Travel Reference
In-Depth Information
stead of being composed of many species,
Nautilus
was beginning to look
much mote like a typical, low-diversity living fossil. In 1995 we named the
other living nautiloid genus
Allonautilus (alio
means "other").
That was all very well, but now we were in a quandary. It appeated that
shell characters and genetic chatacters were giving two very different classi-
fications for the Nautilus species. And because the shell chatacters used orig-
inally to define the living
Nautilus
species by the classical taxonomists Lin-
naeus, Sowetby, and Lightfoot in the eighteenth and nineteenth centuries
were the same ones used by Millet and Kummel in the twentieth century fot
classifying fossil nautiloid species and geneta, it appeated that if the modern-
day species were oversplit (too narrowly defined), so too might be the thou-
sands of fossil nautiloid species. But could the genetic results be trusted?
Didn't the combined paleontological wisdom of so many past students of the
fossil cephalopods mean more than a few genes? To answer these questions,
we had to examine the fossil record, as well as genes and living animals,
using cladistics.
Cladistics to the rescue
Bruce Saunders and I thus embarked on a new attempt to reconsttuct the
phylogeny of all nautiloid geneta since the Jurassic Period. Our intetest was
stimulated equally by our anatomical research on
Nautilus scrobiculatus
and
by the newly emerging DNA work conducted on tissues that the two of us
had obtained in the 1980s. But a third source of evidence also was emerging,
for many new discoveries of fossil nautiloids became available in the early
1990s as well.
We intended to use cladistics to analyze the various genera and species
of nautiluses both living and dead. Our nearly two decades of studying Nau-
tilus species had given us new insight into just what a fossil "species" ought to
encompass in tetms of variability; we thus used the modern animals as a guide
to interpreting fossil taxa. But we needed more than simply an understanding
of variability to conduct such a study: We needed many additional hard-part
