Soft-tissue evidence for homeothermy and crypsis in a Jurassic ichthyosaur

Ichthyosaurs are extinct marine reptiles that display a notable external similarity to modern toothed whales. Here we show that this resemblance is more than skin deep. We apply a multidisciplinary experimental approach to characterize the cellular and molecular composition of integumental tissues in an exceptionally preserved specimen of the Early Jurassic ichthyosaur Stenopterygius. Our analyses recovered still-flexible remnants of the original scaleless skin, which comprises morphologically distinct epidermal and dermal layers. These are underlain by insulating blubber that would have augmented streamlining, buoyancy and homeothermy. Additionally, we identify endogenous proteinaceous and lipid constituents, together with keratinocytes and branched melanophores that contain eumelanin pigment. Distributional variation of melanophores across the body suggests countershading, possibly enhanced by physiological adjustments of colour to enable photoprotection, concealment and/or thermoregulation. Convergence of ichthyosaurs with extant marine amniotes thus extends to the ultrastructural and molecular levels, reflecting the omnipresent constraints of their shared adaptation to pelagic life

Taxation of Electric Vehicles in Europe: A Methodology for Comparison

In Europe, a heterogeneous range of national vehicle taxation systems exists in parallel, so that a simple comparison of electric vehicle (xEV) tax advantages is not straightforward. In this contribution, various European vehicle taxation systems are examined and a methodology is introduced which allows a comprehensible comparison and overview by calculating CO2 based taxation step curves. This methodology provides a powerful tool for benchmarking xEV technologies and analyzing consumer acceptance of xEVs and enables furthermore the discussion about possible future taxation and incentive schemes

Predatory behaviour and taphonomy of a Jurassic belemnoid coleoid (Diplobelida, Cephalopoda)

We describe four complete specimens of the early squid-like cephalopod Clarkeiteuthis conocauda from the Toarcian Posidonienschiefer (Jurassic) each preserved with the bony fish Leptolepis bronni in its arms. Based on the arrangement of prey and predator, we suggest that the cephalopods caught and killed the fishes while still in well-oxygenated waters and then descended into oxygen-depleted water layers (distraction sinking) where the cephalopod suffocated. This explains the exceptional preservation, for which the Posidonienschiefer is famed. This association raises the question for the hunting behaviour of belemnoid Coleoidea. Using the proportions of soft and skeletal body parts of diplobelids and belemnitids, we estimated their body mass and buoyancy and determined the centres of mass and buoyancy. These two points were very close to each other in belemnitids, implying a low hydrodynamic stability (when ignoring the fins), while in diplobelids, the distance between those centres was greater. This suggests that diplobelids usually assumed an oblique to vertical orientation of the body axis while belemnitids could effortlessly achieve a horizontal orientation of their body. Presuming larger fins were attached to the bigger belemnitid rostra, belemnitids were better swimmers and perhaps pursuit predators while diplobelids rather ambushed their prey

Leg 187: Mantle reservoirs and migration associated with Australian-Antarctic rifting (16 November 1999-10 January 2000)

Leg 187 undertook to trace the boundary between Indian and Pacific, ocean-scale mantle provinces across 10- to 30-Ma seafloor of the Southeast Indian Ocean between Australia and Antarctica. The boundary is sharply defined on young seafloor within the Australian Antarctic Discordance (AAD), where it is migrating to the west at ~40 mm/yr. The leg was built around a responsive drilling strategy in which real-time shipboard geochemical analyses from one site were used to guide the selection of subsequent sites from a slate of preapproved targets. This strategy proved highly effective, allowing us to maximize our time on site and to focus on sites that could potentially yield the best definition of the boundary configuration. Using Ba and Zr contents of basalt glasses referenced to our database of younger (0-7 Ma) lavas from the AAD and Zone A (east of the AAD), we were able to assign each of the 23 holes drilled at 13 sites to an Indian, Pacific, or Transitional-Pacific upper mantle type. At three sites we encountered lavas from two of these three mantle types, indicating mixed or transitional mantle sources. From these shipboard identifications of mantle domain, three fundamental observations can be made: No Indian-type mantle occurs east of the regional residual depth anomaly. Pacific- and especially Transitional-Pacific-type mantle occurs throughout the depth anomaly in the study area. Between ~28 and 14 Ma, Indian and Pacific mantle types alternated in western Zone A on a time scale of a few million years. These observations lead to the following tentative conclusions which require careful testing as isotopic data become available. A discrete mantle boundary comparable to the present-day boundary in the AAD cannot be mapped through the entire 14- to 28-Ma time interval encompassed by Leg 187 sites, although comparable boundaries have existed for relatively short, discrete time intervals. We conclude that, in the long term, the eastern limit of the Indian mantle province corresponds closely to the eastern edge of the residual depth anomaly. Its locus must lie close to the -500-m residual depth contour that tracks south to connect with the known location of the Indian/Pacific boundary on younger seafloor of the AAD. West of this boundary, sporadic occurrences of Transitional-Pacific-type and even Pacific-type mantle are interspersed with the predominant Indian-type mantle. The western limit of Pacific or Transitional-Pacific mantle is not closely defined by our data, but it is most likely associated with the western boundary of the depth anomaly. The alternation of Indian-type sites with Pacific- and Transitional-Pacific-type sites in western Zone A on time scales of a few million years can be interpreted in terms of discrete incursions, either of Indian mantle beneath Zone A or, perhaps more likely, of Pacific mantle into the dominantly Indian region of the depth anomaly. Samples from Leg 187 will undergo extensive elemental and isotopic analysis to refine the definition of the isotopic boundary and to improve our understanding of the nature and origin of the AAD, the mantle boundary, and the distinctive Indian Ocean mantle province. In addition, a battery of samples collected as quickly as possible under conditions that were as sterile as possible were placed in a variety of media in order to characterize the microbial population of the deep seafloor. Complementary electron microscope studies will seek to characterize fossil and living microbes involved with biodegradation of basaltic glass and their habitats