|
This is a quickie, as the taxon is just a new
species based on some teeth.
Ricardoestesia Currie, Rigby and Sloan
1990
R. isosceles Sankey 2001
Etymology- "Richard Estes' isosceles triangle",
after the famous paleontologist Richard Estes, who demonstrated the use of
theropod teeth in faunal studies.
Late Campanian-Late Maastrichtian, Late
Cretaceous
Horseshoe Canyon Formation, Judith River Formation,
Scollard Formation, Alberta; Frenchman Formation, Saskatchewan; Canada. Hell
Creek Formation, North Dakota; Hell Creek Formation, South Dakota; Aguja
Formation, Texas; Lance Formation, Wyoming; US.
Holotype- (LSUMGS 489:6238) tooth
Referred- (A.M. 8113) tooth
(LSUMG 489:6233) tooth
(LSUMG 489:6234) tooth
(LSUMG 489:6235) tooth
(LSUGM 489:6264) tooth
(RTMP 91.170.9) tooth
Diagnosis- teeth straight and shaped like an
isoscleles triangle in lateral view.
Description-
This species was originally suggested by Currie,
Rigby and Sloan to account for the stright Richardoestesia teeth in some
collections.
The teeth are similar to Ricardoestesia gilmorei in
most respects. They are laterally compressed with serrations present
posteriorly and sometimes anteriorly. The serrations are small (7-11 per
mm), flattened, uniform in size and have small interdenticle spaces. The
only difference is the straight crown with the tip roughly in the center.
R. golmorei teeth are recurved, as is usual for theropods.
Relationships-
Ricardoestesia can be diagnosed by- teeth
with very small serrations for size; distal half is convex posteriorly on
anterior dentary teeth. The phylogenetic relationships of Ricardoestesia
are obscure due to the many plesiomorphies, although it can be safely omitted
from several groups (Ornithomimosauria, Segnosauria+Oviraptorosauria,
Alvarezsauridae, Troodontidae, Eumaniraptora). Perhaps it is related to
basal coelurosaurs, tyrannosaurs or Bagaraatan. A proper assessment of
Ricardoestesia's relationships would focus on the better known R. gilmorei, so
will not be considered further here.
Reference- Sankey, 2001. Late Campanian southern
dinosaurs, Aguja Formation, Big Bend, Texas. Journal of Paleontology 75(1)
208-215.
If anyone wants a scan of the tooth, I can send it
to them. Just ask.
Mickey Mortimer
|