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Re: Allosaurus topotype



Allosauroidea
Allosauridae = Allosaurus, Neovenator
Sinraptoridae = Sinraptor,Yangchuanosaurus [I believe
these taxa are synonymous]
Carcharodontosauridae = Carcharodontosaurus,
Giganotosaurus [I believe the former and latter may be
synonymous], Acrocanthosaurus
These converted clade names have been diagnosed by
Thomas Holtz (in GAIA 15), and I shall not repeat his
diagnoses here.
I would query Thomas Holtz whether or not Allosauridae
has a distal pubis longer cranially than caudally, and
in ventral view the pubis distal end is triangular.
Allosaurus has no deeply concave "pocket" on the
ventral surface of the ectopterygoidal flange, a trait
in 1996 I thought synapomorphic for Allosaurus.
Allosaurus Marsh 1877: mediolaterally compressed,
dorsally projecting cornual process of lacrimal;
maxillary antrum with fenestrated dorsal wall;
internal mandibular foramen long caudoventral margin
of prearticular; lateral surface of sacral 4 with
spindle-shaped foramen; ischial obturator process with
long, cranially directed lamina extending cranially to
level of pubic-ischiadic contact (from Chure 2000).
Allosaurus fragilis: cornual process with 2 large
pneumatic concavities opening laterally; jugal ventral
margin deflected ventrally at midlength so that
ventral margin is not straight; mtc I reduced more
than in other spp. (from Chure 2000).
Allosaurus whitei [the spp. name is in honour of T.E.
White, the Dinosaur National Monument paleontologist
who inspired many, and Maple White]. Tithonian,
Wyoming, Utah, Colorado.
Type: AMNH 666 Bone Cabin Quarry
Paratype: AMNH 5753 Quarry 3 Aurora, Wyoming
Referred specimens: AMNH 275, 290, 324, 496, 600 [may
be A. fragilis], 680, 704, 726, 728, 736, 737, 851,
5752, 6125, 6128; MCZ 3897; DINO 2560 (= UUVP 6000).
Provisional diagnosis: an Allosaurus with a low,
elongate skull; apexes of lacrimals bluntly rounded;
slender limb bones vs. A. fragilis with its high,
short skull, sharply pointed apexes of lacrimals, and
more robust limb bones.
Chure believes the lacrimal horn variations may be due
to sexual dimorphism. However, enough material is
known to support my tentative erection of another
Allosaurus species within this clade.


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