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Osi A.,MTA ELTE Lendulet Dinosaur Research Group | Barrett P.M.,Natural History Museum in London | Foldes T.,University of Kaposvár | Tokai R.,University of Kaposvár
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.


Csiki-Sava Z.,University of Bucharest | Buffetaut E.,CNRS ENS Geology Laboratory | Osi A.,MTA ELTE Lendulet Dinosaur Research Group | Pereda-Suberbiola X.,University of the Basque Country | Brusatte S.L.,University of Edinburgh
ZooKeys | Year: 2015

The Late Cretaceous was a time of tremendous global change, as the final stages of the Age of Dinosaurs were shaped by climate and sea level fluctuations and witness to marked paleogeographic and faunal changes, before the end-Cretaceous bolide impact. The terrestrial fossil record of Late Cretaceous Europe is becoming increasingly better understood, based largely on intensive fieldwork over the past two decades, promising new insights into latest Cretaceous faunal evolution. We review the terrestrial Late Cretaceous record from Europe and discuss its importance for understanding the paleogeography, ecology, evolution, and extinction of land-dwelling vertebrates. We review the major Late Cretaceous faunas from Austria, Hungary, France, Spain, Portugal, and Romania, as well as more fragmentary records from elsewhere in Europe. We discuss the paleogeographic background and history of assembly of these faunas, and argue that they are comprised of an endemic ‘core’ supplemented with various immigration waves. These faunas lived on an island archipelago, and we describe how this insular setting led to ecological peculiarities such as low diversity, a preponderance of primitive taxa, and marked changes in morphology (particularly body size dwarfing). We conclude by discussing the importance of the European record in understanding the end-Cretaceous extinction and show that there is no clear evidence that dinosaurs or other groups were undergoing long-term declines in Europe prior to the bolide impact. © Zoltán Csiki-Sava et al.


Botfalvai G.,Eötvös Loránd University | Botfalvai G.,MTA ELTE Lendulet Dinosaur Research Group | Haas J.,Geophysical and Space Science Research Group | Bodor E.R.,Geological and Geophysical Institute of Hungary | And 4 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2016

The Csehbánya Formation (Santonian), exposed in the Iharkút open-pit, Bakony Mountains, Hungary, is made up of a cyclic alternation of conglomerate, sandstone, and variegated siltstone and clay deposited in a fluviolacustrine environment. As a result of continuous excavation since 2002 it has yielded rich and diverse continental vertebrate and plant assemblages. A facies and architectural analysis of the Csehbánya Formation at this location identified four main lithofacies associations with eight subtypes consisting of (1) lenticular sandstones representing river channels, (2) conglomerates with sandstone (coarse grained likewise representing channel deposits), (3) heterolithic-channel fill (high density flash flow deposits) (4) splay sandstones produced by crevasse splays, (5) dark sandy siltstone (small-scale stagnant pool deposits with high organic content), (6) greenish-grey claystone (deposits of shallow lakes and ponds), (7) reddish (moderately drained) paleosols, and (8) yellowish, mottled (hydromorphic) paleosols.The sedimentological investigations revealed that the terrestrial deposits exposed by the Iharkút open-pit were formed in an anastomosing fluvial system because: (i) the alluvial architecture is characterized by large proportion of overbank deposits encasing the channel sandstone bodies, (ii) the ribbon shaped sandstone bodies are dominant, (iii) cross-bedding and lateral accretion are almost completely absent in the channel fill deposits and (iv) the sandstone bodies are clearly isolated from each other, embedded in floodplain sediments, suggesting multiple co-existing channels.The most important vertebrate fossil site (SZ-6) was examined in special detail because it shows peculiar lithological features. The layers richest in fossils (Unit 1) of SZ-6 site are interpreted as a lag deposit formed during an episodic high density flash flood event representing a relatively short time interval, i.e., probably within a single rainy season. © 2015 Elsevier B.V.


Osi A.,Eötvös Loránd 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


Osi A.,MTA ELTE Lendulet Dinosaur Research Group | Osi A.,Eötvös Loránd University | Bodor E.R.,Geological and Geophysical Institute of Hungary | Bodor E.R.,Eötvös Loránd University | And 4 more authors.
Cretaceous Research | Year: 2016

Vertebrate remains from the Upper Cretaceous (Santonian) Ajka Coal Formation (Bakony Mountains, western Hungary) are described. Macro- and microfossils collected from two boreholes and from isolated chunks of sediment/matrix dumped on spoil heaps of the Jókai Mine represent pycnodontiform and lepisosteiform fishes, bothremydid turtles, the mosasauroid Pannoniasaurus inexpectatus, the crocodyliforms cf. Theriosuchus, Iharkutosuchus makadii and cf. Allodaposuchus, as well as ankylosaurian and theropod dinosaurs. This unit was deposited in a swampy lacustrine environment, in contrast with the neighbouring and contemporaneous floodplain deposit of the vertebrate-bearing Csehbánya Formation at Iharkút. Despite significant environmental differences, the faunal composition of the Ajka Coal Formation assemblage completely overlaps with that of the Csehbánya Formation, suggesting the occurrence of the same semi-aquatic and terrestrial species in both settings. The ankylosaurian remains further strengthen the previous view that ankylosaurus preferred wetland habitats such as fluvial systems and coastal regions. © 2015 Elsevier Ltd.


