FIGURE 13. Length of skull (maximal length) x zygomatic width (zw) of skulls of some fossil taxa (13.1) and Recent Castor (13.2). Palaeocastor (Palaeoc.) sp. SDSM 4209, Capacikala gradatus (Capacik. grad.) JODA 621 (black square) and SDSM 5489 (grey square), Capacikala (Capacik.) parvus and "Capatanka" (Capat.) minor from Xu 1996 (partially calculated from figure), Palaeocastor (Palaeoc.) nebrascensis UCMP 114635 and "Capatanka" cankpeopi (Capat. cank..) LACM 22443., Palaeocastor fossor, "Capatanka" magnus, Pseudopalaeocastor (Pseudopal.) barbouri, Euhapsis platyceps and E. ellicottae from Martin (1987). Castor canadenis (C. can), C. fiber (C. fib) of adults and juveniles (juv) are illustrated; data from Stefen (2009).