Aquatic Reptiles Research Articles

Freshwater aquatic reptiles (Testudines and Crocodylia) as biomonitor models in assessing environmental contamination by inorganic elements and the main analytical techniques used: a review.

Despite the general lack of studies that use reptiles as bioindicators, the value of freshwater turtles and crocodilians in ecotoxicology has been proven, due to their importance as sentinel species. The aim of this study was to compile information on the use of freshwater turtles and crocodilians as environmental biomonitors of inorganic element contamination. We searched for articles in databases using specific keywords. A total of 104 studies published between the years 1970 and 2020 were collected. We noted a general increase in the number of studies involving turtles and crocodilians during the study time period. The Order Testudines were the subjects of 46% of the analysed publications, and the Order Crocodylia accounted for 54%. Within these studies, we counted 39 species (turtles n = 29 and crocodilians n = 10). Forty chemical elements were evaluated in the analysed articles, of which the majority represented non-essential elements (Hg, Cd, Pb). Although internal organs constituted the main biological matrix chosen for each group (37%), we observed an increase in the use of non-destructive matrices in both groups (scale, blood, tail muscle, carapace). The majority of analysed studies used HNO3 for the sample decomposition, with the majority of analyses being performed using atomic absorption spectroscopy (53%). Mainly blank controls (19%), analyte recovery (18%) and replicates (18%) were used as methods of validating analytical procedures. Furthermore, the studies used certified reference materials, which measure the accuracy of the methods used. We conclude that the increase in the use of aquatic reptiles in environmental monitoring research is mainly due to their ability to reveal integrated changes in ecosystems, aiding in environmental public policy decision-making and effective management plans.

Effects of Simulated Heat Wave on Oxidative Physiology and Immunity in Asian Yellow Pond Turtle (Mauremys mutica)

Global warming has led to an increase in the frequency, duration, and intensity of heat waves in the summer, which can cause frequent and acute heat stress on ectotherms. Thus, determining how ectothermic animals respond to heat waves has been attracting growing interest among ecologists. However, the physiological and biochemical responses to heat waves in reptiles, especially aquatic reptiles, are still poorly understood. The current study investigated the oxidant physiology, immunity, and expression levels of heat shock proteins (HSP) mRNA after exposure to a simulated heat wave (1 week, 35 ± 4°C), followed by a recovery period (1 week, 28 ± 4°C) in juvenile Asian yellow pond turtle (Mauremys mutica), a widely farmed aquatic turtle in East Asia. The contents of malondialdehyde (MDA) in the liver and muscle were not significantly affected by the heat wave or recovery. Of all antioxidant enzymes, only the activity of glutathione peroxidase (GSH-Px) in muscles increased after heat wave, while the total superoxide dismutase (T-SOD), catalase activity (CAT), and total antioxidant capacity (T-AOC) did not change during the study. The organo-somatic index for the liver and spleen of M. mutica decreased after the heat wave but increased to the initial level after recovery. In contrast, plasma lysozyme activity and serum complement C4 levels increased after the heat wave, returning to the control level after recovery. In addition, heat waves did not alter the relative expression of HSP60, HSP70, and HSP90 mRNA in the liver. Eventually, heat wave slightly increased the IBR/n index. Therefore, our results suggested that heat waves did not lead to oxidative damage to lipids in M. mutica, but deleteriously affected the turtles’ immune organs. Meanwhile, the constitutive levels of most antioxidative enzyme activities, HSPs and enhanced blood immune functions might protect the turtles from the threat of heat waves under the current climate scenarios.

