Jahn J. Hornung

The Sail-Backed Reptile Ctenosauriscus from the Latest Early Triassic of Germany and the Timing and Biogeography of the Early Archosaur Radiation

Background Archosaurs (birds, crocodilians and their extinct relatives including dinosaurs) dominated Mesozoic continental ecosystems from the Late Triassic onwards, and still form a major component of modern ecosystems (>10,000 species). The earliest diverse archosaur faunal assemblages are known from the Middle Triassic (c. 244 Ma), implying that the archosaur radiation began in the Early Triassic (252.3–247.2 Ma). Understanding of this radiation is currently limited by the poor early fossil record of the group in terms of skeletal remains. Methodology/Principal Findings We redescribe the anatomy and stratigraphic position of the type specimen of Ctenosauriscus koeneni (Huene), a sail-backed reptile from the Early Triassic (late Olenekian) Solling Formation of northern Germany that potentially represents the oldest known archosaur. We critically discuss previous biomechanical work on the ‘sail’ of Ctenosauriscus, which is formed by a series of elongated neural spines. In addition, we describe Ctenosauriscus-like postcranial material from the earliest Middle Triassic (early Anisian) Röt Formation of Waldhaus, southwestern Germany. Finally, we review the spatial and temporal distribution of the earliest archosaur fossils and their implications for understanding the dynamics of the archosaur radiation. Conclusions/Significance Comprehensive numerical phylogenetic analyses demonstrate that both Ctenosauriscus and the Waldhaus taxon are members of a monophyletic grouping of poposauroid archosaurs, Ctenosauriscidae, characterised by greatly elongated neural spines in the posterior cervical to anterior caudal vertebrae. The earliest archosaurs, including Ctenosauriscus, appear in the body fossil record just prior to the Olenekian/Anisian boundary (c. 248 Ma), less than 5 million years after the Permian–Triassic mass extinction. These earliest archosaur assemblages are dominated by ctenosauriscids, which were broadly distributed across northern Pangea and which appear to have been the first global radiation of archosaurs.

A New Look into the Periorbital Morphology of Goniopholis (Mesoeucrocodylia: Neosuchia) and Related Forms

ABSTRACT The periorbital morphology of goniopholidids is discussed, exploring the diversity of patterns and the relevance of the data for phylogenetic studies. Revision of material is focused on Goniopholis spp. and aff. Goniopholis spp., from England, Germany, and Belgium, providing a comparative description of their interorbital morphology. Traditional interpretation of the interorbital elements in species of Goniopholis (G. simus, G. baryglyphaeus), where the frontal is interpreted as excluded from the orbit by a prefrontal-postorbital contact in the skull roof, is contested and clarified through the analysis of new specimens, including a morphometric analysis. In Goniopholis, failure to identify the palpebral and its subtle contact with the prefrontal has lead to misinterpretation of elements and structures near the orbit, and the differential preservation/loss of palpebrals explains variability of the orbit in shape and orientation. In all European goniophilidids the frontal reaches the primary orbital border and there is no prefrontal-postorbital contact on the dorsal surface of the skull. Extensive contact of the palpebral with the primary orbital border creates a secondary (functional) orbital border, from which the frontal is excluded in most taxa. The condition is not exclusive of European goniopholidids and is paralleled by protosuchids, peirosaurids, and baurusuchids. At least four main morphological patterns are recognized, revealing a high diversity of European goniopholidids.

Reappraisal of Europe’s most complete Early Cretaceous plesiosaurian: Brancasaurus brancai Wegner, 1914 from the “Wealden facies” of Germany

