This comprehensive study examines fossil remains from Niedzwiedzia Cave in the Eastern Sudetes, offering detailed insights into the palaeobiology and adversities encountered by the Pleistocene cave bear Ursus spelaeus ingressus. Emphasising habitual cave use for hibernation and a primarily herbivorous diet, the findings attribute mortality to resource scarcity during hibernation and habitat fragmentation amid climate shifts. Taphonomic analysis indicates that the cave was extensively used by successive generations of bears, virtually unexposed to the impact of predators. The study also reveals that alkaline conditions developed in the cave during the post-depositional taphonomic processes. Mortality patterns, notably among juveniles, imply dwindling resources, indicative of environmental instability. Skeletal examination reveals a high incidence of forelimb fractures, indicating risks during activities like digging or confrontations. Palaeopathological evidence unveils vulnerabilities to tuberculosis, abscesses, rickets, and injuries, elucidating mobility challenges. The cave's silts exhibit a high zinc concentration, potentially derived from successive bear generations consuming zinc-rich plants. This study illuminates the lives of late cave bears, elucidating unique environmental hurdles faced near their species' end.
Caves , Fossils , Ursidae , Animals , Poland , Ursidae/physiology , Paleopathology , Ecosystem , Paleontology
New isolated teeth from the Upper Cretaceous of Ukraine and belonging to the extinct durophagous shark Ptychodus are described here. The taxonomic identification of the examined material reveals a quite diverse Cenomanian shark fauna which comprised both cuspidate and un-cuspidate species of Ptychodus from the coastal areas at the north-western margin of the Ukrainian Massif. In addition, P. latissimus from the Turonian of Ukraine is reported here for the first time. The revision of the Ukrainian record of Ptychodus revealed that most specimens described here are the oldest so far known from this part of the European Peri-Tethys. Moreover, the present study highlights the co-occurrence of cuspidate and un-cuspidate Ptychodus and a variety of shelled macroinvertebrates, which inhabited coastal and offshore areas of the European epicontinental seas during the Late Cretaceous. The availability of different prey items is proposed here as one of the possible drivers, in addition to abiotic environmental factors, for the diversification of shark tooth morphologies, and possible trophic partitioning between cuspidate and un-cuspidate species of the genus Ptychodus.