Sauropterygian remains from the Middle Triassic of Vill\xe1ny, Hungary\u2014new information on the aquatic reptile fauna of Tisza Megaunit (Triassic southern Eurasian shelf region)

Sauropterygia was a diverse clade of secondary aquatic reptiles, which represented one of the most important vertebrate groups in the shallow marine communities during the Triassic. However, despite the long history of collection and examination of sauropterygian remains, previous studies have indicated that the fossil record of this group is incomplete, making the understanding of their palaeobiogeographic relations difficult. Here we describe new sauropterygian remains from the Middle Triassic (Ladinian) Templomhegy Dolomite Member (Villány, southern Hungary), which were unearthed during systematic fieldwork of previous years. Among several non-diagnostic sauropterygian remains, this material contains isolated bones belonging to Nothosaurus sp., Simosauridae indet. and a small-sized nothosaurid. The known faunal composition from Villány is similar to what was described from the Middle Triassic of the Germanic Basin and Bihor Mountains (northwestern Romania). Besides isolated elements, a probably associated skeleton of a small-sized eosauropterygian specimen of unknown affinities is also reported here. This locality widens our knowledge on Triassic sauropterygian distribution and provides new information about the previously not well-known Middle Triassic vertebrate fauna of the one-time southern Eurasian shelf region.

Large‐scale eDNA metabarcoding survey reveals marine biogeographic break and transitions over tropical north‐western Australia

AbstractAimEnvironmental DNA (eDNA) metabarcoding has demonstrated its applicability as a highly sensitive biomonitoring tool across small spatial and temporal scales in marine ecosystems. However, it has rarely been tested across large spatial scales or biogeographical barriers. Here, we scale up marine eDNA metabarcoding, test its ability to detect a major marine biogeographic break and evaluate its use as a regional biomonitoring tool in Australia.LocationNorth‐western Australia (NWA).MethodsWe applied metabarcoding assays targeting the mitochondrial 16S rRNA and CO1 genes to 284 surface seawater eDNA samples collected from 71 mid‐shelf, inshore, coastal and nearshore estuarine sites over 700 km of the NWA coastline.ResultsMetabarcoding detected a wide range of bony fish (404 taxa), elasmobranchs (44) and aquatic reptiles (5). We detected bioregional and depth differentiation within inshore bony fish communities. These findings support the presence of a marine biogeographic break, which is purported to occur in the vicinity of Cape Leveque, demarcating the border between the Kimberley and Canning bioregions. Inshore bony fish and elasmobranch communities, as well as coastal bony fish assemblages, were additionally found to differ between the South and North Kimberley regions suggesting previously unrecognized subregional differentiation amongst these taxa. The overall compositional data have been used to update distribution information for a number of endangered, elusive and data‐deficient taxa, including sawfish (family: Pristidae), northern river shark (Glyphis garricki) and wedgefish (genus: Rhynchobatus).Main conclusionseDNA metabarcoding demonstrated a high level of sensitivity that was able to discern fine‐scale patterns across the large‐scale, remote and oceanographically complex region of North‐western Australia. Importantly, this study highlights the potential of integrating broad‐scale eDNA metabarcoding alongside other baseline surveys and long‐term monitoring approaches, which are crucial for the sustainable management and conservation of marine biodiversity in this unique marine region.

Development of a 16S metabarcoding assay for the environmental DNA (eDNA) detection of aquatic reptiles across northern Australia

A severe lack of distribution data for aquatic reptiles in northern Australia leaves many taxa vulnerable to extirpation and extinction. Environmental DNA (eDNA) technologies offer sensitive and non-invasive genetic alternatives to trapping and visual surveys and are increasingly employed for the detection of aquatic and semi-aquatic reptiles. However, these eDNA approaches have largely applied species-specific primers that do not provide a cost-effective avenue for the simultaneous detection of multiple reptilian taxa. Here, we present a mitochondrial 16S rRNA metabarcoding assay for the broad detection of aquatic and semi-aquatic reptile species. This assay is tested on water samples collected at multiple sampling sites at two tropical locations, including 12 marine and estuarine sites in Roebuck Bay, Western Australia, and four estuarine sites in Cooktown, Queensland, Australia. In total, nine reptile taxa were detected from 10 of the 16 sampled sites, including marine and freshwater turtles, aquatic, semi-aquatic and terrestrial snakes, and terrestrial skinks. However, inconsistencies in the detection of previously observed aquatic reptiles at our sampled sites, such as saltwater crocodile and sea snakes, indicated that further research is required to assess the reliability, strengths and limitations of eDNA methods for aquatic reptile detection before it can be integrated as a broad-scale bioassessment tool.

