Dawn of the Delphinidans: New Remains of Kentriodon from the Lower Miocene of Italy Shed Light on the Early Radiation of the Most Diverse Extant Cetacean Clade.

Nowadays, the infraorder Delphinida (oceanic dolphins and kin) represents the most diverse extant clade of Cetacea, with delphinids alone accounting for more than 40% of the total number of living cetacean species. As for other cetacean groups, the Early Miocene represents a key interval for the evolutionary history of Delphinida, as it was during this time span that the delphinidans became broadly distributed worldwide, first and foremost with the widespread genus Kentriodon and closely related forms. Here, we report on a new odontocete find from Burdigalian (20.4-19.0 Ma) deposits of the Friulian-Venetian Basin of northeastern Italy, consisting of the partial cranium of a small delphinidan with associated ear bones (right periotic, stapes, malleus and tympanic bulla). Osteoanatomical considerations and comparisons allow us to assign the studied specimen to the genus Kentriodon. This is the first confirmed record of Kentriodon from Europe as well as from the whole proto-Mediterranean region. Stratigraphic and phylogenetic considerations suggest that our new specimen may represent the geologically oldest member of Kentriodon. The evolutionary success of Kentriodon may correlate with the emergence of narrow-band high-frequency echolocation as a possible strategy to escape acoustic detection by large marine predators such as the squalodontids. In addition, the relatively high encephalization quotient of Kentriodon spp. may have provided these early dolphins with some kind of competitive advantage over the coeval non-delphinidan odontocetes.

Redescription of the soft-shell turtle Rafetus bohemicus (Testudines, Trionychidae) from the Early Miocene of Czechia.

The taxonomy of the soft-shell turtle Rafetus bohemicus (Liebus, 1930), family Trionychidae, subfamily Trionychinae, is revised based on new and previously mentioned material (including the type material) from the Early Miocene (Burdigalian, MN 3) sites of the Most Basin, Czechia. Given that the diagnosis was so far based only on plastral elements, here we focused on the cranial material and combined our study with previously published data on postcranial elements. 3D models of the skulls derived from CT scans allow us to provide the first complete skull description of R. bohemicus, including several new cranial diagnostic characters of the species. Our results not only enable the distinction of the trionychid genera Trionyx and Rafetus, both recorded from Central Europe during the Early Miocene, but further allow us to provide an emended diagnosis for R. bohemicus. We confirm the conclusions of a previous study according to which Trionyx pontanus, T. preschenensis, T. aspidiformis, and T. elongatus are nomina dubia. R. bohemicus from Brest'any (MN 3) represents the oldest record of this genus in Europe as well as the oldest occurrence of the genus.

Early Miocene remains of Melissiodon from Mokrá-Quarry (Moravia, Czech Republic) shed light on the evolutionary history of the rare cricetid genus.

Background: Melissiodon is a rare cricetid genus endemic to Europe, known from the Early Oligoceneto the Early Miocene. It is usually a very rare find, and even in the few localities where Melissiodon remains are found, those are scarce and fragmentary. Only a few Central European localities have yielded rich remains of the genus. Currently, two species are known from the Early Miocene: Melissiodon schlosseri, which is based on two teeth from the MN2 German locality of Haslach and only found in two other sites of similar age (Ulm-Uniklinik and La Chaux, from Germany and Switzerland respectively); and Melissiodon dominans, found in MN3 and MN4 localities across Europe, even though the scarce and fragmentary remains make some of these attributions dubious. For that reason, Melissiodon dominans has become a catch-all species. However, Mokrá-Quarry represents one of the best documented findings of Melissiodon remains from MN4 localities of Europe. Methods: The Melissiodon assemblage from Mokrá-Quarry has been studied thoroughly, providing metrics and detailed descriptions of all teeth positions, as well as complete comparisons with other MN3 and MN4 localities bearing Melissiodon remains. Results: In this work, new remains of Melissiodon have been identified as a new morphotype that clearly differs from Melissiodon dominans by its unique m1 morphology but still shows some resemblance with Melissiodon schlosseri. Based on that, we here propose the hypothesis of an evolutionary lineage starting from Melissiodon schlosseri, diverging from the lineage leading towards Melissiodon dominans. With this finding, there are at least two different taxa of Melissiodon known during the Early Miocene, prior to the genus extinction. This study arises the certainty that the evolution history of the genus is more complex than previously thought and that more studies are necessary to elucidate it, including a complete revision of the type material of Melissiodon dominans and Melissiodon schlosseri in the light of current knowledge of the genus, which will help to elucidate the attribution of the populations from Mokrá-Quarry. For the time being, the assemblage presented here is referred as Melissiodon aff. schlosseri.

