Oldest evidence of osteophagic behavior by insects from the Triassic of Brazil

Osteopathology and insect traces in the Australopithecus africanus skeleton StW 431

“…Morphological and metrological variables are key in the identification of insect traces on bone but they have little application in identifying a specific causal agent responsible for their creation. 23,[35][36][37] Traces produced by insects are morphologically consistent despite geographical and/or temporal distribution; for example, furrows as described in this study from the Plio-Pleistocene are consistent with traces recently reported from the Jurassic of China. 36 Shallow circular holes have been reported throughout the Mesozoic and well into the Late Cenozoic; the most commonly inferred causal agent of traces during the Mesozoic are dermestids 34,[41][42][43][44] , but this shifts during the Cenozoic to termites being the most commonly inferred agent 21,24,[45][46][47] .…”

“…In that the morphological categories proposed by Pirrone et al 20 and Parkinson 23 are by no means independent of one another -it is widely accepted that they represent transitional morphotypes which relate to the orientation of the excavation relative to the bone surface. [34][35][36][37] For example, if an insect excavates perpendicular to the bone surface and thus penetrates vertically in the bone, the trace would transition through a number of morphologies: initially it would be a pit, transition into a hole, and culminate in a tube. Alternatively, if the excavation is orientated parallel to the bone surface, the initial excavations would potentially take the form of a chamber and culminate in a meandering furrow.…”

“…23,[35][36][37]44 Interestingly, the majority of these authors who have described ichnotaxa in bone have avoided attributing a specific causal agent to the traces for various reasons. 23,[35][36][37] These authors recognise that the trace is a reflection of behaviour, and that behaviour could easily be mimicked by numerous agents belonging to a diversity of insect groups. Simply put, more experimental research is required to begin to better understand and document the minor morphological variables between traces in bone produced by a substantially wider diversity of potential agents.…”

Ectoparasitism and infections in the exoskeletons of large fossil cingulates

“…Therefore, some additional comments on the alterations that we attributed to fleas are necessary. Several works cite post-mortem alterations in bone that, such as perforations generated by necrophagic coleopteran larvae in fossil vertebrate bone (See [ 41 , 35 , 42 ]), which at first glance, might be confused with ante-mortem marks, such as those attributed to fleas in this study. However, their internal morphology diverges, because necrophagic larvae construct chambers with a diameter twice the diameter of the opening.…”

“…A possible reason for this difference is the finality of the excavation. The necrophagic larvae reach for the bone medullary channel to feed on the bone marrow, and consequently, the perforations reach deep portions of the bone and are interconnected (see Fig 2 in [ 42 ]). By contrast, fleas are less invasive because the bone is used as a reproduction site and for feeding on blood, and therefore, the cavity created is not required to reach deeper regions of the bone.…”