Wings O.,Museum fur Naturkunde Berlin | Wings O.,University of Tübingen | Rabi M.,University of Tübingen | Rabi M.,Eötvös Loránd 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.


Szabo M.,MTA ELTE Lendulet Dinosaur Research Group | Gulyas P.,Szilvagyi Karoly utca 13. | Osi A.,MTA ELTE Lendulet Dinosaur Research Group | Osi A.,Eötvös Loránd 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.


Szabo M.,Hungarian Natural History Museum | Gulyas P.,Szilvagyi Karoly utca 13. | Osi A.,Eötvös Loránd 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.


Osi A.,MTA ELTE Lendulet Dinosaur Research Group | Codrea V.,Babes - Bolyai University | Prondvai E.,MTA ELTE Lendulet Dinosaur Research Group | Csiki-Sava Z.,University of Bucharest
Annales de Paleontologie | Year: 2014

Ankylosaurian remains from the Transylvanian Basin, Romania, are extremely rare. More than 100 years after the discovery of the first and only better-known assemblage, namely the type material of Struthiosaurus transylvanicus, new ankylosaurian material has been discovered in the Maastrichtian of the Haţeg Basin, as well as at another locality (Vurpǎr), in the Transylvanian Basin, that is described here. The material consists of one tooth in a small jaw fragment (from the Haţeg Basin) and at least two accummulations of associated, as well as several isolated, postcranial elements (from Vurpǎr). No diagnostic elements are preserved that would overlap with the type of S. transylvanicus, so we cannot assign any of the new specimens to this species. The tooth shows marked differences compared to those of other anklyosaurs including S. austriacus and Hungarosaurus in having only six, more or less equally sized, apically pointed cusps separated by deep grooves. The postcranial material from Vurpǎr represents at least three different individuals. The humerus is the most diagnostic element among the postcranial remains being most similar both in size and morphology to humeri referred to as Struthiosaurus from different European localities, thus here we refer the humerus and probably associated elements preserved in one assemblage to as cf. Struthiosaurus sp.; the remaining specimens from Vurpǎr are retained as Nodosauridae indet. Histological studies have confirmed the adult nature of all sampled bones in the Vurpǎr ankylosaur material suggesting that these fully grown animals were of similar size to Struthiosaurus, a small-bodied nodosaurid the ontogenetic status of which, however, has never been investigated histologically. The obviously diminished body size of the Transylvanian ankylosaurs compared to other members of the clade could be explained by insular dwarfism using the same histology-based argument as presented for Magyarosaurus. © 2014 Elsevier Masson SAS.


Rabi M.,University of Tübingen | Rabi M.,Eötvös Loránd University | Rabi M.,MTA ELTE Lendulet Dinosaur Research Group | Sukhanov V.B.,Russian Academy of Sciences | And 4 more authors.
Journal of Vertebrate Paleontology | Year: 2014

A complete description of the xinjiangchelyid turtles Annemys levensis and A. latiens is provided, based on all available material from the Upper Jurassic type locality of Shar Teg, Mongolia. Annemys latiens was previously known almost exclusively from shell material, but an undescribed skull from Shar Teg is referable to this species and its distinct morphology confirms the presence of two taxa at this locality. Annemys latiens has an elongated skull that markedly differs in proportions from those of A. levensis and resembles the shape of some recent, piscivorous turtles. The overall similarity of the shells of the two Annemys species combined with significant differences in the skull indicate that these turtles probably partitioned the aquatic niche by exploring different feeding strategies. Among xinjiangchelyids, at least three different skull morphotypes can be differentiated, which implies a moderate level of ecological diversification among Late Jurassic Asian turtles. Phylogenetic analysis weakly supports the inclusion of Annemys spp. into Xinjiangchelyidae and places xinjiangchelyids at the stem of Testudines, but the latter result is considered tentative. Phylogenetic definitions of Xinjiangchelyidae, Sinemydidae, and Macrobaenidae are provided for nomenclatural clarity and precision. © 2014 Copyright Taylor & Francis Group, LLC.

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