Fossil Record最新文献

Extant and fossil chelids are restricted to South America and Australasia. Based on morphological data, long-necked and short-necked chelids are hypothesised to form natural groups respectively, whereas molecular and serological data indicate South American and Australasian chelids are monophyletic, regardless of neck-length. Here I provide shell bone histological and microanatomical data and character mapping of seven chelid taxa and the Late Jurassic stem-pleurodiran Platychelys oberndorferi Wagner, 1853 to test both competing hypotheses. The chelid shells show conserved bone microstructures, many of which are plesiomorphic for all turtles. Part of the variation among chelid shell microstructures could be attributed to functional aspects associated with the ecology of the taxa, i.e. adaptation to an aquatic lifestyle. The character mapping further indicates that the hypothesis of clades based on neck length is supported by two synapomorphies (i.e., parallel-fibred bone grading into lamellar bone in internal cortex and vascularisation of internal cortex) and one less tree step (16 instead of 17) in contrast to the molecular-based separation based on geographic distribution. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

An almost complete specimen of the branchiosaurid temnospondyl Apateon gracilis (Credner, 1881) with a skull length of approximately 7 mm from the Early Permian Döhlen Basin in Saxony is described that possesses a nearly complete conspecific specimen of approximately 4 mm skull length in its digestive tract. This is the first evidence of cannibalistic behaviour in small growth stages of branchiosaurids, whose dentition and hyobranchial morphology suggest adaptations to the capture of small invertebrates and feeding on small phyto- and zooplankton by filtering from the water. Therefore, cannibalism in small branchiosaurids certainly represents an exceptional case, possibly triggered by unfavourable environmental conditions. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A rock tumbler, stones, water, plant material, hydrochloric acid, and pepsin were used to simulate a bird gizzard in order to study abrasion rate and influence of stomach juices and foodstuff on gastrolith surface development. The experiment lasted for six months. Each week, the “stomach” was supplied with fresh grass and stomach juices. After the end of the experiment, the set of stones had a combined weight loss of 22.4 %, with softer rock types showing higher abrasion rates. The combination of stomach juices and silica phytoliths within the grass had no visible effect on stone surface development: polish or pitting did not occur. A second experiment combined only pebbles with water in the tumbler. Results indicate that rock abrasion is mainly caused by contacts between moving stones. A comparison with authentic ostrich gastroliths showed that abrasion in the artificial stomach must have been lower than in a real gizzard, but still too high to maintain or develop surface polish. If high polish occasionally seen on sauropodomorph dinosaur gastroliths was indeed caused in a stomach environment, it implies digestive processes different from those of extant birds and the “artificial gizzard”. Geologic origins of polish, such as transport in hyperconcentrated flows, wind blasting, or tectonic movements must be considered for polished fossil gastroliths and isolated clasts in fine-grained sediments (exoliths). (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The Tubulidentata are unique among mammals for being the only order represented nowadays by a single living species, Orycteropus afer: the aardvark. Nevertheless, it is one of the least studied mammalian orders. Aardvarks are currently distributed all over sub-Saharan Africa, but the fossil record extends their spatial range to Europe and Asia. The earliest known Tubulidentata are ca. 20 million years old. About 14 species and three to four genera have been recognised so far, but since the late Pliocene, aardvarks have only been represented by a single genus and are restricted to Africa. The extant aardvark is the only species of Tubulidentata with a large distribution area, i.e. the African continent. There are three known Plio-Pleistocene African species of aardvark: Orycteropus afer (Pallas, 1766), O. crassidens MacInnes, 1956, and O. djourabensis Lehmann et al., 2004. Fossils of these species have been discovered in North-Africa, Kenya, and Chad respectively. The present study is focused on the aardvark material found in the Plio-Pleistocene of East Africa (Ethiopia, Kenya). New specimens from Asa Issie (Ethiopia) and East Turkana (Kenya) are described, and published ones are re-examined in the light of the latest discoveries. This study demonstrates that Kenyan specimens identified as O. crassidens are in fact representatives of the Chadian O. djourabensis. Moreover, additional material from Ethiopia and Kenya shows a close relationship with the latter species too. The presence of specimens of O. djourabensis in Chad and in Kenya during the Plio-Pleistocene implies that this taxon is the oldest-known species of aardvark to have experienced a continental dispersal. It also shows that Tubulidentates were able to cross Africa from east-west during Plio-Pleistocene times, despite the presence of the Rift Valley. It is however not possible to infer the centre of origin of O. djourabensis. Finally, this study suggests that two species of aardvark might have co-existed in Kenya during the early Pleistocene. