The impact of large terrestrial carnivores on Pleistocene ecosystems
Large mammalian terrestrial herbivores, such as elephants, have dramatic effects on the ecosystems they inhabit and at high population densities their environmental impacts can be devastating. Pleistocene terrestrial ecosystems included a much greater diversity of megaherbivores (e.g., mammoths, mastodons, giant ground sloths) and thus a greater potential for widespread habitat degradation if population sizes were not limited. Nevertheless, based on modern observations, it is generally believed that populations of megaherbivores (>800 kg) are largely immune to the effects of predation and this perception has been extended into the Pleistocene. However, as shown here, the species richness of big carnivores was greater in the Pleistocene and many of them were significantly larger than their modern counterparts. Fossil evidence suggests that interspecific competition among carnivores was relatively intense and reveals that some individuals specialized in consuming megaherbivores. To estimate the potential impact of Pleistocene large carnivores, we use both historic and modern data on predator–prey body mass relationships to predict size ranges of their typical and maximum prey when hunting as individuals and in groups. These prey size ranges are then compared with estimates of juvenile and subadult proboscidean body sizes derived from extant elephant growth data. Young proboscideans at their most vulnerable age fall within the predicted prey size ranges of many of the Pleistocene carnivores. Predation on juveniles can have a greater impact on megaherbivores because of their long interbirth intervals, and consequently, we argue that Pleistocene carnivores had the capacity to, and likely did, limit megaherbivore population sizes.
Himalayan fossils of the oldest known pantherine establish ancient origin of big cats
Tseng, Wang, Slater5, Takeuchi, Li, Liu & Xie
Pantherine felids (‘big cats’) include the largest living cats, apex predators in their respective ecosystems. They are also the earliest diverging living cat lineage, and thus are important for understanding the evolution of all subsequent felid groups. Although the oldest pantherine fossils occur in Africa, molecular phylogenies point to Asia as their region of origin. This paradox cannot be reconciled using current knowledge, mainly because early big cat fossils are exceedingly rare and fragmentary. Here, we report the discovery of a fossil pantherine from the Tibetan Himalaya, with an age of Late Miocene–Early Pliocene, replacing African records as the oldest pantherine. A ‘total evidence’ phylogenetic analysis of pantherines indicates that the new cat is closely related to the snow leopard and exhibits intermediate characteristics on the evolutionary line to the largest cats. Historical biogeographic models provide robust support for the Asian origin of pantherines. The combined analyses indicate that 75% of the divergence events in the pantherine lineage extended back to the Miocene, up to 7 Myr earlier than previously estimated. The deeper evolutionary origin of big cats revealed by the new fossils and analyses indicate a close association between Tibetan Plateau uplift and diversification of the earliest living cats.
Kurtén Club starts again this autumn. Björn Kurtén Club is a forum for everyone intressed in paleontology. Main participants are paleontology students, researchers and professors. This year, we have every other week a presentation/introduction, held either by one of the group members or a visiting lecturer, and every other week a group meeting/conversation session. Visit our blog for more information: https://blogs.helsinki.fi/bk-club/ .
First meeting will be held tomorrow, 20.9.2011, at 16.00(-17.00) in room C108, Physicum, Kumpula. Next meetings will be held every Tuesday at the same time in the same place (unless otherwise announced). The program will be available on Kurtén Clubs blog. Suggestions for possible topics and speakers are most welcome.
This week we also have a special lecture by Lars Werdelin (The Swedish Museum of Natural History, http://www.nrm.se/en/menu/researchandcollections/departments/palaeozoology/staff/larswerdelin.477_en.html ) titled
The fossil Carnivora of Africa: review and analysis,
22.9.2011, 15.00, C108.