Jörg W. Schneider

New continental Carboniferous and Permian faunas of Morocco: implications for biostratigraphy, palaeobiogeography and palaeoclimate

Abstract Late Palaeozoic sediments in central Morocco and the High Atlas Mountains document the development of this area during the formation of the Mauretanide part of the Hercynian orogeny. Continental basins formed during the Stephanian and Permian. Although scattered in time, they provide valuable biogeographical and climatic information for the Mauretanides as a link between the Variscides in the east, the Appalachians in the west and the Karoo in the south. New blattid insects in the Souss Basin enable correlation to Early Stephanian B. Furthermore, we document the oldest African tetrapod tracks (Batrachichnus, Dromopus). Litho- and biofacies indicate seasonally wet and dry phases. Wet red beds of the Khenifra Basin have produced tetrapod bones and the tracks Limnopus, Batrachichnus and Dromopus. Macrofloras give a transitional Autunian/Saxonian age. This fits well into the Artinskian wet phase. Similar facies pattern in the Tiddas Basin are correlated by tetrapod tracks as transitional Artinskian to Kungurian. Advanced tetrapod tracks of Synaptichnium and Rhynchosauroides were discovered in the Ikakern Formation of the Argana Basin, dated by pareiasaur remains as Wuchiapingian. Red beds of similar type are known in Europe, for example, from the Late Permian of the Lodève Basin. They originated during the Wuchiapingian wet phase.

A Selachian Freshwater Fauna from the Triassic of Kyrgyzstan and Its Implication for Mesozoic Shark Nurseries

ABSTRACT Habitat partitioning and site fidelity of spawning grounds are well-documented phenomena in extant selachians, but little is known about the reproductive strategies of their fossil relatives. Here we describe the selachian fauna of the Middle to Late Triassic Madygen Formation in southwestern Kyrgyzstan, Central Asia, based on several dozen tooth crowns and egg capsules. The material is assigned to three new taxa: Lonchidion ferganensis, sp. nov., and Palaeoxyris alterna, sp. nov., being teeth and egg capsules of hybodontid sharks, and Fayolia sharovi, sp. nov., being egg capsules of probable xenacanthids. Teeth of L. ferganensis, sp. nov., were almost exclusively found in pelecypod-rich shallow lacustrine mudstones and belong to juvenile individuals. Oxygen and strontium isotope data of tooth enameloid indicate freshwater conditions of the ambient water at the time of tooth mineralization. The egg capsules are common findings in near-shore lake deposits as well. Considering the mass co-occurrence of juvenile teeth and egg capsules in the study area, we propose that hybodontid/xenacanthid sharks recurrently occupied littoral zones of the Madygen lake for spawning. The small number of full-grown individuals points to habitat partitioning of juveniles and adults wherefore the study site is interpreted as a shark nursery. The oviposition strategies inferred from this fossil example are remarkably similar to those of modern sharks, suggesting that the reproductive patterns seen in extant sharks originated well before the Cenozoic.

A SNAPSHOT OF AN EARLY PERMIAN ECOSYSTEM PRESERVED BY EXPLOSIVE VOLCANISM: NEW RESULTS FROM THE CHEMNITZ PETRIFIED FOREST, GERMANY

ABSTRACT A recently excavated locality in the Chemnitz Petrified Forest, lower Permian in age and occurring within the Leukersdorf Formation of the Chemnitz Basin, Germany, provides evidence for an outstanding fossil assemblage buried in situ by pyroclastics. The environment is interpreted as forested lowland that sheltered a dense hygrophilous vegetation of ferns, sphenophytes, and gymnosperms, as well as a diverse fauna of reptiles, amphibians, arthropods, and gastropods. A detailed measured section of the outcrop documents the early volcanic history of the Chemnitz fossil forest, including a paleosol that shows the root systems of Psaronius tree ferns, Arthropitys calamitaleans, and Medullosa and Cordaixylon gymnosperms in the same horizon. Fifty-three trunks are still standing upright and rooted at their place of growth, providing evidence that the top of the paleosol was the land surface on which the forest grew, thereby offering insights into the original plant community structure and density. Taphonomic analysis of both the petrified and adpression-fossil assemblages enable us to reconstruct the direction, estimate the violence and extent of the volcanic events, and their effects on the entire ecosystem. A complete dataset of three-dimensional coordinates resulting from three and one-half years of continuing excavation and study permits the recognition of organ connections and results in the first reconstructions of the excavation site, the floral elements, and the plant community as a whole.