First records of extinct kentriodontid and squalodelphinid dolphins from the Upper Marine Molasse (Burdigalian age) of Switzerland and a reappraisal of the Swiss cetacean fauna.

The Swiss Upper Marine Molasse (OMM) documents a transgression event dated to around 21 to 17 million years in which dolphin and other vertebrate remains have been reported. We revised the whole cetacean (whales and dolphins) OMM assemblage available in main collections, focusing on the identification and interpretation of periotics (bone that contains the inner ear). Periotics are rare, but they provide the richest taxonomic information in the sample and hint to environmental associations. Micro-computerized tomography allowed the reconstruction of bony labyrinths for comparisons and environmental interpretations. Three families are represented by periotics: Kentriodontidae, Squalodelphinidae and Physeteridae. The cetacean taxonomic composition of the Swiss OMM reinforces biogeographical patterns reported for the Mediterranean and Paratethys during the Burdigalian at a regional scale and the Calvert cetacean fauna of the northwest Atlantic at oceanic scale.

Early Miocene larger benthic foraminifera from the northwestern Tethyan Seaway (NW Iran): new findings on Shallow Benthic Zone 25.

The lower Miocene marine units of NW Iran (Hamedan-Miandoab area) were studied to establish a high-resolution biostratigraphy framework in the context of European standard biozonation (SBZ zonal scheme). The units are dominated by larger and small benthic foraminifera together with coralline algae and corals. Due to its position in the Tethyan Seaway between the Mediterranean and Indo-Pacific, the investigated area has high significance in palaeobiogeography. Seven species of benthic foraminifera were described, including Miogypsina globulina, Amphistegina bohdanowiczi, Elphidium crispum, Elphidium sp. 1, Borelis curdica, Austrotrillina asmariensis, and Peneroplis thomasi. The occurrence of Miogypsina globulina in the shallow-marine carbonates of the studied sections documents the Burdigalian SBZ 25 Zone. Austrotrillina asmariensis and Peneroplis thomasi occur with M. globulina. Simultaneously, their stratigraphical range is extended to the Burdigalian in the Middle East. Based on the discovery of lower Miocene deposits in the Hamedan-Miandoab area (previously mapped as Oligocene-Miocene units), the stratigraphy of northwest Central Iran is revised. The biostratigraphic results also present a more precise chronology for the marine transgression in the study area, initiating in the late early Miocene. The coralline algal assemblages and the abundance and diversity of larger benthic foraminifera indicate that shallow-marine Qom Formation got deposited in tropical to subtropical warm waters.

Sharks, rays and skates (Chondrichthyes, Elasmobranchii) from the Upper Marine Molasse (middle Burdigalian, early Miocene) of the Simssee area (Bavaria, Germany), with comments on palaeogeographic and ecological patterns.

Elasmobranch remains are quite common in Miocene deposits and were the subject of numerous studies since the middle of the nineteenth century. Nevertheless, the taxonomic diversity of the Marine Molasse sharks, rays and skates is still largely unknown. Here, we describe 37 taxa from the lower Miocene of the Molasse Basin: 21 taxa could be identified at species level, whereas 15 taxa could only be assigned to genus and one taxon is left as order incertae sedis. The material was collected from deposits of the Auwiesholz Member of the Achen Formation (middle Burdigalian, middle Ottnangian age, ca. 17.8 Ma) exposed near Simssee, Upper Bavaria. This faunal assemblage is a mixture of shallow marine, near-coastal, pelagic and deep-water taxa. The fauna from Simssee displays different biogeographic dynamics at local and regional scales, possibly related to the intense climatic, oceanographic and tectonic events that occurred during the Eggenburgian-Ottnangian stages. The faunal relationships of the early Miocene chondrichthyan faunas from the Mediterranean Sea and Paratethys with others regions are established on the basis of qualitative (presence/absence) data. The beta diversity (Sørensen-Dice coefficient) of the Miocene Molasse elasmobranchs was used to characterize the taxonomic differentiation between localities and regions. According to our results, the fauna from Simssee shows close similarities with those from Switzerland, Austria, France and northern Germany. Faunal similarities and differences are mainly related to tectonic events and oceanographic variables (i.e. migration through seaway passages) or might represent collecting biases.

