Paleobiota of the Posidonia Shale

• The "Monotis"-Dactylioceras bed shows an accumulation of the bivalves Meleagrinella substriata and the ammonite Dactylioceras, that were the most abundant representatives of its group on the Altdorf region, and were probably washed to near epicontinental waters by a rapid event, or as result of a large succession of events. • Several empty ammonite shells from Holzmaden have been found with associated decapods inside. Based on the position of prey and predator, it was suggested that the cephalopods caught and killed the fishes while the schools were still in well-oxygenated waters and then descended into oxygen-depleted water layers where the cephalopod suffocated and died attached to its prey. • A pabulite (fossilized meal which never entered the digestive tract) was recovered from Holzmaden, being composed of an associated Passaloteuthis laevigata with its arms embracing an exuvia of a crustacean. The belemnnite itself can be seen as the remnant of a failed predation attempt from a Hybodus, corroborating a possible tropic chain. This implies active predatory behaviour by the genus towards several kinds of belemnnites, such as Youngibelus. • SMNS 51144 (Saurostomus esocinus) was found with Chondrites sp. burrows in the abdominal cavity, what indicates a possible opportunistic scavenger. Other Chondrites sp. includes SMNS 17500 and MHH 1981/25 (Stenopterygius uniter) that either suggest the ichthyosaurs were preserved immediately below one such bioturbation horizon or scavenger association. There have been various theories about this scenario: either the bones of embryos had been deposited before the body of the adult went to the sea floor, or in the ichthyosaurs' last moments where it sank to the bottom and may have given untimely birth to some of the foetuses, and finally another option follows post mortem hydrostatic pressure being too high to be prevented by the body, exploding or expelling its embryos. • The specimen SMNS 53363 (Eurhinosaurus?) from Aichelberg was found with two encrusted large oysters (Liostrea) on the right pterygoid, considered to be part of a reef stage over bones. • SMNS 80234 (Stenopterygius quadriscissus) represents another female with embryos, yet also shows ribs broken perimortem that may represent either intraspecific aggression or a predation attempt. This specimen has several taxa associated: ammonite aptychi, two ophiuroids (Sinosura brodiei) and an articulated echinoid (Diademopsis crinifera) indicate a short-lived deadfall community. As many of these bivalves show overgrowth the community likely persisted for some time. • Gut contents of the local pterosaurs are known: Campylognathoides preserves hooks of the coleoid Clarkeiteuthis (therefore being one of the few teuthophagous pterosaurs), while Dorygnathus preserves remains of Leptolepis. == Microbial activity ==

Non-fenestrate stromatolite crusts formed in aphotic deep-water environments during intervals of very low sedimentation are recovered in places such as Teufelsgraben, Hetzles. The stromatolites of this region have evidence of live on a deeper shelf environment with a quietwater deposit which suffered repeated phases of stagnant bottom waters, where a depth water habitat developed, probably at more than 100 meters depth. There is a thin, southern widespread stromatolite crust on the top of the Sachrang Formation, called "Wittelshofener Bank", that has made researchers rethink the depth of the major southern basin of the formation, where the absence of phototrophic calcareous benthic organisms (probably due to the lack of light) shows the depth of the basin. On the "Wittelshofener Bank" there is also the only occurrence of ooids, presumably formed in the same deep-water environment. == Cyanobacteria ==

Foraminifera == Dinoflagellata ==

Dinoflagellate cysts The evolutionary burst of the Toarcian dinoflagellates led the first appearance and rapid radiation of the Phallocystaceae (Susainium, Parvocysta, Phallocysta, Moesiodinium and related forms). This occurred at the time of a widespread Lower Toarcian bituminous anoxia-derived shale, which is recovered from the Posidonienschiefer, Pozzale, Italy, Asturias, Spain, Bornholm, Denmark, the Lusitanian Basin of Portugal, the Jet Rock Formation in Yorkshire and to the "Schistes Carton" in northern France. Whether there is a causal connection in this co-occurrence of Phallocystaceae and bituminous facies is a problem still to be resolved. This family has its acme in diversity and quantity in the latest Toarcian and became less important in the Aalenian. == Algae ==

The Posidonia Shale preserves an abundant variety of algae, such as the genus of colonial green algae Botryococcus, or the unicellular algal bodies Tasmanites, and other small examples. Algae are a good reference for changes on the oxygen conditions along the Toarcian. Algal acritarchs Haptophyta Chlorophyta == Fungi ==

Fungal spores, hyphae and indeterminate remains are a rare element of the otherwise open marine deposits of the Posidonienschiefer formation, but were recovered at Dormettingen. These fungal remains are composed mostly of indeterminate spores and indicate oxygenated environments and suitable transportation by rivers. Incertae sedis ==Ichnofossils==

The major ichnological analyses of the Posidonian Shale come from Dotternhausen/Dormettingen, where the ichnogenus Phymatoderma formed the so-called Tafelfleins and Seegrasschiefer. The Tafelflein bed was deposited under anoxic bottom and pore water, where a recover of oxygen allow the Phymatoderma-producers return. The two organic-rich layers (Tafelfleins and Seegrasschiefer) are characterized by the dense occurrence of trace fossils such as Chondrites and Phymatoderma, done episodically due to the fall of the oxygen levels. The coeval more nearshore Swiss deposits referred Posidonian Shale (Rietheim Member) hosted similar trace fossils to those recovered on SW Germany. Ichnofossils in this setting apparently evolved faster to more oxic-to-dysoxic bottom waters. At Unken, laminated deposits of red limestone suggest well oxygenated active waters (as they lack shale), where high amounts of Chondrites are found. ==Invertebrata==

Porifera In the non-bituminous facies located on Obereggenen im Breisgau (Shore of the Black Forest High), especially the lower semicelatum subzone, pyritized individual needles of silica sponges (Demospongiae and Hexactinellida) are found, rarely on pelagic layers to very often on the low depth marine deposits. Notoptera Eoblattida Odonatoptera Odonata Orthoptera Dictyoptera Hemiptera Hymenoptera Neuroptera Hemiptera Coleoptera Amphiesmenoptera Ephemeroptera Mecoptera Raphidioptera Diptera Echinodermata Echinoderm debris is relatively abundant in the shale-free Unken and Salzburg members, including crinoid and brittle star skeletal elements; sea urchins take their place later in the formation, with them having especially diversified at that time, leading to pedicellaria being observed very often. Asterozoa Echinoidea Holothuroidea Crinoidea ==Vertebrata==

Fishes Chondrichthyes Actinopterygii Sarcopterygii Amniota Ichthyosauria Inderminate specimens are known. Plesiosauria Sphenodontia Testudinata Crocodylomorpha Pterosauria Dinosauria == Plantae ==

'', able to resist saline conditions. Storms or floods may be the major events that transported this flora to the sea. The macroflora of the Posidonia Slate can be described as extremely poor in species. Apart from the remains of horsetails, it is without exception the remains of coarse branches and fronds from gymnosperms, which can be assumed were transport resistant. Remains of ferns are completely missing, except for tall arboreal ferns (Peltaspermales). Most of the flora was reported from the area of Braunschweig. In terms of taphonomy, this would result in a comparison with today's reed Phragmites, which can form extensive stocks on the edge of shallow and slowly flowing waters. At Irlbach and Kheleim, NE of Regensburg, where the Posidonienschiefer has a near mainland deposit with abundant sand, a rich deposit filled with plant remains of different kinds (Seeds, reproductive organs, leaves, stems, cuticles and wood) with traces of coal was recovered, however, it was never studied in depth. == References ==