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Article Reference A land micro-mammal fauna from the Early Eocene marine Egem deposits (NP12, Belgium) and the first occurrence of the peradectid marsupial Armintodelphys outside North America
Dental remains of land mammals are sometimes discovered in shallow marine Paleogene deposits of the North Sea Basin. Such is the case for eleven specimens we describe here from the Early Eocene Egemkapel Clay Member in the middle part of the Tielt Formation, found in Ampe quarry at Egem in Northwestern Belgium. The small fauna consists of 6 taxa, including the neoplagiaulacid multituberculate Ectypodus, the erinaceomorph insectivore Macrocranion, the nyctitheriid Leptacodon, an eochiropteran bat possibly belonging to a palaeochiropterygid, an unidentified perissodactyl possibly belonging to an equoid, and a new species of the peradectid marsupial Armintodelphys. The latter represents the first European occurrence of the genus, which was previously only known from the North American late Early and early Middle Eocene of the Wind River and Green River basins in Wyoming and the Uinta Basin in Utah. Biogeographic and biostratigraphic analyses of peradectid marsupials suggest that Armintodelphys dispersed between North America and Europe around the time of the Early Eocene Climatic Optimum. The Egemkapel Clay Member has been dated as middle NP12, early late Ypresian, whereas the Egem mammal fauna can be correlated to the fauna of Avenay from the Paris Basin, which is the international reference-level MP8+9 of the mammalian biochronological scale for the European Paleogene.
Located in Library / RBINS Staff Publications
Article Reference A land snail's view of a fragmented landscape
Habitat fragmentation may influence the genetic structure of populations, especially of species with low mobility. So far, these effects have been mainly studied by surveying neutral markers, and much less by looking at ecologically relevant characters. Therefore, we aimed to explore eventual patterns of covariation between population structuring in neutral markers and variation in shell morphometrics in the forest-associated snail Discus rotundatus in relation to habitat fragment characteristics. To this end, we screened shell morphometric variability and sequence variation in a fragment of the mitochondrial 16S rDNA gene in D. rotundatus from the fragmented landscape of the Lower Rhine Embayment, Germany. The 16S rDNA of D. rotundatus was highly variable, with a total of 118 haplotypes (384 individuals) forming four clades and one unresolved group. There was a geographic pattern in the distribution of the clades with the river Rhine apparently separating two groups. Yet, at the geographic scale considered, there was no obvious effect of fragmentation on shell morphometrics and 16S rDNA variation because G(ST) often was as high within, as between forests. Instead, the age of the habitat and (re-)afforestation events appeared to affect shell shape and 16S rDNA in terms of the number of clades per site. The ecologically relevant characters thus supported the presumably neutral mitochondrial DNA markers by indicating that populations of not strictly stenecious species may be (relatively) stable in fragments. However, afforestation after large clearcuts and habitat gain after the amendment of deforestation are accompanied by several, seemingly persistent peculiarities, such as altered genetic composition and shell characters (e.g. aperture size). (C) 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 839-850.
Located in Library / RBINS Staff Publications
Article Reference A large Late Miocene cetotheriid (Cetacea, Mysticeti) from the Netherlands clarifies the status of Tranatocetidae
Located in Library / RBINS Staff Publications 2019
Article Reference A large meteoritic event over Antarctica ca. 430 ka ago inferred from chondritic spherules from the Sør Rondane Mountains
Large airbursts, the most frequent hazardous impact events, are estimated to occur orders of magnitude more frequently than crater-forming impacts. However, finding traces of these events is impeded by the difficulty of identifying them in the recent geological record. Here, we describe condensation spherules found on top of Walnumfjellet in the Sør Rondane Mountains, Antarctica. Affinities with similar spherules found in EPICA Dome C and Dome Fuji ice cores suggest that these particles were produced during a single-asteroid impact ca. 430 thousand years (ka) ago. The lack of a confirmed crater on the Antarctic ice sheet and geochemical and 18O-poor oxygen isotope signatures allow us to hypothesize that the impact particles result from a touchdown event, in which a projectile vapor jet interacts with the Antarctic ice sheet. Numerical models support a touchdown scenario. This study has implications for the identification and inventory of large cosmic events on Earth.
