Hunted hunters – prey of Aspidorhynchus (Actinopterygii) within isolated gastrointestinal tracts from the late Jurassic of the Solnhofen Archipelago

The Late Jurassic fossil deposits of southern Germany, collectively known as the 'Solnhofen Archipelago', are one of the world's most important sources of Mesozoic vertebrates. Complete skeletons of cartilaginous fishes (Chondrichthyes), whose skeletal remains are rare in the fossil record and therefore all the more valuable, are represented, among others, by exceptionally well-preserved rays (superorder Batomorphii). Despite their potential for research in several areas, including taxonomy, morphology, ecology, and phylogeny, the number of studies on these chondrichthyans is still very limited. Here, we identify a previously unknown ray, †Apolithabatis seioma gen. et sp. nov., which represents the first record of a ray species from the upper Kimmeridgian of Painten, Germany, and thus the oldest Late Jurassic ray taxon from Germany based on skeletal remains. This new batomorph is characterised by a unique body shape and a combination of skeletal features that distinguish it readily from all other known Late Jurassic rays. Two different morphometric approaches confirm differences in body shape and proportions to all known Late Jurassic conspecifics. We thus extend the recent taxonomic revision of these rays and include all described holomorphic specimens in a phylogenetic framework using strict cladistic principles. The phylogenetic analysis reveals all Late Jurassic batomorphs to represent a monophyletic group, for which we introduce the new order Apolithabatiformes, which is sister to all other batomorphs representing a stem group. While the phylogenetic relationships within Apolithabatiformes ord. nov. remain largely unresolved, †Apolithabatis gen. nov. is placed as the sister to †Aellopobatis. This highlights that, despite considerable progress in our understanding of the diversity and phylogeny of early rays, difficulties remain in establishing robust relationships within batomorphs. We therefore emphasise the importance of comprehensive studies of completely preserved fossil cartilaginous fishes to obtain a better understanding of chondrichthyan evolution and their systematics in deep time.

<p>Trophic interactions of extinct fishes are central to our understanding of evolution, paleoecology and their role in the paleo-communities, but can be challenging, as these are limited by the incompleteness of the fossil record and by a lack of behavioural data. The extensive fossil record of Actinopterygii comes mostly from Conservation-Lagerstätten. They provide exceptionally rich information on fossil ecosystems and open outstanding windows into the evolution of life. The best-preserved Late Jurassic actinopterygians are known from the Solnhofen Archipelago, Germany. Despite that the diversity ichthyofauna of the Solnhofen Archipelago has been extensively explored in the last several decades, the dietary preferences of most fish remain unknown or have to be deduced by analogy from dentition and jaw morphology.</p><p>The aim of this study was to reconstruct the trophic levels of Late Jurassic fish assemblages using Sr/Ca and Ba/Ca measured from phosphatic fish remains, mostly ganoin and cycloid scales recovered from the Ettling locality, which is characterized by exceptionally well-preserved fossil fishes and moderate diagenetic alteration. We classified fish species into four trophic levels (durophagous, lower, middle, and higher trophic level) based on morphology available from the literature. Mean values of Sr, Ca, Ba and their ratios measured by Thermo Scientific iCAP Q inductively coupled plasma mass spectrometer in this study are in accordance with the mean values of previous studies. Differences in values between cleaned and uncleaned samples showed that the cleaning process successfully isolated primary dietary Sr content while dissolving away the diagenetic strontium present in carbonate in the pore spaces. All trophic levels showed low variation of Sr/Ca (0.003 - 0.008 μg/g) and high variation of Ba/Ca values (0.0003 - 0.0014 μg/g). The results showed significant differences between the middle and higher trophic levels (p = 0.03), while durophagous and lower trophic levels fell into the same range of values as the higher trophic level. </p><p>We demonstrate that enamel of fossil vertebrates from the Solnhofen Archipelago still contains near-in vivo Sr, Ba, and Ca. The clear distinction between middle and higher trophic levels offers a new functional perspective on the ecological and evolutionary relationships among fishes. However, future studies should not neglect the importance of diagenetic alteration of the samples; proper sample cleaning before measuring isotopic signatures, and careful selection of the analyzed tissue (i.e. tooth enamel instead of scales or bones due to its resistance to diagenesis).</p>

