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Re: Dinosaur counts
In a message dated 96-01-13 15:11:29 EST, firstname.lastname@example.org (Glen J. Kuban)
> Anyway, since I monitor the C/E controversy and may write on this
>someday, I thought I would ask here: What does the 775 general count
>recently posted represent? Is that the number of genera ever
>named/published? What is the best estimate of the number of valid
>names (eliminating synonyms, dubia, etc)? An even tougher question
>might be: about how many different or valid *species* are known?
>Since even professionals seem to disagree along "lumper" and "splitter"
>lines, maybe even some plausible ranges of numbers would suffice here.
>Another, perhaps even more speculative question might be: how many
>dinosaur genera/species are likely to have lived in the entire
>mesozoic? This will lead of course automatically provide estimates of
>the percentage of dinosaurs that have already been found and the
>percentage remaining to be found.
At the risk of sounding like a never-ending commercial, I address these very
questions (with references to many current works) in _Mesozoic Meanderings_
#2, the third printing of which will be available shortly. (I'm still adding
cladograms to it. It could well be the most cladogram-rich archosaur
publication ever written.) _MM_ #2 provides the only published listing of all
archosaur _species_ (excluding advanced crocodylians and avialan birds)
The 775 genera are all the distinct dinosaur genera based on fossil body
parts, from well founded to highly dubious, including _nomina nuda_, that I
have come across in a 25-year search of the literature. Misspelled names are
not included, since they are legion. (But they _are_ included in _MM_ #2.)
Removing synonyms and dubious names would cut this number down to about half.
Current _MM_ #2 counts for Theropodomorpha, Sauropodomorpha, and Ornithischia
are: 194 genera (52 doubtful), 258 species (102 doubtful); 111 genera (17
doubtful), 165 species (37) doubtful); and 204 genera (52 doubtful), 299
species (85 doubtful); respectively. When I say doubtful, however, they're
DOUBTFUL; other workers might raise those counts somewhat.
I estimate on the order of 50,000 dinosaur genera and up to half a million
individual species populated the Mesozoic from the Middle Triassic through
the end of the Cretaceous, a period of time longer than 160 million years. As
much as 90% of these taxa, however, lived in non-depositional regions where
their fossils would not be preserved, and we are highly unlikely ever to find
them. Also, many of these taxa were small (e.g., crow-size), birdlike forms
(dino-birds) seldom found (because of their small size and fragility) even in
regions favorable to fossilization. Altogether, I estimate several thousand
dinosaur genera were alive at any one time during the Mesozoic (but only
about a hundred or two of the _big_ dinosaurs), which is entirely in line
with estimates for extant mammals, birds, and reptiles.