The holotype of Brancasaurus brancai is one of the most historically famous and anatomically complete Early Cretaceous plesiosaurian fossils. It derived from the Gerdemann & Co. brickworks clay pit near Gronau (Westfalen) in North Rhine-Westphalia, northwestern Germany. Stratigraphically this locality formed part of the classic European “Wealden facies,” but is now more formally attributed to the upper-most strata of the Bückeberg Group (upper Berriasian). Since its initial description in 1914, the type skeleton of B. brancai has suffered damage both during, and after WWII. Sadly, these mishaps have resulted in the loss of substantial information, in particular many structures of the cranium and limb girdles, which are today only evidenced from published text and/or illustrations. This non-confirmable data has, however, proven crucial for determining the relationships of B. brancai within Plesiosauria: either as an early long-necked elasmosaurid, or a member of the controversial Early Cretaceous leptocleidid radiation. To evaluate these competing hypotheses and compile an updated osteological compendium, we undertook a comprehensive examination of the holotype as it is now preserved, and also assessed other Bückeberg Group plesiosaurian fossils to establish a morphological hypodigm. Phylogenetic simulations using the most species-rich datasets of Early Cretaceous plesiosaurians incorporating revised scores for B. brancai, together with a second recently named Bückeberg Group plesiosaurian Gronausaurus wegneri (Hampe, 2013), demonstrated that referral of these taxa to Leptocleididae was not unanimous, and that the topological stability of this clade is tenuous. In addition, the trait combinations manifested by B. brancai and G. wegneri were virtually identical. We therefore conclude that these monotypic individuals are ontogenetic morphs and G. wegneri is a junior synonym of B. brancai. Finally, anomalies detected in the diagnostic features for other “Wealden” plesiosaurians have prompted reconsiderations of interspecies homology versus intraspecific variability. We therefore propose that the still unresolved taxonomy of B. brancai should emphasize only those character states evident in the examinable fossil material, and specifically accommodate for growth-related modifications delimited via osteologically mature referred specimens.

Metatetrapous valdensis Nopcsa, 1923 and the Presence of Ankylosaur Tracks (Dinosauria: Thyreophora) in the Berriasian (Early Cretaceous) of Northwestern Germany

Metatetrapous valdensis Nopcsa, 1923 from the late Berriasian of northwestern Germany was the first dinosaur ichnotaxon ever attributed to a thyreophoran trackmaker. However, the subsequent lost of the original material made this identification and the status of the ichnotaxon questionable for many subsequent authors. This situation was aggravated by the fact that there are only very brief original descriptions accompanied by a single drawing. A reconsideration of the original description recognizes M. valdensis as a valid ichnotaxon, which, albeit showing great resemblance in pes morphology to similar ichnotaxa, stands out from them by a tetradactyl manus. It not only holds its original systematic attribution, but also has sparked early hypotheses on the phylogeny of dinosaurs already in 1922, possibly for the first time based upon tracks. Two surviving natural hypichnial casts of ankylosaurian pes imprints from the same stratum cannot be straightforwardly identified with the type material due to a lack of documentation. However, comprehensive circumstantial evidence, including complete accordance in size and morphology among others, strongly supports such an association. The tracks confirm the presence of ankylosaurs in this lacustrine-deltaic setting as a very rare element of the local dinosaur fauna.

Cenomanian–Turonian marine amniote remains from the Saxonian Cretaceous Basin of Germany

The Saxonian Cretaceous Basin constitutes an important source of rare Late Cretaceous marine amniote fossils from Germany. It is also historically famous, having been documented in a series of monographic works published by the distinguished German palaeontologist Hanns Bruno Geinitz in the nineteenth century. The most productive rock units include the upper Cenomanian Dolzschen Formation and upper Turonian Strehlen and Weinbohla limestones (lower Strehlen Formation). A survey of curated specimens recovered from these deposits has now identified isolated teeth of probable polycotylid and elasmosaurid plesiosaurians, as well as several humeri that are referred to protostegid marine turtles. The Saxonian Cretaceous Basin formed a continuous epeiric seaway with the Bohemian Cretaceous Basin during late Cenomanian – Turonian time. A western connection to the North Sea Basin also existed via the North German and Munsterland Cretaceous basins. The Mesozoic marine amniote remains from these regions therefore record a coeval northern European fauna that was probably homogeneous across the northern peri-Tethyan margin during Late Cretaceous time.

