RHINOCEROTIDAE GRAY, 1821

Maguire, Kaitlin Clare & Schmitz, Joshua X. Samuels and Mark D., 2018, The fauna and chronostratigraphy of the middle Miocene Mascall type area, John Day Basin, Oregon, USA, PaleoBios 35, pp. 1-51 : 27

RHINOCEROTIDAE GRAY, 1821

Referred specimens —From -884: podial, UCMP 475; cuneiform(?), UCMP 35669. From -903: pisiform, UCMP

2176. From JDNM-70: partial tooth, JODA 4275; enamel fragments, JODA 15303. From JDNM-71A,B,D: enamel fragments, JODA 10314 and JODA 15677;molar fragment, JODA 15555 and 15644. From JDNM-4: tooth fragments; JODA 15326, JODA 15341, JODA 15612, JODA 15613, JODA 15615, JODA 15631, JODA 15678, JODA 15720, JODA 15790, JODA 15792, JODA 16124.

Occurrence — UCMP -884, UCMP -903, JDNM-4, JDNM-70, JDNM-71A, JDNM-71B, JDNM-71D.

Description and Remarks —Specimens of Rhinocerotidae are very rare in the Mascall type area but fragmentary postcranial elements and pieces of enamel have been found in all units of the Mascall Formation. Tooth material is fragmentary but contains the typicalHunter- Schreger bands characteristic of Rhinocerotidae ( Rensberger and von Koenigswald 1980) . To the south, by the Crooked River, rhinocerotid material is more abundant, but still mainly represented by fragmentary postcranial material. A calcaneum (UCMP 1682) from the Beaver Creek locality (UCMP -895) is assigned to Teloceras medicornutum Osborn, 1904 ( Prothero 2005). A partial maxilla with P2 and P3 (UCMP 41121 from V4948) most likely belongs to Aphelops Cope, 1874 because the teeth are brachydont and lack an antecrochet; however, they have a well-developed crochet. Although fragmentary and rare, the rhinocerotid material from the type Mascall demonstrate the persistence of this family throughout the Mascall Formation.