Re: Deinonychus and Velociraptor

[lwitmer@acl.nyit.edu]

In reponse to recent postings by DAVEH47@delphi.com and Peter Buchholz 
about the synonymy of Deinonychus and Velociraptor, I have a few comments.  
As Des Maxwell announced to this list on May 12th, he and I are 
redescribing the skull of Deinonychus based on newly discovered material as 
well as existing material.  In fact, all known skull material of this beast 
is now sitting (locked up) in a Lane cabinet in my lab.  One of the several
objectives of our study is to assess Greg Paul's alpha taxonomy.  Des is in 
the field right now (on our DinoSoc-funded Cloverly dinosaur project) so I 
won't give much away, and the research is still in progress.

The synonymy of the generic names Deinonychus and Velociraptor 
fundamentally involve two issues: (1) the nature of specific similarities 
and differences, and (2), more generally, the scientific interpretation of 
such resemblances.  With regard to the first issue, after detailed study of 
Deinonychus as well as the holotypic and new material of Velociraptor 
(thanks to Mark Norell at the AMNH), we find D. antirrhopus and V. 
mongoliensis to be even more different than anyone supposed.  Greg made a 
few minor (and understandable) mistakes that impacted significantly on his
restorations and interpretations.  

But so what?  We say they are different species, as did Greg.  Species are 
what really count.  We all agree that D. antirrhopus, V. mongoliensis, and 
a third species, Saurornitholestes langstoni, are all very closely related
---more closely to each other than any are to other theropods.  Therefore, 
we all agree on the evolutionarily most important issue: that there is a 
clade with three species.  The name for this clade is at issue: Greg says 
the name is Velociraptor, whereas we would go up a step and say 
Velociraptorinae.  The Linnean system forces us to make this decision, 
although we recognize it to relate more to taxonomic bookkeeping than much 
else.

Why do we recognize Deinonychus as a distinct, monotypic taxon?  Again, two 
issues...  The first is the nitty gritty science of morphology, 
stratigraphy, and biogeography---D. antirrhopus and V. mongoliensis are 
simply too widely separated in appearance, time, and location for our 
tastes.  The second issue is a bit fuzzier and relates to the probable 
level of species diversity for these small theropods.  It seems unlikely 
that over the known time span of this clade (on the order of 30 my) that we 
would have found all the species within the clade and that there were only 
three.  Instead, it seems more likely that each of the three known species 
represents a twig of perhaps separate and perhaps quite extensive radiations.   
 
In other words, the clade was probably very diverse, and we have sampled 
just a small bit of it.  Could we sink them all within Velociraptor?  Sure, 
it wouldn't hurt my feelings.  However, it would run counter to the 
traditional application of this taxonomic category.

What's the upshot of all this?  If you're tabulating a list of taxa, you 
may feel like you need to know which "generic pigeonhole" ?. antirrhopus 
can be stuffed into.  In this case, sensible application of traditional 
criteria would say stuff it into Deinonychus.  That's what Des and I will 
advocate.  If you're interested in the science surrounding these 
fascinating animals, then you'll recognize that the important issue is that 
there are three known species in the clade---and about this there has never 
been any controversy.  -- Larry Witmer

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Lawrence M. Witmer, PhD             |   (after 1 Sept 95)
Assistant Professor of Anatomy      |   Dept of Biological Sciences and
Department of Anatomy               |   College of Osteopathic Medicine
NY College of Osteopathic Medicine  |   Ohio University
Old Westbury, NY  11568  USA        |   Athen, Ohio  45701  USA
e-mail: lwitmer@acl.nyit.edu        |   e-mail:witmer@mail.oucom.ohiou.edu
phone:  (516) 626-6944 ext. 6808    |
fax:    (516) 626-6936              |
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