Located in Library / RBINS Staff Publications 2021
Article Reference A large new collection of Palaeostylops from the Paleocene of the Flaming Cliffs area (Ulan-Nur Basin, Gobi Desert, Mongolia), and an evaluation of the phylogenetic affinities of Arctostylopidae (Mammalia, Gliriformes)
Arctostylopids are enigmatic mammals known from the Paleocene and early Eocene of Asia and North America. Based on molar similarities, they have most often been grouped with the extinct Notoungulata from South and Central America, but tarsal evidence links them to Asian basal gliriforms. Although Palaeostylops is the best known arctostylopid genus, some points of its content and species level taxonomy are uncertain. Here we report 255 upper and lower jaw fragments of Palaeostylops, five calcanea, three astragali, as well as the first known arctostylopid distal tibia. This new material was collected from the late Paleocene of the Flaming Cliffs area in Mongolia, in a single lens almost exclusively containing arctostylopid remains. Our study of the morphology and size of the new Palaeostylops dental material confirms the validity of two species, P. iturus and P. macrodon, and illustrates their morphological and biometrical variability and diagnostic differences. The distal tibia of Palaeostylops is relatively unspecialised and resembles the Asian gliriforms Pseudictops and Rhombomylus. We also review the relevance of the historically important genus Palaeostylops in view of other, more recently described but less abundant arctostylopid genera. Palaeostylops remains the reference taxon for the arctostylopid anterior dentition and postcranial morphology. For both anatomical regions, arctostylopids differ significantly from notoungulates, and present a mosaic of characters also seen in basal gliriforms. The notoungulate-like molars of Palaeostylops are highly specialized for arctostylopids and the arctostylopid molar morphotype is therefore better illustrated by the early middle Paleocene Asiostylops. This morphotype does not present any similarities to notoungulates, but shares a number of derived characters with basal gliriforms. Among gliriforms, the primitive arctostylopid morphotype is most similar to Astigale from the early Paleocene of South China, and we suggest that Arctostylopidae may therefore be more closely related to Astigalidae than to any other group.
Located in Library / RBINS Staff Publications
Article Reference A Late Devonian refugium for Colpodexylon (Lycopsida) at high latitude
Located in Library / RBINS Staff Publications 2021
Article Reference A late early to early middle Eocene mammal assemblage from Bayan Ulan (Inner Mongolia, China): Implication for the reassessment of the Arshantan Asian Land Mammal Age
Paleogene mammal localities of North China are particularly well represented in the Erlian Basin, Inner Mongolia. Among them, the locality of Bayan Ulan is most famous for its late Paleocene Gashatan fauna. However, the younger Arshantan fauna of the same site is not well known, since no extensive study has been done so far. Here, we present a small mammal assemblage based on dental and tarsal material from a new Arshantan collection retrieved from the red beds of the late early to early middle Eocene Arshanto Formation at Bayan Ulan. It consists of at least six different taxa: the basal lagomorph Dawsonolagus antiquus, the large pantodont Pantolambdodon sp., the tapiroid Schlosseria magister, and the rhinocerotoids Hyrachyus crista and Rhodopagus guoi nov. sp. The assemblage is dominated by perissodactyls, especially Lophialetidae and Hyracodontidae. For the first time, p4-m1 of Dawsonolagus antiquus, tarsal material from Pantolambdodon sp., and lower dentition and tarsals of Hyrachyus crista are described and illustrated. Unlike other described Arshantan faunas, the Bayan Ulan Arshantan mammal assemblage has been collected exclusively from a single locality, which contributes to the reassessment of the misunderstood Arshantan Asian Land Mammal Age.
Located in Library / RBINS Staff Publications 2021
Article Reference A late surviving Pliocene seal from high latitudes of the North Atlantic realm: the latest monachine seal on the southern margin of the North Sea
Located in Library / RBINS Staff Publications 2018
Article Reference A link between host dispersal and parasite diversity in two sympatric cichlids of Lake Tanganyika
1. A major goal in ecology is to unravel how species assemblages emerge and how they are structured across the landscape. Host–parasite systems are particularly interesting in this context, as limited host dispersal may promote the differentiation of parasite communities. 2. We examined whether the patterns of species diversity in Cichlidogyrus, a genus of monogenean parasitic flatworms with a direct life cycle, are consistent with the hypothesis that parasite diversity is driven by host dispersal. This was carried out by comparing two sympatric cichlid hosts (Tropheus moorii and Simochromis diagramma) with contrasting dispersal abilities. Genetic connectivity among host populations along the Zambian shoreline of Lake Tanganyika was estimated using microsatellite genotyping. Cichlidogyrus parasites were isolated and identified morphologically to the species level. 3.Simochromis diagramma, a host with a high dispersal capacity, was infected by a low number of Cichlidogyrus species, and the parasite assemblages were similar among host populations. In contrast, T. moorii, a host with a low dispersal capacity, was infected by a large number of Cichlidogyrus species, and the parasite assemblages differed strongly among host populations. These outcomes were thus as expected from the hypothesis. 4. Because of the strong host specificity of these Cichlidogyrus species, a lack of connectivity among host populations might facilitate allopatric speciation of the parasite.
Located in Library / RBINS Staff Publications
Article Reference A little-known German naturalist: Konrad Miller (1844-1933) and his malacological contributions
Located in Library / RBINS Staff Publications 2019