Avian pellets from the late Oligocene of Enspel, Germany—ecological interactions in deep time

Abstract

Ecological interactions in deep time can be elucidated by direct evidence, such as gut contents, from fossil deposits of exceptional preservation (referred to as Konservat-Fossillagerstatten). We have analysed isolated, microvertebrate-containing pellets from the upper Oligocene lake deposit of Enspel, Germany, which are unusually abundant at this location, and identified these, on the basis of content and corrosion pattern, as casts of a bird of prey. The pellets contained the remains of a minimum of one to six prey individuals each. The main prey species were rodents, but other vertebrate prey include cyprinid fishes, frogs and anguimorph lizards. This is the first record of a lizard from Enspel. A seed was also present in one pellet, which possibly was being carried by the co-preserved rodent. It is unlikely that any of the four bird species known from Enspel produced the pellets. One hypothesis to explain their occurrence in the middle of the lake involves subaerial dessication of the pellets in gullies on the crater wall, followed by transport of the then-buoyant pellets by flowing water.