Axial skeleton and appendages play pivotal roles in locomotion,bracing and body protection.In certain lineages,axial skeleton including rib and sternums,and limbs hasexperienced marked modifications for varioushabitats and locomotory patterns.Given the importance of Hox genes in morphologically evolutionary diversification,we have conducted an analysis of coding regions for all 39 Hox gene family members and relevant regulatory factors(Bmi1,Mll and E2f6)from 28 mammals representing all mammalian families.