Organisation of Hoxa clusters in vertebrates. This figure includes the two complete chondricthyan sequences (Little Skate and Horn Shark), two members of the sarcopterygian clade (Human and Indonesian coelacanth, Latimeria menadoensis) and an actinopterygian (ray-finned fish), Polypterus senegalus. The Skate and Horn Shark clusters are remarkably similar in overall length and intergenic distance.
Mulley et al. BMC Evolutionary Biology 2009 9:218 doi:10.1186/1471-2148-9-218