Sciuravids are generally small rodents. The skull is generally smaller and more gracile than that in ischyromyids with a less pronounced postorbital constriction (Fig. 6.1). A weak, low sagittal crest is present in the early Eocene Knightomys (Korth, 1984) but lost in the known middle Eocene specimens of Sciuravus (Dawson, 1961). The anterior root of the zygoma originates anterior to the tooth row. A large, distinct interparietal bone is present. The infraorbital foramen is small, circular, and unmodified; attachment for the masse-ter muscle is limited to the ventral side of the zygoma (protrogomorphous). Wood (1981) stated that the skull of Prolapsus was hystricomorphous, but other authors have refuted this and recognized the genus as protrogomorphous (Korth, 1984; Wilson, 1986; Wilson and Runkel, 1991). The auditory bullae are ossified but only weakly attached to the skull. There is no carotid canal.
KeywordsMiddle Eocene Late Eocene Cheek Tooth Mental Foramen Dental Morphology
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