Data from: Feeding ecology and habitat preferences of top predators from two Miocene carnivore-rich assemblages

Carnivoran-rich fossil sites are uncommon in the fossil record and, accordingly, provide valuable opportunities to study predators from vantages that are rarely applied to ancient faunas. Through stable isotopes of carbon and a Bayesian mixing model, we analyze time-successive (nearly contemporaneous), late Miocene carnivoran populations from two fossil sites (Batallones-1 and Batallones-3) from central Spain. Stable isotopes of carbon in tooth enamel provide a reliable and direct methodology to track ancient diets. These two carnivoran-dominated fossil sites display differences in the composition and abundance of the carnivoran species, with some species present at both sites and some present only in one site. This disparity has been interpreted as the consequence of habitat differences between Batallones-1, the older site, and Batallones-3, the younger site. However, carbon isotope values of carnivore and herbivore tooth enamel suggest a common habitat of C3 woodland originally present at both sites. The differences in the carnivoran faunas may be rather the consequence of the dynamics of species entrance and exit from the Madrid Basin during the time elapsed between Batallones-1 and Batallones-3 and changes in population densities due to biotic factors. We infer higher levels of interspecific competition in Batallones-3 than in Batallones -1, because of the larger number of similar-sized, sympatric predators, the clear overlap in their δ13C values (except for the amphicyonid Magericyon anceps), and similarity of their preferred prey: the hipparionine horses. Finally, carbon stable isotopic composition of Indarctos arctoides teeth implies that this ursid was a carnivorous omnivore rather than a herbivorous omnivore. This work demonstrates the insights that stable isotopes can provide in characterizing the feeding ecology and trophic interactions of ancient carnivoran taxa.

富含食肉目（Carnivoran）动物的化石点在化石记录中较为稀缺，这为研究者提供了宝贵的契机，得以运用鲜有应用于古动物群的研究视角来剖析史前捕食者。本研究借助碳稳定同位素与贝叶斯混合模型（Bayesian mixing model），对西班牙中部两处晚中新世（late Miocene）的食肉动物化石点——Batallones-1与Batallones-3——的时间序列（近乎同期）种群展开分析。牙釉质（tooth enamel）中的碳稳定同位素是追踪古生物食谱的可靠且直接的研究手段。这两处以食肉目动物为优势类群的化石点，其食肉物种的组成与丰度存在显著差异：部分物种在两处遗址均有产出，部分则仅见于其中一处。此前这种差异被归因于较老的Batallones-1与较年轻的Batallones-3之间的生境差异。然而，食肉动物与植食动物的牙釉质碳同位素数据显示，两处遗址原本均为C3林地的统一生境。因此，食肉动物群的组成差异更可能源于Batallones-1至Batallones-3的时间间隔内，物种迁入与迁出马德里盆地的动态过程，以及生物因素驱动的种群密度变化。我们推断，Batallones-3的种间竞争水平高于Batallones-1，依据包括：该遗址中体型相近的同域（sympatric）捕食者数量更多；除犬熊科（amphicyonid）的Magericyon anceps外，其余捕食者的δ¹³C碳同位素比值存在明显重叠；且它们的偏好猎物均为三趾马亚科（hipparionine）马匹。最后，Indarctos arctoides的牙釉质碳稳定同位素组成表明，该熊科（ursid）动物属于食肉性杂食动物，而非植食性杂食动物。本研究证实了稳定同位素技术在解析古食肉目类群的摄食生态学（feeding ecology）与营养相互作用（trophic interactions）方面的重要研究价值。