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StephanPickering@cs.com wrote-
Walkersaurus hesperis (Waldman 1974) is a ceratosaur.
This is quite interesting. I've heard it is
similar to Monolophosaurus and seem to have a Dilophosaurus comparison in my
memory somewhere. Any support for its ceratosaurian nature (or at least
coelophysoid, dilophosaurid or neoceratosaurian nature, given that recent
analyses have made Ceratosauria sensu lato paraphyletic)?
Megalosaurus/Metriacanthosaurus are closer to each other
than either is to any known ceratosaur (Megalosaurus = Torvosaurus).
Although I recall Paul (1988)
synonymized these genera, the only phylogenetic analyses containing both (Holtz,
1994, 2000, etc.) haven't found them to be sister taxa. Rather, they are
successively closer to Avetheropoda/Neotetanurae, with Megalosaurus being less
derived than Torvosaurus in his 2000 phylogeny (with Eustreptospondylus in
between). Of course, this would be a lot easier to defend if Megalosaurus
were ever redescribed (which I hear is in the works, seemingly forever).
If only I noted their placement in Holtz's most recent SVP 2001
phylogeny.
The recent attempted resurrection of "Magnosaurus" is most
unfortunate, as von Huene's nomenclature was rather confusing: the name was
originally in 1932 applied to BMNH R3542, a right tibia of the ceratosaur
Sarcosaurus, von Huene naming it Sarcosaurus andrewsi
(1932:51-52). In the same 1932 monograph, ! ! on page 219, von Huene
gave BMNH R3542 yet a second name, Magnosaurus woodwardi! The ceratosaur
Sarcosaurus woodi = Sarcosaurus andrewsi BMNH R3542 = Magnosaurus
woodwardi BMNH R3542. Alas: 1932:220, von Huene stumbles on his shadow, when
he gives the name Magnosaurus also to BMNH 41352, von Huene's 1926
Megalosaurus lydekkeri which is an indeterminate theropod tooth from
Dorsetshire, his 1932 Magnosaurus being a "n.g." for Megalosaurus
nethercombensis and, at the end of his short discussion, a "subgenus" of
Megalosaurus. Now, we have, in 2001, the name Magnosaurus being
used for Eustreptospondylus, which is not a
ceratosaur.
Hmm. I never knew M.
woodwardi was the type species, nor did I know a Magnosaurus woodwardi
existed. Was the name Magnosaurus applied to Megalosaurus lydekkeri or M.
nethercombensis first? One thing I would be cautious about is synonymizing
Sarcosaurus woodi with S? andrewsi. I've never seen an educated opinion of
the latter, but the two species cannot be compared as far as I know (with S.
woodi lacking a preserved tibia).
To rephrase the paradigms involved:
Megalosaurus/Metriacanthosaurus are a closely knit group of theropods not
sharing any diagnostic ceratosaur synapomorphies.
Eustreptospondylus/Streptospondylus/Poekilopleuron are closer to the
"spinosaurs" than to Megalos! ! aurus/Metriacanthosaurus ("spinosaur" I
use advisedly, the type being lost, and Horrorwood's attempted conjuration of it
in Jurassic Park III wishful thinking).
I would say-
Megalosaurus, Torvosaurus and Eustreptospondylus are basal tetanurines, the
latter two probably close to spinosaurids. Theropod "Streptospondylus"
remains appear close to Eustreptospondylus. Metriacanthosaurus may be
sinraptorid, while Poekilopleuron could be carnosaurian. None of these
taxa are "ceratosaurs" though.
Mickey
Mortimer
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