A leatherback turtle (Testudines, Dermochelyidae) from the Miocene of the Westerschelde, the Netherlands

The Westerschelde Estuary in The Netherlands is known for its rich vertebrate fossil content. In a recent trawling campaign aimed at sampling a late Miocene marine vertebrate assemblage, over 5000 specimens were retrieved, all currently stored in the Natuurhistorisch Museum Rotterdam. One specimen is a well preserved fragment of a dermochelyid sea-turtle carapace. The Westerschelde specimen is an addition to the scant hypodigm of dermochelyids from the Miocene North Sea. The carapace fragment is described and identified as Psephophorus polygonus. The various secondary marks present on the fragment are suggestive of both predatory and scavenging origin. Based on the assumption that P. polygonus had a similar carapace structure as recent D. coriacea, the minimal size of the complete carapace is estimated to have been 168 x 126 cm. Furthermore, based on the physical traits of the Westerschelde specimen and a reexamination of P. polygonus specimens, including the neotype stored at the Naturhistorisches Museum Wien (Austria), it is argued that previously assigned characteristics cannot be used as discriminative taxonomic properties of dermochelyids in general, and of P. polygonus in particular. An improved cladistic analysis on dermochelyids is performed based on previously defined and new taxonomic characters. Using this analysis it is argued that Psephophorus calvertensis is a junior synonym of P. polygonus. Hence, a new diagnosis of Psephophorus polygonus is defined. The ‘addition’ of P. calvertensis to the species P. polygonus confirms its presence on both sides of the Atlantic Ocean. Therefore, we suggest P. polygonus to have had a cosmopolitan distribution, similar to the extant species Dermochelys coriacea

Investigating seasonal mobility in Irish giant deer Megaloceros giganteus (Blumenbach, 1799) through strontium isotope (87Sr/86Sr) analysis

Giant deer Megaloceros giganteus (Blumenbach, 1799) fossils are commonly found in Lateglacial deposits throughout Ireland. While their migrational behaviour has been suggested, it has never been researched. We hypothesise that giant deer underwent seasonal migrations, specifically during Late Pleistocene cold periods as a behavioural adaptation. Giant deer required a high nutrient uptake and were maladapted to the cold‐dry steppe of the Pleistocene glacials. Migration allowed for optimal nutrient uptake during summer, while avoiding the harsh winter conditions of the glacials by moving to sheltered, low‐lying areas. In this study strontium isotope analysis (87Sr/86Sr) of sequentially sampled dental enamel is conducted for the first time on giant deer that were previously sampled in the same manner for δ13C and δ18O, allowing correlations between the isotope data sets. One specimen from Ballybetagh, Dublin generated results indicating seasonal mobility behaviour. This individual was perhaps pushed to migrate at the Younger Dryas stadial onset as the vegetation giant deer depended on disappeared in Ireland. Adaptive mobility behaviour in response to climate was perhaps imperative to their survival through previous glacial periods, but other Eurasian populations would need to be analysed to make such a general conclusion

Cranial morphology of the tanystropheid Macrocnemus bassanii unveiled using synchrotron microtomography

The genus Macrocnemus is a member of the Tanystropheidae, a clade of non-archosauriform archosauromorphs well known for their very characteristic, elongated cervical vertebrae. Articulated specimens are known from the Middle Triassic of Alpine Europe and China. Although multiple articulated specimens are known, description of the cranial morphology has proven challenging due to the crushed preservation of the specimens. Here we use synchrotron micro computed tomography to analyse the cranial morphology of a specimen of the type species Macrocnemus bassanii from the Besano Formation of Monte San Giorgio, Ticino, Switzerland. The skull is virtually complete and we identify and describe the braincase and palatal elements as well the atlas-axis complex for the first time. Moreover, we add to the knowledge of the morphology of the skull roof, rostrum and hemimandible, and reconstruct the cranium of M. bassanii in 3D using the rendered models of the elements. The circumorbital bones were found to be similar in morphology to those of the archosauromorphs Prolacerta broomi and Protorosaurus speneri. In addition, we confirm the palatine, vomer and pterygoid to be tooth-bearing palatal bones, but also observed heterodonty on the pterygoid and the palatine.Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

Late Cretaceous sauropod tooth morphotypes may provide supporting evidence for faunal connections between North Africa and Southern Europe