The playa environments of the Lodève Permian basin (Languedoc-France).

The Lodeve Permian synrift sequence is represented by thick stacked climate-controled playa cycles which have been constrained by structural, sedimentological, geochemical and paleontological processes. The present paper merges the different results in order to better constrain the dynamics and palaeoecologycal evolution of the playa system from Late Cisuralian to Early Lopingian time. In this depositional environment, thining upwards sheet-flood sequences represent flooding events; they are relayed by ephemeral ponding, suspension settling and limited carbonate precipitation accompanied by large amounts of shallow to subaerial sedimentary structures... (Ver mas) (current and wind ripples, desiccation cracks, rain drops, etc.). The aridity of the climate contrasts with the surprising abundance of the fauna encountered into carbonate-rich silty-clay playa-lake deposits. Ephemeral pools are colonized by numerous shellfish: Choncostraca, Triopsids, and Insects, which led to intense burrowing of the overbank deposits (Scoyenia facies). Tetrapods are common and dominated by several types of reptiles after footprints: Pelycosauria, Parareptilia and Lepidosauria in the Rabejac Fm, and Mammalian reptiles (Therapsida) on the top of the fluvial deposits of the Salagou Fm near La Lieude farm. In addition, elements of a weighty herbivorous Pelycosaurian and a small amphibian Tupilakosaurid, only described in the Triassic before, have been also found in the Upper part of the Permian series of this sector.

Early Triassic Archosaur-Dominated Footprint Assemblage from the Argana Basin (Western High Atlas, Morocco)

An assemblage of abundant and well-preserved tetrapod footprints has been discovered in the Tanamert Member (T3) of the Triassic Timezgadiouine Formation (Argana basin, western High Atlas, Morocco). It is the first fossil record from T3. Surfaces from different localities show a uniform tetrapod ichnofauna that consists of chirotherian and small lacertoid forms. The chirotherians are assigned to the plexus Protochirotherium—Synaptichnium, their trackmakers interpreted as basal archosaurs. The lacertoid imprints show close affinities with Rhynchosauroides and may reflect archosauromorphs or lepidosauromorphs. Protochirotherium—Synaptichnium assemblages are characteristic of the Early Triassic and were known previously only from units of this age in central Europe. Biostratigraphically, the European record implies a wide-spread pre-Anisian Protochirotherium—Synaptichnium dominated assemblage preceding the first appearance of Chirotherium barthii near the Olenekian-Anisian boundary. The stratigraphic position of T3 between Late Permian (uppermost T2) and Middle Triassic (T4) and the European correlatives suggest an Early Triassic age of this unit. It is the first record of Early Triassic continental deposits in Morocco. The surfaces from T3 open up perspectives for further contributions to ecology, biogeography and locomotion of early archosaurs. Furthermore, excellent outcrops and quality of footprint preservation in the Argana basin offer a potential for clarification of ichnotaxonomic and biostratigraphic issues.

