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.

富含食肉目动物的化石点在化石记录中较为罕见，因此为我们提供了难得的研究古代捕食者的视角——这类视角在古动物群研究中鲜有应用。本研究借助稳定碳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化石点（Batallones-1与Batallones-3）中时间序列上连续（近乎同期）的食肉目动物种群展开分析。牙齿珐琅质中的稳定碳同位素，是追踪古生物食性的可靠且直接的研究手段。这两处以食肉目动物为主的化石点，在食肉目物种的组成与丰度上存在差异：部分物种在两处均有发现，部分则仅见于其中一处。此前学界将这一差异归因于年代更早的Batallones-1与年代较晚的Batallones-3之间的生境差异。然而，食肉动物与植食动物牙齿珐琅质的碳同位素值显示，两处化石点最初均为C3林地这一共同生境。因此，两处食肉目动物群的差异，更可能源于Batallones-1与Batallones-3形成间隔期内，物种在马德里盆地（Madrid Basin）的迁入与迁出动态，以及生物因素导致的种群密度变化。我们推断，Batallones-3中的种间竞争水平高于Batallones-1，依据包括：该点共存的同体型捕食者数量更多、各类群的δ¹³C值存在显著重叠（犬熊科（Amphicyonidae）的Magericyon anceps除外），且它们偏好的猎物均为三趾马亚科（Hipparionini）的马类。最后，对Indarctos arctoides牙齿的稳定碳同位素组成分析显示，该熊科（Ursidae）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，稳定同位素技术可有效揭示古食肉目类群的食性生态与营养级互作关系。