Tuesday, January 17, 2012

Agnolin and Novas's (2011) cheating for unenlagiine monophyly?

Here's a quick example of the fun I find when checking matrices for my analysis.  Agnolin and Novas (2011) took Hu et al.'s (2009) matrix and recoded some paravians, as well as adding three new characters to support unenlagiine monophyly- maxilla elongate, postantral wall extensive, teeth grooved.  They got a result that's fairly unique in placing unenlagiines as avialans instead of dromaeosaurids.  I'm adding the data into my matrix and notice the matrix has five new characters added instead of three, all of which are only present in Buitreraptor and Austroraptor.  Well, except the last one, which is seemingly the third they list (grooved teeth) since its codings would suggest it is tooth-based (though wrongly coded for Garudimimus, ornithomimids and Confuciusornis) and present in Sinornithosaurus (and incorrectly in Compsognathus).  As if two phantom characters weren't bad enough, the authors clearly didn't actually check if taxa had them, instead merely going through the matrix and marking anything with cranial material '00000'.  This includes taxa which can't be coded for maxilla elongation or maxillary postantral wall elongation like Tanycolagreus, Coelurus, Mononykus, Falcarius, Alxasaurus, Protarchaeopteryx and Caenagnathus, and even some taxa with no cranial material like Archaeornithomimus and Anserimimus.  Sure none of those taxa are close to unenlagiines so their coding really doesn't matter here, but it sets such a bad precident.  Someone who didn't notice this could go through the matrix and see Protarchaeopteryx is coded as lacking a posteriorly extensive postantral wall and think the authors must have examined the material since it's certainly not illustrated or stated in the literature, and thus code it that way in their own matrix.  But no, I've seen the specimen and the whole maxillary area is crushed so much that you can't even tell if the hole in it is the antorbital fenestra or just damage, let alone see any internal details of the thing.  I'm not even going to go through their new character codings because I can't trust them one bit.

And by the way, contra Agnolin and Novas, their matrix generates 16210 most parsimonious trees of 1409 steps, not 145 trees of 1440 steps.  I was suspicious about the added unenlagiine characters, both real and phantom, but it turns out that the trees have the same topology when either the two phantom characters or all five new characters are excluded.  So I guess they weren't cheating for unenlagiine monophyly after all.


  1. Hey Mickey

    Sorry if this is not the issue, but I think you will anyway.

    Sarcolestes leedsi (Ornithischia) was described as a theropod in 1893 by Lydekker in "Quarterly Journal of the Geological Society 1893, v. 49, p. 284-288.

    And there is another book in this name "Syntarsus mexicanum" of a Middle Jurassic Coelophysoidea Tamaulipas, Mexico. The source is ...

    González, De Stefano & Hernandez 2002 in González, A. H., y de Stéfano, A., eds., Fósiles de México -Coahuila: una ventana a través del tiempo: Gobierno del Estado de Coahuila, p. 214-215.

    Syntarsus mexicanum (González, De Stefano & Hernandez 2002) p. 146

  2. Sarcolestes is in the ex-theropod cladogram, though I have yet to write its entry.

    Very interesting to hear about "Syntarsus" mexicanum. I've emailed Gonzalez for more details, though my hunch is that it's the specimen below. Do you happen to have a pdf? Note the formation was incorrectly placed as Middle Jurassic by Fastovsky et al. (1995).

    Toarcian, Early Jurassic
    La Boca Formation, Mexico
    Material- (IGM 6624) partial twelfth dorsal vertebra (13.1 mm), partial thirteenth dorsal vertebra (20 mm), partial synsacrum (61.5 mm- 16.2, 12.7, 9.6, 9.6, 13.4 mm), incomplete fused pelvis
    ?...(IGM 6625) posterior braincase, incomplete laterosphenoid, fragments
    Comments- Discovered in 1994, Munter (1999) found IGM 6624 to be sister to Megapnosaurus based on the antitrochanter projecting into the acetabulum. It differs in having ilia contact sacral neural spines two and three. The skull fragments may not belong to the same individual or taxon and were thought to be more derived by Munter due to their pneumatized paroccipital roots. However, this has since been found to exist in coelophysids such as "M." kayentakatae, making the possibility it belongs to the same individual more likely. Munter and Clark later (2006) described the specimens and included IGM 6624 in Carrano et al.'s (2002) matrix where it emerged sister to Coelophysis+Megapnosaurus (excluded due to lacking fused sacral neural spines), and Rauhut's (2003) matrix where it was in the clade of Coelophysis+Megapnosaurus (the latter a chimaera of rhodesiensis and kayentakatae). They considered IGM 6625 provisionally theropod.
    References- Clark, Montellano, Hopson, Hernandez and Reynoso, 1998. The Jurassic vertebrates of Huizachal canyon, Tamaulipas. Avances en Investigacion, Paleontologia de Vertebrados. Universidad Autonoma del Estado de Hidalgo Publicacion Especial 1. 1-3.
    Munter, 1999. Two theropod dinosaur specimens from Huizachal Canyon, Mexico. Journal of Vertebrate Paleontology. 19(3), 65A.
    Munter, 1999. Two theropod dinosaur specimens from Huizachal Canyon, Mexico. Masters thesis. George Washington University.
    Munter and Clark, 2006. Theropod dinosaurs from the Early Jurassic of Huizachal Canyon, Mexico. In Carrano, Gaudin, Blob, Wible (eds.). Amniote paleobiology: Perspectives on the evolution of mammals, birds, and reptiles. University of Chicago Press, Chicago. 53-75.

  3. An update- Scheetz, Chure, Harris and others are on the case. So far we've determined that if such an article exists, it's not on pages 214-215, which are about extintion. Harris is ILLing the whole book, so we'll know soon if "Syntarsus" mexicanum exists.

    Out of curiosity, what was your source for learning about the name?

  4. Hey Mickey

    I was checking measures and Nopcsaspondylus hungaricus Megalosaurus and found a job in 1902 Nopcsa this data. Mentioned, possibly because such an error: Megalosaurus horridus Leidy 1859 at page 13.

    The reference is: Notizen. Uber cretacische Dinosaurier. Nopcsa 1902

    or I could interpret the true measure of the tooth of Megalosaurus hungaricus and Nopcsaspondylus of the vertebra. Not if you could help me.