COMPLEX TETRAPOD BURROWS FROM MIDDLE TRIASSIC RED BEDS OF THE ARGANA BASIN (WESTERN HIGH ATLAS, MOROCCO)

ABSTRACT Although burrowing ability has been widespread in tetrapods for more than 300 million years, subsurface dwelling structures that indicate communal behavior are poorly evidenced from pre-Cenozoic strata. Here we present recently discovered tetrapod burrows from Middle Triassic red beds of the Argana Basin in central Morocco, whose complexity suggests an origin by gregarious animals. The well-preserved burrows occur in interbedded mudstones and sandstones interpreted as channel and overbank deposits of ephemeral, braided streams. All burrows originate from the top of thick-bedded sandstones and descend as moderately inclined (10°–30°), partially spiral tunnels to laterally extended, branched chambers in underlying mudstones. Tunnel segments are biconvex to planoconvex in cross section, up to 20 cm wide and 12 cm in maximum height and exhibit transverse scratch marks along the ceilings and sidewalls. Distinctive burrow characteristics include a laterally sinuous geometry (wavelength &lgr;  =  38–45 cm; amplitude A  =  5–10 cm) of the tubelike passages and the presence of grouped alcoves in terminal chambers. We attribute the burrows to procolophonids or therapsids based on closely associated tetrapod tracks and the limited diameter of the excavations. Our findings represent the second oldest record of communal fossorial behavior by tetrapods and the oldest example from low-latitude areas. Beyond providing refuge from predators, these elaborate underground structures probably functioned as a buffer against diurnal or seasonal variations of air temperature and humidity in a semiarid habitat that was situated just north of the paleoequator.

New hybondontoid shark from the Permocarboniferous (Gzhelian-Asselian) of Guardia Pisano (Sardinia, Italy)

Numerous isolated teeth, fin spine fragments and dermal denticles of a hybodont shark from a lacustrine limestone horizon at the top of lithofacies B of the Late Carboniferous to Early Permian succession of the Guardia Pisano Basin (Sulcis area, southwestern Sardinia, Italy) are assigned to a new species of the genus Lissodus Brough, 1935. Lissodus sardiniensis sp. nov. is erected on the basis of about 500 teeth, which show a unique feature of only one pair of lateral cusps that are bent in the direction of the prominent central cusp. Weak heterodonty allows distinction of symphyseal, mesial to anterolateral, and lateral teeth. Lissodus sardiniensis sp. nov. was a freshwater-adapted durophagous shark of bottom dwelling habit, an interpretation supported by general construction of the dentition and the morphology of the dermal denticles. The association with Acanthodes, diplodoselachid sharks and branchiosaurs allows the reconstruction of a five-level trophic chain for the Guardia Pisano Basin. The discovery of Lissodus in Sardinia is presently the southernmost known occurrence of that genus in the Late Palaeozoic of Europe. This new find adds significantly to knowledge of migration routes of aquatic organisms, especially freshwater sharks, between the single European basins in the Late Pennsylvanian, and changes in palaeobiogeography during the Early Permian.

Lower Cambrian (Atdabanian/Botomian) Shallow-Marine carbonates of the Görlitz Synclinorium (Saxony/Germany)

SummaryGeological, papaeontological and microfacies studies in the Lower Cambrian carbonate complex of the Görlitz Synclinorium (eastern Germany/Saxony/Lusatian region) provide new data for the fossil content, depositional history and palaeogeography. The Lower Cambrian of the Görlitz Synclinorium belongs to the facies zones 5, 7 and 8 ofWilson (1975)-platform rim with connections to the open ocean and to the restricted platform areas. An extraordinarily rich fauna was found with elements which are in some cases new for Europe (Rhombocorniculum cancellatumCobbold,Fordilla sibiricaKrasilova, Calodiscus lobatus Hall,Archaeooides granulatusQian,Archiasterella pentactinaSdzuy,Allonia sp.,Obliquatheca aldanicaSysoiev,Conotheca circumflexaMissarzhevsky,Microcornus elongatusMissarzhevsky,Lenalituus sp.,Pelagiella cf.lorenziKobayashi,Beshtashella sp.,Comluella sp.,Cambroclavithidae gen. et sp. indet., Helcionellidae gen. et sp., indet. Eocrinoidea gen. et sp. indet.) This fauna indicates Lower Cambrian (higher Atdabanian/Botomian) age and reveals palaeobiogeographical connections to the Siberian Platform, to the Mediterranean area and to China. A somewhat new stratigraphical subdivision of the Lower Cambrian sequence (Zwetau Formation) is described. New units are established within the Ludwigsdorf Member (the carbonatic lower part of the sequence), the ‘Lower Ludwigsdorf Member’ (massive dolostone) and the ‘Upper Ludwigsdorf Member’ (bedeed limestones and their equivalents). The subsequentLusatiops Member is subdivided intoSerrodiscus Bed (claystones) andLusatiops Bed (siltstones).

