RE: Haha, more questions

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

> From: Dino Rampage [mailto:dino_rampage@hotmail.com]
>
> 1) What is Dryptosaurus' relationship to other theropods? All
> seem to agree
> that it is a non- maniraptoran coelurosaur, but is it close to
> the base of
> Coelurosauria, or more closely related to the Tyrannosaurs? I've seen it
> mentioned somewhere on the list that Dryptosaurus was a basal
> Tyrannosauroid
> (note the word "TyrannosaurOid")

In a couple of recent to-be-published analyses (one of them the most
comprehensive theropod analysis that I know of... :-), it comes out as a
basal tyrannosauroid.

> 2) How is Troodon related to the other coelurosaurs? They used to
> be called
> Arctometatarsalia, then Bullatosaurs, and now their placement is somewhat
> uncertain. Do they occupy a place within the maniraptoriforms, like the
> tyrannosaurs & ornithomimids, or within the maniraptors, or as Oyvind M
> Padron's cladogram states, within the Deionychosauria itself??

The arctometatarsalian and bullatosaurian hypothesis were the same one, and
(sadly for me) that hypothesis has been pretty well rejected.

Based on _Sinovenator_ and other material, troodontids are almost certainly
closer to dromaeosaurids and avialians than are oviraptorosaurs or
therizinosauroids.  However, there are no strongly secure topologies beyond
that, as basalmost dromaeosaurids, basalmost troodontids, and basalmost
avialians are so gosh-darned similar that the various alternative hypotheses
are only a step or three different from each other.

> 3) Alvarezsaurs. Weird avialans, weird troodont relatives, or weird
> ornithomimid relatives?

Possibly.  Possibly also weird maniraptorans, sister taxon to troodontids +
dromaeosaurids + avialians (various combinations) OR sister taxon to
enigmosaurs + paravians.

Weird is the operative word for these folks...

> 4) Is Meagraptor believed to be an aberrant giant Gondwanan dromaeosaur?

By some, yet.  Others have alternative hypotheses.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796