Hans-Ulrich Pfretzschner

Larval ontogeny of Micromelerpeton credneri (Temnospondyli, Dissorophoidea)

Abstract A growth series of 97 specimens of the dissorophoid temnospondyl Micromelerpeton credneri from the Permo-Carboniferous of Central Europe is taken as a basis for ontogenetic investigations. Whereas the dermal skull roof is already ossified and sutured in the smallest specimen with a skull length of 6 mm, the ossification sequence of the postcranium can be reconstructed. Compared to branchiosaurids and Recent urodeles, the ossification of the postcranial skeleton is delayed. For the first time, external gills are described in Micromelerpeton credneri. Their three pairs of branches shorten proportionally during ontogeny. A Cartesian transformation and biometric analyses show allometric changes in the dermal skull roof. Whereas the preorbital region elongates slightly (due to positive allometric growth of nasal length and negative allometric growth of orbits) and grows in width isometrically, the postorbital skull table shows isometry in length (due to positive allometry of frontal length and negative allometry of parietal length) and distinct negative allometry in width (due to negative allometry of parietal and supratemporal width). The interorbital width relatively decreases. The cheek region shows positive allometry both in length and in width, shifting the jaw articulation posteriorly. In this way proportionally more space and attachment area for the adductor musculature are provided and the gape enlarges proportionally. The positive allometric growth of the diameter of the sclerotic ring indicates increased importance of the optical sense. Transformation into the adult stage took place gradually and in a longer period of time during ontogeny than in extant amphibians.

Biomechanics in the Enamel of Mammalian Teeth

The formation of mammalian enamel is strictly determined genetically but yields important functional adaptations on the levels of gross morphology and micro-structure. Differentiation of enamel thickness is frequently found in hypsodont teeth of smaller and medium-sized mammals. It is mainly due to the position on the leading or trailing edge. In the enamel microstructure, the Schmelzmuster, defined as a specific combination of different enamel types, again shows a close relationship to the leading or trailing edge especially in small mammals. The various enamel types, defined by prism orientation, have different functional meanings. Some, like Hunter-Schreger bands, reinforce enamel to resist tensile forces and possess crack-stopping properties as well. In hypsodont molars of larger mammals, specific stresses occur near the enamel-dentine junction. The characteristic modified radial enamel found in this region is regarded as a special adaptation to these stresses. Modified radial enamel evolved convergently in several lineages. Because enamel types are mainly functionally determined, the taxonomical value of enamel structures is largely restricted to the level of Schmelzmuster.

Hunter-Schreger-Bänder im Zahnschmelz von Säugetieren (Mammalia)

ZusammenfassungHunter-Schreger-Bänder (HSB) sind eine auffällige Struktur im Schmelz von Säugetierzähnen, die als Bruchsicherung verstanden werden kann. Eine einfache Methode zur Beobachtung der Bänder wird beschrieben. Die hellen und dunklen Bänder werden durch die unterschiedliche Orientierung der Schmelzprismen hervorgerufen. Die häufige Aufgabelung der HSB sowie der regelmäßige Übergang der Schmelzprismen von einem Band zum nächsten, der mit einem Richtungswechsel der Prismen verbunden ist, wird beschrieben. Da dieser Richtungswechsel einer strengen Regel unterliegt, kann ein Strukturmodell entworfen werden, das sowohl den Lauf der Prismen wie die Vergabelung der HSB deutet. Eine frühere Strukturanalyse von Shellis und Poole (1979) zum Schmelz von Daubentonia kann nicht bestätigt werden.SummaryHunter-Schreger bands (HSB) are a remarkable structure of the enamel in many mammalian teeth. This structure prevents cracks in the enamel. A simple method for observation of this structure is introduced. The light and dark bands are due to differences in the orientation of the enamel prisms. The frequent bifurcation of the HSB and the regular transition of prisms from one band to the next, which implies bending of the prisms, is described. Since this bending is strictly regulated, a structural model can be presented to explain both the course of the prisms and the mode of bifurcation of the HSB. An earlier structural interpretation of the enamel of Daubentonia is not confirmed.

