Small mammal bone accumulations produced by mammalian carnivores

Abstract

Small mammal bone assemblages from the scats of three families of mammalian carnivores are described here as a means of assessing paleontological bone assemblages. These are the Viverridae, Canidae, and Mustelidae. Marking behavior by the carnivores or their use of latrine areas can produce concentrations of bone comparable with those produced from owl pellets, but the nature of the bone assemblages is very different. Skeletal element preservation has a characteristic pattern related to the relative strength of the individual elements, so that the strongest elements are the ones that best survive the physical abrasion of the predator's teeth. Bone breakage is greatest in canids and least in some viverrids. Digestion of the bone occurs to a certain extent with all carnivores, with moderate rounding but little corrosion of either bones or teeth in viverrid-derived bone assemblages, very great rounding and severe corrosion of bone and tooth enamel (but little corrosion of tooth dentine) in canids, and moderate rounding and slight to moderate corrosion of bone and tooth dentine (but less of enamel) in mustelid-derived bone assemblages. Tooth marks are generally rare except in canid-derived bone assemblages. These patterns may enable the identification of predators responsible for the accumulation of fossil predator assemblages, and a consideration of the hunting and other behavior of that type of predator then permit the identification of possible biases in the fossil fauna. In the viverrids, for instance, the mongoose selected for large prey size and against cranial elements, while the genet took all prey sizes available to it and all body parts. Larger canids such as foxes and coyotes took both large and small species, but proportionally more of the most common prey species were present. Skulls were underrepresented. The small canid, the bat-eared fox, selected for the smallest prey species available to it but took all body parts. Mustelids took all sizes of prey, although not necessarily in proportion to their abundance in the habitat, and large species were underrepresented. If the predator type is known, therefore, for a fossil assemblage, these biases can be taken into account in assessing the paleoecological significance of the fauna. An example from the Olduvai Pleistocene deposits is given.

Small Mammal Taphonomy: Intraspecific Bone Assemblage Comparison between South and North American Barn Owl,Tyto alba, Populations

“…These works describe interspecific bone patterns of contemporary agents of bone deposition, assuming that each deposition agent produces a fixed bone pattern, with little or no intraspecific variation. Taphonomic studies have concentrated on definitive descriptions of bone patterns produced by several modern predators (Dodson & Wexlar, 1979;Korth, 1979;Hoffman, 1988;Andrews, 1990a;Kusmer, 1990), often characterizing composition and fragmentation of bone and teeth remains left by diverse predators (Noe-Nygaard, 1977;Behrensmeyer & Dechant Boaz, 1980;Gifford, 1981;Andrews & Evans, 1983;Andrews, 1990a, b).…”

New data on fish diet and bone digestion of the Eurasian otter (Lutra lutra) (Mammalia: Mustelidae) in central France

“…Digestion in the otter produces feces in which the bones tend to be broken and digested like in most other mammalian carnivores. For example, Andrews and Evans (1983), Andrews (1990) and Matthews (2002) have shown that feces of small felids generally contain extremely broken bones with high levels of rounding and polishing produced by digestion. They also found that scats of small canids contain digested bones, but the degree of breakage is slightly less than in small felids.…”

“…There are many descriptions of current assemblages originating from various predators such as nocturnal and diurnal birds of prey (Mayhew 1977;Dodson & Wexlar 1979;Andrews 1990;Laroulandie 2002), crocodiles (Fisher 1981) and carnivores (Andrews & Evans 1983;Andrews 1990;Mondini 2001;Campmas & Beauval 2008). Modern carnivores produce feces containing bones that display varying degrees of damage and digestion.…”

Tafonomia da assembleia fossilífera de mamíferos da “Fenda 1968”, bacia de São José de Itaboraí, Estado do Rio de Janeiro, Brasil

“…Além disso, o grande número de falanges e metapodiais completos na tafocenose estudada, os quais, segundo Behrensmeyer & Dechant-Boaz (1980) são as partes do esqueleto preferidas pelos predadores, pode sugerir que os animais encontrados na fenda estudada não faziam parte da dieta dos predadores locais. Andrews & Evans (1983) e Faith et al (2007 ao analisarem, respectivamente, assembleias geradas por mamíferos carnívoros e mudanças na representatividade óssea produzidas por carniceiros (hienas), observaram que os elementos proporcionalmente mais encontrados em concentrações ósseas de vertebrados sob interferência de carnívoros e carniceiros são úmeros e tíbias, os quais não são abundantes na tafocenose da "Fenda 1968". Outro fator que deve ser levado em consideração é que a quantidade de animais carnívoros paleocênicos representada na bacia de São José de Itaboraí aparentemente é baixa se comparada à quantidade de herbívoros/frugívoros registrada (ver em Bergqvist et al, 2006 a listagem das famílias presentes na bacia).…”