Distribution of CCD-like characters on mammalian phylogeny. Potential CCD-like features of Afrotheria optimized on a mammalian phylogeny . Data on age at eruption are not yet known for small afrotherians (tenrecs, golden moles, sengis) or aardvarks. Based on the metric data presented in Figure 2 and in the text, we predict that when such data are available, age at complete cheek tooth eruption in small afrotherians will greatly postdate age at female sexual maturity (corresponding to long, horizontal red lines in elephants, hyraxes and manatees). Ages at completion of dental eruption in Trichechus and Petrogale concinna are arbitrarily set at the end of their recorded lifespan, reflecting the fact that these animals continually erupt supernumerary teeth. Dotted vertical lines represent 1.0 ratio of age at complete dental eruption/age at female sexual maturity (red, scale at bottom) and possession of 19 thoracolumbar vertebrae (blue, scale at top). Boxes at the center represent characters relating to phenotype observed in at least some afrotheres and human CCD patients, as follows: AN, unfused and projecting anterior nasal (black); MS, unfused metopic suture (black); PF, palatal fenestrae (black); CL, absent clavicles (black); TC, non-descended testicles (black), abdominal and ascrotal testicles (gray), scrotal testicles (white); VN, vertebral number (20 or more, black; 19 or less, white); DE, delayed eruption (after twice age at female sexual maturity, black; at or near female maturity, white). Scandentia, Dermoptera and Pholidota are not included owing to lack of data on dental ontogeny. Ages at female sexual maturity are taken from  except where indicated in Additional file 1. Vertebral data for sea cows represent averages from . Petrogale is coded based on P. concinna for age at complete dental eruption and P. penicillata for thoracolumbar vertebral number owing to the lack of intact skeletons of the former in available collections.