Croc classification (was Re: Sarcosuchus and Dumbing things down)

["Steve Salisbury" <steve_salisbury@bigpond.com>]

As huge a shock as it might be to some of you, there are a few of us fossil
croc people out there who actually prefer to use a 'traditional'
classification.  Short-comings of the cladistic method and its philosophy
aside, there are a number of good reasons for this.

>      The broader term "crocodylian" should apply to members of Crocodylia,
> but we still are faced with two different concepts of what Crocodylia
> includes.  The traditional concept is Crocodylia sensu lato, used by Alfred
> Romer, Robert Carroll, Encyclopaedia Britannica, and lots of other
> references, and relatively recently in Mike Benton's 1997 classification.

Contrary to the assertions of several cladists, Owen did not use the term
'Crocodylia' (with a ?y¹ instead of an ?i¹) when he emended Gmelin's
Crocodili in 1842 to additionally encompass fossil taxa.  The latter
spelling was introduced in 1973  by Rodney Steel, who considered it to be in
accord with the correct spelling of Crocodylus (note that Steel's motivation
had nothing to do with the establishment of a crown group).  Up until 1973,
Crocodilia was broadly equivalent to what most cladists now call
Crocodylomorpha.  About the only point of contention prior to 1973 (and
indeed for about a decade after) was whether Sphenosuchia should be placed
in Crocodilia or Thecodontia.

The usage of Crocodilia as an ordinal taxonomic term from 1842 to 1973 is
the reason these animals are referred to as crocodilians (with an 'i').
Eusuchians, mesosuchians (such as pholidosaurids) and protosuchians are all
crocodilians.  Within a traditional Linnean classification, Crocodylia is an
invalid term, since Crocodilia has priority, having been used consistently
for over 130 years.

I therefore fully endorse Sereno when he calls Sarcosuchus a crocodilian.
Only one problem: he's a cladist.

Steve




---------------------------
Steve Salisbury

Palaeontology and Geology, Queensland Museum
PO Box 3300, South Brisbane, Q 4101, Australia

www.Qmuseum.qld.gov.au