Darwin’s Tree of Life is Numbered. Resolving the Origins of Species by Mass

A new view of the tree of life has been conceived and implemented to construct a molecular-based phylogeny for a wide range of animal species without the need for gene or protein sequences using mass map data in a so-called “phylonumerics” approach. Numerical mass map data generated following the proteolytic digestion of proteins expressed across an array of organisms are used to build phylogenetic-like mass trees using a purpose built MassTree algorithm. The algorithm inputs sets of numbers for each organism and builds the tree, by default, using a relaxed Neighbour-Joining Approach with mid-point rooting. Single point mutations are also uniquely identified from peptide mass differences and these mutations displayed on branches of the mass trees. Here a wide array of animal species comprising insects, fish, birds, land and aquatic reptiles, and large mammals are successfully resolved and correctly grouped according to their origins on such a number-based tree. The mass tree is found to be highly congruent with that generated using sequence data and can be used to study evolutionary pathways at the molecular protein level without sequence generation or alignment. Mass trees provide a useful complement and viable alternative to conventional gene sequence trees. The approach brings together previously disparate fields and provides a universally applicable means with which to represent life forms and their evolutionary history employing a new molecular-based phylogeny that should find widespread application among the evolutionary biology community.

A simple framework for estimating potential distributions of amphibious marine species and implications for conservation

Due to their complexity, coral reefs are difficult to study especially when considering the role that the interplay between the terrestrial and marine environments has in shaping distribution of marine, terrestrial, and amphibious species. Many organisms live in remote areas of the ocean and inhabit both terrestrial and marine environments. Such amphibious lifestyle poses analytical difficulties due to broad distribution and scale of coral reefs. Ecological niche modeling is a widely used technique that allows to estimate the environmental set of conditions (niche) in which organisms can survive and reproduce. Estimating the distributions of species with complex life histories (i.e., dependent on various natural resources) at broad geographic scales is crucial, as many of these taxa are threatened (i.e., amphibians, aquatic reptiles, birds, and mammals). However, distribution estimates of such species remain challenging; thus, here we propose an approach to account for marine and terrestrial environmental domains to estimate the distribution of amphibious species. We also test whether inclusion of both environments leads to improved estimates of these species’ distributions. First we calibrated ecological niche models for marine and terrestrial domains separately, and subsequently we outlined a method to combine the marine–terrestrial potential distributions by integrating estimates of the two ecological niches into a single predictive model. Our ecological niche models produced inaccurate distribution predictions of species with amphibious life histories when only one of the environments was used in model calibration. When both aquatic and terrestrial environments were included, our models predicted narrower and more accurate potential distributions. Accounting for the dual environments involved in shaping the niches of amphibious species and their distributions is essential for studying the ecology and proposing conservation management actions for the species studied here. Models that take into account only a subset of the environmental factors are prone to overestimating species’ distributions and should be interpreted with caution.

A “scuttled saurian”?: A lower jaw bone of Tylosaurus kansasensis (Squamata: Mosasauridae) with an embedded tooth reexamined using CT scanning

Mosasaurs are a group of extinct large-bodied obligatory aquatic reptiles known from Late Cretaceous marine localities around the world, including the inland sea of North America. The behavior of these well-known reptiles has been discussed and suggest that many of the species were prone to intraspecific combat and highly popularized with explosive predation-focused narratives.Using computed tomography (CT) we examined a splenial (a lower jaw element) belonging to a young mosasaur. The splenial was collected from the Smoky Hill Chalk Member of the Niobrara Formation (Late Coniacian, Late Cretaceous), on the border of Ness and Trego counties. It is referable as Tylosaurus based on general morphology and specifically referable to Tylosaurus kansasensis based on locality data. This individual was originally hypothesized to have been killed by a larger mosasaur based on the presence of a tooth embedded in the splenial.However, examination of the CT scans suggests an alternative scenario for the tooth’s placement, suggesting the tooth may have been placed there through either diagenetic processes or post-mortem scavenging. We stress the importance of being cautious in interpreting behavior in the fossil record. Additionally, we note the need for better descriptions and illustrations of individual bones of the mosasaur skull in future scientific studies, which are sorely lacking at present.

