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RE: Discovery frequency

There was sufficient interest in the "frequency count" of dinosaurs to post
the references to the list, so here they are. I am also including an
abstract and some quotes from the paper that Peter Dodson and I wrote (the
third in the series originated by Peter).

Counting dinosuars: How many kinds were there?, Peter Dodson, Proc. Natl.
Acad. Sci. USA, Vol. 87, pp. 7608-7612, October 1990

Making The Fossil Record of Dinosaurs, by Peter Dodson and Susan D. Dawson,
Modern Geology, Vol. 16, pp. 3-15, 1991.

Counting More Dinosaurs--How Many Kinds Are There (1996?), by Thom Holmes
and Peter Dodson, Dinofest International:  Proceedings of a Symposium Held
at Arizona State University (editors D. Wohlberg, E. Stump, G. Rosenberg),
pp. 125-128, 1997.

Abstract from the Holmes/Dodson paper: "The description of new kinds of
dinosaurs is an on-going activity. It had been determined previously [in the
Dodson/Dawson paper cited above] that new dinosaurs have accrued in the
interval between 1970 and 1988 at the rate of 6.1 genera per year, for a
total of 285 valid genera. In this paper, we bring the count of dinosaurs up
to date as of the end of 1995. Between 1989 and 1995, 51 genera of dinosaurs
have been added to the list bringing the total to 336 genera, at a rate of
7.3 per year. The top three countries in total dinosaur genera continue to
be the United States, Mongolia and China. In the U.S., 15 new genera were
described, while China dn Argentina each had 8 and Mongolia had 6. With 37%
of all new dinosaurs, theropods seem disproportionately represented. An
important trend is the discovery of dinosaurs of Early Cretaceous age and
the exploitation of certain geographic areas previously poorly known or
underrepresented, including Europe, Africa, Southeast Asia, Australia, and

As for what constituted a "valid" genus for our study: "In general, in order
for a genus to be included, it must have been validly described and based on
fossils that are in principal diagnostic. Genera based solely on teeth or
isolated, non-diagnostic skeletal elements are excluded on principle.
Several of the names on this list represent new names by reason of
preoccupation (Alwalkeria Chatterjee and Creisler 1993 = Walkeria Chatterjee
1987 preoccupied; and Ultrasauros Olshevsky 1991 = Ultrasaurus Jensen 1985

The paper includes information on the distribution of the new dinosaurs by
infraorder, geography, and geologic age and includes complete citations for
all 51 new genera.

Another point of interest from Dodson's 1990 paper (cited above) is his
estimate on the total number of possible dinosaur genera. "The number of
dinosaurs that have ever lived is estimated at 900-1200 genera. The fossil
record of dinosaurs is presently about 25% complete."

--Thom Holmes
dinosaur author at large

-----Original Message-----
From: Michael de Sosa [mailto:ofsosa@uclink4.berkeley.edu]
Sent: Wednesday, December 01, 1999 1:54 PM
To: tholmes@dolphinsoft.com
Subject: Re: Discovery frequency


I'd like a ref for this please.  Thanks!

Thom Holmes wrote:

> I believe the "frequency statistics" originated with Peter Dodson as a
> result of the research he and Osmolska and Weishampel did on the first
> edition of The Dinosauria (circa 1989).  When we both were with The
> Society, this figure was frequently used. Peter and I co-authored a paper
> 1996(?) on the number of valid dinosaur genera, adding to the stats from
> original Dinosauria, and re-confirming a frequency of discovery of about 7
> or 8 new dinosaurs named (published) each year from 1990 to 1995. This can
> also be viewed as about 1 new dinosaur every 7 weeks, although the basis
> the stat is really the number of new dinosaur genera published each year
> peer-reviewed journals that consisted of more than fragmentary material.
> criteria for "valid" genera created a total list of currently accepted
> dinosaur genera of about 325 at that time. My impression is that this rate
> of discovery has continued since 1995. The number is up around 350 or so
> now. I can provide a ref and more detail on our criteria if anyone would
> like it.
> --Thom Holmes
> dinosaur author at large

Michael A. de Sosa
Undergraduate Student
University of California - Berkeley

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