[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Tyrannosaurs, dwarf, early, and otherwise...
A couple of major summaries of the information in question are forthcoming
in the next few months/year. Some quick reviews:
"_Nanotyrannus_" is a juvenile. Most of the alledged fusions of the skull
previously reported cannot be confirmed by subsequent examination. The bone
texture is very clearly juvenile, however. The specimen demonstrates clear
_Tyrannosaurus_ and _T. rex_ synapomorphies. In almost every case, those
features in which it differs from adult _T. rex_ are those features which
differ from juvenile and adult _Gorgosaurus_. The simplest explanation is
that it is a juvenile _T. rex_, although the possibility does remain it is a
juvenile of an as yet otherwise unknown Hell Creek _Tyrannosaurus_ species.
"_Alb./Dinotyrannus megagracilis_"'s identity is less certain. Those
features that do differ from adult _T. rex_ are also found in subadult (but
not necessarily adult) _Gorgosaurus_. It is very likely a subadult _T.
rex_, but more complete material may demonstrate it is unique.
Earliest tyrannosaurids: _Alectrosaurus olseni_ is the oldest named definite
tyrannosaurid. Older material includes teeth from Aptian-Albian of Asia and
the Cenomanian of North America. If _Siamotyrannus_ is a tyrannosaurid, it
is even older (Barremian). _Stokesosaurus_ (a Late Jurassic form) has been
referred to Tyrannosauridae or Tyrannosauroidea, and is even older still;
its placement here, however, remains uncertain.
All these forms are smaller than classic Campano-Maastrichtian tyrannosaurids.
Hope this helps. Keep watching the skies... er, journals (and books).
Thomas R. Holtz, Jr.
Deptartment of Geology Director, Earth, Life & Time Program
University of Maryland College Park Scholars
College Park, MD 20742
Webpage: http://www.geol.umd.edu Phone:301-405-4084
Email:firstname.lastname@example.org Fax: 301-314-9661