The two archaeofaunal assemblages from Haithabu (Viking period) and Schleswig (early Middle Age) belong to the largest such bone complexes ever recovered in Northern Europe. More than 800,000 animal bones were recovered from both sites in the course of the last three decades and investigated by traditional archaeozoological methods. More recently and independently from the latter, stable isotopic ratios of the light elements carbon, nitrogen, and oxygen were analyzed on a total of 440 animal bone finds representing 67 vertebrate species from both sites producing a data set comprising 1,760 individual isotopic ratios. In addition, stable strontium isotopic ratios were obtained from 68 animal teeth and bones of four species. In this paper, an attempt is made to synthesize archaeozoological and archaeometrical data on a larger scale. By becoming familiar with the specific potential of each method, we raise questions concerning not only palaeobiodiversity and palaeoecology of fish and birds in the area, trophic webs, and prey/predator relationships, but also human meat-provisioning, import of animals and animal products, and the reconstruction of hunting areas. This transdisciplinary approach led to an improvement in the quality of our interpretations and the validation of previously confirmed and/or rejected assumptions. It is still too early to expect answers to all these questions, but we are convinced that, in attempting to do so, the potential of coordinating such methods for future research will become evident, and we therefore strongly recommend an intensification of archaeometric analyses of archaeofaunal assemblages.