Conflicting evidence for the use of caudal autotomy in mesosaurs

The early Permian mesosaurs were the first amniotes to re-invade aquatic environments. One of their most controversial and puzzling features is their distinctive caudal anatomy, which has been suggested as a mechanism to facilitate caudal autotomy. Several researchers have described putative fracture planes in mesosaur caudal vertebrae — unossified regions in the middle of caudal vertebral centra — that in many extant squamates allow the tail to separate and the animal to escape predation. However, the reports of fracture planes in mesosaurs have never been closely investigated beyond preliminary descriptions, which has prompted scepticism. Here, using numerous vertebral series, histology, and X-ray computed tomography, we provide a detailed account of fracture planes in all three species of mesosaurs. Given the importance of the tail for propulsion in many other aquatic reptiles, the identification of fracture planes in mesosaurs has important implications for their aquatic locomotion. Despite mesosaurs apparently having the ability to autotomize their tail, it is unlikely that they actually made use of this behaviour due to a lack of predation pressure and no record of autotomized tails in articulated specimens. We suggest that the presence of fracture planes in mesosaurs is an evolutionary relic and could represent a synapomorphy for an as-yet undetermined terrestrial clade of Palaeozoic amniotes that includes the earliest radiation of secondarily aquatic tetrapods.

The internal cranial anatomy of Champsosaurus (Choristodera: Champsosauridae): Implications for neurosensory function

Although isolated Champsosaurus remains are common in Upper Cretaceous sediments of North America, the braincase of these animals is enigmatic due to the fragility of their skulls. Here, two well-preserved specimens of Champsosaurus (CMN 8920 and CMN 8919) are CT scanned to describe their neurosensory structures and infer sensory capability. The anterior portion of the braincase was poorly ossified and thus does not permit visualization of a complete endocast; however, impressions of the olfactory stalks indicate that they were elongate and likely facilitated good olfaction. The posterior portion of the braincase is ossified and morphologically similar to that of other extinct diapsids. The absence of an otic notch and an expansion of the pars inferior of the inner ear suggests Champsosaurus was limited to detecting low frequency sounds. Comparison of the shapes of semicircular canals with lepidosaurs and archosauromorphs demonstrates that the semicircular canals of Champsosaurus are most similar to those of aquatic reptiles, suggesting that Champsosaurus was well adapted for sensing movement in an aquatic environment. This analysis also demonstrates that birds, non-avian archosauromorphs, and lepidosaurs possess significantly different canal morphologies, and represents the first morphometric analysis of semicircular canals across Diapsida.

A new choristodere (Reptilia: Choristodera) from an Aptian–Albian coal deposit in China

Choristoderes are a small clade of freshwater aquatic reptiles known from deposits of Jurassic–Miocene age. They show their greatest diversity in the Early Cretaceous of Asia, with seven recorded genera including longirostrine and brevirostine taxa, long- and short-necked taxa, and representatives of both neochoristoderes and non-neochoristoderes. The latter, informal grouping, comprising Monjurosuchus, Philydrosaurus, Hyphalosaurus, Khurendukhosaurus and, probably, Shokawa, is distinguished by the closure of the lower temporal fenestra. This differentiates them from typically diapsid stem choristoderes like the Jurassic Euramerican Cteniogenys and from all neochoristoderes like Champsosaurus and Simoeodosaurus. The recent description of Coeruleodraco jurassicus from the Callovian/Oxfordian of China provided the first example of an Asian non-neochoristodere with an open lower temporal fenestra. Here, we describe a second, geologically younger, genus and species from the Shahai Formation of Badaohao locality in western Liaoning, considered to be Aptian–Albian in age. This adds an eighth choristodere genus to the Early Cretaceous Asian record. The new species shares the diapsid skull morphology of C. jurassicus, demonstrating that a lineage of small, brevirostrine choristoderes with fully diapsid skulls persisted in Asia until the latter part of the Early Cretaceous. https://zoobank.org:pub:2D0B390A-6291-4C29-A72A-4F6A507C608B

