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From: chiaraviglio@husc2.UUCP
Newsgroups: talk.origins,sci.bio
Subject: Re: Dinosaur Heresies
Message-ID: <1223@husc2.UUCP>
Date: Fri, 20-Mar-87 20:13:57 EST
Article-I.D.: husc2.1223
Posted: Fri Mar 20 20:13:57 1987
Date-Received: Sun, 22-Mar-87 19:16:10 EST
References: <14011@cca.CCA.COM> <629@bcsaic.UUCP>
Organization: Harvard Univ. Science Ctr., Cambridge, MA
Lines: 53
Xref: utgpu talk.origins:435 sci.bio:154
Summary: How to make some educated guesses

These answers are from old memories, so caveat emptor.

In article <629@bcsaic.UUCP>, michaelm@bcsaic.UUCP (Michael Maxwell) writes:
> In article <14011@cca.CCA.COM> g-rh@cca.UUCP (Richard Harter) writes:
> >[mini-review of Bakker "Dinosaur Heresies"]
> >...  (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?
> 
> I'm curious--how do we know there weren't any tiny dinosaurs, but their bones
> just haven't survived in sufficient quantities for us to find and identify?
> I suppose the answer is that bones of tiny animals--mammals (and birds?) have
> survived, and we have found them.

	This sounds right.

>                                    So my question is perhaps better worded,
> how easy is it to distinguish mammal bones from tiny dinosaur bones?  How do
> we know that we haven't found fossils of tiny dinosaurs, but just incorrectly
> identified them as mammals (or birds)?  If I recall correctly, most of the
> Mesozoic mammal bones that have been found are jaws and teeth, and I guess
> the dinosaur teeth pattern is quite different from the mammalian pattern.
> Is this correct?

	Yes.  Also, if I recall correctly, the other bones are different as
well (mammal and reptile bones in general are different -- skulls and pelvises
come to mind).

> Has anyone tried to estimate what percentage of the species of dinosaurs that
> were extant during the Mesozoic have been found?  This is related to the
> question of the preceding paragraph--if we've found fossils of 1% of the
> dinosaur species that existed, then it would seem quite possible that we might
> have just missed the small ones.  Clearly we cannot know what percent of the
> unknown number number of species that existed N is (where N is the number of
> species we've found), but is it possible to estimate what that unknown number
> is?

	I don't know what the number is, but it is possible to estimate it by
looking at the rate of discovery of new fossil types -- the decline (after
adjusting for rate of search) gives a hint as to how much is left.  Things
that could mess this up include undiscovered jackpot formations and poor
recording of search missions.

	Incidentally, are you sure we haven't actually found some small
dinosaurs?  I seem to remember reading of ones about the size of chickens.

-- 
	-- Lucius Chiaraviglio
	   lucius@tardis.harvard.edu
	   seismo!tardis.harvard.edu!lucius

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