled by the
allosaurs. Bakker explains that like modern hawks and eagles, allosaurs had
extended families in which older siblings helped the parents to raise the next
generation.
Is that true? Do some raptors do that today? I never heard of such a thing.
Something interesting is a remark about Como Bluff concerning camarasaurs. The
article says that Bakker has found whole teeth, but rarely shed ones... meaning
to him that this is the sign of migrations, being that the sauropods were not
stopping to feed. Locales in the Cretaceous that have high percentages of shed
teeth mean these were feeding grounds where the sauropods stuck around for an
extended time.
There's an interesting comment that Bakker makes about preservation that's
counter intuitive to whatcha would think... A pristine and complete skeleton is
pretty much a near-useless prize. "It tells you very little because it was
never part of the food chain. The better looking the specimen, the less
information it contains. You want chewed up junk."
The article talks about Bakker's environmental scenario for the Como Bluff
area; A plentiful wet season, and a lean dry season. So, what did the allosaurs
do? A lack in juvenile allosaur teeth about 1/3rd of the way grown at these
lair sites means that the allosaurs packed up and left during part of the year,
only to return with better environmental conditions. The missing teeth were
found at ancient perennial lake shores. So, during the dry season, everyone in
the neighborhood corraled around water holes. He says, "We see evidence of
broken bones, compression fractures, bite wounds, bacterial infections that eat
away the jawbone. Our allosaurs just get wacked.".
The rest of the article goes on to express concern about Bakker's habit of not
publishing in peer-reviewed journals, though he says that his reputation of
spurring peer-reviewed journals is unfair. Kay Behrensmeyer from the
Smithsonian, a fellow grad student from Harvard, and Phil Currie, are both
quoted expressing concern. Bakker responds by saying that he does submit his
work for review but that he prefers museum bulletins and symposia proceedings
because "they publish longer papers and place more emphasis on long-term field
work". The article says that Bakker's latest, most complete shed-tooth study,
will appear in September as a peer-reviewed monograph by the University of
Indiana Press.
The article also says that some of his colleagues question the way he
interprets his work. Jack Horner says "Dinosaurs shed their teeth on a regular
basis. It was like a conveyor belt. Just because you find shed teeth doesn't
mean they were feeding on something.". Brent Breithaupt, director of the
Geologic Museum at the University of Wyoming says, " What I have one of the
biggest problems with is the idea that 150 million years ago an activity
occurred right there at a given spot. If we're talking about footprints, you
can say, 'Yes, a dinosaur was there.' But I still believe that the teeth and
bones were deposited somewhat randomly through a change in velocity of a stream
or something like that."
Bakker responds by saying that teeth are shed away from feeding sites, but only
a few such cases have been found in his study. He says that the key point is
that predators leave copious shed teeth where they feed heavily. He says that
the patterns he is documenting have never been done by anyone else, anywhere.
His interest lies not in the day to day life of a dinosaur, but in developing a
time-averaged portrait of dinosaur behavior. The work has inspired researchers
like Behrensmeyer to do similar studies on the environment of human ancestors
in Africa by collecting croc teeth, and the finding of bones of adult and
juvenile theropods mixed together in locales like Canada, Argentina, and Japan,
are, as Phil Currie says, "in concentrations that are just too high to be
coincidental."
I know that the Canadian theropods are albertosaurs (or has it now been
permanently changed to gorgosaurs?), but... Is Argentina Giganotosaurs?... and
what is Japan?... Where can I get papers on these things???
Illustrations are by James Gurney. His feathered baby allosaurs are just
adorable. <G>. And that's about it for the article, besides this:
Bakker says, "Can I put my e-mail address in the story so graduate students can
write me if they want to do this?"........ zorilla47@aol.com
Kris