Sylvie Wenz

An Early Cretaceous faunal and floral continental assemblage: Las Hoyas fossil site (Cuenca, Spain)

Abstract The fossiliferous beds of Las Hoyas (province ofCuenca, Spain) are composed of limestones (probably Late Hauterivian). The main fossiliferous facies consists of laminated limestone from a lake-basin plain with bottom waters perennially anoxic. The floral and faunal assemblage is similar to that of Montsech (prov. of Lerida, Spain), with divergences especially in the insects and some tetrapods. Bottom-dwelling invertebrates are scarce. Most of invertebrates are arthropods: three crustaceans and a relatively diversified entomofauna. The fishes are the main component of the vertebrate fauna both in number of individuals and diversity (13 different taxa). Among tetrapods the most abundant is a new genus of Caudata. Reptiles are represented by a chelonian, a little lizard and an atoposaurid crocodile. Finally, a new bird is reported from Las Hoyas, with an intermediate phylogenetic position between Archaeopteryx and Ornithurae.

A giant Upper Jurassic turtle revealed by its trackways

Exceptional fossilization of large tetrapod swimming traces occurs in the Cerin Lagerstatte (Jura Mountains, France). These trackways are imprinted in Jurassic (Late Kimmeridgian) lagoonal fine-grained limestones and are attributed to giant turtles, which swam with a simultaneous movement of their forelimbs like the modern ones. These turtles swam in very shallow waters close to land, perhaps near a nesting area. As a major consequence, these new ichnologic data place the origin of true large marine turtles during the Jurassic period and not during the Cretaceous period as previously considered on the basis of skeletal remains.

Akromystax tilmachiton gen. et sp. nov., a new pycnodontid fish from the Lebanese Late Cretaceous of Haqel and En Nammoura

Abstract Akromystax tilmachiton, gen. et sp. nov., is described from Late Cretaceous Cenomanian beds in the Lebanon. The new taxon is the first new pycnodont to be published from the recently discovered locality of en Nammoura. It is a member of the Pycnodontidae that presents an unexpected combination of primitive and derived characters, including autapomorphies such as: hypertrophy of the lateral laminae of the mesethmoid, covering the lateral portion of the ethmoidal region plus part of the lower jaw; extrascapular bone forming part of the border of the orbit; expansion of the premaxilla, which bears no less than eight molariform teeth arranged in at least two rows; opercular and preopercular bones separated from each other; unique pattern of scale ossification; overlapping of the spines of the ventral keel scales; first ventral keel scale markedly larger than other keel scales. A new type of replacement teeth is reported for the first time in a pycnodontiform fish. Akromystax tilmachiton is at present the most primitive taxon of the family Pycnodontidae, despite its relatively derived characters, and confirms the mosaic evolution of the pycnodonts. The new taxon is present in the localities of Haqel, Early Cenomanian, and en Nammoura, Middle Cenomanian. It is an interesting common element of both localities, indicating that their paleoichthyofaunas, contrary to previous thought, are more similar than other components of their fossil associations.

A new pycnodontiform fish from the Early Cretaceous of Las Hoyas (Cuenca, Spain)

Stenamara mia is a new genus and species of a rare pycnodontiform fish from the Barremian, early Cretaceous, lacustrine beds of Las Hoyas, province of Cuenca, Spain. It was previously considered Eomesodon sp., but a number of characters clearly separates it from the genus Eomesodon: lack of prognathism; absence of nuchal plates; presence of a parietal process and of only two rows of teeth in the prearticular; and peltate pattern of ossification and distribution of scales, that is, scales are present only before the level of the unpaired fins, and are complete only in the ventralmost abdominal area. The unique combination of these and other characters, plus the following autopomorphies, diagnoses the new taxon: presence of a strongly curved dorsal prominence that results in an ovoid shape of the contour of the body; body deeper than long, with maximum body height near 125% of standard length; and narrow, high cloaca formed by only two differentiated scales, the posterior one considerably longer than the anterior one. Stenamara mia nov. gen. nov. sp. is considered a primitive Pycnodontidae, pending a cladistic analysis to determine precisely its phylogenetic relationships.

The underlying substrate ofthe Cerin Lithographic Limestones

Abstract The Cerin Lithographic Limestones do not cover a wide area. They correspond to numerous lagoon in-fillings of limited development, within a wide emerged area characterized by sandy (skeletal) limestones mainly of coral origin (Landaize Limestones). At the village of Cerin where an excavation for paleoecological studies is located, the sandy Landaize Limestones provide the lithographic limestone substrate. Their cementation is partly of supratidal and/or intertidal origin, but frequently shows phreatic freshwater features. Finally, microbial cements (bacteria or cyanobacteria) reflect a major process of lithification. The original substrate consisted of grainstones, the top of which was considerably eroded, producing uneven relief with steep slopes and even cliffs, sometimes reaching several metres in height. The erosion processes were probably mechanical in origin, but also biochemical (biokarst) and especially biological (bioerosion by grazing, boring and microbial erosion). Lime mud which produced the lithographic limestones filled the hollows between the substrate reliefs. Around areas where the uneven rocky substrate had steep gradients locally developed gravity flows occur. These are capped with microbial films which are affected by superficial slides showing more or less concentric or complex wavy structures. Locally, true slumps giving rolls and synsedimentary microfolds also occur.

Naiathaelon okkidion nov. gen. nov. sp., (Teleostei, Elopomorpha) from the Early Tithonian of Canjuers (Var, France)

Abstract Naiathaelon okkidion nov. gen. nov. sp., previously reported as Anaethalion , is defined from the Eaply Tithonianof Canjuers (Var, France). Its combination of plesiomorphic and apomorphic characters leads to consider it as an Elopomorpha incertae sedis . The genus Anaethalion is therefore restricted to Bavarian and Cerin outcrops. Added to other still undescribed related forms, Naiathaelon okkidion is part of an elopomorph assemblage particular to Canjuers outcrop, and increases the number of primitive Elopocephala of currently unresolved relationships.

Eichstätt and Cerin: Geochemical comparison and definition of two different plattenkalk types

Abstract Bed-by-bed analyses of a lateral set of profiles in the Eichstatt area, and of one profile of Cerin reveal some analogies and some differences. The analogies are: A.1) There appear three distinct lithofacies which differ in their contents of insolubles in 1 : 3 : 10 ratios. A.2) The 12 analyzed elements can be separated into 3 groups: a “clastic group” (Si, Al, K, Fe) with very similar trends in profile, caused by the detrital input of silicate minerals; a “semiclastic group” (Ti, Rb, Ba, P), which follows the clastic trend, but not quantitatively; and Mn, S, Sr (and Mg) which form the “diagenetic group” with special behaviour. The differences are: B.1) Cerin in general is purer than Eichstatt, but according to the correlation lines in 2-element-diagrams it has relatively less K and Al, more Si and Fe, and more Mg in the carbonate phase. B.2) For Eichstatt it can be suggested that the sediment was brought into the plattenkalk basin as a ready mixture of carbonate and non-carbonates. At Cerin the relation between thickness and contents of insolubles proves the “Seibold-rule”: dilution of insoluble input by in situ carbonate production. Cerin is a simple rhythmite, whereas Eichstatt is dominated by “undulations”. These features, and the differences described in B.2, are used as the basis for definition of “Plattenkalk C-type” and “E-type”.