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Re: Valid Synapomorphies or not?

Steven Mahon wrote: 

I've done some research & have found lists of
synapomorphies that unite the following: Troodontidae,
Troodontidae + other groups, Ornithomimoidea (sensu
Sereno), Ornithomimoidea + other groups, & "Coeluria".

Troodontidae
1.most distal posterior serration forming tip of tooth

Also found in Compsognathus, but this doesn't really affect the use of it as a troodontid synapomorphy.

2.enlarged elongate maxillary fenatra

Hm... needs quantified. And you mean "fenestra", not "fenatra". And is the fenestra elongated or enlarged?

3.dentary dentaryfornina inside lateral groove

Better phrased as "row of foramina inside a groove on lateral dentary". Also in Carnotaurus, Giganotosaurus, and Baryonyx, but this doesn't really affect the use of it as a troodontid synapomorphy.

4.calcaneum lost

The calcanea are not lost in troodontids, they are fused to the astragalus to form the astragalocalcaneum. This fusion is also in Bagaraatan and Zupaysaurus. It is not present in Sinovenator.

5.tongue-like extension of articular surface
metatarsal III


Absent in Sinovenator.

6.metatarsal IV most robust in pes

Troodontidae + other groups
7.lateral depression in braincase


Absent in Sinovenator (Xu et al. 2002).

8.fibula reduced to splint 

Not in Sinovenator or Sinornithoides.

9.arctometatarsus

Hm. This character is rarely used hto unite anything except certain coelurosaurs within their own respective groups. It's not present in basal ornithomimosaurs (Harpymimus & Garudimimus: Kobayshi & Lü 2003) or troodontids (Sinovenator: Xu et al. 2002). It is present in Alioramus, but the condition is uncertain in Eotyrannus.

10.maxilla broadly contacts naris 

Not in Sinovenator.

11.nasals narrow caudally
12.numerous teeth

How many? "Numerous" is rather vague. Norell et al. 2000 use "teeth few (<100) [0], or numerous [1]". Therefore, the number of teeth is greater than 100 in troodontids apparently. Uncertainty is present as Makovicky et al. 2003 regard Byronosaurus as having ~64. Pelecanimimus (a basal ornithomimosaur) has 220 teeth.

13.enlarged serrations 

Sinovenator lacks large denticles (serrations) (Xu et al. 2002).

14.teeth w/ blood grooves
15.inter dental plates absent

Absence of interdental plates can be problematic, as some seem to believe that the absence results from fusion, but I won't deny that it is a possible synapomorphy of the Troodontidae. Also absent in alvarezsaurids and Pelecanimimus.

16.no basisphenoid recess
17.inflated parasphenoid

The parasphenoid is not inflated in Sinovenator, a basal troodontid (Xu et al. 2002).


Ornithomimoidea
18.dorsal premaxillary process dorsoventrally
flattened
19.orbital flange on prefrontal
20.maxillary & dentary teeth implanted in groove
21.flexor depression proximal to distal condyles on
proximal manual phalanges
22.paired flexor processes on manual phalanx I-1
23.dorsolateral tubercle on manual phalanx I-1
24.metacarpal-phalangeal joint of digit 1 w/
approximately 15 degrees maximum extension
25.metacarpal III at least 75% the width of metacarpal
II
26.metacarpals w/ 60-70% of shafts in contact
27.metacarpal I at least 60% the length of metacarpal
II
28.subnarial foramen absent
29.nasal anteroventral process absent


I'll refer you to the following:

Shigeru Suzuki, Luis M. Chiappe, Gareth J. Dyke, Mahito Watabe, Rinchen Barsbold, and Khisigjaw Tsogtbataar (2002). A New Specimen of Shuvuuia deserti Chiappe et al., 1998 from the Mongolian Late Cretaceous with a Discussion of the Relationships of Alvarezsaurids to Other Theropod Dinosaurs. Contributions in Science 494: 1-18

http://www.cmnh.org/dinoarch/2003Jan/msg00160.html

"Coeluria" 

What is "Coeluria"?

30.cervical epipophyses not overhanging the
postzygopophyses
31.posterior dorsal neural spines lower than long

Heres what I need to know:
1. any others I'm missing

It's rather relevant to what data set you are using, I'm afraid. I sure in some analyses you could find more, in others you could find less. It is not as though there were one consensus on coelurosaur phylogeny, especially considering there are quite a few alternate views.

Nick Gardner

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