Plesiosaurian fossils from Baltic glacial erratics: evidence of Early Jurassic marine amniotes from the southwestern margin of Fennoscandia

Abstract Early Jurassic plesiosaurian fossils are rare in the Scandinavian region, with a few isolated bones and teeth known from Bornholm, and anecdotal finds from East Greenland. The only other identifiable specimens derive from Toarcian-aged (based on ammonites) erratics deposited during Late Pleistocene glacial advances near the town of Ahrensburg, NE of Hamburg in northern Germany. The geographical source of these transported clasts is debated, but reconstructed ice-flow directions and lithofacies comparisons implicate either the offshore Baltic Sea between the Island of Bornholm and Mecklenburg–Vorpommern (Germany) or, less probably, south of the Danish Archipelago (Mecklenburg Bay). These regions collectively bordered the Fennoscandian landmass and adjacent Ringkøbing-Fyn Island in the late Early Jurassic, and were dominated by near-shore marine deltaic to basinal settings. The Ahrensburg plesiosaurian remains include postcranial elements reminiscent of both the microcleidid Seeleyosaurus and the rhomaelosaurid Meyerasaurus. These occur alongside other classic ‘Germanic province’ marine amniotes, such as the teleosaurid crocodyliform Steneosaurus and ichthyosaurian Stenopterygius cf. quadriscissus: thus, advocating faunal continuity between Scandinavia and southern Germany during the Toarcian, and a less pronounced marine reptile faunal provinciality than previously assumed.

Ankylosaur Remains from the Early Cretaceous (Valanginian) of Northwestern Germany

A fragmentary cervico-pectoral lateral spine and partial humerus of an ankylosaur from the Early Cretaceous (early Valanginian) of Gronau in Westfalen, northwestern Germany, are described. The spine shows closest morphological similarities to the characteristic cervical and pectoral spines of Hylaeosaurus armatus from the late Valanginian of England. An extensive comparison of distal humeri among thyreophoran dinosaurs supports systematic differences in the morphology of the distal condyli between Ankylosauria and Stegosauria and a referral of the Gronau specimen to the former. The humerus fragment indicates a rather small individual, probably in the size range of H. armatus, and both specimens are determined herein as ?Hylaeosaurus sp.. A short overview of other purported ankylosaur material from the Berriasian-Valanginian of northwest Germany shows that, aside from the material described herein, only tracks can be attributed to this clade with confidence at present.

First evidence of a large predatory plesiosaurian from the Lower Cretaceous non-marine ‘Wealden facies’ deposits of northwestern Germany

Sachs, S., Hornung, J.J., Lallensack, J.N. & Kear, B.P., November.2017. First evidence of a large predatory plesiosaurian from the Lower Cretaceous non-marine ‘Wealden facies’ deposits of northwestern Germany. Alcheringa 42, 501-508. ISSN 0311-5518. Here, we describe the incomplete mandible of a large-skulled ‘pliosauromorph’ plesiosaurian from the Lower Cretaceous (Berriasian) of northwestern Germany. The fossil derives from limnic–brackish ‘Wealden facies’ deposits of the Deister Formation (Bückeberg Group), and is preserved as a natural mould in fine-grained sandstone. Examination of the original remains, in conjunction with a three-dimensional photogrammetrically digitized ‘cast’, revealed a conspicuous rosette of symphyseal alveoli, which would otherwise typically characterize Early–Middle Jurassic macrophagous plesiosaurians including rhomaleosaurids and the pliosaurid Simolestes. The Deister Formation ‘pliosauromorph’ represents the first record of a large-bodied plesiosaurian macrocarnivore from the ‘Wealden-facies’ strata of Europe, and thus adds a previously unrecognized trophic level of aquatic apex predators to the Early Cretaceous non-marine ecosystems of Europe. Sven Sachs* [sachs.pal@gmail.com] Naturkunde-Museum Bielefeld, Abteilung Geowissenschaften, Adenauerplatz 2, 33602 Bielefeld, Germany and Im Hof 9, 51766 Engelskirchen, Germany; Jahn J. Hornung [jahn.hornung@yahoo.de] Niedersächsisches Landesmuseum Hannover, Willy-Brandt-Allee 5, 30169 Hannover, Germany; Jens N. Lallensack [jens.lallensack@uni-bonn.de] Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 8, 53115 Bonn, Germany; Benjamin P. Kear [benjamin.kear@em.uu.se] Museum of Evolution, Uppsala University, Norbyvägen 16, Uppsala SE-752 36, Sweden.

