The rich earliest Eocene mammal assemblage of Dormaal in northeast Belgium has yielded most of the earliest modern mammals of Europe and is the the reference-level for MP7 in the Mammalian Biochronological Scale of the European Paleogene. Despite the fact that several other localities in Europe, such as Silveirinha in Portugal, Le Quesnoy, Pourcy, Sotteville-sur-Mer, Rians, Palette, and Fordones in France, and the Suffolk Pebble Beds in England, contain faunas that have been correlated to Dormaal, none of them preserve the same fauna as Dormaal with the exception of Erquelinnes in southwest Belgium. Here we describe the new vertebrate site of Clairoix, located only 13 km from Le Quesnoy in the Paris Basin, France, but 225 km southwest of Dormaal. About 150 kilograms of sandy matrix has produced a collection of about 400 vertebrate specimens including 118 isolated mammal teeth. The fauna is composed of the following typical MP7 species: the herpetotheriid marsupial Peratherium constans, the amphilemurid erinaceomorph Macrocranion vandebroeki, the hyaenodonts Arfia gingerichi and Prototomus minimus, the carnivoraforms Dormaalocyon latouri and Gracilocyon solei, and the omomyid primate Teilhardina belgica. Besides these index taxa, the arctocyonid Landenodon woutersi, the louisinid “condylarths” Paschatherium dolloi and Paschatherium yvetteae, a perissodactyl, and several rodents also are present at Clairoix. As in Dormaal, the relative abundance analysis of the species from Clairoix indicates that P. dolloi and P. yvetteae are the most abundant species, followed by M. vandebroeki and T. belgica, respectively. In term of number of specimens, Paschatherium represents more than 50% of the fauna, which corresponds to the acme of Paschatherium defined across the Paleocene–Eocene boundary in continental Europe. The composition and relative abundance of the mammal fauna of Clairoix are very similar to those of Dormaal and Erquelinnes and suggest a similar or very close age. The results of this work also suggest that the mammal assemblage of these three localities does not only correspond to a different paleoenvironment than that of other MP7 correlated faunas but also to an older age closer to the Paleocene–Eocene Thermal Maximum. Fish, frog, lizard, crocodilomorph, and snake remains were also collected and support a fluvial paleoenvironment at Clairoix. Grant Information This research was supported by the BRGM ‘Régolithe’ Scientific Program and the Belgian Science Policy Office (project BR/121/A3/PalEurAfrica).
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RBINS Staff Publications 2016
The Messel Pit is a Konservat-Lagerstätte in Germany, representing the deposits of a latest early to earliest middle Eocene maar lake, and one of the first palaeontological sites to be included on the list of UNESCO World Heritage Sites. One aspect of Messel that makes it so extraordinary is that its sediments are rich in different fossilised organisms – microfossils, plants, fungi, invertebrate animals and vertebrates – that are rarely preserved together. We present an updated list of all taxa, named or not, that have been documented at Messel, comprising 1409 taxa, which represent a smaller but inexactly known number of biological species. The taxonomic list of Labandeira and Dunne (2014) contains serious deficiencies and should not be used uncritically. Furthermore, we compiled specimen lists of all Messel amphibians, reptiles and mammals known to us. In all, our analyses incorporate data from 32 public collections and some 20 private collections. We apply modern biodiversity-theoretic techniques to ascertain how species richness tracks sampling, to estimate what is the minimum asymptotic species richness, and to project how long it will take to sample a given proportion of that minimum richness. Plant and insect diversity is currently less well investigated than vertebrate diversity. Completeness of sampling in aquatic and semiaquatic, followed by volant, vertebrates is higher than in terrestrial vertebrates. Current excavation rates are one-half to two-thirds lower than in the recent past, leading to much higher estimates of the future excavation effort required to sample species richness more completely, should these rates be maintained. Species richness at Messel, which represents a lake within a paratropical forest near the end of the Early Eocene Climate Optimum, was generally higher than in comparable parts of Central Europe today but lower than in present-day Neotropical biotopes. There is no evidence that the Eocene Messel ecosystem was a “tropical rainforest.”
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RBINS Staff Publications 2024
Introduction Raoellidae are small artiodactyls retrieved from the middle Eocene of Asia (ca - 47 Ma) and closely related to stem Cetacea. Morphological observations of their endocranial structures allow for outlining some of the early steps of the evolutionary history of the cetacean brain. The external features of the brain and associated sinuses of Raoellidae are so far only documented by the virtual reconstruction of the endocast based on specimens of the species Indohyus indirae. These specimens are however too deformed to fully access the external morphology, surface area, and volume measurements of the brain. Methods We bring here new elements to the picture of the raoellid brain by an investigation of the internal structures of an exceptionally well-preserved cranium collected from the Kalakot area (Jammu and Kashmir, India) referred to the species Khirtharia inflata. Micro-CT scan investigation and virtual reconstruction of the endocast and associated sinuses of this specimen provide crucial additional data about the morphological diversity within Raoellidae as well as reliable linear, surfaces, and volumes measurements, allowing for quantitative studies. Results We show that, like I. indirae, the brain of K. inflata exhibits a mosaic of features observed in earliest artiodactyls: a small neocortex with simple folding pattern, widely exposed midbrain, and relatively long cerebellum. But, like Indohyus, the brain of Khirtharia shows unique derived characters also observed in stem cetaceans: narrow elongated olfactory bulbs and peduncles, posterior location of the braincase in the cranium, and complex network of blood vessels around the cerebellum. The volume of the brain relative to body mass of Khirtharia inflata is markedly small when compared to other early artiodactyls. Conclusion We show here that, cetaceans that nowadays have the second biggest brain after humans, derive from a group of animals that had a lower-than-average expected brain size. This is probably a side effect of the adaptation to aquatic life. Conversely, this very small brain size relative to body mass might be another line of evidence supporting the aquatic habits in raoellids.
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