RE: Adios, "Brachiosaurus" brancai

[Jaime Headden <qi_leong@hotmail.com>]

On a purely technical level, I do think it is hasty to dismiss the identity of 
*"Brachiosaurus" brancai* as a species of *Brachiosaurus*, for a few reasons:

  *Brachiosaurus* currently contains the two species, largely because naming a 
genus to contain a single species split from a genus formerly containing it and 
only one other species (producing two monotypic species) results in NO relative 
information gain, nor is there any resolution gained doing so without any other 
information produced that this enables (such as one of these species being 
closer to another described non-*Brachiosaurus* species.

  When the two species are placed into a complex together, and this also 
happens to include species of other monotypic genera that may or may not be 
just as close, but that these genera are produced on the basis of naming a 
genus and a species for the sake of it (I'm looking at you, *Sauroposeidon 
proteles*!) then again, no resolution is gained from producing extra genera. 
This is largely why, contrary to Mike Taylor's comment on SV-POW!, 
*Giraffatitan* receives so little attention. 

  It should be noted that almost every single study in the last two decades to 
include *brancai* has cited Paul's work coining the name as a subgenus (a 
purely arbitrary rank that offers no information to this concern, and a 
practice Paul performed largely contiguously with a disavowal of phylogenetic 
taxonomy -- Paul, 1988a [Predatory Dinosaurs of the World] and 1988b 
[Segnosaurs]. and Paul 2002 [Dinosaurs of the Air]), so it seems curious how 
*Giraffatitan* has been ignored. The issue stems largely from how *altithorax* 
(not *Giraffatitan*) has been ignored, and not used to anchor the discussion 
when using *Brachiosaurus*, such that it leaves us with the feeling that 
*brancai* (not *altithorax*) is the preferred species at this interesting 
juncture in sauropod evolution (origin of titanosauriforms); this also tells 
use that we should continue to use *brancai*.

  Complexing the genera by recognition of *Giraffatitan* (which workers are 
still permitted to ignore) is not substantiated by a study that forces 
*brancai* closer to any other taxon other than *Brachiosaurus altithorax*, and 
from what I understand (unless Mike is willing to email me a copy of the paper) 
based on the SV-POW! post, the study receives a polytomy of "brachiosaurs." The 
questiuon here is: How is this information better conveyed by placing a species 
into a genus, versus placing all the species into a single genus? What does 
*Brachiosaurus* mean if it will only ever be synonymous with *altithorax*? The 
utility of nesting taxonomy is that containers can hold more than one internal 
"object" or name, and it seems a waste to support this for some tax and not 
others (especially since I suspect there is a drive to have genera -- a 
"species" is just not sexy enough to care about, and this issue plagues the 
*altithorax* problem).

  So my question is this: Why do we need *Giraffatitan*, and cannot have a 
*Brachiosaurus proteles* etc.?

Cheers,

Jaime A. Headden

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

"Human beings, who are almost unique in having the ability to learn from the 
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----------------------------------------
> Date: Thu, 10 Sep 2009 00:02:23 +0100
> From: mike@indexdata.com
> To: dinosaur@usc.edu
> Subject: Adios, "Brachiosaurus" brancai
>
> The new JVP 29(3) includes my paper showing that the well-known
> Tanzanian brachiosaur "Brachiosaurus" brancai is not congeneric with
> the type speces Brachiosaurus altithorax. For more (including a
> pretty picture), check out the summary on Sauropod Vertebra Picture of
> the Week: 
> http://svpow.wordpress.com/2009/09/09/brachiosaurus-brancai-is-not-brachiosaurus/
>
> (And now we get into another discussion about what a "genus" is ...)

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