A cautionary tail: Cyrtura temnospondyla Jaekel, 1904, an enigmatic vertebrate specimen from the Late Jurassic Solnhofen Limestone

publisher: Elsevier articletitle: A cautionary tail: Cyrtura temnospondyla Jaekel, 1904, an enigmatic vertebrate specimen from the Late Jurassic Solnhofen Limestone journaltitle: Comptes Rendus Palevol articlelink: http://dx.doi.org/10.1016/j.crpv.2014.10.007 content_type: article copyright: Copyright © 2014 Académie des sciences. Published by Elsevier Masson SAS All rights reserved.This document is the authors' final accepted version of the journal article. You are advised to consult the publishers' version if you wish to cite from it

A new stem turtle from the Middle Jurassic of the Isle of Skye, Scotland, and a reassessment of basal turtle relationships

A recent phylogenetic analysis of turtle interrelationships suggests that the Middle Jurassic was a crucial time period for understanding the evolution of crown-group turtles. However, turtle material of this age is scarce worldwide. Here, a new stem turtle, Eileanchelys waldmani, from the Middle Jurassic (Bathonian) of the Isle of Skye, Scotland, is described and compared to other basal species. With cranial and postcranial remains of several individuals, this is the most comprehensive Middle Jurassic turtle material known to date. Eileanchelys waldmani documents an intermediate stage in the evolution of early turtles between the Early Jurassic Kayentachelys aprix and the crown-group. Whereas most stem turtles are interpreted as terrestrial forms, taphonomic evidence suggests that E. waldmani may have been aquatic (freshwater), indicating that basal turtles were ecologically more diverse than previously thought. This new material provides the basis for a reassessment of other Middle Jurassic turtle remains from the UK, especially revisions of material from Kirtlington and Stonesfield (Oxfordshire). The material from Kirtlington is attributed to Paracryptodira and represents the earliest occurrence of this group. The name 'Protochelys blakii', which had been proposed for the Stonesfield remains, is considered to be a nomen dubium as this material lacks diagnostic features. However, this material is remarkable as it consists of fossilised epidermal scales from the carapace. A new phylogeny is proposed, resulting from a cladistic analysis of a revised and updated version of a previously published data set. Nineteen new species are included in order to achieve a more thorough representation of basal turtle taxa. Heckerochelys romani and Condorchelys antiqua are found to be more basal than Eileanchelys waldmani. Chengyuchelyids (Middle Jurassic of China) may be stem turtles more basal than Kallokibotion bajazidi. Naomichelys speciosa is closely related to meiolaniids and Mongolochelys efremovi, while Siamochelys peninsularis is nested within xinjiangchelyids

First report of Plesiochelys etalloni and Tropidemys langii from the Late Jurassic of the UK and the palaeobiogeography of plesiochelyid turtles

Plesiochelyidae is a clade of relatively large coastal marine turtles that inhabited the shallow epicontinental seas that covered western Europe during the Late Jurassic. Although the group has been reported from many deposits, the material is rarely identified at the species level. Here, we describe historical plesiochelyid material from the Kimmeridge Clay Formation of England and compare it with contemporaneous localities from the continent. An isolated basicranium is referred to the plesiochelyid Plesiochelys etalloni based notably on the presence of a fully ossified pila prootica. This specimen represents the largest individual known so far for this species and is characterized by remarkably robust features. It is, however, uncertain whether this represents an ontogenetic trend towards robustness in this species, some kind of specific variation (temporal, geographical or sexual), or an abnormal condition of this particular specimen. Four other specimens from the Kimmeridge Clay are referred to the plesiochelyid Tropidemys langii. This contradicts a recent study that failed to identify this species in this formation. This is the first time, to the best of our knowledge, that the presence of Plesiochelys etalloni and Tropidemys langii is confirmed outside the Swiss and French Jura Mountains. Our results indicate that some plesiochelyids had a wide palaeobiogeographic distribution during the Kimmeridgian