The Cretaceous Kem Kem beds of Morocco and equivalent beds in Algeria have produced a rich fossil assemblage, yielding, amongst others, isolated sauropod teeth, which can be used in species diversity studies. These Albian-Cenomanian ( approximately 113-93.9 Ma) strata rarely yield sauropod body fossils, therefore, isolated teeth can help to elucidate the faunal assemblages from North Africa, and their relations with those of contemporaneous beds and geographically close assemblages. Eighteen isolated sauropod teeth from three localities (Erfoud and Taouz, Morocco, and Algeria) are studied here, to assess whether the teeth can be ascribed to a specific clade, and whether different tooth morphotypes can be found in the samples. Two general morphotypes are found, based on enamel wrinkling and general tooth morphology. Morphotype I, with mainly rugose enamel wrinkling, pronounced carinae, lemon-shaped to (sub)cylindrical cross-section and mesiodistal tapering towards an apical tip, shows affinities to titanosauriforms and titanosaurs. Morphotype II, characterized by more smooth enamel, cylindrical cross-section, rectangular teeth with no apical tapering and both labial and lingual wear facets, shows similarities to rebbachisaurids. Moreover, similarities are found between these northwest African tooth morphotypes, and tooth morphotypes from titanosaurs and rebbachisaurids from both contemporaneous finds from north and central Africa, as well as from the latest Cretaceous (Campanian-Maastrichtian, 83.6 Ma-66.0 Ma) of the Ibero-Armorican Island. These results support previous hypotheses from earlier studies on faunal exchange and continental connections between North Africa and Southern Europe in the Cretaceous

La intertextualidad como método de análisis filosófico

Ombrotrophic peatlands are a recognized global carbon reservoir. Without restoration and peat regrowth, harvested peatlands are dramatically altered, impairing its carbon sink function, with consequences for methane turnover. Previous studies determined the impact of commercial mining on the peat physico-chemical properties, and the effects on methane turnover. However, the response of the underlying microbial communities catalyzing methane production and oxidation have so far received little attention. We hypothesize that with the return of Sphagnum post-harvest, methane turnover potentials and the corresponding microbial communities will converge in a natural and restored peatland. To address our hypothesis, we determined the potential methane production and oxidation rates in a natural (as a reference), actively mined, abandoned, and restored peatland over two consecutive years. In all sites, the methanogenic and methanotrophic population size were enumerated using qPCR assays targeting the mcrA and pmoA genes, respectively. Shifts in the community composition was determined using Illumina MiSeq sequencing of the mcrA gene, and a pmoA-based t-RFLP analysis, complemented by cloning and sequence analysis of the mmoX gene. Peat mining adversely affected methane turnover potentials, but rates recovered in the restored site. The recovery in potential activity was reflected in the methanogenic and methanotrophic abundances. However, the microbial community composition was altered, more pronounced for the methanotrophs. Overall, we observed a lag between the recovery of the methanogenic/methanotrophic activity and the return of the corresponding microbial communities, suggesting a longer duration (>15 years) is needed to reverse mining-induced effects on the methane-cycling microbial communities

Evolutionary History of Saber-Toothed Cats Based on Ancient Mitogenomics

Saber-toothed cats (Machairodontinae) are among the most widely recognized representatives of the now largely extinct Pleistocene megafauna. However, many aspects of their ecology, evolution, and extinction remain uncertain. Although ancient-DNA studies have led to huge advances in our knowledge of these aspects of many other megafauna species (e.g., mammoths and cave bears), relatively few ancient-DNA studies have focused on saber-toothed cats [1–3], and they have been restricted to short fragments of mitochondrial DNA. Here we investigate the evolutionary history of two lineages of saber-toothed cats (Smilodon and Homotherium) in relation to living carnivores and find that the Machairodontinae form a well-supported clade that is distinct from all living felids. We present partial mitochondrial genomes from one S. populator sample and three Homotherium sp. samples, including the only Late Pleistocene Homotherium sample from Eurasia [4]. We confirm the identification of the unique Late Pleistocene European fossil through ancient-DNA analyses, thus strengthening the evidence that Homotherium occurred in Europe over 200,000 years later than previously believed. This in turn forces a re-evaluation of its demography and extinction dynamics. Within the Machairodontinae, we find a deep divergence between Smilodon and Homotherium (∼18 million years) but limited diversity between the American and European Homotherium specimens. The genetic data support the hypothesis that all Late Pleistocene (or post-Villafrancian) Homotherium should be considered a single species, H. latidens, which was previously proposed based on morphological data [5, 6]. Paijmans et al. present ancient DNA from some of the most recognized extinct Pleistocene megafauna: the saber-toothed cats. The results elucidate the evolutionary history of these iconic carnivores and provide genetic evidence that saber-toothed cats existed in Europe over 200,000 years later than previously believed.This project received funding from the European Research Council (consolidator grant GeneFlow no. 310763 to M.H.), European Union’s Seventh Framework Programme for research, technological development, and demonstration (grant no. FP7-PEOPLE-2011-IEF-298820 to R.B.), and Lundbeck Foundation (grant no. R52-A5062 to M.L.Z.-M.)

