[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
RE: Willie Wonka and the New Papers
And at long last my e-mail service has included a way to make messages plain
text, thus I can return to the DML...
David Marjanovic wrote-
> So *Megalosaurus* is not a spinosauroid at all... Yay Torvosauridae.
Yet reading the paper results in seeing only one character suggested that would
exclude Megalosaurus from the Spinosauroidea- the third alveolus isn't largest
(the fourth is). They further state that in spinosauroids (Torvosaurus,
Dubreuillosaurus, Eustreptospondylus, Magnosaurus, spinosaurids), the dentary
is laterally expanded to accomodate this alveolus, whereas Megalosaurus shows a
much more subtle expansion around the third to sixth alveoli.
This is fine, but the authors also note a character of Megalosaurus which is
only found in some spinosauroids- paradental groove open only anteriorly. This
is shared with Dubreuillosaurus and "Walkersaurus", but not with Magnosaurus or
Torvosaurus among spinosauroids.
I should try adding the holotype to a non-maniraptoriform supermatrix I've been
working on (including all codings from Smith et al., 2007; Tykoski, 2005;
Carrano and Sampson, 2007; Rauhut, 2003; Azuma and Currie, 2000; Allain, 2002;
Ezcurra and Novas, 2006; etc.). Notably, Poekilopleuron falls out basal to the
rest of the megalosauroids, leaving open the possibility Megalosaurus has a
similar position and simply hadn't evolved the expanded third alveolus and
dentary yet. It would still be a spinosauroid though, using Holtz et al.'s
(2004) stem-based definition. Using Sereno's node-based
(Torvosaurus+Spinosaurus) definition, even taxa like eustreptospondylids and
Poekilopleuron fall outside Spinosauroidea in the supermatrix.