All The Dinosaurs That Lived

From: Dinogeorge@aol.com

In a message dated 96-01-13 15:11:29 EST, paleo@ix.netcom.com (Glen J. Kuban) writes:
>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.

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.