YUOMYIDAE AND

Li, Qian & Meng, Jin, 2015, New ctenodactyloid rodents from the Erlian Basin, Nei Mongol, China, and the phylogenetic relationships of Eocene Asian ctenodactyloids, American Museum Novitates 2015 (3828), pp. 1-60 : 46

YUOMYIDAE AND CHAPATTIMYIDAE

Yuomyidae was established by Dawson et al. (1984), which includes Advenimus , Saykanomys , Yuomys , and Petrokozlovia . Chapattimys , Saykanomys , and Petrokozlovia , however, were included in the Chapattimyidae by Hussain et al. (1978). Wang (1994) considered Yuomyidae as a group that was composed of Advenimus (and Saykanomys ), Yuomys , Dianomys , and Petrokozlovia , whereas Chapattimyidae include Chapattimys , Birbalomys , Bolosomys , Chkhikvadzomys , and perhaps Boromys . Averianov (1996) recognized two families, Chapattimyidae and Tamquammyidae , among ctenodactyloids and suggested Yuomyidae (Dawson et al., 1984; Flynn et al., 1986) is a junior synonym of Chapattimyidae Hussian et al., 1978 . Subsequently, Tong (1997) rearranged his Chapattimyidae and Yuomyidae . Meng et al. (2001) pointed out that Averianov’s Chapattimyidae is roughly equivalent to Tong’s Yuomyidae and Chapattimyidae (1996) .

The relationship of the Yuomyidae and Chapattimyidae in the Ctenodactyloidea is problematic. The distinction between the Chapattimyidae and Yuomyidae has been ambiguous since their establishment (Hussain et al., 1978; Dawson et al., 1984). The similarities between Yuomyidae and Chapattimyidae were also recognized by Wang (1994). Hertenberger (1982) and Dawson et al. (1984) considered Chapattimyidae to be an offshoot of primitive ctenodactyloids distributed in the Indo-Pakistan subcontinent, and Flynn et al. (1986) suggested the family is related to Miocene baluchimyines of the same realm. However, when their diagnoses are compared, the two families are distinguished from each other primarily by their molariform P4/p4 morphologies. Other features are partly overlapping, such as the hystricomorph, in both families. Our phylogenetic analysis further indicates that Dawson’s (1984) Yuomyidae , Averianov’s (1996) Chapattimyidae , and Tong’s (1997) Yuomyidae and Chapattimyidae are not monophyletic ( fig. 18 ). The paraphyletic nature of each family has been demonstrated by phylogenetic analyses of selected ctenodactyloids (Averianov, 1996; Dashzeveg and Meng, 1998). The monophyletic Yuomys clade in our analysis includes different genera from the Yuomyidae and Chapattimyidae . However, we consider that it is difficult to distinguish Yuomyidae from Chapattimyidae based only on tooth morphology. Therefore, we did not redefined Yuomyidae and Chapattimyidae , but used Yuomys clade temporarily for the taxa in the clade.

Figures

FIG. 18. Strict consensus of six most parsimonious trees generated in a phylogenetic analysis of ctenodactyloid interrelationships. See text for discussion.