The First Record of the Pterosaur Ichnogenus Purbeckopus in the Late Berriasian (Early Cretaceous) of Northwest Germany

A hypichnium of a manus imprint (preserved as plaster cast) indicates for the first time the presence of the large pterosaur ichnotaxon Purbeckopus cf. pentadactylus Delair, 1963 in the late Berriasian of northwest Germany. It is only the second record of Purbeckopus globally and the first pterosaur track from Germany. It provides evidence of a very large pterosaur (wingspan c. 6 m) in this area and from this time period not yet represented by skeletal remains. When compared with the English type material, the specimen exhibits some differences that are related mostly to different properties of the substrate on which both were left. These include, in the German track, an impression of the metacarpo-phalangeal joint of the wing finger, normally not present in pterosaur tracks. Also interesting is the rather blunt termination of the deeply impressed digits I–III, indicating rather short and blunt claws, which seem more suitable for walking than for grasping or climbing. The specimens of Purbeckopus in England and Germany occur in different environments: the English locality was situated close to a brackish lagoon, while the German site belongs to a limnic-deltaic system at the margin of a large, freshwater lake.

A mosasaur fauna (Squamata: Mosasauridae) from the Campanian (Upper Cretaceous) of Hannover, northern Germany

Hornung, J.J., Reich, M. & Frerichs, U., February 2018. The mosasaur fauna (Squamata: Mosasauridae) from the Campanian (Upper Cretaceous) of Hannover, northern Germany. Alcheringa 42, 543-559. ISSN 0311-5518. Isolated teeth and a humerus from the Campanian of Hannover indicate a considerable local diversity of mosasaur taxa. The lower Misburg Formation (lower Campanian of the Lehrte West Syncline) yields Clidastes sp. (Mosasaurinae), Prognathodon sp. (Mosasaurinae), ?Hainosaurus sp. (Tylosaurinae) and an unidentified mosasaurid. It further confirms the presence of the genus Clidastes in northern central Europe and also proves the early Transatlantic distribution of a basal member of Prognathodon during the lower Campanian. ?Hainosaurus sp. is similar to roughly contemporaneous material of Hainosaurus sp. from southern Sweden. The upper Misburg Formation (upper upper Campanian) shows a different taxonomic composition with Tylosaurus sp. (Tylosaurinae), a second indeterminate species of Prognathodon and ?Platecarpus sp. The limited material of Prognathodon sp. shows closest affinities to P. lutugini (Yakovlev) from eastern Europe. The records of Tylosaurus and ?Platecarpus are among the stratigraphically youngest of these taxa. Facies and lithology of the Misburg Formation indicate that the mosasaurs lived in an open marine, mid-sublittoral environment with a water-depth around 70–100 m. In the contemporaneous chalk facies, deposited in somewhat deeper waters, as well as in shallow littoral deposits, mosasaurs are very rare and of lower diversity. Jahn J. Hornung [jahn.hornung@yahoo.de] Landesmuseum Hannover, Willy-Brandt-Allee 5, 30169 Hannover, Germany; Current address: Fuhlsbüttler Strasse 611, 22337 Hamburg, Germany; Mike Reich [mreich@lrz.uni-muenchen.de & mike.reich@lmu.de] SNSB—Bavarian State Collection of Palaeontology and Geology & Ludwig-Maximilian-Universität München, Department of Earth and Environmental Sciences, Section Palaeontology and Geobiology & GeoBio-CenterLMU; all: Richard-Wagner-Str. 10, 80333 Munich, Germany; Udo Frerichs [udofrerichs@web.de] Arbeitskreis Paläontologie Hannover, Buchenweg 7, 30855 Langenhagen, Germany