Late Triassic Tetrapod-Dominated Ichnoassemblages from the Argana Basin (Western High Atlas, Morocco)

Diverse tetrapod track assemblages with Scoyenia invertebrate traces were discovered in the Triassic Timezgadiouine and Bigoudine formations of the Argana Basin (Western High Atlas, Morocco). The ichnofossils occur in alluvial plain sandstones and mudstones of the Irohalène Member (T5) and Tadart Ouadou Member (T6) considered Carnian-Norian in age by vertebrate remains and palynomorphs. Tetrapod footprints are assigned to Apatopus, Atreipus-Grallator, Eubrontes isp., Parachirotherium, cf. Parachirotherium postchirotherioides, Rhynchosauroides ispp., and Synaptichnium isp. They can be referred to lepidosauromorph/ archosauromorph, basal archosaur, and dinosauromorph trackmakers. Apatopus, represented by 11 tracks of a more than 4 m long trackway, is recorded for the first time outside of North America and Europe. The assemblage concurs with the proposed Late Triassic age of the track-bearing beds by the occurrence of Apatopus, Atreipus-Grallator, and Eubrontes. If this is accepted, the stratigraphic range of Synaptichnium and Parachirotherium, hitherto known only from Early or Middle Triassic deposits, has to be extended to the Carnian-Norian. The occurrence of Eubrontes in the Irohalene Member (T5) provides further evidence for large theropods in pre-Jurassic strata. All assemblages are referred to the Scoyenia ichnofacies indicating continental environments with alternating wet and dry conditions.

Notostraca trackways in Permian playa environments of the Lodève basin (France)

For nearly 20 years, Dr. Lapeyrie, surgeon at Lodeve, has gathered many fossils coming from the Salagou Formation of the Lodeve Permian basin. They are Insects, Notostraca, plants and ichnofossils. Among the latter, appears a multitude of Arthropoda trackways, finely preserved, which were collected in the top of sequences deposited in a playa environment. The locomotion experiments undertaken with extant animals suggested allocation of the majority of these trackways to Notostraca which are also known by several hundreds of remains (carapace, appendages, body whole). From these different parts, it was described as Triops cancriformis permiensis and Lepidurus occitaniacus. All these trackways were made under water and correspond to various etho-morphotypes known in the literature under the name of Acripes for the walking prints, Rusophycus for resting traces (= stationary digging; horizontal, procline and opisthocline positions) and Cruziana for locomotion active and digging. Many fossiliferous slabs clearly allow to see the passage from one activity to another. A similar situation was also filmed with the modern Lepidurus. The following ichnotaxa were distinguished: Acripes multiformis nov. isp, Rusophycus eutendorfensis, R. carbonarius, R. versans, R. minutus, R. furcosus, Cruziana problematica, C. pascens and Scoyenia, isp., less common. With also numerous footprints, this assemblage characterizes the Scoyenia facies restricted to overbank settings. For the Salagou Formation, they correspond to a floodplain/playa in which shallow and temporary pools were inhabited by Nostotraca, Insects, Arachnids and Conchostraca (= Spinicaudata + Laevicaudata), this last group only known by body-fossils. This distal playa environment under arid climate lasted during most of the Permian, possibly between Upper Cisuralian to lower Lopingian.