Monday, June 24, 2013
A note on the taxonomy used in this blog
I am alone among my fellow tyrannosauroid colleagues, where I do not use the generic names Gorgosaurus or Tarbosaurus. My reason is that taxonomic names (i.e., genera) should be used to reflect phylogenetic relationships between pairs of sister species. This approach maximizes the information content of the name.
The cladogram above shows the present consensus on tyrannosaurid phylogenetic relationships, where Albertosaurus libratus and A. sarcophagus are sister species, and Tyrannosaurus rex and T. bataar are also sister species. If A. libratus is bumped up to the genus Gorgosaurus, and if T. bataar is bumped up to Tarbosaurus, then the information content regarding its sister species relationship is lost. Also, the generic status implies a greater morphological and phylogenetic distance between the sister species than actually exists.
Notice the taxa that are not paired with sister species (Bistahieversor, Alioramus, Teratophoneus, Daspletosaurus), which mark successive lineages that contain multiple species (more than two). In these cases, generic status for each species is reasonable to emphasize their phylogenetic and morphological distinctiveness.
It has been argued that bestowing a genus name for every species makes communication more efficient. However, this is not truly expedient if the sister group relationship still needs to be spelled out. It also runs against the grain of using binomials in the first place.
In short, I'll adjust the taxonomy the day it is shown that A. libratus and A. sarcophagus, or T. bataar and T. rex, are no longer sister species. Until then, I stand apart with - I think - a defensible conviction.
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