The newly recognized Konservat-Lagerstätte of Ettling (Bavaria), field site of the Jura-Museum Eichstätt (JME), is unique among Late Jurassic plattenkalk basins (Solnhofen region) in its abundant, extremely well preserved fossil vertebrates, almost exclusively fishes. We report actinopterygians (ginglymodins, pycnodontiforms, halecomorphs, aspidorynchiforms, “pholidophoriforms,” teleosts); turtles; and non-vertebrates (echinoderms, arthropods, brachiopods, mollusks, jellyfish, sponges, biomats, plants) in a current faunal list. Ettling has yielded several new fish species (Bavarichthys incognitus; Orthogonikleithrus hoelli; Aspidorhynchus sanzenbacheri; Macrosemimimus fegerti). Upper and lower Ettling strata differ in faunal content, with the lower dominated by the small teleost Orthogonikleithrus hoelli (absent from the upper layers, where other prey fishes, Leptolepides sp. and Tharsis sp., occur instead). Pharyngeal and stomach contents of Ettling fishes provide direct evidence that Orthogonikleithrus hoelli was a primary food source during early Ettling times. Scarcity of ammonites and absence of vampyromorph coleoids at Ettling differ markedly from the situation at other nearby localities in the region (e.g., Eichstätt, Painten, Schamhaupten, the Mörnsheim beds), where they are more common. Although the exact biochronological age of Ettling remains uncertain (lack of suitable index fossils), many Ettling fishes occur in other plattenkalk basins of Germany (e.g., Kelheim) and France (Cerin) dated as Late Kimmeridgian to Early Tithonian (eigeltingense horizon), suggesting a comparable geologic age. The Ettling deposits represent an independent basin within the larger Upper Jurassic “Solnhofen Archipelago”, a shallow subtropical sea containing scattered islands, sponge-microbial and coral reefs, sandbars, and deeper basins on a vast carbonate platform along the northern margin of the Tethys Ocean.

Cricosaurus represents one of the most important radiations within Metriorhynchidae, a specialized marine clade of Crocodylomorpha that flourished in marine environments from the Middle Jurassic until the Early Cretaceous. Here, we describe a new species of Cricosaurus, Cricosaurus rauhuti sp. nov., from the Mörnsheim Formation (lower Tithonian) of southern Germany. The specimen is the first three-dimensionally preserved Cricosaurus from this realm, and it is represented by a partially preserved cranium and lower jaw that has autapomorphic characters that distinguish it from any other species of Cricosaurus. The phylogenetic analysis shows that the new species is more closely related to some non-European forms from the Late Jurassic and one taxon from the Valanginian of Germany (all 3D-preserved) than to other Late Jurassic Cricosaurus from southern Germany (all 2D-preserved). Our exploratory analyses confirm that this is not a preservation bias. For the first time, this shows that there are two clades of Cricosaurus present during the Late Jurassic in Germany. Furthermore, it provides additional evidence of a close faunal relationship between Europe and South America in the Late Jurassic, as also evidenced by the fossil record of other marine reptiles. Finally, the distribution of metriorhynchids in localities of the Solnhofen Archipelago suggests a change in the taxic diversity of the region during the early Tithonian, which might be the result of environmental changes in the Solnhofen Archipelago. http://zoobank.org/urn:lsid:zoobank.org:pub:488705BF-AEAD-4F02-BB4E-429E3117BCD1

