Sunday, May 1, 2011

Pneumatocrania and Holtz's thesis

Everyone knows Holtz's famous 1994 paper revolutionizing theropod phylogeny.  What fewer people have seen is the 1992 thesis that preceded it, which included its own phylogenetic analysis.  The analysis had largely similar characters (128 vs. 126) and included Procompsognathus, Piatnitzkysaurus, Eustreptospondylus and Chilantaisaurus in addition to the taxa from 1994.  It also split Ornithomimosauria into Harpymimus, Garudimimus and Ornithomimidae, and did not include Abelisauridae.

The results are similar to the 1994 paper, with the following differences.
- Procompsognathus is outside Eutheropoda.
- Elaphrosaurus is a non-avetheropod tetanurine more derived than Torvosaurus, though on page 264 he notes the characteristics of abelisaurids indicates they and Elaphrosaurus are neoceratosaurs.
- Megalosaurus is a basal carnosaur (along with Piatnitzkysaurus).
- Chilantaisaurus is carnosaur in a trichotomy with Allosaurus and Acrocanthosaurus, and Eustreptospondylus is sister to this group.

Some new names are proposed.
- Eutheropoda is the group containing Ceratosauria sensu lato and Tetanurae, but not Procompsognathus.  It's been used informally this way online since the 90s, including on Holtz's site, but I think Novas et al. (2003) have been the only authors to publish it.  They used it in the same way (excluding Herrerasaurus and Eoraptor this time), but it's just an abstract.
- Eumaniraptora is first used here, though in a different sense than what was later adopted once it was published in 1997.  In Holtz's thesis, Eumaniraptora is what we would now call Maniraptoriformes- the group containing paravians, oviraptorids and arctometatarsalian taxa.
- Holtz used Dinoaves for the Paraves group of dromaeosaurids and Archaeopteryx, though this originally referred to something like Tetanurae when Bakker coined it.
- Arctometatarsalia is proposed here, with the same content as the 1994 paper.  
- Pneumatocrania is a name that hasn't made it to the internet before now.  It was Holtz's name for his clade of oviraptorids and 'arctometatarsalians', since they were diagnosed in part by pneumatic skulls.  Of course, we now know dromaeosaurines reduced their pneumaticity and most of the characters used are problematic (see characters 17, 64, 68, 69, 103, 115, 116 and 121 in my link above), so the topology hasn't been found since.

My favorite part of the thesis is the detailed discussion of twenty-nine poorly known theropod taxa.  This includes prescient aspects such as a maniraptoriform Microvenator and a suggestion of elaphrosaur affinity for Chuandongocoelurus almost a decade before I thought the same thing on the DML.  It also features some common but incorrect ideas of the early 90's though, such as neoceratosaurian spinosaurids and Carcharodontosaurus.

Thanks to Tom Holtz for permission to write about this interesting piece of theropod history.

References- Holtz, 1992. An unusual structure of the metatarsus of Theropoda (Archosauria: Dinosauria: Saurischia) of the Cretaceous. Unpublished PhD thesis. Yale University. 347 pp.

Holtz, 1994. The phylogenetic position of the Tyrannosauridae: Implications for theropod systematics. Journal of Paleontology. 68(5), 1100-1117.

Novas, Haro and Canale, 2003. Un nuevo terópodo basal de la Formación Ischigualasto (Carniano) de la provincia de San Juan, Argentina. Ameghiniana. 40(4), 63R.


  1. Sigh.

    Mickey, ragging on you again. It is not necessary, either for communication or for relaying of a scientific concept, to mention or bandy unpublished (especially thesis) nomenclature, in defiance of one of the most common reasons for doing so: because it's there.

  2. Much like Chinleana's "Holbrookosaurus" post, just because YOU don't find it interesting doesn't mean no one else does. As someone who refrains from discussing taxa published online whose paper versions aren't out yet (e.g. Daemonosaurus) and has stated on multiple occasions that you would basically never name a taxon yourself, maybe just maybe you're not the intended audience of posts on unofficial names.