Mike Reich

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.

Ancient Origin of the Modern Deep-Sea Fauna

The origin and possible antiquity of the spectacularly diverse modern deep-sea fauna has been debated since the beginning of deep-sea research in the mid-nineteenth century. Recent hypotheses, based on biogeographic patterns and molecular clock estimates, support a latest Mesozoic or early Cenozoic date for the origin of key groups of the present deep-sea fauna (echinoids, octopods). This relatively young age is consistent with hypotheses that argue for extensive extinction during Jurassic and Cretaceous Oceanic Anoxic Events (OAEs) and the mid-Cenozoic cooling of deep-water masses, implying repeated re-colonization by immigration of taxa from shallow-water habitats. Here we report on a well-preserved echinoderm assemblage from deep-sea (1000–1500 m paleodepth) sediments of the NE-Atlantic of Early Cretaceous age (114 Ma). The assemblage is strikingly similar to that of extant bathyal echinoderm communities in composition, including families and genera found exclusively in modern deep-sea habitats. A number of taxa found in the assemblage have no fossil record at shelf depths postdating the assemblage, which precludes the possibility of deep-sea recolonization from shallow habitats following episodic extinction at least for those groups. Our discovery provides the first key fossil evidence that a significant part of the modern deep-sea fauna is considerably older than previously assumed. As a consequence, most major paleoceanographic events had far less impact on the diversity of deep-sea faunas than has been implied. It also suggests that deep-sea biota are more resilient to extinction events than shallow-water forms, and that the unusual deep-sea environment, indeed, provides evolutionary stability which is very rarely punctuated on macroevolutionary time scales.

Floodplain habitats of braided river systems: depositional environment, flora and fauna of the Solling Formation (Buntsandstein, Lower Triassic) from Bremke and Fürstenberg (Germany)

The Solling Formation is the most distinctive unit of the Early Triassic Buntsandstein of the epicontinental Central European Basin. The Solling Formation of Bremke and Fürstenberg has yielded one of the richest and most diversified plant collections of the Middle Buntsandstein to date, one of the oldest floras in Europe after the end-Permian mass extinction. Based on the plant fossils, the Middle Buntsandstein ecosystem from Bremke and Fürstenberg represents not only one of the earliest floras in Europe after the end-Permian extinction but also one of the earliest Triassic occurrences of insect herbivory from any documented flora worldwide and thus provides a rare glimpse into the third pulse of herbivore expansion. Integrated palaeobotanical, palaeontological and sedimentological studies have enabled reconstruction of two different floodplain environmental settings of the Solling Formation, including their vegetation, the plant–insect interactions and revealing how important taphonomy and environmental settings were for the preservation of Middle Buntsandstein plants. At Bremke a levee-crevasse splay complex is reconstructed that tributed into perennial backwsamps and at Fürstenberg unconfined subaerial flows formed a sandy aggradational floodplain with ephemeral ponds. A rich plant community was established and became preserved in backswamps and ponds. This suggests that the scarcity of Buntsandstein floras is clearly related to taphonomical processes and not to extreme environmental conditions under arid or semi-arid climates.

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.

Chapter 14 Palaeobiogeography of Ordovician echinoderms

Abstract The palaeobiogeographical distribution of the six major clades of Ordovician echinoderms (asterozoans, blastozoans, crinoids, echinozoans, edrioasteroids and stylophorans) is analysed based on a comprehensive and up-to-date database compiling 3701 occurrences (1938 species recorded from 331 localities) of both complete specimens and isolated ossicles. Although historically biased towards a limited number of regions (Europe, North America, Russia), the resulting dataset makes it possible to identify six main palaeobiogeographical provinces for Ordovician echinoderms: Laurentia, Baltica, West Gondwana, East Gondwana, Avalonia and Siberia. At a global scale, the high endemicity of echinoderms during the Early to Middle Ordovician coincides with the time of maximum dispersal of continental masses. Late Ordovician faunas tend to become more cosmopolitan, possibly as a consequence of changing palaeogeography and/or relatively higher sea-levels in the Sandbian–Katian interval. Regional biodiversity patterns of Ordovician echinoderms confirm that their major diversification during the Ordovician is not a single, universal evolutionary event, but rather results from the complex addition of contrasted local evolutionary trends.

Sea Pens (Octocorallia: Pennatulacea) from the Late Cretaceous of Northern Germany

Abstract The Late Cretaceous white chalk of the Isle of Rügen, northeastern Germany, yields a highly diverse marine floral and faunal assemblage with more than 1,400 described species, including pennatulacean corals. All the new collected material, composed of fragments of the axial rods, belongs to ‘Graphularia’ quadrata Voigt, 1958, which was revised, and a new species, ‘Graphularia’ rugia. Analyses of the microstructure of axial rods of modern and fossil sea pens facilitate the discussion of the systematic relationships of the fossil material. ‘Graphularia’ quadrata shows an affinity to the Funiculinidae, whereas the new species ‘Graphularia’ rugia resembles the axial structure of the Pennatulidae.

A new ophiocistioid (Echinodermata) from the Silurian of Gotland, Sweden

From the early Silurian of Gotland, Sweden, the new ophiocistioid goniodont Linguaserra franzenae sp. nov. is described, figured and discussed within the Linguaserridae Reich & Haude, 2004. The evolutionary history of linguaserrid ophiocistioids is briefly discussed in relation to other members of the Ophiocistioidea. This new echinoderm species not only represents the first documented occurrence of this group from the Llandovery but also establishes the stratigraphically oldest record of goniodonts in the world.

Comment on supposed holothurian body fossils from the middle Ordovician of Wales (Botting and Muir, Palaeontologia Electronica: 15.1.9A)

Light and SEM study of body fossils from the Middle Ordovician of Wales recently described as the oldest articulated holothurians by Botting and Muir (Palaeontologia Electronica Article number: 15.1.9A) finds no traits that allow them to be assigned to the Echinodermata.

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.

Morphology and Ecological Setting of the Basal Echinoid Genus Rhenechinus from the Early Devonian of Spain and Germany

Based on newmaterial from Germany and Spain, the echinoid “Lepidocentrus” ibericus from the Early Devonian (Emsian) of northern Spain is shown to be congenericwith Rhenechinus from the Hunsrück Slate of south-western Germany. New information on the lantern, pedicellariae and internal structure of the theca is provided, and confirms this genus as amember of the Echinocystitidae—Proterocidaridae clade and the most primitive of all Devonian echinoids. The two environmental settings in which Rhenechinus is found are very different: the Spanish specimens come from a relatively shallow—water bryozoan meadow setting while the German specimens are preserved in a deep-water setting.We deduce that the rare echinoid specimens from the Hunsrück Slate are all allochthonous, whereas the Spanish material is preserved in situ.