Killing in the Pliocene: shark attack on a dolphin from Italy

Abstract: Shark bite marks, including striae, sulci and abrasions, in a well‐preserved fossil dolphin skeleton referred to Astadelphis gastaldii (Cetacea, Delphinidae) from Pliocene sediments of Piedmont (northern Italy), are described in detail. The exceptional combination of a fossil dolphin having a significant part of the skeleton preserved and a large number of bite marks on the bones represents one of the few detailed documentations of shark attack in the past. Most bite marks have been referred to a shark about 4 m long with unserrated teeth, belonging to Cosmopolitodus hastalis, on the basis of their shape and their general disposition on the dolphin skeleton. According to our hypothesis, the shark attacked the dolphin with an initial mortal bite to the abdomen from the rear and right, in a similar way as observed for the living white shark when attacking pinnipeds. A second, less strong, bite was given on the dorsal area when the dolphin, mortally injured, probably rolled to the left. The shark probably released the prey, dead or dying, and other sharks or fishes probably scavenged the torn body of the dolphin.     

Host preferences and behaviour of oxpeckers: co-existence of similar species in a fragmented landscape

The host preferences and behaviour of red-billed and yellow-billed oxpeckers (Buphagus erythrorynchus and Buphagus africanus) were studied at two locations in Kenya and combined with previously published data from East and South Africa. Red-billed oxpeckers are generally more common and have a greater niche breadth with respect to host preferences than yellow-billed oxpeckers, possibly due to the behavioural dominance of the latter. Otherwise, the host preferences are remarkably similar: both prefer larger species of ungulates and are found predominantly on species with manes. There are also no significant differences in the time–activity budgets of the two species controlling for site and host species, and differences in the proportion of time spent on different body parts of hosts are small in absolute magnitude even when statistically significant. Despite these and other basic ecological similarities, no evidence for competitive displacement was detected by comparing host preferences in areas of sympatry with areas of allopatry, even though each species appears to depress the population size of the other when sympatric. Traditional single-community competition theory cannot explain the geographical ecology of these two species. Instead, co-existence appears to be dependent on the patterns of extinction and colonization characterized by metapopulations distributed among a fragmented habitat.     

Systematic and comparative anatomy of Cymbidieae (Orchidaceae)

Cymbideae comprise an assemblage of 28 genera nearly all of which are represented in this study. Their anatomy is relatively homogenous with the exception of Govenia , in which roots lack velamen and pseudobulb vascular bundles lack sclerenchyma, conditions that do not obtain in other genera. Marginal fibre bundles in leaves of Grammatophyllum and Porphyroglottis consist of clusters of thicker-walled, narrower, epidermis-facing fibres as well as thinner-walled, wider, mesophyll-facing fibres. This feature also occurs in some species of Maxillaria . Baculate tilosomes appear in the roots of a majority of genera in Cymbidieae, as they do in species of Maxillaria , confirming DNA analyses showing a close relationship between tribes Cymbidieae and Maxillarieae. Govenia is singled out both on anatomical and molecular grounds as being ill-placed in Cymbidieae. Cladistic analysis produces only a few tentative hypotheses of phylogenetic relationships among the 28 genera, showing that anatomical characters are of limited value in assessing affinities within this tribe. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 139 , 1–27.