Figure 1.

Current status of the investigation of Hox gene inventory in different sarcopterygian groups along with a generally accepted tree for these groups. We use a tritomy node for turtles, squamates (lizards and snakes) and archosaurs (birds and crocodiles), reflecting the current controversy on the relationships among them. Note that relevant information in most amphibian and reptile groups is either incomplete or missing.

Liang et al. BMC Evolutionary Biology 2011 11:25   doi:10.1186/1471-2148-11-25
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