A reassessment of the late jurassic turtle Eurysternum wagleri (Eucryptodira, Eurysternidae)

Eurysternum wagleri is one of the first named, yet most poorly understood turtles from the Late Jurassic of Europe. Over the years, many specimens have been referred to and many species synonymized with E. wagleri, but little consensus is apparent, and the taxonomy is therefore highly confusing. Based on the rare, only known illustration of the lost holotype and on the reassessment of select individuals, the species E. wagleri is recharacterized herein. Eurysternum wagleri is diagnosed by a deep pygal notch, a carapace with a pentagonal outline, a contribution of vertebral 5 to the posterior carapace margin, three cervical scales, very wide vertebral scales with a well-developed radiating pattern, well-developed costoperipheral fontanelles in medium-sized individuals, a plastron connected to the carapace by ligaments, gracile, peg-like bony projections of the hyo- and hypoplastra, and large, oval-to-quadrangular lateral plastral fontanelles. A lectotype is designated for Acichelys redenbacheri, and this taxon is interpreted as the junior subjective synonym of Eurysternum wagleri. All other, previously proposed synonymies are rejected, because they lack characters that would allow diagnosing them as E. wagleri

The benefit of high-resolution operational weather forecasts for flash flood warning

International audienceIn Mediterranean Europe, flash flooding is one of the most devastating hazards in terms of human life loss and infrastructures. Over the last two decades, flash floods brought losses of a billion Euros of damage in France alone. One of the problems of flash floods is that warning times are very short, leaving typically only a few hours for civil protection services to act. This study investigates if operationally available shortrange numerical weather forecasts together with a rainfall-runoff model can be used as early indication for the occurrence of flash floods. One of the challenges in flash flood forecasting is that the watersheds are typically small and good observational networks of both rainfall and discharge are rare. Therefore, hydrological models are difficult to calibrate and the simulated river discharges cannot always be compared with ground "truth". The lack of observations in most flash flood prone basins, therefore, lead to develop a method where the excess of the simulated discharge above a critical threshold can provide the forecaster with an indication of potential flood hazard in the area with leadtimes of the order of the weather forecasts. This study is focused on the Cévennes-Vivarais region in the Southeast of the Massif Central in France, a region known for devastating flash floods. The critical aspects of using numerical weather forecasting for flash flood forecasting are being described together with a threshold – exceedance. As case study the severe flash flood event which took place on 8–9 September 2002 has been chosen. The short-range weather forecasts, from the Lokalmodell of the German national weather service, are driving the LISFLOOD model, a hybrid between conceptual and physically based rainfall-runoff model. Results of the study indicate that high resolution operational weather forecasting combined with a rainfall-runoff model could be useful to determine flash floods more than 24 hours in advance

A Jurassic stem pleurodire sheds light on the functional origin of neck retraction in turtles

Modern turtles are composed of two monophyletic groups, notably diagnosed by divergent neck retraction mechanisms. Pleurodires (side-necked turtles) bend their neck sideways and protect their head under the anterior margin of the carapace. Cryptodires (hidden-necked turtles) withdraw their neck and head in the vertical plane between the shoulder girdles. These two mechanisms of neck retraction appeared independently in the two lineages and are usually assumed to have evolved for protective reasons. Here we describe the neck of Platychelys oberndorferi, a Late Jurassic early stem pleurodire, and find remarkable convergent morphological and functional similarities with modern cryptodires. Partial vertical neck retraction in this taxon is interpreted to have enabled fast forward projection of the head during underwater prey capture and offers a likely explanation to the functional origin of neck retraction in modern cryptodires. Complete head withdrawal for protection may therefore have resulted from an exaptation in that group

The Benefit of High-Resolution Operational Weather Forecasts for Flash Flood Warning

