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From: g-rh@cca.UUCP
Newsgroups: talk.origins,sci.bio
Subject: Dinosaur Heresies
Message-ID: <14011@cca.CCA.COM>
Date: Mon, 16-Mar-87 08:32:56 EST
Article-I.D.: cca.14011
Posted: Mon Mar 16 08:32:56 1987
Date-Received: Wed, 18-Mar-87 02:49:22 EST
Reply-To: g-rh@cca.UUCP (Richard Harter)
Organization: Computer Corp. of America, Cambridge
Lines: 71
Xref: utgpu talk.origins:416 sci.bio:144


	Bakker, the enfant terrible of paleontology, has finally written
a book called "Dinosaur Heresies" which I can heartily recommend.  Bakker
is the man who argued and publicized the view that the dinosaurs were
warm blooded.  The book goes over a lot of interesting ideas with a lot
of supporting detail and argument.  Among the topics are:

(a) A lot of detail and discussion on the argument that the dinosaurs
were warm blooded.  These include the Haversian canal arguments, the
predator/prey ratio arguments, and the arguments from physiological
structure that dinosaurs must have had high energy metabolisms.  He
does not discuss the high growth rate of the young argument.  (It is
now known that Hadrosaurs grew very fast -- 9 feet in the first year.
Fast growth rate in the young is characteristic of warm blooded animals
and not of cold blooded animals.)

	He also debunks the theory that dinosaurs were homeothermic, i.e.
that they depended on the thermal inertia of large body mass to preserve
a high internal temperature.

(b) He discusses the arguments for classifying dinosaurs as a class rather
than as two subclasses subordinate to reptilia.  He also discusses the
arguments (which he supports) for classifying birds (Aves) as a subclass
of the dinosaurs.

(c)  He discusses the general superiority of gizzards and the probability
that the long necked high grazers (brontosaurus, et al) had gizzards.
(The great advantage of the gizzard is that mechanical reduction and
enzymatic softening of food can be done concurrently without interfering
with the consumption of food.)  He argues that the relatively small heads
of brontosaurs (a term he uses generically for long necked, four legged
plant grazers, rather than just for Apatosaurus) did not bar them from
being warm blooded.

(d) He convincingly argues that dinosaurs were land animals rather than
swamp animals, and that the traditional picture of plant eating dinosaurs
living in swamps and eating soft water plants is seriously in error.

(e) He is a skeptic about the extraterrestrial hypotheses for the great
dying.  He is inclined to place the onus on ecological collapse due to
the joining of the continents at the end of the Cretaceous.  [My opinion
is that Bakker is generally right, but that the coup-de-grace for the
dinosaurs was indeed extraterrestrial.]

(f) He discusses the general argument that the dinosaurs were, on the
whole, more successful than the mammals.  He argues strongly for their
physiological superiority.  And, of course, there is the blunt fact that
for 150 million years the dinosaurs preempted all large land niches
and displaced the therapsids (protomammals) with ease.

	I can't do justice to the book here; go get a copy and read it.
Some obvious questions that occurred to me are: (1)  If the birds are
modern dinosaurs and the dinosaurs metabolism was superior to that of
the mammals, then we should expect that the birds today are metabolicly
more effecient than mammals.  Is this true?  (2)  One of the striking
things about dinosaurs is that they were large -- there were no very
small dinosaurs (and some got very large indeed.)  Why?  Lack of thermal
insulation is the obvious answer.  However thermal protection was evolved
at least twice (fur for the pterosaurs and feathers for the birds).  It
is also notworthy that the branches that developed thermal protection
did occupy small body niches and took to the air.  (3)  Why didn't any of
the dinosaurs (except birds) survive the great dying.  In previous great
dyings the dinosaurs came back nicely; moreover the old forms did not go
totally extinct.  For example, brontosaurus and kindred were typical of
the Jurassic and went extinct at the Jurassic-Creataceous die out; however
the group did not die out, even though they lost their pre-eminance;
Alamosaurus lived in the Cretaceous.

-- 

Richard Harter, SMDS Inc. [Disclaimers not permitted by company policy.]