A new Late Jurassic turtle from Spain: phylogenetic implications,taphonomy and palaeoecology

Abstract: The Jurassic was an important period in the evolution of Testudinata and encompasses the origin of many clades, and this is especially true of Jurassic turtles from Western Europe. A new genus and species of Late Jurassic turtle, Hispaniachelys prebetica gen. et sp. nov. from the upper Oxfordian of the Prebetic (Southern Spain), is described on the basis of postcranial material. The specimen is the only known tetrapod from the Mesozoic of the Prebetic and the oldest turtle from southern Europe. A mosaic of characters indicates this is a new genus: it displays basal features including dorsal epiplastral processes/reduced cleithra, no medial contact of the extragulars and a long first thoracic rib, alongside derived characters including an absence of mesoplastra and the vertebral 3/4 sulcus crossing neural 5. The phylogenetic position of the new taxon is hard to resolve, and it might be either a paracryptodire or a basal testudine, but it is distinct from Plesiochelys. A complex taphonomic history is shown by a range of overlying grazing traces and bioerosion on the carapace. The carapace was subsequently overturned and buried ventrally up, terminating grazing activity, and was then bored by sponges before final burial. Scanning electron microscopy reveals phosphatic microspheroids associated with bacterial decay in the vascular cavities of the cancellous bone, suggesting the carapace may have acted as a closed microenvironment in which decay‐derived authigenic minerals formed.     

Composition and implications of diverse lipids in New Zealand Geothermal sinters

Microbial adaptations associated with extreme growth environments, including high temperatures and low pH, are of interest to astrobiologists and origin of life researchers. As part of a survey of microbial lipids present in terrestrial geothermal settings, we examined four silica sinters associated with three different hot spring areas of the Taupo Volcanic Zone (TVZ), New Zealand. Dominant bacterial lipids include free fatty acids, 1,2‐diacylglycerophospholipids, 1,2‐di‐O‐alkylglycerols, 1‐O‐alkylglycerols, wax esters, alkanols, alkan‐1,2‐diols and various hopanoids, whereas dominant archaeal lipids include both archaeol and glycerol dialkyl glycerol tetraethers. Although many of these compounds occur in other settings, in the TVZ sinters their distributions (with high abundances of β‐OH fatty acids and high‐molecular‐weight (> C₁₈) fatty acyl components) and carbon isotopic compositions (ranging from ?40 to +4, with up to 25 variability in a single sample) are unusual. In addition, we have identified a range of unusual compounds, including novel macrocyclic diethers and hopanoids. The distributions of these compounds differ among the study sites, suggesting that, where preserved in ancient sinters, they could serve as an important tool in studying past hydrothermal environments.     

Interactive effects of water table and precipitation on net CO2 assimilation of three co-occurring Sphagnum mosses differing in distribution above the water table

Sphagnum cuspidatum , S. magellanicum and S. rubellum are three co-occurring peat mosses, which naturally have a different distribution along the microtopographical gradient of the surface of peatlands. We set out an experiment to assess the interactive effects of water table (low: −10 cm and high: −1 cm) and precipitation (present or absent) on the CO₂ assimilation and evaporation of these species over a 23-day period. Additionally, we measured which sections of the moss layer were responsible for light absorption and bulk carbon uptake. Thereafter, we investigated how water content affected carbon uptake by the mosses. Our results show that at high water table, CO₂ assimilation of all species gradually increased over time, irrespective of the precipitation. At low water table, net CO₂ assimilation of all species declined over time, with the earliest onset and highest rate of decline for S. cuspidatum . Precipitation compensated for reduced water tables and positively affected the carbon uptake of all species. Almost all light absorption occurred in the first centimeter of the Sphagnum vegetation and so did net CO₂ assimilation. CO₂ assimilation rate showed species-specific relationships with capitulum water content, with narrow but contrasting optima for S. cuspidatum and S. rubellum . Assimilation by S. magellanicum was constant at a relatively low rate over a broad range of capitulum water contents. Our study indicates that prolonged drought may alter the competitive balance between species, favoring hummock species over hollow species. Moreover, this study shows that precipitation is at least equally important as water table drawdown and should be taken into account in predictions about the fate of peatlands with respect to climate change.