In Mediterranean Europe, flash flooding is one of the most devastating hazards in terms of loss of human life and infrastructures. Over the last two decades, flash floods have caused damage costing a billion Euros in France alone. One of the problems of flash floods is that warning times are very short, leaving typically only a few hours for civil protection services to act. This study investigates if operationally available short-range numerical weather forecasts together with a rainfall-runoff model can be used for early indication of the occurrence of flash floods. One of the challenges in flash flood forecasting is that the watersheds are typically small, and good observational networks of both rainfall and discharge are rare. Therefore, hydrological models are difficult to calibrate and the simulated river discharges cannot always be compared with ground measurements. The lack of observations in most flash flood prone basins, therefore, necessitates the development of a method where the excess of the simulated discharge above a critical threshold can provide the forecaster with an indication of potential flood hazard in the area, with lead times of the order of weather forecasts. This study is focused on the Cévennes-Vivarais region in the Southeast of the Massif Central in France, a region known for devastating flash floods. This paper describes the main aspects of using numerical weather forecasting for flash flood forecasting, together with a threshold - exceedance. As a case study the severe flash flood event which took place on 8¿9 September 2002 has been chosen. Short-range weather forecasts, from the Lokalmodell of the German national weather service, are used as input for the LISFLOOD model, a hybrid between a conceptual and physically based rainfall-runoff model. Results of the study indicate that high resolution operational weather forecasting combined with a rainfall-runoff model could be useful to determine flash floods more than 24 hours in advance.JRC.H.7-Land management and natural hazard

The comparative osteology of Plesiochelys bigleri n. sp., a new coastal marine turtle from the Late Jurassic of Porrentruy (Switzerland)

During the Late Jurassic, several groups of eucryptodiran turtles inhabited the shallow epicontinental seas of Western Europe. Plesiochelyidae are an important part of this first radiation of crown-group turtles into coastal marine ecosystems. Fossils of Plesiochelyidae occur in many European localities, and are especially abundant in the Kimmeridgian layers of the Swiss Jura Mountains (Solothurn and Porrentruy). In the mid-19th century, the quarries of Solothurn (NW Switzerland) already provided a large amount of fossil turtles, most notably Plesiochelys etalloni, the best-known plesiochelyid species. Recent excavations in the Porrentruy area (NW Switzerland) revealed new fossils of Plesiochelys, including numerous well-preserved shells with associated cranial and postcranial material.Out of 80 shells referred to Plesiochelys, 41 are assigned to a new species, Plesiochelys bigleri n. sp., including a skull–shell association. We furthermore refer 15 shells to Plesiochelys etalloni, and 24 shells to Plesiochelys sp. Anatomical comparisons show that Plesiochelys bigleri can clearly be differentiated from Plesiochelys etalloni by cranial features. The shell anatomy and the appendicular skeleton of Plesiochelys bigleri and Plesiochelys etalloni are very similar. However, a statistical analysis demonstrates that the thickness of neural bones allows to separate the two species based on incomplete material. This study furthermore illustrates the extent of intraspecific variation in the shell anatomy of Plesiochelys bigleri and Plesiochelys etalloni

A review of the fossil record of turtles of the clade Thalassochelydia

The Late Jurassic (Oxfordian to Tithonian) fossil record of Europe and South America has yielded a particularly rich assemblage of aquatic pan-cryptodiran turtles that are herein tentatively hypothesized to form a monophyletic group named Thalassochelydia. Thalassochelydians were traditionally referred to three families, Eurysternidae, Plesiochelyidae, and Thalassemydidae, but the current understanding of phylogenetic relationships is insufficient to support the monophyly of either group. Given their pervasive usage in the literature, however, these three names are herein retained informally. Relationships with marine turtles from the Cretaceous have been suggested in the past, but these hypotheses still lack strong character support. Thalassochelydians are universally found in near-shore marine sediments and show adaptations to aquatic habitats, but isotopic evidence hints at a broad spectrum of specializations ranging from freshwater aquatic to fully marine. A taxonomic review of the group concludes that of 68 named taxa, 27 are nomina valida, 18 are nomina invalida, 18 are nomina dubia, and 5 nomina oblita