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RE: T. Rex Dethroned as Biggest Flesh-Eating Dinosaur
Thomas R. Holtz, Jr. wrote:
To be fair, they mention both a) that _Spinosaurus_ was already
interepreted as bigger than _T.
rex_ back in Stromer's day, and that b) _Giganotosaurus_ was already known
to be bigger than _T. rex_. So it isn't the reporter's fault. Reporters
rarely get to write their own headlines.
As a potential fly in the ointment, the possibility has been raised that the
type material for _S. aegyptiacus_ might come from two different theropods
(in this case, two very big theropods) (Rauhut, 2003). Under this
interpretation, the cranial material represents a _Baryonyx_-like animal,
whereas the long-spined dorsal vertebrae come from a theropod closer to
allosaurids. If this _Spinosaurus_-chimera idea proves to be correct (I'm
not holding my breath), then the cranial material described by dal Sasso et
al. (2005), including the specimen MSNM V4047, would belong to the former.
The tall-spined vertebrae would presumably get to keep the name
_Spinosaurus_, so the super-large theropod (represented by MSNM V4047) would
not be _Spinosaurus_.
Having said this, the _Spinosaurus_-chimera interpretation is controversial,
and at the moment there is no compelling evidence to split up the cranial
material from the vertebrae. But who knows what tomorrow (and further
expeditions to the Sahara) may bring.
Also, also in the theropod 'big leagues' is _Deltadromeus_ (possibly a
junior synonym of _Bahariasaurus_). A specimen (IPHG 1912 VIII) referred to
_Deltadromeus_ by Sereno et al. (1996) indicates a theropod 13-13.5 m long.
This puts it on par (lengthwise, anyway) with a large specimen of
_Tyrannotitan_ was also pretty big; the femur of the holotype was only
slightly shorter than that of the _Giganotosaurus_ holotype: 140 cm vs 143
cm (Novas et al., 2005). That's longer than the femur of the _T. rex_
specimen named "Sue" - but not by much.
dal Sasso, C., Maganuco, S., Buffetaut, E. and Mendez, M.A. (2005). New
on the skull of the enigmatic theropod _Spinosaurus_, with remarks on its
sizes and affinities. J. Vert. Paleontol. 25: 888-896.
Novas, F.E, de Valai, S., Vickers-Rich, P. and Rich, T. (2005). A large
Cretaceous theropod from Patagonia, Argentina, and the evolution of
carcharodontosaurids. Naturwissenschaften 92: 226-230.
Rauhut, O.W.M. (2003). The interrelationships and evolution of basal
theropod dinosaurs. Special Papers in Palaeontology 69: 1-213.
Sereno, P.C., Dutheil, D.B., Iarochene, M., Larsson, H.C.E., Lyon, G.H.,
Magwene, P.M., Sidor, C.A., Varricchio, D.J., and Wilson, J.A. (1996).
Predatory dinosaurs from the Sahara and Late Cretaceous faunal
differentiation. Science 272: 986-991.