Formation mechanisms of macroscopic globules in andesitic glasses from the Izu–Bonin–Mariana forearc (IODP Expedition 352)

The Izu–Bonin–Mariana volcanic arc is situated at a convergent plate margin where subduction initiation triggered the formation of MORB-like forearc basalts as a result of decompression melting and near-trench spreading. International Ocean Discovery Program (IODP) Expedition 352 recovered samples within the forearc basalt stratigraphy that contained unusual macroscopic globular textures hosted in andesitic glass (Unit 6, Hole 1440B). It is unclear how these andesites, which are unique in a stratigraphic sequence dominated by forearc basalts, and the globular textures therein may have formed. Here, we present detailed textural evidence, major and trace element analysis, as well as B and Sr isotope compositions, to investigate the genesis of these globular andesites. Samples consist of K2O-rich basaltic globules set in a glassy groundmass of andesitic composition. Between these two textural domains a likely hydrated interface of devitrified glass occurs, which, based on textural evidence, seems to be genetically linked to the formation of the globules. The andesitic groundmass is Cl rich (ca. 3000μg/g), whereas globules and the interface are Cl poor (ca. 300μg/g). Concentrations of fluid-mobile trace elements also appear to be fractionated in that globules and show enrichments in B, K, Rb, Cs, and Tl, but not in Ba and W relative to the andesitic groundmass, whereas the interface shows depletions in the latter, but is enriched in the former. Interestingly, globules and andesitic groundmass have identical Sr isotopic composition within analytical uncertainty (87Sr/86Sr of 0.70580±10), indicating that they likely formed from the same source. However, globules show high δ11B (ca. + 7‰), whereas their host andesites are isotopically lighter (ca. – 1 ‰), potentially indicating that whatever process led to their formation either introduced heavier B isotopes to the globules, or induced stable isotope fractionation of B between globules and their groundmass. Based on the bulk of the textural information and geochemical data obtained from these samples, we conclude that these andesites likely formed as a result of the assimilation of shallowly altered oceanic crust (AOC) during forearc basaltic magmatism. Assimilation likely introduced radiogenic Sr, as well as heavier B isotopes to comparatively unradiogenic and low δ11B forearc basalt parental magmas (average 87Sr/86Sr of 0.703284). Moreover, the globular textures are consistent with their formation being the result of fluid-melt immiscibility that was potentially induced by the rapid release of water from assimilated AOC whose escape likely formed the interface. If the globular textures present in these samples are indeed the result of fluid-melt immiscibility, then this process led to significant trace element and stable isotope fractionation. The textures and chemical compositions of the globules highlight the need for future experimental studies aimed at investigating the exsolution process with respect to potential trace element and isotopic fractionation in arc magmas that have perhaps not been previously considered

Stiffening in the carpus of Prosantorhinusgermanicus (Perissodactyla, Rhinocerotidae) from Sandelzhausen (Germany)

<jats:title>Abstract</jats:title><jats:p><jats:italic>Prosantorhinus</jats:italic><jats:italic>germanicus</jats:italic> is a small, short-legged, teleoceratine rhino from the Miocene of Sandelzhausen (Bavaria, Germany). <jats:italic>P.</jats:italic><jats:italic>germanicus</jats:italic> shows a high variation in some of its carpal bones. A unique modification of the articulation of Intermedium and Carpale 4 is described here. Special emphasis is given to additional articulation facets at the palmar processes of both bones. These additional contacts, working as stop facets, are unique among rhinos and restrict the flexion of the mid-carpal joint. Some individuals show these additional facets which prohibit the flexion within the wrist and therefore stiffen the carpus. Carpale 4 specimens without the additional facets show knob-like structures instead. These knobs are most likely precursory structures of those facets and the facets are fully developed in heavier males. A skeletal sexual dimorphism is not visible in the sample as all bones are in the same size range. The wrist stiffening in the mid-carpal joint supports a greater bodyweight and therefore could coincide with <jats:italic>P.</jats:italic><jats:italic>germanicus</jats:italic> as a proposed dwarfed rhinoceros species. The stiffening can also be interpreted in favor of a semiaquatic mode of life. The stiffened carpus is more resistant against injuries while walking on muddy grounds in a wet environment.</jats:p&gt

