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What a fun time is to be had in Germany. All these bizarre new
pterosaurs.. and dare I mention the work on theropods that was done?
Be patient, you will be informed in time..
_Avimimus portentosus_, as is well known, was not found as an
articulated specimen, but as bits and pieces scattered over about 5
square km. Matt Troutman writes..
> Perle has said the skull is that of a juvenile oviraptorid. The
> carpometacarpus and ulna are that of a bird ( Parvicursor has been
> suggested ) and the pelvis and rest of the body is up for grabs ( I
> think oviraptorid too ).
The premax referred to _A. portentosus_ may be from a hadrosaur, as
Norman indicated in WDO (1990). It is toothless and has
denticulations like those seen on some ornithopod beaks. It is of
incidental interest that Chatterjee thought these structures to be
teeth, thus thought _Avimimus_ to be toothed, and thus included an
incorrect character coding in his cladistic analysis of _Protoavis_.
I'm unsure about the hind limbs of _Avimimus_. There is a fourth
trochanter, thus the limb is not from a bird. Oviraptorosaurs also
lack a fourth trochanter (_Microvenator_ apparently only has a scar
in this location. Ostrom (1970) asserts no fourth troch. is
present), but Barsbold (1983) reported one for _Oviraptor_, and
Barsbold, Maryanska and Osmolska (1990) therefore wrote as if _all_
oviraptorosaurs have one. I do not have Barsbold's paper to hand -
can someone verify the presence of this feature in _Oviraptor_? If it
is there, it presumably marks a reversal. It is definitely absent in
all of the well preserved 3-D oviraptors the AMNH team have prepped.
Dromaeosaurids, including _Deinonychus_, DO have a fourth trochanter,
despite Ostrom (1976) and (just about) every other author that
followed. Thus lack of a fourth troch. is NOT an unambiguous
synapomorphy of Maniraptora, but only of Aves. Notably, the femur of
_Avimimus_ is like that of dromaeosaurids, _Unenlagia_,
_Archaeopteryx_ and troodontids in having a 'posterior trochanter'.
Chiappe has also identified this feature in enantiornithine birds.
_Avimimus_ is somewhat like some oviraptorosaurs in having a robust,
'finger-shaped' lesser trochanter that is well separated from the
greater trochanter by a marked furrow. However, this feature is
variable in oviraptorosaurs: in _Microvenator_ it is very tall
(higher than the greater troch.), while in _Chirostenotes_ it is
described by Sues (1997/8) as being more distally located than in any
other Cretaceous theropod.
So, is the hindlimb of _Avimimus_ from an oviraptorosaur? I still
And will you Americans please publish and figure all of the
_Ornitholestes_ material some time! For such a well known theropod
it's incredibly poorly known.
Matt also listed this as a character seen only in Aves..
> 7) Hypertrophy of the forelimb.
Well, it's a subjective character (like some of Gauthier's early
ones.. viz, 'neural spines large', 'skull large') - but have you seen
the arms on 'Bambi'/'_Linsterosaurus_'? Judging from a skeletal
reconstruction Pete Buchholz sent me, the arms on this critter are of
_Archaeopteryx_-like proportions. The animal is from the Two Medicine
Fm. (Campanian) and was found jumbled with hadrosaur bones. Pete
has previously discussed it extensively on this list, and in
I drove through a place in Europe called Buchholz the other day.
"You drive all night, and you see a light, and it comes right down
and lands on the ground, and out comes the man from Mars, and you try
to run but he's got a gun, and he shoots you dead, and he eats your
head, and now you're in the man from Mars, you go out at night,
God knows why I learnt that at the age of 16.