The first haramiyoid mammal from Asia

A lower molar of a haramiyoid mammal is described from the Toutunhe Formation of Liuhuanggou near Urumqi in the southern Junggar Basin, Xinjiang, China. It is referred to Eleutherodon sp., otherwise exclusively known from the Upper Bathonian of England. It is the first record of the order Haramiyida from Asia and the first Mesozoic mammal described from the southern Junggar Basin. Apart from the English specimens of Eleutherodon and Staffia from the Upper Jurassic of East Africa, it is the geologically youngest haramiyoid known. It is the first vertebrate taxon from the Toutunhe Formation that is probably not endemic and lends some support to the dating of the Formation as late Middle Jurassic, probably Bathonian.

Ein weiteres Exemplar vonLethe?corbieri Nel 1993 (Lepidoptera, Satyridae) aus dem Unter-Oligozän von Céreste (Süd-Frankreich)

A new specimen of the family Satyridae from Céreste is described. The specimen is an isolated right forewing. It is classified as a satyr because of the swelling at the base of some veins and of the presence of a postdiscal eye-spot. The color patterns as well as the dimensions of the wing characterize the fossil as a member of the speciesLethe? corbieri (Nel et al. 1993).Together with other fossil butterflies this specimen demonstrates the importance of the satyres in the Oligocène of Southern France. Among modern butterflies only the families of the Satyridae and the Hesperiidae are highly specialized on grasses as host plants for their caterpillars. Besides some satyrs true skippers are also known from the Oligocène of Southern France. The frequency of fossils of these two families probably indicates a Lower Oligocene spreading of grasses in Europe.KurzfassungEin neuer Saytridenfund aus Céreste wird beschrieben. Es handelt sich um einen isolierten rechten Vorderflügel. Die Zugehörigkeit zur Familie der Satyridae folgt aus der verdickten Basis der Flügeladern und der Anwesenheit eines postdiskalen Augenflecks. Von den bisher aus Süd-Frankreich beschriebenen Arten läßt sich der Fund der ArtLethe? corbieri (Nel et al. 1993) zuordnen. Er unterstreicht die Häufigkeit der Satyriden im Oligozän Südfrankreichs. Dies ist insofern bemerkenswert, als die rezenten Satyriden die einzige Familie von Tagfaltern darstellen, deren Raupen sich fast ausschließlich von Gräsern ernähren. Eine vergleichbare Spezialisierung auf Gräser findet man sonst nur noch bei den Hesperiidae, die ebenfalls im Oligozän Süd-Frankreichs nachgewiesen sind. Die relative Häufigkeit der beiden Schmetterlingsfamilien kann als mögliches Indiz für eine zunehmende Bedeutung der Gräser in den Florengesellschaften des Unter-Oligozäns gewertet werden.

Biometric study of ruminant carpal bones and implications for phylogenetic relationships

The mammalian Carpus is a complex of several small bones with multiple interactions during walking. Therefore, it is highly probable that different mammalian families developed distinctive constellations in their Carpi, which could be useful for biometric identification of phylogenetic groupings. The carpal bones of nineteen extant ruminant species (nine bovid, nine cervid, and one moschid) have been investigated to search for biometric traits which are diagnostic for the three families. Additionally, we searched for diverging functional adaptations in the carpal constellations. Therefore, measurements have been taken from the five main carpals, which are carrying the body weight. As a sesamoid bone, Os carpi accessorium was excluded. After transformation of the data into their natural logarithms, multivariate methods of factor analyses and discriminant analyses were performed for each bone. Bivariate plots of the factor scores allowed a clear separation of bovids and cervids. The only one species of the Moschidae (Moschusmoschiferus) lies closer to the cervids than to the bovids. The grouping is due to phylogenetic relationships and not due to functional differences in the groups or differing habitat preferences. Generally, the carpals of cervids are more slender and higher in contrast to the bulky and flat carpals in bovids. This approach could be used to assign isolated carpal bones found in fossil sites to their ruminant family.