An approach for identifying fossil habitats using ungulate long bones

Die Langknochen verschiedener rezenter Huftiere, von denen das bevorzugte Habitat bekannt ist, wurden vermessen und mittels Faktorenanalyse ausgewertet, um so das Habitat fossiler Huftiere zu bestimmen. So konnten anhand der Anpassungen der Langknochen rezente Boviden unterschieden werden, die Grasland, Wald oder Gebirge bewohnen. Ebenso konnte gezeigt werden, dass unpaarhufige Pferde gleiche Anpassungen zeigen, wie paarhufige Grasland-Boviden. Untersuchte rezente Cerviden konnten hinsichtlich verschiedener Habitate nicht voneinander getrennt werden. Bei den Boviden und Equiden sind die Metapodien allein ausreichend, um die Habitate Wald und Grasland zu unterscheiden. Die Anwendung des Rezentansatzes auf fossile Vertreter der Boviden und Equiden ließ eine Bestimmung des fossilen Habitats zu. Mit Hilfe der Diskriminanzanalyse ist es außerdem möglich die Habitatzuordnung zu quantifizieren. Mit den bestimmten fossilen Habitaten wurde eine Reihe von Karten für das Miozän Europas erstellt, um somit Aussagen über eine mögliche Ausbreitung großer Grasländer zu treffen. Aufgrund einer geringen Fundstellendichte kann gegenwärtig nur gesagt werden, dass Waldhabitate im Osten Europas häufiger waren, als im Westen Europas.The long bones of different recent hoofed animals were measured. The preferred habitat of these ungulates was known. The data was analysed by means of factor analysis. In a second step the unknown habitat of fossil ungulates was identified by the same statistical analysis. Bovids living in grasslands, forests and mountainous regions were distinguished by different adaptations to habitat of their long bones. Odd-toed horses are showing same adaptations like even-toed bovids living in grasslands. Examined recent cervids are not distinguishable by different habitats. The measurements of metapods are sufficient to differentiate the habitats grassland and forest. The usage of the described method allows an identification of habitats in fossil bovids and equids. It is also possible to quantify the probabilities of habitat membership of extinct ungulates by means of discriminant analysis. Different maps were reconstructed for the Miocene of Europe to show a possible spread of open grasslands. There are more fossil sites with identified forests in Eastern Europe than in Western Europe, but the overall number of sites is too low to make a concrete statement

CONCH - a new software for quantitative morphological analyses of ammonoid shells

Species description in palaeontology is based on the morphology of preserved hard parts. Ammonoids have extensive intraspecific variation of conch shape, ornamentation, size and the morphology of the suture line. However, ammonoid species were usually differentiated and validated from each other on the grounds of subtle morphological differences of the adult stage. This procedure does not account for intraspecific variation or ontogenetic changes. The few available quantitative studies of ammonites have improved our understanding and the way of species description, documenting a wide intraspecific variability in conch parameters. Studies of intraspecific variation are likely not more widespread for three reasons: 1) not enough material from a single bed, 2) poor preservation of the fossil material and 3) it is a time-consuming process. Here we present a new software which significantly reduces the amount of time by 50% or more necessary to measure standard distances for spirally coiled monomorph or heteromorph shells, i.e. diameter, whorl height, whorl interspace, umbilical width, and ornamentation. Our software allows the collection of morphological data in 10, 30 or 45 degree steps. It is possible to collect more data from a single shell to precisely document ontogenetic changes compared to data collected from sectioned specimens. The set of marker placed along the shell outline can be saved as a project file, displaced markers can be corrected, and the project files can be shared with other researchers. Based on basic shell parameters indices and expansion ratios can be calculated. A dataset summarizing the morphology of a collection of heteromorph ammonite shells from the Hauterivian (Lower Cretaceous) heteromorph ammonite genus Aegocrioceras from Northwestern Germany will be presented

Figure 8. Virtual 3D in Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia)