Large-scale stable isotope characterization of a Late Cretaceous dinosaur-dominated ecosystem

Abstract In the Cretaceous of North America, environmental sensitivity and habitat specialization have been hypothesized to explain the surprisingly restricted geographic ranges of many large-bodied dinosaurs. Understanding the drivers behind this are key to determining broader trends of dinosaur species and community response to climate change under greenhouse conditions. However, previous studies of this question have commonly examined only small components of the paleo-ecosystem or operated without comparison to similar modern systems from which to constrain interpretations. Here we perform a high-resolution multi-taxic δ13C and δ18O study of a Cretaceous coastal floodplain ecosystem, focusing on species interactions and paleotemperature estimation, and compare with similar data from extant systems. Bioapatite δ13C preserves predator-prey offsets between tyrannosaurs and ornithischians (large herbivorous dinosaurs), and between aquatic reptiles and fish. Large ornithischians had broadly overlapping stable isotope ranges, contrary to hypothesized niche partitioning driven by specialization on coastal or inland subhabitat use. Comparisons to a modern analogue coastal floodplain show similar patterns of ecological guild structure and aquatic-terrestrial resource interchange. Multi-taxic oxygen isotope temperature estimations yield results for the Campanian of Alberta (Canada) consistent with the few other paleotemperature proxies available, and are validated when applied for extant species from a modern coastal floodplain, suggesting that this approach is a simple and effective avenue for paleoenvironmental reconstruction. Together, these new data suggest that dinosaur niche partitioning was more complex than previously hypothesized, and provide a framework for future research on dinosaur-dominated Mesozoic floodplain communities.

Identification of Telocytes in the Pancreas of Turtles-A role in Cellular Communication.

The existence of telocytes (TCs) has not yet been established in the pancreases of aquatic reptiles. Here, we report TCs in the exocrine pancreas of Pelodiscus sinensis using transmission electron microscope (TEM), immunohistochemistry (IHC), and immunofluorescence (IF) techniques. TCs surrounded the acini and ducts of the connective tissue of the exocrine pancreas and between lobules and gland cells. The cells were located preferably close to the blood vessels, interlobular ducts, and nerve fibers. Ultrastructurally, TCs exhibited small and large bodies with thick and thin portions, podoms, and podomers, and prolongations that form dichotomous branching with hetero-cellular and homo-cellular junctions. The podom (thick) portions showed caveolae, mitochondria, rough endoplasmic reticulum, and vesicles. The nucleus carries heterochromatin and is irregular in shape. The shape of TCs depends on the number of telopodes (Tps) bearing long, short, spindle, triangular, and “beads on a string” shapes with twisted, tortuous prolongations and ramifications. Shed extracellular vesicles and exosomes were found frequently released from projections and Tps within connective tissue in the vicinity of the acini and collagen fibers. IHC and IF results showed CD34+, α-SMA+, and vimentin+, long and triangle-shaped TCs, consistent with the TEM findings. The presence of shaded vesicles from TCs might implicate their possible role in immune surveillance, tissue regeneration as well as regulatory functions in the reptilian pancreas.

The first record of freshwater plesiosaurian from the Middle Jurassic of Gansu, NW China, with its implications to the local palaeobiogeography

Plesiosaurs are one of the common groups of aquatic reptiles in the Mesozoic, which mainly lived in marine environments. Freshwater plesiosaurs are rare in the world, especially from the Jurassic. The present paper reports the first freshwater plesiosaur, represented by four isolated teeth from the Middle Jurassic fluviolacustrine strata of Qingtujing area, Jinchang City, Gansu Province, Northwest China. These teeth are considered to come from one individual. The comparative analysis of the corresponding relationship between the body and tooth sizes of the known freshwater plesiosaur shows that Jinchang teeth represent a small-sized plesiosaurian. Based on the adaptive radiation of plesiosaurs and the palaeobiogeographical context, we propose a scenario of a river leading to the Meso-Tethys in the Late Middle Jurassic in Jinchang area, which may have provided a channel for the seasonal migration of plesiosaurs.

