The chequered pattern (often called Schreger pattern), which can be seen by unaided eye on transverse profiles of several proboscidean tusks and which can be emphasized by the spreading pattern of the cracks or by mineral discoloration, is an autapomorph feature of the clade Elephantoidea. The pattern differs among proboscidean taxa; therefore, it allows the coarse differentiation of elephants, mammoths, and some other basal groups. Such identification methods could facilitate efforts concerned with protection of the remaining elephant populations through ivory trade restrictions, since the tooth dentine from extinct Mammuthus primigenius and from extant Loxodonta africana and Elephas maximus are the most common raw materials of the ivory carvings. The aim of this study was to show the internal structure of proboscidean ivory and to revise the existing theories on the aforementioned pattern of the elephantoids with reflections on the events which lead to the development of this microstructure. Thin sections and natural crack surfaces with various orientations of M. primigenius, Elephas antiquus, Prodeinotherium, and Deinotherium tusk fragments were used to produce a three-dimensional model which explains the features on all profiles. The ''phase shift'' model is introduced, which assumes a sinusoid undulation of the dentinal tubules in radial profiles in the case of elephantoids. The model was confirmed by photomicrographs, scanning electron microscopic images, interpretation of natural crack surfaces, and radial displacement analysis of the dentinal tubules. The latter proved that the adjacent waves are not in the same phase. Several new nondestructive distinguishing methods are described here on the basis of the correlation between some microscopic and macroscopic features related to the Schreger pattern.

Teeth of iguanodontian ornithopods and ceratopsians could be remarkably similar, thus the referral of isolated dental material to particular neornithischian clades can be highly problematic. These groups are represented by the rhabdodontid Mochlodon vorosi and the basal coronosaurian Ajkaceratops kozmai in the Upper Cretaceous Csehbánya Formation at Iharkút (western Hungary). Whereas teeth of the former taxonMochlodon are common elements at the locality, no dental material belonging to the latter speciesAjkaceratops was identified until now. Here we used mathematical statistical approaches, as well as tooth wear and dental microstructure analysis in order to decide whether the teeth previously referred to Mochlodon can be treated as a homogenous sample, or some remains belong rather to Ajkaceratops.According to our results, there was a striking morphological and structural convergence between the teeth of the latterboth taxa. However, the wear study revealed the existence of two different patterns within the sample. One is characterized by straight and parallel microstriations that suggest orthal movements during the jaw closure. This pattern was associated with Mochlodon. The other pattern appeared only on a few teeth, and it can be differentiated by its distinctive curved microstriations that indicate circumpalinal chewinga significant palinal component. Since Because curved striations were have never been described in ornithopods, but were are found in several neoceratopsians, this pattern was associated here with Ajkaceratops. Here we present the first teeth that can provisionally be referred to the latter genus. We believe that the methodology discussed in this paper will facilitate distinguishing ceratopsian and ornithopod teeth in other localities as well.

No abstract

Terrace ages deduced from diverse geochronological records yielded inconsistent data in the Danube valley in Hungary. The problem of discrepancies in the different chronological datasets has to be resolved before the Quaternary tectonic and climatic processes leading to valley incision and terrace formation may be properly evaluated. To establish a more robust chronology of the Danube valley in Hungary, new cosmogenic nuclide-(10 Be depth profiles, 26 Al/ 10 Be burial durations and burial depth profile) and luminescence-based (pIRIR 290) terrace ages were acquired and compared to revised paleontological and published U/Th and magnetostratigraphic data. All the applied geo-chronometers led to concordant terrace ages, with the exception of the U/Th method applied on travertine deposits covering terraces. U/Th ages predating the last interglacial manifest a bias towards younger ages, and so they were ignored in relation to the quantification of terrace ages. As a result, terrace ages from the Late Pliocene to Late Pleistocene were settled. With regard to data from the Middle Pleistocene onwards, the combination of diverse methodologies led to a tighter bracketing of terrace ages than would be possible using a single dating method. The modelling of cosmogenic 26 Al and 10 Be concentrations enabled to derive surface denudation rates and their combination with paleontological data also allowed us to decide between diverse landscape evolution scenarios.