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Abstract Tusks are ever‐growing teeth present in mammals of the clade Paenungulata. Unlike the perpetually growing incisors of rodents, tusks are not used in mastication, and in at least some paenungulatans, the tusk is composed of dentin alone in adults. Few studies have provided tissue‐level information on tusks of adult paenungulatans with embedding techniques that identify epithelial and other soft tissues. In order to examine the mineralized tissues as well as the cells that form teeth, we studied a single, subadult rock hyrax (Procavia capensis) using microCT and paraffin histology with traditional staining as well as RUNX2 immunohistochemistry, and compared its teeth to scans of adult hyraxes. Three‐dimensional reconstructions from microCT volumes revealed that the tusk of this specimen is the only fully erupted replacement tooth, the first adult premolar (P1) is starting to erupt, and the first permanent molar (M1) is fully erupted, whereas all other replacement teeth and M2 remain in crypts. The tusk has a thin layer of enamel on its dorsal side; this is confirmed by histology. All deciduous premolars still possess roots that are in the process of resorption. Amelogenesis has progressed to maturation or nearly so in P1–P3. Notable histological characteristics of replacement premolars include the lack of a stellate reticulum in all except P4, and expression of RUNX2 in ameloblasts, a marker which is expressed by ameloblasts at all stages of amelogenesis. Since the pulp chambers of replacement premolars are relatively large compared to adults, a lengthy time in crypts may be important for dentin production. The results confirm that the hyrax has thin enamel on tusks, supporting the hypothesis that enamel is of limited importance for non‐feeding behaviors. 

Abstract Recently, Yohe and Krell (The Anatomical Record, vol. 306:2765–2780) lamented the incongruence between genetics and morphology in the vomeronasal system of bats. Here, we studied 105 bat species from 19 families using histology, iodine‐enhanced computed tomography (CT), and/or micro‐CT. We focused on structural elements that support a functional peripheral vomeronasal receptor organ (vomeronasal organ [VNO]), together comprising the “vomeronasal complex.” Our results support prior studies that describe a functional VNO in most phyllostomid bats, miniopterids, and some mormoopids (most knownPteronotusspp.). All of these species (or congeners, at least) have vomeronasal nerves connecting the VNO with the brain and some intact genes related to a functional VNO. However, some bats have VNOs that lack a neuroepithelium and yet still possess elements that aid VNO function, such as a “capsular” morphology of the vomeronasal cartilages (VNCs), and even large venous sinuses, which together facilitate a vasomotor pump mechanism that can draw fluid into the VNO. We also show that ostensibly functionless VNOs of some bats are developmentally associated with ganglionic masses, perhaps involved in endocrine pathways. Finally, we demonstrate that the capsular VNC articulates with the premaxilla or maxilla, and that these bones bear visible grooves denoting the location of the VNC. Since these paraseptal grooves are absent in bats that have simpler (bar‐shaped or curved) VNCs, this trait could be useful in fossil studies. Variable retention of some but not all “functional” elements of the vomeronasal complex suggests diverse mechanisms of VNO loss among some bat lineages.