Myocricetodon sivalensis, LINDSAY, 1988

Antoñanzas, Raquel López, 2009, First Potwarmus from the Miocene of Saudi Arabia and the early phylogeny of murines (Rodentia: Muroidea), Zoological Journal of the Linnean Society 156 (3), pp. 664-679 : 671

‘ MYOCRICETODON ’ SIVALENSIS LINDSAY, 1988

‘ Myocricetodon ’ sivalensis was erected by Lindsay (1988) on the basis of 36 isolated cheek teeth from the Middle Miocene localities YGSP 591 and YGSP 592, Kamlial Formation, Potwar Plateau, Pakistan. Additional material of this species has been recorded from the Middle Miocene localities H-GSP 81.14a, H-GSP 81.14, H-GSP 82.27, and H-GSP 82.24 of the Lower Manchar Formation, Sind, Pakistan ( Wessels, 1996). ‘ M. ’ sivalensis does not fit the diagnosis of Myocricetodon as emended by Jaeger (1977b), and according to Tong & Jaeger (1993) and the results of the cladistic analysis conducted below, the assignment of this species to the genus Myocricetodon should be rejected.

The M1s of ‘ Myocricetodon ’ sivalensis are distinct from AJ 7 in having a short, anteriorly weak, but distinct, straight longitudinal crest and an anterolophule. The enterostyle is lacking in most of specimens of ‘ M. ’ sivalensis, but as only one specimen of Potwarmus flynni sp. nov. is available, the significance of this difference cannot be assessed. The M2 of ‘ M. ’ sivalensis has the lingual branch of the anterior cingulum connected to the enterostyle or to the base of the hypocone, and shows a short and anteriorly weak longitudinal crest. In contrast, in AJ11 and AJ12 the longitudinal crest is completely absent or relictual, and the lingual branch of the anterior cingulum is short and interrupted before reaching the base of the protocone. The m1 of ‘ M. ’ sivalensis differs from AJ 13 in having a longitudinal crest, the anterior part of the tooth unreduced, possessing an anteroconid, and having a posterior cingulum that bears a large hypoconulid. In contrast, AJ13 has its anterior part very reduced and lacks an anteroconid, longitudinal crest, and hypoconulid.