16S rRNA sequencing reveals likely beneficial core microbes within faecal samples of the EU protected slug Geomalacus maculosus

The EU-protected slug Geomalacus maculosus Allman occurs only in the West of Ireland and in northern Spain and Portugal. We explored the microbial community found within the faeces of Irish specimens with a view to determining whether a core microbiome existed among geographically isolated slugs which could give insight into the adaptations of G. maculosus to the available food resources within its habitat. Faecal samples of 30 wild specimens were collected throughout its Irish range and the V3 region of the bacterial 16S rRNA gene was sequenced using Illumina MiSeq. To investigate the influence of diet on the microbial composition, faecal samples were taken and sequenced from six laboratory reared slugs which were raised on two different foods. We found a widely diverse microbiome dominated by Enterobacteriales with three core OTUs shared between all specimens. While the reared specimens appeared clearly separated by diet in NMDS plots, no significant difference between the slugs fed on the two different diets was found. Our results indicate that while the majority of the faecal microbiome of G. maculosus is probably dependent on the microhabitat of the individual slugs, parts of it are likely selected for by the host

Tylosaurine mosasaurs (Squamata) from the Late Cretaceous of northern Germany

Two genera of tylosaurine mosasaurs, Tylosaurus and Hainosaurus, are recorded for the first time from Germany. Tylosaurus sp. is represented by two isolated tooth crowns, originally described as Mosasaurus? alseni (here considered a nomen dubium) from the latest Santonian–Early Campanian, which are very similar to T. ivoensis and T. gaudryi. The material of Hainosaurus sp. comprises a maxillary with associated postorbitofrontal, two pterygoid teeth and several indeterminate cranial fragments. The specimen from the Late Campanian is slightly less derived than H. bernardi from the Maastrichtian in retaining labiolingually less compressed anterior maxillary teeth and unserrated pterygoid teeth with only very weak carinae. Despite only minor skeletal differences, the genus Hainosaurus is considered to be distinct from Tylosaurus because of its significant modification of the dental apparatus compared to the plesiomorphic condition in the latter. This dental morphology suggests a phylogenetic trend from a generalised-piercing marginal dentition in Tylosaurus towards the increasingly labiolingually compressed, symmetrical, strongly bicarinate cutting marginal teeth in Hainosaurus spp. from the Early through Late Campanian and Maastrichtian. A similar trend is also present in pterygoid teeth with very indistinct unserrated carinae in the Campanian Hainosaurus sp. towards serrated ones in the Maastrichtian H. bernardi. A short review indicates the presence of Hainosaurus in northern, central and western Europe (Sweden to Spain) since the Early Campanian, and the occurrence of Tylosaurus spp. in the same area until the Late Campanian. Hainosaurus persisted until the end of the Maastrichtian; outside Europe it may have been present in the Late Campanian of the USA and the Maastrichtian of the Democratic Republic of Congo. Judging from a simple, uni- to bicarinate, stoutly conical tooth morphology in aigialosaurs and very basal mosasaurs as well as phylogenetic patterns, the development of blade-like cutting tooth crowns appears to have been convergent in several clades of large-bodied Campanian–Maastrichtian mosasaurids. These include both mosasaurines ('Leiodon' mosasauroides, Prognathodon? sectorius, Prognathodon? kianda, Eremiasaurus heterodontus) and tylosaurines (Hainosaurus spp.)

Where are all the Ordovician sea cucumbers (Echinodermata)?

The Ordovician Period witnessed the first evidence of appearance of all modern echinoderm clades as well as it is the most concentrated interval of echinoderm diversity in Earthâs history. This knowledge is largely based on reports from Baltica, Avalonia, Laurentia and Gondwana. However, the Ordovician record of sea cucumbers (Holothuroidea) and their allies, like echinoids and ophiocistioids (Echinozoa), is sparse and patchy. The earlier published Cambrian or Ediacaran records of echinozoan echinoderms (e.g., sea cucumbers) are based on misinterpreted specimens of other phyla. Neither the origins of the Echinozoa nor the split of holothuroids from ophiocistioids or echinoids are properly understood. One reason for this is the fact that less than 100 (articulated) Ordovician specimens of sea urchins, sea cucumbers and ophiocistioids have been recovered worldwide so far. In general, fossil remains of the Holothuroidea are limited to (1) innumerable microscopic and/or mesoscopic ossicles of the body wall, (2) five distinct calcareous plates which supported the anus in some (more highly evolved) sea cucumber groups, and (3) a total of usually ten radial and interradial elements of the calcareous ring surrounding the pharynx. The latter represents a synapomorphy for the entire group and is important in the higher-level group systematics. In addition, to date, there are only about two dozen known Phanerozoic localities (Konservat-Lagerstätten and obrution deposits) that have yielded (4) articulated body fossils of holothurians. Few attempts have been made to use disarticulated fossils of Echinodermata to understand the distribution, diversity and early radiation of Holothuroidea, Echinoidea and Ophiocistioidea. Only during the last two decades, advanced micropalaeontological and macropalaeontological techniques have been combined to investigate these understudied echinoderm groups in greater detail. This will help to gain further understanding about the Early Palaeozoic echinozoan echinoderms. In this presentation, a short overview of known holothurian finds (mostly from Baltica) is given