Intestinal B cells in the red-eared slider turtle, Trachemys scripta: Anatomical distribution and implications for ecological interactions with pathogenic microbes.

Disease is a significant threat in the global decline of reptile species. Many aquatic reptiles live in habitats with high levels of opportunistic microbial pathogens, yet little is known about their immune system. Gut-associated lymphoid tissue is vital for protection against ingested pathogens and maintenance of normal gut microbiota. In mammals, gut mucosal immunity is well-characterized and mucosal surfaces are coated in protective antibodies. However, reptiles lack lymph nodes and Peyer's patches, which are the major sites of mammalian B cell responses. The presence or distribution of mucosal B cells in reptiles is unknown. In this study, we first set out to determine if B cells could be detected in intestinal tissues of red-eared slider turtles, Trachemys scripta. Using whole-mount immunochemistry and a primary antibody to turtle antibody light chains, we identified widely distributed B cell aggregates within the small intestine of hatchling turtles. These aggregates appeared similar to isolated lymphoid follicles (ILFs) in mammals and the frequency was much higher in distal intestinal sections than in proximal sections. To determine if these structures were inducible in the presence of microbes, we introduced an enteric Salmonella species through oral gavage. Analysis of intestinal tissues revealed that hatchlings exposed to Salmonella exhibited significantly more of these aggregates when compared with those that did not receive bacteria. These studies provide the first evidence for B cell-containing ILF-like structures in reptiles and provide novel information about gut immunity in nonmammalian vertebrates that could have important implications for ecological interactions with pathogens.

Biodiversity value of remnant pools in an intermittent stream during the great California drought

Abstract In many intermittent streams, remnant pools persist after flow ceases and provide refuge for aquatic organisms able to tolerate stagnant water conditions. The conservation value of these pools may be greatly under‐appreciated, especially in regions with a Mediterranean climate, where perennial streams have been substantially modified or disturbed by human activities. Fish, amphibians, aquatic reptiles, and aquatic invertebrates were sampled from 15 remnant pools and three seeps at Coyote Creek, California, USA, in the late summer of 2014, during the height of the most intense drought that California has experienced in 500 years. Patterns of vertebrate and invertebrate species richness and community composition were compared with abiotic factors (e.g. water quality and habitat size). Thirteen vertebrate species and 172 invertebrate taxa were identified from remnant pools and seeps. Overall vertebrate richness and composition were not correlated with abiotic factors, but fish species richness increased with remnant pool size and depth. Invertebrate taxon richness increased with pool size. Invertebrate community composition differed by habitat type (pool versus seep) and gradients in composition were correlated with several abiotic factors (e.g. pool size, substrate, and canopy cover). Remnant pools at Coyote Creek supported a full assemblage of native fishes and numerous imperilled taxa, including California red‐legged frogs and California floater mussels. Nearly all native fishes and imperilled taxa are absent from artificially perennial and urbanized reaches of Coyote Creek just a few kilometres downstream of the study area. Remnant pools in intermittent streams should be a focus of conservation efforts in regions with a Mediterranean climate, especially during extreme droughts. Native fauna adapted to harsh intermittent flow regimes can thrive in these habitats, whereas non‐native taxa may fare poorly. Furthermore, remnant pools supported by deep groundwater sources, such as those along geological faults, may provide both ecological refuge and evolutionary refugia for freshwater biota.

Prospects for freshwater turtle population recovery are catalyzed by pan-Amazonian community-based management

Sustainable use as a mechanism for the conservation and recovery of exploited wildlife populations remains intensely debated, including for freshwater turtles, a diverse and imperiled group of aquatic reptiles that are an important food source for many residents of tropical regions. Here we evaluated the geographical extent of recovery options for a heavily exploited tropical freshwater turtle fauna across 8.86 M km2 of South American river catchments under scenarios of Business-as-Usual (BAU), Protection (Pr) and Community-Based-Management (CBM). For the widespread indicator species, Podocnemis unifilis, demographic analysis showed that populations subject to moderate levels of female harvest (≤10%) can recover over broad areas if concurrent headstarting of hatchlings is practiced more widely. With regional strengthening of the protected area network unlikely, CBM developed with harvest frameworks derived from demographic rates appropriate to tropical species could catalyze a rapid continental scale recovery of Amazonian freshwater turtles within a few decades.

