Oldest known pantherine skull and evolution of the tiger

The tiger is one of the most iconic extant animals, and its origin and evolution have been intensely debated. Fossils attributable to extant pantherine species-lineages are less than 2 MYA and the earliest tiger fossils are from the Calabrian, Lower Pleistocene. Molecular studies predict a much younger age for the divergence of modern tiger subspecies at <100 KYA, although their cranial morphology is readily distinguishable, indicating that early Pleistocene tigers would likely have differed markedly anatomically from extant tigers. Such inferences are hampered by the fact that well-known fossil tiger material is middle to late Pleistocene in age. Here we describe a new species of pantherine cat from Longdan, Gansu Province, China, Panthera zdanskyi sp. nov. With an estimated age of 2.55–2.16 MYA it represents the oldest complete skull of a pantherine cat hitherto found. Although smaller, it appears morphologically to be surprisingly similar to modern tigers considering its age. Morphological, morphometric, and cladistic analyses are congruent in confirming its very close affinity to the tiger, and it may be regarded as the most primitive species of the tiger lineage, demonstrating the first unequivocal presence of a modern pantherine species-lineage in the basal stage of the Pleistocene (Gelasian; traditionally considered to be Late Pliocene). This find supports a north-central Chinese origin of the tiger lineage, and demonstrates that various parts of the cranium, mandible, and dentition evolved at different rates. An increase in size and a reduction in the relative size of parts of the dentition appear to have been prominent features of tiger evolution, whereas the distinctive cranial morphology of modern tigers was established very early in their evolutionary history. The evolutionary trend of increasing size in the tiger lineage is likely coupled to the evolution of its primary prey species

Facebook as an instrument of election campaigning and voters’ engagement: comparing Czechia and Poland

Adding to the growing scholarship on the use and role of social media in election campaigning, this article examines and compares the character and determinants of Internet users’ engagement with political party communication in 2013 and 2015 Parliamentary election campaigns in Czechia and Poland. Apart from the relationship between the thematic focus of party-produced content and the level of users’ interactivity, the study also explores the way the tonality of users’ comments is influenced by different types of party communication, as well as by users’ gender. The results suggest that the level of support for a party status is largely independent of the content of the message in both countries. The type of content has, however, an effect on the intensity of criticism by the users, with policy-related subjects generating more negativity than mobilization- or campaign-oriented statuses. Finally, the study points to both gender gaps and gender as a strong predictor of user negativity, as female users – while constituting a minority of participants in both countries – tend to be significantly less negative in their comments towards the home party. Overall, the comparative study reveals both similarities and differences in the way Czech and Polish parties utilize Facebook as campaign platform, as well as in their respective Internet users’ engagement with parties messages

The Making of a Monster: Postnatal Ontogenetic Changes in Craniomandibular Shape in the Great Sabercat Smilodon

Derived sabercats had craniomandibular morphologies that in many respects were highly different from those of extant felids, and this has often been interpreted functionally as adaptations for predation at extreme gape angles with hypertrophied upper canines. It is unknown how much of this was a result of intraspecific postnatal ontogeny, since juveniles of sabercats are rare and no quantitative study has been made of craniomandibular ontogeny. Postnatal ontogenetic craniomandibular shape changes in two morphologically derived sabercats, Smilodon fatalis and S. populator, were analysed using geometric morphometrics and compared to three species of extant pantherines, the jaguar, tiger, and Sunda clouded leopard. Ontogenetic shape changes in Smilodon usually involved the same areas of the cranium and mandible as in extant pantherines, and large-scale modularization was similar, suggesting that such may have been the case for all felids, since it followed the same trends previously observed in other mammals. However, in other respects Smilodon differed from extant pantherines. Their crania underwent much greater and more localised ontogenetic shape changes than did the mandibles, whereas crania and mandibles of extant pantherines underwent smaller, fewer and less localised shape changes. Ontogenetic shape changes in the two species of Smilodon are largely similar, but differences are also present, notably those which may be tied to the presence of larger upper canines in S. populator. Several of the specialized cranial characters differentiating adult Smilodon from extant felids in a functional context, which are usually regarded as evolutionary adaptations for achieving high gape angles, are ontogenetic, and in several instances ontogeny appears to recapitulate phylogeny to some extent. No such ontogenetic evolutionary adaptive changes were found in the extant pantherines. Evolution in morphologically derived sabercats involved greater cranial ontogenetic changes than among extant felids, resulting in greatly modified adult craniomandibular morphologies

Locating specimens of extinct tiger (Panthera tigris) subspecies: Javan tiger (P.t. sondaica), Balinese tiger (P.t. balica), and Caspian tiger (P.t. virgata), including previously unpublished specimens

Recent advances in multivariate statistics, and in ancient DNA techniques, have greatly increased understanding of tiger phylogeography. However, regardless of advances in analytical methodology, researchers will continue to need access to specimens for morphological measurements and sampling for genetic analysis. The tiger has become increasingly endangered, and out of the nine putative tiger subspecies, three (Javan, Balinese, and Caspian) have become extinct in the last 100 years, leaving the specimens kept in natural history collections as the only materials available for research. Frustratingly little information is widely available concerning the specimens of these extinct tiger subspecies. We conducted an extensive search for specimens of extinct tiger subspecies, and also developed a simple on-site method to assign unprovenanced and probable Indonesian specimens to either Javan/Balinese or Sumatran subspecies. We located a total of 88 Javan, 11 Balinese, and 46 Caspian tigers, including seven new Javan tigers, and three Balinese tigers that were not widely known previously. These specimens are critical for research in order to understand the intraspecific phylogeny and evolutionary history of the tiger

Lost populations and preserving genetic diversity in the lion Panthera leo: Implications for its ex situ conservation

The original publication is available at www.springerlink.comTwo of the eight recognized lion subspecies, North African Barbary lion (Panthera leo leo) and South African Cape lion (Panthera leo melanochaita), have become extinct in the wild in the last 150 years. Based on sequences of mitochondrial DNA (mtDNA) control region (HVR1) extracted from museum specimens of four Barbary and one Cape lion, the former was probably a distinct population characterized by an invariable, unique mtDNA haplotype, whilst the latter was likely a part of the extant southern African lion population. Extinction of the Barbary line, which may still be found in "generic" zoo lions, would further erode lion genetic diversity. Therefore, appropriate management of such animals is important for maintaining the overall genetic diversity of the species. The mtDNA haplotype unique to the Barbary lion, in combination with the small size of the HVR1 analyzed (c. 130 bp), makes it possible and cost-effective to identify unlabelled Barbary specimens kept in museums and "generic" captive lions that may carry the Barbary line. An initial study of five samples from the lion collection of the King of Morocco, tested using this method, shows that they are not maternally Barbary. © Springer 2006.Ross Barnett, Nobuyuki Yamaguchi, Ian Barnes and Alan Coope