Molecular phylogeny based on mitochondrial and Fgf10ECR3 sequence and comparative anatomy based on molar crown/root ratio. (A) Neighbor-joining tree based on Fgf10ECR3 diversity depicts a single monophyletic clade (red branches) that contains all species with hypsodont molars. (B) Neighbor-joining tree modified from Fabre et al. 2012, depicting phylogenetic relationship based on mitochondrial DNA sequence among all examined species. (C) Buccal view of lower first molar, depicting brachydont (bra) and hypsodont (hyp) phenotypes. a, Peromyscus maniculatus (Cricetidae); b, Mus musculus (Muridae); c, Lophuromys flavipunctatus (Muridae); d, Acomys cahirinus (Muridae); e, Napaeozapus insignis (Dipodidae); f, Neotoma micropus (Cricetidae); g, Microtus californicus (Cricetidae); h, Chaetodipus hispidis (Heteromyidae); I, Dipodomys ordii (Heteromyidae).