Re: STRANGE THEROPOD SKULLS

["Jaime Headden" <jaemei@hotmail.com>]

<<*Cryolophosaurus* is so early in the fossil record, possibly the first 
true carnosaur (Eucarnosauria? with Carnosauria including that group and 
all other basal tetanurines {megalosaurs, torvosaurs, abelisaurs, and 
*Eustreptospondylus*} excluding Coelurosauria and spinosaurs and 
*Bagaraatan*---however he fits in, and I've yet to see a skeleton or 
single bone of this creature)>>

<While I agree that Crylophosaurus is a carnosaur, I think there is 
more than a little evidence for a "higher" position. Sereno et.al. 1996 
argued for a position in the Allosauroidea. This position is based on 
nasal participation in the antorbital fossa, basipterygoid process very 
short, basioccipital excluded from the basal tubera, articular with 
pendant medial process, and surangular twice maximum depth of angular. I 
agree with their postion in this matter.

Abelisaurs may belong the Ceratosauria in the taxon Neoceratosauria as 
Novas speculated.

Spinosaurs are related to Torvosauridae and Afrovenator in the 
Torvosauroidea according to Sereno et.al.  More will be published on 
this when Sereno publishes his newest findings from Morocco.>

[Not my post, Tom Holtz']
<<<I still find it hard to believe that the jugal does project so far 
<<<dorsally as to suture with the squamosal and therefore divide the 
<<<laterotemporal fenestra into two - this is utterly unique if true. 

<Based on the partial picture Hammer and Hickerson show I think it is 
true.>

     >>snip<<

<<How about this: *Baryonyx's* pelvis shows remarkable similarity to the 
referred pelvis of *Megalosaurus* (OUM, no number given) as seen in _The 
Dinosauria_ and _Dinosaurs: the Encyclopedia_. And don't get me started 
about *Afrovenator* and *Eustreptospoindylus*---though Afro and 
sinraptorids is also very interesting.... Hmm. Would *Piatnitzkysaurus* 
and *Monolophosaurus* and *Yangchuanosaurus* sound interesting as a 
group: look at their pelves (especially the ischia).>>

<The pelvis may not be a great diagnostic feature in theropods.>

Actually, it's very diagnostic. Especially the ischium. I've stated this 
before on the list. Strait as opposed to curved (and which direction it 
is curved); booted or not, laterally compressed or expanded; possession 
of a dorsal ridge (indicative of sinraptorids); obturator flange as 
opposed to obturator prong (or primitive to advanced gradient); long or 
short subacetabular puboischial symphysis; large, small, deep, shallow, 
narrow, and/or wide ischial peduncle (is this the right term for the 
ilial-ischial articulation?). I'm in the process of formulating a table 
of characters exclusive of pelves that also include other basal 
tetanurines and advanced ceratosaurs and "megalosaurs", for variation 
and comparison.

But you're right, too. It's not a great character, but in the abscence 
of a skull or braincase for _the_ most indicative characters, the pelvis 
provides the number-two character set that is almost as good as the 
cranium. Also, better to use when you lack braincases to examine.

<Baryonyx and Megalosaurus may have some relation but you cannot base it 
on some general similiarities.>

Oops. I meant this to assume a basal tetanurine status for Meggie, 
excluding him from the Ceratosauria. But size of skull compared to body 
size is interesting to note [could be indicative of diet alone, though).

<Function-related parts of the body can look extremely similiar in 
unrelated animals with similiar lifestyles.>

Elongated ischium (as in any of my carnosaurs) are very similar to each 
other, sure, but not so inclusive of ceratosaurs, coelophysoids, and 
Coelurosaurs. This only refines the grouping (see below).

<Afrovenator and Eustreptospondylus may have some relation but 
Afrovenator and sinraptorids have relation. Sinraptorids and 
carcharodontosaurs is more likely.>

With *Afrovenator* (see below)

<Piatnitzkysaurus may be related to Monolophosaurus and Yangchuanosaurus 
if it is a allosaur and the latter two are too.>

Piat may be a basal allosauriform, Mono an allosauroid basal to both 
sinraptorids and allosaurids and more advanced than Cryo (actually, 
nearly all carnosaurs are more advanced than Cryo).

Skip this if you want, but I've developed a clade that parts of which 
I've posted.

Carnosauria
\_Torvosauria
  |_Megalosauridae
  | |_Megalosaurus
  | |..Magnosaurus
  | \..Poikilopleuron
  \_Torvosauroidea
    |_Torvosaurus
    \_Crylophosaurus
      \_"Eucarnosauria"
        \_Piatnitzkysaurus
          | \_Eustreptospondylidae
          |   |_Eustreptospondylus
          |   \_Becklespinax
          |    \_Carcharodontosauroidea
          |      |_Neovenator
          |      \_Afrovenator
          |        \_Carcharodontosauridae
          |          |_Acrocanthosaurus
          |          \_Carcharodontosaurinae
          |            |..Bahariasaurus
          |            \_Giganotosaurus
          |              \_Carcharodontosaurus
          \_Allosauroidea
            \_Monolophosaurus
              |..Altispinax
              |  \..Valdoraptor
              |_Sinraptoridae
              | \_Metricanthosaurus
              |   |_Yangchuanosaurus
              |   | \_Sinraptor
              |   \..Szechuanosaurus
              \_Allosauridae
                |..Tendaguru allosaur
                |..Australian allosaur
                |..Chilantaisaurus
                \_Allosaurinae
                  |..Antrodemus
                  \_Allosaurus
                    |..Labrosaurus
                    |..Saurophaganax
                    \..Epanterias

Notes: *Chilataisaurus* may be a carcharodontosaur~
       *Bahariasaurus* may not~
       the "megalosaurs" and Torvo group may not be inclusive and
            neither would be the "eustreptospondylids"~
       *Szechuanosaurus* could be an allosaurid~
       all taxa listed below *Allosaurus* could be genuine or junior
            synonyms of that famous form~
       *Allosaurus* may be junior ro *Antrodemus*~
       *Afrovenator* may be a derived member of Sinraptoridae and
            still preclusive of carcharodontosaurs, thus uniting
            Carcharodontosauroidea and Sinraptoridae into
            Carcharodontosauriformes, where "Carch" is older thus has
            precedence~
       *Valdoraptor*, based on a metatarsus and referred metatarsals,
            could be congeneric with *Altispinax*, but is
            differentiated because of no comparable fossils between
            the two; *Becklespinax* can also be included in this, with 
            *Altispinax* the older and valid genus~
       *Magnosaurus* and *Poikilopleuron* may be congeneric with
            *Megalosaurus*, as may *Torvosaurus*.

Not listed are possible Tetanurans Abelisauria.


Please do not hesitate to criticize.

Jaime A. Headden

"Load photon bays!"

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