The last European varanid: demise and extinction of monitor lizards (Squamata, Varanidae) from Europe

Remains of a varanid lizard from the middle Pleistocene of the Tourkobounia 5 locality near Athens, Greece are described. The new material comprises cranial elements only (one maxilla, one dentary, and one tooth) and is attributed to Varanus, the genus to which all European Neogene varanid occurrences have been assigned. Previously, the youngest undisputed varanid from Europe had been recovered from upper Pliocene sediments. The new Greek fossils therefore constitute the youngest records of this clade from the continent. Despite being fragmentary, this new material enhances our understanding of the cranial anatomy of the last European monitor lizards and is clearly not referable to the extant Varanus griseus or Varanus niloticus, the only species that could be taken into consideration on a present-day geographic basis. However, these fossils could represent a survivor of the monitor lizards of Asian origin that inhabited Europe during the Neogene

Evolutionary history of saber-toothed cats based on ancient mitogenomics

Saber-toothed cats (Machairodontinae) are among the most widely recognized representatives of the now largely extinct Pleistocene megafauna. However, many aspects of their ecology, evolution, and extinction remain uncertain. Although ancient-DNA studies have led to huge advances in our knowledge of these aspects of many other megafauna species (e.g., mammoths and cave bears), relatively few ancient-DNA studies have focused on saber-toothed cats, and they have been restricted to short fragments of mitochondrial DNA. Here we investigate the evolutionary history of two lineages of saber-toothed cats (Smilodon and Homotherium) in relation to living carnivores and find that the Machairodontinae form a well-supported clade that is distinct from all living felids. We present partial mitochondrial genomes from one S. populator sample and three Homotherium sp. samples, including the only Late Pleistocene Homotherium sample from Eurasia. We confirm the identification of the unique Late Pleistocene European fossil through ancient-DNA analyses, thus strengthening the evidence that Homotherium occurred in Europe over 200,000 years later than previously believed. This in turn forces a re-evaluation of its demography and extinction dynamics. Within the Machairodontinae, we find a deep divergence between Smilodon and Homotherium ( 18 million years) but limited diversity between the American and European Homotherium specimens. The genetic data support the hypothesis that all Late Pleistocene (or post-Villafrancian) Homotherium should be considered a single species, H. latidens, which was previously proposed based on morphological data

Genetics of decayed sexual traits in a parasitoid wasp with endosymbiont-induced asexuality.

Trait decay may occur when selective pressures shift, owing to changes in environment or life style, rendering formerly adaptive traits non-functional or even maladaptive. It remains largely unknown if such decay would stem from multiple mutations with small effects or rather involve few loci with major phenotypic effects. Here, we investigate the decay of female sexual traits, and the genetic causes thereof, in a transition from haplodiploid sexual reproduction to endosymbiont-induced asexual reproduction in the parasitoid wasp Asobara japonica. We take advantage of the fact that asexual females cured of their endosymbionts produce sons instead of daughters, and that these sons can be crossed with sexual females. By combining behavioral experiments with crosses designed to introgress alleles from the asexual into the sexual genome, we found that sexual attractiveness, mating, egg fertilization and plastic adjustment of offspring sex ratio (in response to variation in local mate competition) are decayed in asexual A. japonica females. Furthermore, introgression experiments revealed that the propensity for cured asexual females to produce only sons (because of decayed sexual attractiveness, mating behavior and/or egg fertilization) is likely caused by recessive genetic effects at a single locus. Recessive effects were also found to cause decay of plastic sex-ratio adjustment under variable levels of local mate competition. Our results suggest that few recessive mutations drive decay of female sexual traits, at least in asexual species deriving from haplodiploid sexual ancestors