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Russian Journal of Theriology

Mammalian humerus from the Early Cretaceous of West Siberia // Russian J. Theriol. Vol.3 (for 2004). No.2: 5158 [in English].

A distal humerus fragment from the Early Cretaceous Shestakovo locality in Kemerovo Province, West Siberia is described and referred to Symmetrodonta. This humerus is characterized by relatively narrow distal epiphysis, large entepicondylar foramen, globular radial condyle, ellipsoidal ulnar condyle, coalesced articular surfaces of both condyles, and a unique additional articular platform for the radius laterally to the radial condyle. This structure of the elbow joint is structurally intermediate between cynodonts, morganucodontids, and multituberculates on the one hand and crown Theria on the other. Among mammals with the similar structure of the elbow joint the humerus from Shestakovo is most similar with the humerus of the Early Cretaceous symmetrodont Zhangheotherium from China, and it might belong to a new tinodontid symmetrodont being described from the same locality on dental remains. KEY-WORDS: Humerus, anatomy, musculature, Symmetrodonta, Early Cretaceous, West Siberia.