Serpulid microbialitic bioherms from the upper Sarmatian (Middle Miocene) of the central Paratethys Sea (NW Hungary) – witnesses of a microbial sea

We present previously unknown stacked bowl-shaped bioherms reaching a size of 45 cm in diameter and 40 cm in height from weakly solidified peloidal sand from the upper Sarmatian of the Paratethys Sea. The bioherms were mostly embedded in sediment, and the “growth stages” reflect a reaction on sediment accretion and sinking into the soft sediment. The bioherms are spirorbid–microclot–acicular cement boundstones with densely packed Janua tubes surrounded by microclots and acicular cement solidifying the bioherm. The surrounding sediment is a thrombolite made of peloids and polylobate particles (mesoclots) which are solidified synsedimentarily by micrite cement and dog-tooth cement in a later stage. The shape of the bioherms reflects a series of growth stages with an initial stage (“start-up stage”) followed by a more massive “keep-up stage” which grades into a structure with a collar-like outer rim and a central protrusion and finally by a termination of growth (“give-up stage”). The setting was a shallow subtidal environment with normal marine or elevated saline, probably oligotrophic, conditions with an elevated alkalinity. The stacked bowl-shaped microbialites are a unique feature that has so far been undescribed. Modern and Neogene microbialite occurrences are not direct analogues to the described structures, but the marine examples, like in The Bahamas, Shark Bay and the Persian Gulf, offer insight into their microbial composition and environmental parameters. The microbialites and the surrounding sediment document a predominance of microbial activity in the shallow marine environments of the Paratethys Sea during the late Middle Miocene, which was characterized by a warm, arid climate.</p

A novel widespread cryptic species and phylogeographic patterns within several giant clam species (Cardiidae: Tridacna) from the Indo-Pacific Ocean

Giant clams (genus Tridacna) are iconic coral reef animals of the Indian and Pacific Oceans, easily recognizable by their massive shells and vibrantly colored mantle tissue. Most Tridacna species are listed by CITES and the IUCN Redlist, as their populations have been extensively harvested and depleted in many regions. Here, we survey Tridacna crocea and Tridacna maxima from the eastern Indian and western Pacific Oceans for mitochondrial (COI and 16S) and nuclear (ITS) sequence variation and consolidate these data with previous published results using phylogenetic analyses. We find deep intraspecific differentiation within both T. crocea and T. maxima. In T. crocea we describe a previously undocumented phylogeographic division to the east of Cenderawasih Bay (northwest New Guinea), whereas for T. maxima the previously described, distinctive lineage of Cenderawasih Bay can be seen to also typify western Pacific populations. Furthermore, we find an undescribed, monophyletic group that is evolutionarily distinct from named Tridacna species at both mitochondrial and nuclear loci. This cryptic taxon is geographically widespread with a range extent that minimally includes much of the central Indo-Pacific region. Our results reinforce the emerging paradigm that cryptic species are common among marine invertebrates, even for conspicuous and culturally significant taxa. Additionally, our results add to identified locations of genetic differentiation across the central Indo-Pacific and highlight how phylogeographic patterns may differ even between closely related and co-distributed species

Revision of the Cretaceous shark Protoxynotus (Chondrichthyes, Squaliformes) and early evolution of somniosid sharks

Due to the peculiar combination of dental features characteristic for different squaliform families, the position of the Late Cretaceous genera Protoxynotus and Paraphorosoides within Squaliformes has long been controversial. In this study, we revise these genera based on previously known fossil teeth and new dental material. The phylogenetic placement of Protoxynotus and Paraphorosoides among other extant and extinct squaliforms is discussed based on morphological characters combined with DNA sequence data of extant species. Our results suggest that Protoxynotus and Paraphorosoides should be included in the Somniosidae and that Paraphorosoides is a junior synonym of Protoxynotus. New dental material from the Campanian of Germany and the Maastrichtian of Austria enabled the description of a new species Protoxynotus mayrmelnhofi sp. nov. In addition, the evolution and origin of the characteristic squaliform tooth morphology are discussed, indicating that the elongated lower jaw teeth with erected cusp and distinct dignathic heterodonty of Protoxynotus represents a novel functional adaptation in its cutting-clutching type dentition among early squaliform sharks. Furthermore, the depositional environment of the tooth bearing horizons allows for an interpretation of the preferred habitat of this extinct dogfish shark, which exclusively occupied shelf environments of the Boreal- and northern Tethyan realms during the Late Cretaceous.publishedVersio

Ecological divergence of Chaetopteryx rugulosa species complex (Insecta, Trichoptera) linked to climatic niche diversification

Climate is often considered to be an important, but indirect driver of speciation. Indeed, environmental factors may contribute to the formation of biodiversity, but to date this crucial relationship remains largely unexplored. Here we investigate the possible role of climate, geological factors, and biogeographical processes in the formation of a freshwater insect species group, the Chaetopteryx rugulosa species complex (Trichoptera) in the Western Balkans. We used multi-locus DNA sequence data to establish a dated phylogenetic hypothesis for the group. The comparison of the dated phylogeny with the geological history of the Western Balkans shows that lineage formation coincided with major past Earth surface and climatic events in the region. By reconstructing present-day habitat conditions (climate, bedrock geology), we show that the lineages of C. rugulosa species complex have distinct climatic but not bedrock geological niches. Without exception, all splits associated with Pliocene/Pleistocene transition led to independent, parallel split into ‘warm’ and ‘cold’ sister lineages. This indicates a non-random diversification on the C. rugulosa species complex associated with late Pliocene climate in the region. We interpreted the results as the diversification of the species complex were mainly driven by ecological diversification linked to past climate change, along with geographical isolation

Chronology and integrated stratigraphy of the Miocene Sinj Basin (Dinaride Lake System, Croatia)

a b s t r a c t a r t i c l e i n f o In the Miocene, the intra-montane basins of the Dinaric Mountain Chain harbored a series of long-lived lakes constituting the so-called Dinaride Lake System. The thick lacustrine sedimentary records of these lakes provide an excellent opportunity to study evolution and radiation of mollusks in an isolated environment. The 500 m thick infill that accumulated in the Sinj Basin is one of the key records because of its excellent mollusk preservation. Recent studies on the depositional history, pollen assemblages and large mammals have enhanced the understanding not only of Lake Sinj, but also of the regional climatic developments and faunal migratory patterns. A reliable chronology of the development of Lake Sinj, which is crucial for global correlation of its endemic realm, was still lacking. In this paper we present a detailed time-frame for the Miocene Sinj basin based on palaeomagnetic and 40 Ar/ 39 Ar data. We conclude that deposition took place between 18.0 to 15.0 Ma, a time span that correlates with the upper Burdigalian and lower Langhian Mediterranean stages and Ottnangian, Karpatian and lowermost Badenian Paratethys stages. Furthermore, we determined the timing of several events in mollusk evolution, important for correlation across the Dinarides. An age of 15.0 Ma is attributed to the large mammals Conohyus and Gomphotherium, preserved in the upper part of the basin stratigraphy