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Szabo M.,Hungarian Natural History Museum | Gulyas P.,Szilvagyi Karoly utca 13. | Osi A.,Eotvos Lorand University | Osi A.,MTA ELTE Lendulet Dinosaur Research Group
Cretaceous Research | Year: 2016

Lepisosteid fishes are well known from the Upper Cretaceous of Europe, but only by fragmentary remains from some Cenomanian and Campanian-Maastrichtian deposits. Here we report various cranial and postcranial remains of gars, discovered in the Upper Cretaceous (Santonian) Csehbánya Formation of Iharkút (Bakony Mountains, Hungary). These remains represent one of the most diverse assemblages of lepisosteid fish material from Upper Cretaceous continental deposits of Europe. Based on tooth morphology, scale-microstructure and the features of the supracleithrum we refer these remains to the genus Atractosteus. Besides some uncertain remains from the Cenomanian of France and Spain, the Santonian aged fossils from Iharkút represent the oldest undisputable occurrence of the family Lepisosteidae in the European continental Cretaceous. Using tooth crown morphology, the surface microstructure of the ganoid scales and the anatomy of the supracleithrum a review of the Late Cretaceous lepisosteid record suggests the occurrence of both Atractosteus and Lepisosteus in the European archipelago. © 2015 Elsevier Ltd.

Wings O.,Museum fur Naturkunde Berlin | Wings O.,University of Tubingen | Rabi M.,University of Tubingen | Rabi M.,Eotvos Lorand University | And 7 more authors.
Naturwissenschaften | Year: 2012

A spectacular new terrestrial Konzentratlagerstätte is introduced from the Turpan Basin of Xinjiang, China that probably belongs to the late Middle Jurassic Qigu Formation. It contains a mass accumulation of " xinjiangchelyid" turtles preliminarily identified as Annemys sp. In the zone with the highest turtle concentration, complete and articulated turtle skeletons are tightly packed at a density of up to 36 turtles per square meter. The fossiliferous layer is thickened here and shows an erosional base. This high concentration zone outcrops approximately 10 m in length and shows no decrease in turtle density after exposing 2 m of the layer into the hillside. Adjacent is a more expansive zone of at least 10m by 30 m. In this region, the fossiliferous layer is evenly thick, and approximately five, fully disarticulated turtles are present per square meter. A conservatively estimated 1,800 turtles may, therefore, have been deposited at this site. It is likely that these aquatic turtles gathered in a retreating water hole in a riverine environment during a drought, much as some aquatic turtles will do today, but perished when the habitat dried up completely. A following catastrophic rainfall event caused a debris flow, possibly channelized in a dry river bed, which transported complete turtles, disarticulated turtles, and mudstone clasts and deposited them after a short distance. This taphonomic model is consistent with previous environmental reconstructions of the Turpan Basin during the late Middle Jurassic in predicting the episodic breakdown of regional monsoonal circulation resulting in a seasonally dry climate with severe episodic droughts. © Springer-Verlag Berlin Heidelberg 2012.

Osi A.,MTA ELTE Lendulet Dinosaur Research Group | Barrett P.M.,Natural History Museum in London | Foldes T.,University of Kaposvar | Tokai R.,University of Kaposvar
Anatomical Record | Year: 2014

Feeding in thyreophoran dinosaurs is poorly understood. Although the group existed for over 130 million years, only the Early Jurassic basal thyreophoran Scelidosaurus harrisonii and the Late Cretaceous ankylosaurid Euoplocephalus tutus have been studied from this perspective in detail. In contrast to the earlier, conservative hypothesis of a simple "orthal pulping" feeding mode with no or limited tooth-tooth contact, recent studies have demonstrated precise dental occlusion with differing jaw mechanisms in these two species. Here, we describe the first detailed study of feeding related characters in a nodosaurid ankylosaur, Hungarosaurus tormai, from the Late Cretaceous of Hungary. Dental wear patterns comprising small, apical, and low-angled facets on the maxillary and steep, extended, and bowl-like facets on the dentary teeth reveal sophisticated tooth-tooth contact in this basal nodosaurid. The presence of two different scratch generations (vertical and low-angled) on the dentary teeth unambiguously demonstrate a multiphasic powerstroke, which is further supported by the morphology of the quadrate-articular and mandibular symphyseal joints and by the architecture of the reconstructed jaw adductors. Chewing started with an initial slicing phase associated with orthal movement that was followed by a retractive powerstroke with significant occlusal contact. Because of the curved tooth rows, these movements were probably facilitated by some mediolateral translation and/or axial rotation of the mandibles to produce precise shearing along the whole tooth row. These results demonstrate that complex jaw mechanisms and dental occlusion were more widespread among thyreophorans than thought previously and that palinal movement was present in at least two ankylosaurian lineages. © 2014 Wiley Periodicals, Inc.

Szabo M.,MTA ELTE Lendulet Dinosaur Research Group | Gulyas P.,Szilvagyi Karoly utca 13. | Osi A.,MTA ELTE Lendulet Dinosaur Research Group | Osi A.,Eotvos Lorand University
Annales de Paleontologie | Year: 2016

Isolated but well-preserved remains of pycnodontiform fishes from the Upper Cretaceous (Santonian) Csehbánya Formation at Iharkút, western Hungary are described here. The assemblage contains cranial (premaxilla/dentary, vomers, prearticulars, teeth) and postcranial (possible contour scales) remains allowing the identification of the Iharkút pycnodontiforms as cf. Coelodus sp. Supported by sedimentological and stable isotope studies, the Iharkút fossils represent one of the few certainly freshwater occurrences of the group in the Upper Cretaceous of Europe. An estimated value of minimum number of individuals indicates that the remains of at least 28 individuals were hitherto discovered, suggesting that these medium-sized hard-shelled prey consuming fishes were quite abundant in the Iharkút freshwater habitats. © 2016 Elsevier Masson SAS.

Osi A.,Eotvos Lorand University | Osi A.,MTA ELTE Lendulet Dinosaur Research Group | Prondvai E.,MTA ELTE Lendulet Dinosaur Research Group | Prondvai E.,Ghent University | And 2 more authors.
Historical Biology | Year: 2016

Ankylosaurian dinosaurs were low-browsing quadrupeds that were traditionally thought of as simple orthal pulpers exhibiting minimal tooth occlusion during feeding, as in many extant lizards. Recent studies, however, have demonstrated that effective chewing with tooth occlusion and palinal jaw movement was present in some members of this group. Qualitative and quantitative analysis of feeding characters (i.e. craniodental features, tooth wear patterns, origin and insertion of jaw adductors) reveal at least three different jaw mechanisms during the evolution of Ankylosauria. Whereas, in basal members, food processing was restricted to simple orthal pulping, in late Early and Late Cretaceous North American and European forms a precise tooth occlusion evolved convergently in many lineages (including nodosaurids and ankylosaurids) complemented by palinal power stroke. In contrast, Asian forms retained the primitive mode of feeding without any biphasal chewing, a phenomenon that might relate to the different types of vegetation consumed by these low-level feeders in different habitats on different landmasses. Further, a progressive widening of the muzzle is demonstrated both in Late Cretaceous North American and Asian ankylosaurs, and the width and general shape of the muzzle probably correlates with foraging time and food type, as in herbivorous mammals. © 2016 Informa UK Limited, trading as Taylor & Francis Group

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