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Re: when is a Lazarus Taxon not a Lazarus Taxon?

> hi.
> sorry, friends, but I found myself with another question...
> Imagine that a gorgonopsid fossil is found from the mid-Jurassic strata.
> If
> that were all that were unusual {the rock layer}, then it would be Lazarus
> Taxon.  Right?
> But what if that Jurassic gorgonopsid was smaller than its Permian
> relatives, and adapted for climbing cycads (and the trees so common to
> dino
> programs *g*) ?   Would that still be a Lazarus Taxon, as its still
> recognizably a gorgonopsid?  Or is there another word for this Jurassic
> climber?
> sorry for these odd questions.  thank you for your time and assistance, my
> friends.

What you are describing is a variant on the "Lazarus taxon." Traditionally
Lazarus taxa were considered at the species or genus-level, for what
that's worth. Nevertheless, what you describe has all the essential.

That thing that makes a critter a Lazarus taxon is our limited knowledge
of its stratigraphic and distributional record, and not properties of the
organism per se. (Although obviously the new life habit is what allowed it
to "escape" from our recovery of the record for an interval). But say that
_Dilophosaurus_ was actually present in the Middle Jurassic of the
American West (where we have almost no terrestrial fossil record). If we
were to discover a _Dilophosaurus_ from the end of the Middle Jurassic
that would constitute a Lazarus taxon, as it seemingly went extinct and
then reappears in the fossil record stages later.

Hope this helps,

                Thomas R. Holtz, Jr.
        Senior Lecturer, Vertebrate Paleontology
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
        Mailing Address:
                Building 237, Room 1117
                College Park, MD  20742

Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796