The Late Jurassic-Early Cretaceous (164-100 Ma) represents one of the main transitional periods in life history. Recent studies unveiled a complex scenario in which abiotic and biotic factors and drivers on regional and global scales due to the fragmentation of Pangaea resulted in dramatic faunal and ecological turnovers in terrestrial and marine environments. However, chondrichthyan faunas from this interval have received surprisingly little recognition. The presence of numerous entire skeletons of chondrichthyans preserved in several localities in southern Germany, often referred to as Konservat-Lagerstätten (e.g., Nusplingen and the Solnhofen Archipelago), provides a unique opportunity of to study the taxonomic composition of these assemblages, their ecological distributions and adaptations, and evolutionary histories in detail. However, even after 160 years of study, the current knowledge of southern Germany's Late Jurassic chondrichthyan diversity remains incomplete. Over the last 20 years, the systematic study and bulk sampling of southern Germany's Late Jurassic deposits significantly increased the number of known fossil chondrichthyan genera from the region (32 in the present study). In the present work, the fossil record, and the taxonomic composition of Late Jurassic chondrichthyans from southern Germany are reviewed and compared with several contemporaneous assemblages from other sites in Europe. Our results suggest, inter alia, that the Late Jurassic chondrichthyans displayed extended distributions within Europe. However, it nevertheless also is evident that the taxonomy of Late Jurassic chondrichthyans is in urgent need of revision.

The fossil record's oldest known calculus (an enterolith of the gastrointestinal tract), from the Kimmeridge Clay Formation (Upper Jurassic), UK

Predation is one of the key factors governing patterns in natural systems, and adjustments of prey behaviors in response to a predator stimulus can have important ecological implications for wild fish. To investigate the effects of predators on the behavior of prey fish and to test whether the possible effects varied with predator size, black carp (Mylopharyngodon piceus) and snakehead (Channa argus) (a size-matched predator treatment with a similar body size to prey fish and a larger predator treatment with approximately 2.7 times of the body mass of prey fish) were selected to function as prey and predator, respectively. Their spontaneous activities were videorecorded in a central circular arena surrounded by a ring holding the stimulus fish. The distance between prey and predator fish was approximately 200% of the distance between two prey fish, which suggested that black carp can distinguish their conspecifics from heterospecifics and probably recognize the snakehead as a potential predator. The prey fish spent substantially less time moving and exhibited an overall shorter total distance of movement after the size-matched or large predator was introduced, which possibly occurred due to increased vigilance or efforts to reduce the possibility of detection by potential predators. However, there was no significant difference in either distance or spontaneous activities between two predator treatments. These findings suggested that (1) an anti-predator strategy in black carp might involve maintaining a safe distance, decreasing activity and possibly increased vigilance and that (2) the behaviors of prey response to predators were not influenced by their relative size difference.

ABSTRACTAlthough the type species of Ophiopsis was long considered O. procera, the genus originally included the single species Ophiopsis muensteri, which subsequent authors moved to Furo. Following the International Commission on Zoological Nomenclature code, Furo muensteri is here recognized as the type species of Ophiopsis by monotypy (Article 68.3). Ophiopsiella, gen. nov., is erected to include all remaining previously described ‘Ophiopsis’ species. Exceptionally well preserved new Ophiopsiella attenuata from the Upper Jurassic plattenkalk of Ettling (Bavaria, Germany) represents the first record of this species from Ettling, allowing for a partial revision of it and Ophiopsiella procera. New evidence allows for an emended diagnosis of Ophiopsiella attenuata, which differs from all other Ophiopsidae in the following combination of features: 27–28 dorsal fin rays, 42 vertical scale rows, and a long, low, posteroventrally inclined dorsal fin lacking elongate anterior fin rays or a strongly concave posterior border. A neotype for O. attenuata is designated, as the type is lost. ‘Ophiopsis’ attenuata actually contains two anatomically different morphotypes corresponding to distinct species, one of which is indistinguishable from ‘Ophiopsis’ procera. Exceptional preservation of the new material provides new morphological information, particularly regarding the dermal cranial bones. This revision changes the known distribution of ophiopsids in the Upper Jurassic of southern Germany and France, with possible broader paleobiogeographic and paleoecological implications for this region during the Late Jurassic. Ophiopsids remain poorly known compared with other halecomorphs (e.g., Amiidae), and closer investigation of their morphology and taxonomic relationships is therefore important to understanding broader patterns of halecomorph evolution.http://zoobank.org/urn:lsid:zoobank.org:pub:6B250A32-9FAA-4EF6-9D91-6D1C5E91E547