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Most pycnodontiform fishes are represented by their distinctive dentition alone, whereas articulated skeletons are very rare and the systematic position of most taxa based upon isolated teeth and the association of upper and lower dentitions to a specific taxon is still somewhat ambiguous in most cases. The vomerine dentition of the Late Jurassic pycnodontiform Athrodon wittei (Fricke, 1876), which is described here for the first time, is characterised by a high number of lateral tooth rows and the distinct morphology of the teeth. The dentition of Athrodon differs from most other pycnodont dentitions in the peculiar arrangement of the teeth into irregular rows and not well-differentiated principal row. The absence of regular tooth rows is not considered plesiomorphic here but most probably was achieved independently in different pycnodont lineages. The high number of lateral tooth rows (> four) is considered to be autapomorphic for Athrodon. The pycnodont fish Nonaphalagodus from the Albian of Texas, which also is known by isolated dentitions only, resembles Athrodon in the high number of vomerine tooth rows but differs in that this taxon displays the more derived feature of the teeth being arranged more regularly and individualized rows. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Five Late Viséan ammonoid assemblages of North Variscan provenance are described from the locality Chebket el Hamra (Jerada Basin, north-eastern Morocco). These assemblages are composed of 27 species of the genera Eoglyphioceras, Girtyoceras, Sulcogirtyoceras, Metadimorphoceras, Goniatites, Arnsbergites, Hibernicoceras, Paraglyphioceras, Lusitanoceras, Sudeticeras, Neoglyphioceras, Lusitanites, Ferganoceras, Praedaraelites, and Pronorites. The new subfamily Arnsbergitinae is described, as well as the thirteen new species Eoglyphioceras minutum n. sp., Girtyoceras ibnkhaldouni n. sp., Metadimorphoceras anguinosum n. sp., Arnsbergites ferrus n. sp., Arnsbergites proiecturus n. sp., Arnsbergites rufus n. sp., Hibernicoceras touissitense n. sp., Hibernicoceras artilobatum n. sp., Paraglyphioceras celeris n. sp., Lusitanoceras zirari n. sp., Sudeticeras ibnbajjahi n. sp., Sudeticeras horoni n. sp., and Pronorites owodenkoi n. sp. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We describe a specimen of Eocetus sp. from the middle Eocene Stockletten Formation of Rohrdorf, Bavaria, Germany, consisting of a lumbar vertebral body and transverse processes. This specimen constitutes the first record of Eocetus, and the first confirmed record of the family Protocetidae from Europe. This new observation further supports the hypothesis that protocetids were highly aquatic and that their method of aquatic locomotion was sufficient for them to spread far from their center of origin in Indo-Pakistan. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Old collections, new records, and data from global literature are used for taxonomic revisions and for a new reconstruction of the evolutionary history of the triangularly coiled clymenids, the Wocklumeriaceae, and their ancestors. Epiwocklumeria applanata is first reported from the topmost Wocklum Limestone at Hasselbachtal and Drewer, and this supports the distinction of an applanata Subzone just prior to the global Hangenberg Event which wiped out the whole group. The Wocklumeriaceae and Glatziellidae record of the famous Oberrödinghausen Railway Cut and of other Rhenish sections is revised. The Maïder of Southern Morocco has yielded first Parawocklumeria patens, paprothae, Wocklumeria sphaeroides plana, Kielcensia ingeniens n. sp., and Synwocklumeria mapesi n. sp. Parawocklumeria distributa Czarnocki forms the type-species of Tardewocklumeria n. gen. Lecto- and neotypes for several taxa are designated. The variability and paedomorphic patterns of Wo. sphaeroides are discussed. The Wocklumeriaceae represent the terminal Famennian (Upper Devonian VI-C/D) radiation of a long-ranging lineage which evolved in parallel to other clymenid groups. They are characterized by sutural features and by longidomic and very slowly expanding whorls. The polyphyletic traditional Gonioclymeniina are divided into the suborder Wocklumeriina (with Wocklumeriaceae, Glatziellaceae n.superfam. and Biloclymeniaceae) and into the Gonioclymeniaceae of the Clymeniina. Gyroclymenia Czarnocki is regarded as a junior synonym of Pleuroclymenia Schindewolf which, however, does not include the ‘Pleuro.’ americana and eurylobica groups. Pleuroclymenia represents the ancestral form of the Wocklumeriina and also the phylogenetical link with Platyclymenia (Varioclymenia) of the Clymeniaceae. The Gonioclymeniaceae had their roots in advanced Platyclymeniidae.

Alte Aufsammlungen, Neunachweise und globale Literaturdaten werden für taxonomische Revisionen und für eine neue Rekonstruktion der Evolution der Dreiecksclymenien (Wocklumeriaceae) und ihrer Vorfahren benutzt. Epiwocklumeria applanata wird zum ersten Mal im Hasselbachtal und bei Drewer nachgewiesen, und diese Funde bestätigen die Abtrennung einer applanata-Subzone im unmittelbar Liegenden des Hangenberg-Event, welcher zum Aussterben der gesamten Gruppe führte. Die Verbreitung von Wocklumeriaceae und Glatziellidae im klassischen Profil des Bahneinschnittes bei Oberrödinghausen und an anderen Fundorten im Rheinischen Schiefergebirge wird revidiert. Der Maïder in Süd-Marokko lieferte erstmalig Parawocklumeria patens, paprothae, Wocklumeria sphaeroides plana, Kielcensia ingeniens n. sp. und Synwocklumeria mapesi n. sp. Parawocklumeria distributa Czarnocki bildet die Typus-Art von Tardewocklumeria n.gen. Weiterhin werden die Variabilität und paedomorphe Erscheinungen bei Wo. sphaero