Figure 8. Virtual 3D reconstruction and outline drawing of the bony labyrinth of UFRJ-DG 1036-M, details of anatomy in posteromedial view. Abbreviations: aa, anterior ampulla; asc, anterior semicircular canal; av, vestibular aqueduct; can, cochlear canaliculus; cc, common crus; cf, cochlear fossula; co, cochlear canal; fsg, foramen singulare; f sup vest, foramen for the superior vestibule area; lsc, lateral semicircular canal; psc, posterior semicircular canal; scc, secondary common crus; sl. s., secondary bony lamina sulcus; vasc. sulc., impression of vascular sulci left on the bony cochlear canal.Published as part of <i>Billet, Guillaume, Muizon, Christian De, Schellhorn, Rico, Ruf, Irina, Ladevèze, Sandrine & Bergqvist, Lilian, 2015, Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia), pp. 956-987 in Zoological Journal of the Linnean Society 173 (4)</i> on page 970, DOI: 10.1111/zoj.12219, <a href="http://zenodo.org/record/10106367">http://zenodo.org/record/10106367</a&gt

Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia)

International audienc

Figure 10 in Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia)

Figure 10. Strict consensus cladogram (518 steps, consistency index = 0.36, retention index = 0.71) of the analysis with 50 taxa searching for the relationships of the UFRJ-DG petrosals under study.Published as part of <i>Billet, Guillaume, Muizon, Christian De, Schellhorn, Rico, Ruf, Irina, Ladevèze, Sandrine & Bergqvist, Lilian, 2015, Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia), pp. 956-987 in Zoological Journal of the Linnean Society 173 (4)</i> on page 973, DOI: 10.1111/zoj.12219, <a href="http://zenodo.org/record/10106367">http://zenodo.org/record/10106367</a&gt

Figure 16. Virtual 3D in Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia)

Figure 16. Virtual 3D reconstruction and outline drawing of the petrosal of Proterotherium (MNHN-F-SCZ 205), (postero)lateroventral view. Abbreviations: a.b.X n., notch/sulcus for the auricular branch of the vagus nerve (X); acan n, notch housing the external aperture of the cochlear canaliculus; acf, external aperture of the cochlear fossula; ci, crista interfenestralis; cpa, crista parotica; fi, fossa incudis; fs, facial sulcus; fv, fenestra vestibuli; ias, internal carotid artery sulcus; ips, sulcus of inferior petrosal sinus; md.ips, crest-like mediodorsal border of sulcus for inferior petrosal sinus; pg, posterior occipital groove; pps, postpromontorial tympanic sinus; pr, promontorium; rtp, rostral tympanic process; sqs, squamosal articulation surface of petrosal; stf, stapedial fossa; stl n, stylomastoid notch; thl, tympanohyal; tt, tegmen tympani; ttf, tensor tympani fossa; v.e.m., ventral extent of mastoid surface.Published as part of <i>Billet, Guillaume, Muizon, Christian De, Schellhorn, Rico, Ruf, Irina, Ladevèze, Sandrine & Bergqvist, Lilian, 2015, Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia), pp. 956-987 in Zoological Journal of the Linnean Society 173 (4)</i> on page 978, DOI: 10.1111/zoj.12219, <a href="http://zenodo.org/record/10106367">http://zenodo.org/record/10106367</a&gt

Figure 14 in Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia)

Figure 14. Strict consensus cladogram (551 steps, consistency index = 0.33, retention index = 0.67) of the unconstrained 49 taxa analysis, with UFRJ-DG 119-M, 275-M, 347-M, and 1035−1038-M petrosals scored as pertaining to Miguelsoria.Published as part of <i>Billet, Guillaume, Muizon, Christian De, Schellhorn, Rico, Ruf, Irina, Ladevèze, Sandrine & Bergqvist, Lilian, 2015, Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia), pp. 956-987 in Zoological Journal of the Linnean Society 173 (4)</i> on page 976, DOI: 10.1111/zoj.12219, <a href="http://zenodo.org/record/10106367">http://zenodo.org/record/10106367</a&gt