Vertebrate fossils from the Kimmeridgian of Brunn: the oldest fauna from the Solnhofen Archipelago (Late Jurassic, Bavaria, Germany)

The fossil record of chondrichthyans (chimaeras, sharks, rays and skates) consists largely of isolated teeth, with holomorphic specimens being extraordinary exceptions. However, numerous of these more or less completely preserved specimens are known from several Upper Jurassic deposits of Europe, enabling detailed analysis of their morphology. Batomorphs (rays and skates) resembling modern guitarfishes and wedgefishes (Rhinopristiformes) are among the most common Jurassic chondrichthyans found, but they have been only sporadically studied up to now, resulting in large knowledge gaps concerning their taxonomy and phylogeny. Here, we present the most detailed revision of Late Jurassic holomorphic batomorphs to date, quantitatively analysing body proportions of specimens from Germany (Solnhofen Archipelago), France (Cerin) and the UK (Kimmeridge), using both geometric and traditional morphometrics. Furthermore, we identify qualitative morphological characters for species discrimination, to clarify the taxonomic identity and diversity of Late Jurassic batomorphs based on holomorphic specimens. Our results support the validity of Belemnobatis sismondae, Kimmerobatis etchesi and Spathobatis bugesiacus, as well as that of the previously doubtful Asterodermus platypterus. Moreover, we describe Aellopobatis bavarica, a new taxon, which has hitherto been considered to be a large-sized morphotype of Spathobatis bugesiacus. Our results highlight that the diversity of holomorphic batomorphs during the Late Jurassic was greater than previously thought, and suggest that this group was already well-established and diverse by this time. This study thus provides vital information about the evolutionary history of Late Jurassic batomorphs and has direct implications for batomorph species that are based on isolated teeth only.

More or less complete and articulated skeletons of fossil air-breathing vertebrates with a long neck and tail often exhibit a body posture in which the head and neck are recurved over the back of the animal. Additionally, the tail is typically drawn over the body, while the limbs have a rigid appearance. In palaeontological literature, this “opisthotonic posture” of such fossils still requires a causal interpretation in an etiological context. According to this hypothesis, there is a presumption of a cerebral disorder generating perimortem muscle spasms that are preserved by rapid burial or other sequestration of a skeleton in the fossil record. We re-evaluate this “opisthotonic posture hypothesis” by analysing the non-avian theropods Compsognathus longipes and Juravenator starki from the famous South Franconian plattenkalks of the Upper Jurassic Solnhofen Archipelago. Decay experiments with the extant domestic fowl Gallus gallus L. and analysis of the theropods’ constructional morphological constraints reveal that the opisthotonic posture is not a peri- but a postmortem phenomenon. By analysing the timeline of decomposition, it is possible to recognise different stages of decay, depending on the varying decay resistance of soft tissues. Adipocere formation must have blocked further decay until embedding was completed by minimal sedimentation. Analyses of the palaeoenvironment of the basins of the Solnhofen Archipelago show that the conditions of deposition of individual basins cannot be considered to be similar, even inside the same time frame. Therefore, a generalised approach of looking at the depositional setting must be excluded. Assumptions by Faux and Padian (2007) that the accepted palaeoenvironmental reconstruction of the Solnhofen Fossillagerstatte has to be questioned in the light of the opisthotonic posture hypothesis enforce the need for a review of palaeoecological factors of the Franconian Plattenkalks from a taphonomic perspective.