The first record of a nearly complete choristodere (Reptilia: Diapsida) from the Upper Jurassic of Hebei Province, People’s Republic of China

Choristodera are freshwater aquatic reptiles known from the Middle Jurassic to the Miocene. Their fossil record shows a peak in diversity in the Early Cretaceous of eastern Asia, most notably in the Jehol Biota of China but also in Japan and Mongolia. However, until now, the only Jurassic records from Asia have been rare disarticulated elements from Middle Jurassic microvertebrate sites in Transbaikalian Siberia, with a possible jaw fragment from the Late Jurassic of Xinjiang, China. Here we describe Coeruleodraco jurassicus gen. et sp. nov., a new, fully articulated choristodere skeleton from the Tiaojishan Formation of China, which is considered to be of Late Jurassic (Oxfordian) age. As such, the new specimen represents the first complete Jurassic choristodere recovered worldwide, and also provides important information on the pre-Cretaceous history of the group in eastern Asia. In its proportions and postcranial characters the new taxon resembles previously described Asian taxa such as Philydrosaurus, but it is distinct in possessing several apparently plesiomorphic characters, including a short antorbital region, paired external nares and an open lower temporal fenestra. Phylogenetic analysis places the new choristodere as the sister taxon of a non-neochoristoderan clade comprising Asian and European taxa, whereas the European Jurassic Cteniogenys becomes the sister taxon to all other Choristodera. http://zoobank.org/urn:lsid:zoobank.org:pub:5478E013-CC19-487A-ACC0-021A88633338

Filling the biostratigraphical gap: First choristoderan from the Lower – mid-Cretaceous interval of Europe

Choristodera is a clade of extinct aquatic reptiles whose fossils have been found in freshwater and marginal marine deposits from Europe, Asia and North America. The European record is the most extensive, spanning at least the Middle Jurassic to early Miocene, and incorporates the stratigraphically oldest and youngest members of the group. Despite this, there is an unexplained ∼70 myr gap in European choristoderan fossil occurrences. Here we fill this hiatus with the discovery of an isolated choristoderan dorsal vertebra from the lower Cenomanian ‘Rotkalk’ red limestone facies of the Essen Greensand Formation in Mülheim/Ruhr, North Rhine-Westphalia, western Germany. This specimen represents the first identifiable European choristoderan from the Kimmeridgian–Campanian interval, and displays a diagnostic state combination including an amphiplatyan centrum with synapophyses on the transverse processes that are level with the neurocentral suture. The palaeobiogeographical distribution of choristoderans thus likely transected the entire Laurasian landmass throughout the Cretaceous, with perceived stratigraphical interstices being a result of incomplete sampling.

Detection of the European pond turtle (Emys orbicularis) by environmental DNA: is eDNA adequate for reptiles?

Abstract Recent studies have demonstrated the potential of combining molecular technologies with environmental sampling to detect various vertebrate species in aquatic ecosystems. The European pond turtle (Emys orbicularis) is a threatened and elusive aquatic reptile with shy behaviour. We aimed to develop and evaluate a methodology to detect the presence of this secretive aquatic reptile in ponds from environmental water samples. First, we determined that reptilian DNA can be isolated and amplified from water samples in artificial and natural ponds with known turtle density. Then we compared the potential of two water sampling methods (through filtration or precipitation) and found no significant differences between these approaches. Finally, we demonstrated that the eDNA concentration detected is not correlated with the number of E. orbicularis individuals or biomass. Detection of eDNA was higher in artificial ponds with small volumes of water or in the shallow waters of natural ponds. The eDNA-based methodology aims to detect the presence of specific species, even at low density, with better accuracy than visual observation. However, our study indicates that this method of population monitoring should be applied with caution to aquatic reptiles.