No abstract

Structures previously suggested to be footprints or tracks, but which have been little described, were observed within Quaternary inland dunes of the European Sand Belt. Excavation of these in several localities of the eastern part of the belt in Poland reveal that they are hoofprints of various ungulate mammals, both wild and domestic, as well as footprints of humans, ranging from potentially as early as the fifth to sixth century to the 19th century or later. Trample grounds and horizons with high densities of tracks are associated with other signs of intensifying usage of dune habitats for pasture and farming, including constrained movement of livestock, relatively well-developed paleosols, and evidence of ploughing. The presence of such abundant life traces not only reflects the presence of individual animals and people in an area, but sheds light on the potential processes and feedbacks that the tracemakers were involved in, in terms of maintaining and modifying the habitats themselves, which were dynamic and changeable. Footprints and their associated sedimentological records can be integrated with archaeological and historical data to analyse anthropogenic influence through time on physical landscapes and on the wild biota.

I n a heterogenous database environment, accessing data across different types of data models requires an integration of conceptual schemas. This conceptual schema can exist in various forms such as relational, object-oriented, hierarchical , or network.This paper provides a mechanism, a mapping function -for the transformation of an object-oriented schema to a relational schema and a query translation to access an object-oriented database for the relational database user. KEYWORDS : object-oriented data model (OODM), relational data model (RDM), object-oriented database (OODB), relational database (RDB), schema transformation, query translation.

Interpreting changes in ecosystem structure from the fossil record can be challenging. In a prominent example, the traditional view that brachiopods were ecologically dominant over bivalves in the Paleozoic has been disputed on both taphonomic and metabolic grounds. Aragonitic bivalves may be underrepresented in many fossil assemblages due to preferential dissolution. Abundance counts may further understate the ecological importance of bivalves, which tend to have more biomass and higher metabolic rates than brachiopods. We evaluate the relative importance of the two clades in exceptionally preserved, bulk-sampled fossil assemblages from the Pennsylvanian Breathitt Formation of Kentucky, where aragonitic bivalves are preserved as shells, not molds. At the regional scale, brachiopods were twice as abundant as bivalves and were collectively equivalent in biomass and energy use. Analyses of samples from the Paleobiology Database that contain abundance counts are consistent with these results and show no clear trend in the relative ecological importance of bivalves during the middle and late Paleozoic. Bivalves were probably more important in Paleozoic ecosystems than is apparent in many fossil assemblages, but they were not clearly dominant over brachiopods until after the Permian–Triassic extinction, which caused the shelly benthos to shift from bivalve and brachiopod dominated to merely bivalve dominated.

The earwigs, Dermaptera, are a group of insects which have been present since the Mesozoic. They have a relatively sparse fossil record, yet their life activities on and in soil or sediment leave traces with the potential for long-term preservation. These may include some burrows seen in Quaternary dunes and other sandy substrates. The well-known, cosmopolitan, sand-dwelling species Labidura riparia is examined as a potential model and reference for dermapteran tracemakers there and elsewhere in the geological record, through experimentally produced shelter burrows and trackways from wild-caught, laboratory-raised specimens. Shelter burrows were typically U-shaped with a pair of surface entrances, and these U-shapes could be additionally modified into Y-shapes or linked together to form a network. Trackways of L. riparia generally resembled those of other insects but may show features consistent with dermapteran anatomy such as tail-drag impressions produced by cerci.