A new Miocene skate from the Central Paratethys (Upper Austria): the first unambiguous skeletal record for the Rajiformes (Chondrichthyes: Batomorphii).

A new fossil skate, Ostarriraja parva gen. et sp. nov., represented by a single partial articulated skeleton collected from the early Miocene fish-bearing strata of Upper Austria, is described here in detail. This taxon exhibits a unique combination of skeletal and dental features (e.g. nasal capsules broad and oval; presence of pectoral arch; compound radial articulated with single radial segments in serial fashion; separated pelvic girdle condyles; reduced catenated calcification of radials; about 86 pectoral radials; 20-21 pelvic-fin radials; 65-70 predorsal vertebrae) that clearly support its assignment to a new genus of the order Rajiformes, and the phylogenetic analyses reveal its basal position within the group. The comparison between Ostarriraja and the holomorphic batoids from Late Cretaceous of Lebanon traditionally aligned with skates concurs to suggest that this Neogene occurrence represents unquestionably the first known skeletal record for the group. The morphological and phylogenetic affinities of Ostarriraja with the living skates suggest a close association of this taxon with the temperate-cold water environments hypothesized for the Central Paratethys during the early Miocene. http://zoobank.org/urn:lsid:zoobank.org:pub:8BB8F0F3-35C5-47FA-AE3C-2CBF445C4BCA.

An Early Miocene bumble bee from northern Bohemia (Hymenoptera, Apidae).

A new species of fossil bumble bee (Apinae: Bombini) is described and figured from Early Miocene (Burdigalian) deposits of the Most Basin at the Bílina Mine, Czech Republic. Bombus trophoniussp. n., is placed within the subgenus Cullumanobombus Vogt and distinguished from the several species groups therein. The species is apparently most similar to the Nearctic B. (Cullumanobombus) rufocinctus Cresson, the earliest-diverging species within the clade and the two may be related only by symplesiomorphies. The age of the fossil is in rough accordance with divergence estimations for Cullumanobombus.

Mid-Burdigalian Paratethyan alkenone record reveals link between orbital forcing, Antarctic ice-sheet dynamics and European climate at the verge to Miocene Climate Optimum.

The Early Ottnangian Cooling (EOC), a distinct cold-spell in European climate at ~ 18 Ma preceding the Miocene Climate Optimum, is frequently reported in Paratethys records; however, the duration, magnitude, and underlying causes are poorly understood. A new palaeoclimatic data-set provides unexpected insights into this event. UK'37-based sea-surface temperatures > 24 °C between ~ 18.1 and 17.7 Myrs substantially exceed existing estimates, and indicate a significantly warmer European climate than previously assumed for this usually poorly recovered time interval. The EOC is expressed as an average drop of 2-3 °C in Paratethyan water temperatures between ~ 18.1 and 17.8 Myrs with two distinct cold snaps at ~ 17.86 Ma and ~ 17.81 Ma. The short duration of the EOC excludes Tethyan Seaway closure as its underlying cause, although the enhanced palaeoclimatic sensitivity of the Paratethys due to this palaeogeographic configuration potentially contributed to the magnitude of SST deterioration during the EOC. The revealed palaeoclimatic pattern shows a strong correlation with isotope event Mi-1b in deep-sea δ18O records, and we propose a tight palaeoclimatic link between the Southern Ocean and the Paratethys/Mediterranean realm as an alternative hypothesis. The interplay of modulations in the long-term (~ 400 kyrs) and short-term (~ 100 kyrs) eccentricity cycles most likely acted as pacemaker of this palaeoclimatic interaction.