Zubehör zu Vermessungsarbeiten

Fluchtstabe sind 2 m lange, runde Stangen von 3 cm Durchmesser aus Holz oder Leichtmetall, die in 50 cm Abstanden rot und weis gestrichen sind und am unteren Ende angespitzt und mit einer Stahlspitze versehen sind. Sie konnen entweder in den Boden eingestosen werden oder mit Hilfe eines Stabstativs aufgestellt werden. Das Stabstativ ist ein Dreifus mit einer Klemme am Stativkopf, die den Fluchtstab halt. Zur endgultigen senkrechten Ausrichtung kann ein Lattenrichter (Abschn. 4.3) benutzt werden.

Dinosaur teeth from the Jurassic Qigu and Shishugou Formations of the Junggar Basin (Xinjiang/China) and their paleoecologic implications

Abstract The Middle and early Late Jurassic Qigu and Shishugou Formations of the southern and central Junggar Basin yielded teeth of theropods (Theropoda indet.), sauropods (Eusauropoda indet.), and stegosaurs. The dinosaur assemblage of the southern Junggar Basin is less diverse and is represented by smaller forms than in the central part of the basin. The microwear of the teeth of Eusauropoda indet. resembles that observed in Camarasaurus and may have formed as a result of biting through resistant woody materials. Carbon and oxygen isotope data of the sauropod and theropod teeth indicate feeding within a C3-plant ecosystem in a continental setting. Differences in enamel δ13C and δ18O values between Eusauropoda indet. and the theropod teeth are comparable to those observed in other herbivorous and carnivorous vertebrates, and suggest at least partial preservation of original dietary signals.KurzfassungAus den mitteljurassischen und früh-spätjurassischen Qigu- und Shishugou-Formationen des südlichen und zentralen Junggar-Beckens werden Zähne von Theropoden (Theropoda indet.), Sauropoden (Eusauropoda indet.) und Stegosauriern beschrieben. Die Dinosaurier-Vergesellschaftung des südlichen Junggar-Beckens ist weniger mannigfaltig und wird durch kleinere Formen repräsentiert als im zentralen Teil des Beckens. Die Microwear der Zähne von Eusauropoda indet. ähnelt dem bei Camarasaurus beobachteten Muster und könnte durch das Beißen auf hartes verholztes Pflanzenmaterial entstanden sein. Die Kohlenstoff- und Sauerstoffisotopie der Zähne der Sauropoden und Theropoden weist auf die Nahrungsaufnahme in einem kontinentalen Ökosystem mit C3-Pflanzen hin. Die Unterschiede in den δ13C- and δ18O-Werten des Zahnschmelzes der Eusauropoda indet. und den Theropoden-Zähnen sind vergleichbar mit denen anderer herbivorer und karnivorer Wirbeltiere. Die Werte lassen vermuten, dass die originalen ernährungsbedingten Isotopen-Zusammensetzungen zumindest teilweise erhalten geblieben sind.

Analyzing ungulate long bones as a tool for habitat reconstruction

The long bones (humerus, radius, metacarpus, femur, tibia, metatarsus) of 51 extant bovid and 7 equid specimens were measured in order to test the hypothesis that they show adaptations to different habitats. We performed factor analyses (FAs) with principal component extraction method and plotted the extracted factors (Fs) in simple scatterplots. The preferred habitats (grassland, forest, mountainous regions) were labeled in the plots, and our results show three clearly separated clusters for F2 vs. F3. According to our interpretation, F1 reflects the body size of the specimens while F2 is most probably reflecting cursorial adaptations. F3 is largely affected by dimensional bone characteristics adapted to maneuver in the environment, and therefore, F3 is somehow linked to habitat. The investigated equids are plotting within the cluster of bovids preferring grassland habitats, which is surprising because of different constructions of the metapodials in perissodactyls and ruminants. Performed linear discriminant analyses (LDAs) are supporting our FA results. This approach combines biometrics with statistics and presents a tool, which easily can be applied helping to identify the paleo-habitat or the paleo-ecology of extinct bovids with implications on fossil localities.