There is a lot of interest in the fossils of southern Florida, many of
which were documented by Ed Petuch. Because Petuch has an earned
reputation as a splitter, many people tend to doubt that it is possible
to get so many new species in so short a time and so small an area. Most
of the people reading CONCH-L are not familiar with modern concepts of
evolution, nor with geology, and thus they try to evaluate all Petuch's
species based on their understanding of modern shells, which is not fair.
An article in Nature, vol 293, p427-428 by P.G. Williamson, 1981,
'Paleontological documentation of speciation in Cenozoic molluscs from
Turkana Basin', shows both why Petuch is on the right track in his
determinations, and why he is so disparaged for his work. This article,
dealing with fresh water shells of 13 lineages in Plio-Pleistocene stream
and lake deposits in East Africa, is a classic work which shows that
rapid evolution of new species is possible (taking only about 5000 to
50,000 years), that when intermediates are found they show great
variability, and that new species can be reasonably widespread relatively
rapidly (over an area comparable in size to southern Florida). This
article does not name new species, but it does show how they were
documented. Some 33,000 specimens (from bulk samples, not selected
specimens) representing 13 lineages were measured, averaging 18
measurements per shell. Petuch makes about one measurement per type
specimen, writes very short descriptions, and it is not clear how many
specimens are used to base a new species on, nor what he does with
specimens that seem to fit between species. Williamson's measurements,
used to describe, document and compare species, allow a high level of
certainty that what is described is a distinct species. The collection
of specimens was done in a very well defined stratigraphic and geographic
context. (This area was worked over by many geologists over many years,
especially to document its human fossils made famous by the Leakeys.)
Petuch has done his own stratigraphy, but it is rather rough in
comparison, and because much of the material has come from dredging which
tends to mix the layers, it is less than 100% accepted by many workers.
Also because of privacy problems with quarrys that exclude collectors,
locations given by Petuch can be vague.
Overall, many of the Plio-Pleistocene species that Petuch named have a
high probability of standing the test of time (except by those workers
who disagree with everything he does and reject almost all his species
offhand). However, the variability showed during speciation probably led
to many extra names, as the extremes in these variable, short lived
populations got named unnecessarily.
Petuch considers himself as a pioneer, working in an area which was
previously poorly documented and where new material was being found
abundantly. Instead of trying to spend the time documenting everything
to the strict modern standards which are now required for describing
acceptable new species, Ed uses the older, simpler standard, allowing him
to roughly document everything and give it a handle and a context for
further workers to build upon. Many specialists would have preferred him
to not name new species unless they could be named to a higher standard.
Petuch feels that a few mistakes are less important than bringing this
exciting new material to a wide audience (he is a teacher by
profession), and that new species names and new stratigraphic names are
necessary to document it.
There are abundant problems left, and many detailed studies can be made
in any of the groups that Petuch dealt with. There will be many
corrections made, details will be documented better, and our
understanding of these fossils and their time will increase tremendously.
Overall I feel that Petuch made a very valuable addition to our
understanding of the Florida Plio-Pleistocene, and that the fossils he
named must be taken seriously and not dismissed without the sort of
studies that his detractors wanted him to do.
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