First bone-cracking dog coprolites provide new insight into bone consumption in Borophagus and their unique ecological niche

Abstract

Borophagine canids have long been hypothesized to be North American ecological ‘avatars’ of living hyenas in Africa and Asia, but direct fossil evidence of hyena-like bone consumption is hitherto unknown. We report rare coprolites (fossilized feces) of Borophagus parvus from the late Miocene of California and, for the first time, describe unambiguous evidence that these predatory canids ingested large amounts of bone. Surface morphology, micro-CT analyses, and contextual information reveal (1) droppings in concentrations signifying scent-marking behavior, similar to latrines used by living social carnivorans; (2) routine consumption of skeletons; (3) undissolved bones inside coprolites indicating gastrointestinal similarity to modern striped and brown hyenas; (4) B. parvus body weight of ~24 kg, reaching sizes of obligatory large-prey hunters; and (5) prey size ranging ~35–100 kg. This combination of traits suggests that bone-crushing Borophagus potentially hunted in collaborative social groups and occupied a niche no longer present in North American ecosystems.

Peer Review #1 of "Hypercarnivorous teeth and healed injuries to Canis chihliensis from Early Pleistocene Nihewan beds, China, support social hunting for ancestral wolves (v0.1)"

“…Such a scenario is consistent with a hypercarnivorous dentition in C. chihliensis frequently used for bone consumption, as also seen in late Pleistocene European Cuon (Iurino & Sardella 2014). Bone-crushing behavior in canids has been linked to collaborative hunting and competitive consumption of carcasses within the same family group of predators (Wang et al 2008;Wang et al 2018). Such a behavior is especially prevalent among large, hypercarnivorous canids, and Van Valkenburgh et al (2019) recently linked high tooth fractures in extant gray wolves to limited prey availability.…”

Iterative evolution of large-bodied hypercarnivory in canids benefits species but not clades

“…A few species (e.g., some Enhydrocyon) yielded mass estimates just under 20 kg, even though other morphological evidence suggests that they were large and hypercarnivorous (e.g., ref. 56 ). The regression estimates account only for mean mass; these species may have easily been over 20 kg in life.…”

Combined visual and biochemical analyses confirm depositor and diet for Neolithic coprolites from Skara Brae

“…The best known coprolite assemblages are predominantly of canid origin, and have been studied since the nineteenth century (Buckland 1823). More recently, canid coprolites have been examined using μCT scanning to analyse their internal structure (Bravo-Cuevas et al 2017;Wang et al 2018). The internal composition of the four intact coprolites from Skara Brae resembles that of finds examined in Wang et al (2018), (Payne and Munson 1985 t.5) Sylvilagus remains in dog faeces (Payne and Munson 1985 attributed to the extinct bear-dog Borophagus parvus, with a number of fragmented bones entrapped completely or almost completely within the fossilized faecal matter.…”

“…Initially used only to generate 2-dimensional cross-sectional data (e.g. Farlow et al 2010), it has more recently been combined with 3-dimensional (3D) digital imaging techniques for more comprehensive analysis of content and structure (Milàn et al 2012a, b;Bravo-Cuevas et al 2017;Wang et al 2018). This has permitted identification of the coprolite depositor as well as its prey and other food items.…”