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RE: Senter et al. 2004 impressions II



Mickey Mortimer wrote:

The following changes in tree length are required for different topologies- Sinovenator as a bullatosaurian troodontid- 16 more steps. Troodontids (with Sinovenator) as deinonychosaurs- 12.

I wonder how many extra steps is required to put _Bambiraptor_ in the Dromaeosauridae (sensu Senter et al.) and remove it from the Microraptoria? I mention this because the phylogeny of Senter et al. (2004) regards certain features associated with aerial locomotion evolving *twice* as the most parsimonious explanation for the distribution of these features. But if _Bambiraptor_ were to jump over to the Dromaeosauridae, then the most parsimonious explanation would be that these characters would be primitive (plesiomorphous) for Paraves, and secondarily lost in the dromaeosaurids.


One potential complication is that the holotype for _Bambiraptor_ is an immature individual, and this may be pulling this taxon into the Microraptoria - especially if (and this is a big "if") certain microraptorian characters are pedomorphic.

Regarding the synonymy of Jiufotang microraptorians, Senter et al. state the manual proportions that diagnose Cryptovolans are also seen in other Chinese microraptorians. However, this is not true. Czerkas et al. (2002) diagnosed Cryptovolans by its high III-1/III-3 ratio. If we examine the III-2/III-1 ratios, we see Cryptovolans has 23-24%, lower than any other theropod. Microraptor zhaoianus' is 41%, Microraptor gui's 64%, NGMC 91's 43%, Sinornithosaurus' 39% and Graciliraptor's 51%.

The Jiufotang microraptorians appear ripe for a morphometric study, along the lines of the allometric analyses done for the _Archaeopteryx_ specimens (e.g., Houck et al., 1990; Senter and Robins, 2003).




Tim

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