Komodo monitor (Varanus komodoensis) feeding behavior and dental function reflected through tooth marks on bone surfaces, and the application to ziphodont paleobiology

Abstract

Most functional interpretations of ziphodont dentition are based on limited morphometric, behavioral, and taphonomic studies, but few are based on controlled observations of a modern ziphodont consumer. The purpose of this study is to determine through controlled feeding observations if the behaviors indicative of a ziphodont consumer are reflected by tooth marks left on bone surfaces by Varanus komodoensis, the Komodo monitor. We document feeding behavior, expand upon dental function, and correlate these aspects with tooth mark production. We also discuss the significance and limits of applying these data to fossil assemblages.Goat carcasses were fed to 11 captive individuals. V. komodoensis modifies bone surfaces extensively. Individuals exhibit a “medial-caudal arc'7 when defleshing, followed by inertial swallowing. Bone crushing was not observed. The vast majority of tooth marks are scores, with pits being significantly less common. Tooth furrows and punctures are rare. “Edge marks” are produced on flat elements. Marks are elongate and narrow, with variable lengths and curvature. Over one-third of the marks occur within parallel clusters. Striations are evident on 5% of all marks.Both feeding behavior and tooth marks indicate that ziphodont crowns are ideal for defleshing by being drawn distally through a carcass. Crowns are poorly built for crushing, and within-bone nutrients are acquired through swallowing. Mark production is a by-product of the distal crown movement during the flesh removal process. Scores are the consequence of apical dragging. Edge marks and striated scores result respectively from distal and mesial carinae contact. Mark curvature is the consequence of arcing motions. Parallel clusters may result from repetitive defleshing strokes and/or from multiple crown contacts during a stroke.These observations can be used to draw functional, behavioral, and taphonomic interpretations from fossil assemblages. When they are provisionally applied to theropod tooth marks, similar crown function and defleshing behavior with little bone crushing is apparent. Differences occur concerning mark frequency and curvature, relating potentially to taphonomic biases and rostral motion, respectively.