The fishes of the genus Aspidorhynchus (Aspidorhynchidae) are among the most abundant predators in the palaeolagoons of the Solnhofen archipelago (Late Jurassic, southern Germany). They have been known since the end to the nineteenth century and the last revision of the genus was published more than 20 years ago. During these last two decades, numerous complete and excellently preserved specimens have been collected. The high morphological diversity shown by the new material made a new revision of these fishes necessary. This new taxonomic revision led us to revalidate the species A. ornatissimus Agassiz, 1834, which has hitherto been considered a junior synonym of the type species of the genus, A. acutirostris (Blainville, 1818), as well as to recognize high intraspecific variation in the latter species. These results helped to improve the distinction and, thus, the diagnoses of A. acutirostris, A. ornatissimus, and A. sanzenbacheri Brito and Ebert, 2009, which are the three valid species of this genus in the Solnhofen archipelago. We have been able to explain most of the intraspecific diversity of A. acutirostris by means of patterns of ontogenetic variation that encompass most of the other nominal species, thus largely reflecting early taxonomic hypotheses. Furthermore, the detailed morphological study led us to the recognition of some important anatomical structures previously unknown for aspidorhynchids: a connection between the temporal, infraorbital and supraorbital sensory canals in the frontal bone, the presence of an Y-shaped antorbital bone, and the presence of an interoperculum.

The so-called “Solnhofen limestones” of southern Germany are widely recognized for their abundance of Late Jurassic fossil vertebrates, with pterosaurs being no exception. Within the recognized plenitude of the pterosaurs within this assemblage, although ctenochasmatid remains are relatively abundant, gnathosaurines are scarce, with only one known Solnhofen representative of the group known thus far. The Late Kimmeridgian locality of Brunn (near Regensburg, Germany) represents the oldest locality of the Solnhofen complex (“Solnhofen Archipelago” in recent literature), with only one pterosaur having been described from this locality to date. Here, a second pterosaur taxon from within this locality and a new gnathosaur is introduced, Spathagnathus roeperi gen. et sp. nov., whose novel tooth and dental enamel features add to the known dental diversity for the group. The new taxon represents the oldest occurrence of a gnathosaurine and contributes to the paleoenvironmental stratigraphic range for the Gnathosaurinae within the overall fossil assemblage of the Solnhofen Archipelago. Furthermore, the new taxon adds to the known diversity of ctenochasmatids in the Late Jurassic and underlines the importance of this early radiation of pterodactyloid pterosaurs during this time.

Occurrence and biomagnification of perfluoroalkyl substances (PFAS) in Lake Michigan fishes

Fragmentary remains of a large, robustly built theropod dinosaur were recovered from the marine middle Callovian Ornatenton Formation of north-eastern Northrhine-Westphalia, Germany. The specimen includes a premaxilla, maxilla, lacrimal, postorbital, dentary, several caudal vertebrae, ribs, fibulae, astragalus, and partial calcaneum. It is here described as a new species of megalosauroid, Wiehenvenator albati n. gen. n. sp., diagnosed by a strongly reduced maxillary antorbital fossa on the base of the ascending process of the maxilla, a very short anterior ramus of the lacrimal with an additional pneumatic depression anteroventral to the lacrimal fenestra, a transversely expanded orbital facet in the postorbital, and a laterally flexed proximal end of the ascending process of the astragalus. Phylogenetic analysis recovers Wiehenvenator as a megalosaurine megalosaurid, sister taxon to the Late Jurassic genus Torvosaurus. It thus adds to the considerable diversity of megalosauroids in the Middle Jurassic. A time-calibrated phylogeny of theropods indicates a rapid radiation of averostran theropods between the Toarcian and the Bathonian. This radiation was probably triggered by the Pliensbachian-Toarcian extinction event, which might have been more important for theropod evolution than the Triassic-Jurassic extinction. The fossil record indicates a faunal turnover from megalosauroid dominated Middle Jurassic to allosauroid / coelurosaur dominated Late Jurassic faunas. However, differences in the Middle and Late Jurassic theropod fossil records both in respect to geographic distribution of localities, as well as sampled environments make this inference problematic, at least in respect to allosauroids. An analysis of environmental preferences of allosauroids and megalosauroids indicates that the former preferred inland environments, whereas the latter are more common in nearshore environments.