Paschatherium

Abstract: A new mammal fauna from the earliest Eocene of Le Clot (Corbieres, Southern France) is described. Some taxa identified there, such as Corbarimys hottingeri and Paschatherium plaziati, allow a correlation with the previously described Corbieres fauna of Fordones. Moreover, the presence at Le Clot of Lessnessina praecipuus, which is defined in Palette (Provence, Southern France) allows correlating both localities. All three of these localities are referred to the MP7 reference level, even if a direct correlation with the type locality of MP7 (Dormaal, Belgium) is not ascertained. A Southern Europe biochronological sequence is proposed for the beginning of the Eocene: Silveirinha, Fordones/Palette/Le Clot, Rians/Fournes. The diagnosis of a new species of a neoplagiaulacid multituberculate (?Ectypodus riansensis nov. sp.) is proposed. From a compilation of data concerning the earliest Eocene faunas from both Northern Europe and Southern Europe, we conclude that two faunas corresponding to two distinct palaeobiogeographical provinces existed in Western Europe. This faunal disparity, probably related to climatic differences, makes correlations particularly difficult between the two provinces.

Abstract: Mammal faunas from five outcrop sections in the Tienen Formation (Dormaal, Orp-le-Grand, Hoegaarden, Erqueiinnes, and Levai), representing the Paleocene-Eocene transition in Belgium, have been analysed (Smith 1999) The study of the Dormaai fauna, the nchest and most diversified among these, permitted to speciQ reference level MW of the mammalian biochronological scale for the European Paleogene (SchmidtKittler 1987) This fauna is characterised by the first occurrence of modem mammal groups among which the most typical species are: Teilhardina belgica (euprimate), Diacodexis gigasei (artiodactyl), Microparamys nanus (rodent), Miacis latouri (miacid carnivore), Prototomus n sp D, and Afia n sp E (hyaenodontid creodonts) These CO-occur with species of persisting primitive groups, such as Paschatherium dolloi (hyopsodontid condylarth), Landenodon woutersi (arctocyonid), Platychoerops georgei (plesiadapid primate), Palaeosinopa russelli (pantolestid), and Apatemys teilhardi (apatotherid) Recent excavations in the stratotype of the Dormaal Sand Member (see Smith & Smith 1996) have led to a better understanding of the biodiversity and the palaeobiogeographical affinities of the mammal fauna at the Paleocene/Eocene boundary in Belgium About 14,000 teeth have been identified, per ta i~ng to fifty-five taxa, including 37 genera, 20 families, and 13 orders About 99% of the specimens, belonging to fifty taxa, come from Dormaal The palaeoecological analysis of the Dormaai m m mal fauna, microfaunas and floras (Steurbaut et al 1999) indicates a warm and humid ciimate in a wooded area, dominated by a large nver system This environment was rich in insects as showed by the numerous forest mammal species with insectivomus and arboreai tendencies Of the 37 mamrnal genera discovered in Belgium, 25 are also present in the other MP7 localities of North Europe Only 12 are known from southem Europe Paradoxically, at least 22 genera are comrnon with North Arnerica The Asiatic faunas are not well known but at least five genera are common with East Asia The close palaeobiogeographical affinities of the marnmals within the Anglo-FrancoBelgian Basin suggest that there were faunal exchanges throughout that area, resulting from the existence of land bridges between England and the rest of NW Europe Our observations also confirm Marandat's (1997) hypothesis that two geographically or climatologically isolated provinces existed in Europe at the PaleoceneEocene boundary: The Anglo-Franco-Belgian Basin in the north and the peri-mesogean basins in the south The strong affinities between the North European and North Amencan faunas aiso c o n f m the hypothesis that a land bridge via Greenland existed between these areas (Kurten 1966) The low afinities between the European and Asian faunas suggest that there was no direct land connection between these continents and that the few cornrnon genera should have crossed the Bering Strait, North Arnenca, and Greenland A few genera, persisting

Abstract: New dental and postcranial remains of the alleged louisinine hyopsodontid “condylarth” Microhyus from the European Paleocene/Eocene transition are described, and prompt a reevaluation of the genus. New specimens belonging to Microhyus musculus from Dormaal (MP7, Belgium ) provide the first evidence of the lower dentition of the type species. We describe M. musculus? from Pourcy (MP7, France) and cf. Microhyus sp. from Berru (MP6a, France). A rich original assemblage of M. reisi from Silveirinha (MP7, Portugal ) allows a detailed description of the morphological dental variation within that species. Well-preserved astragali and calcanei from Silveirinha can be confidently attributed to Microhyus reisi. Functional analysis of these elements suggests that Microhyus was a terrestrial mammal capable of rapid running or jumping. The pedal morphology of Microhyus is very similar to that of Paschatherium. These louisinines share some derived characters with the hyopsodontids Apheliscus and Haplomylus (e.g., the occurrence of a cotylar fossa on the astragalus) but they differ from Hyopsodus. Therefore, in view of the pedal morphology alone, the hyopsodontids may be polyphyletic. Given the dental similarities between Microhyus and the early representatives of the order Macroscelidea, we compared the tarsal morphology of louisinines with that of modern macroscelidids (Paleogene tarsal remains are currently unknown for this group). Macroscelidids and louisinines present some similarities in their astragalar morphology; however, the macroscelidid astragalus appears to be too specialized to be compared with that of Microhyus and Paschatherium.

Abstract: The micromammal faunas from two European sections close to the Paleocene-Eocene boundary (PEb), Tremp in Spainand Dormaal in Belgium, share several species and paleoecological features in spite of their different chronological and paleo-biogeographical situation: the Tremp faunas contain no immigrant taxa, while the Dormaal faunas post-dated the Mammal DispersalEvent.BothsectionscanbecorrelatedwiththeCarbonIsotopeExcursion(CIE)event,whichliesseveralmetersabovetheTremplocali-tiesandcouldhavebegunsub-contemporaneouslywiththeDormaalSanddeposits. Oneofthemostremarkablefeaturesofthesefaunasisthedominanceinallthesamplesofdentalmicro-remainsofthecondylarthgenus Paschatherium .Herewestudythefeaturesanddistri-bution of Paschatherium species and discuss the significance of their acme in relation to the PEb and the Initial Eocene Thermal Maxi-mum. INTRODUCTION Micromammal teeth obtained by screen washing even appar-ently barren sediments in outcrops and cores are widely usedfor biostratigraphy and palaeoenvironmental studies in conti-nental deposits of Cenozoic age, and are here used to detect aregional bioevent around the Paleocene-Eocene boundary(PEb) (~55 m.y. ago). Mammalian paleofaunas from the North-ern Hemisphere underwent a major turnover across the PEb,known as the Mammalian Dispersal Event (MDE, Hooker2000). A continuous, local mammalian succession in NorthAmerica allows us to correlate this event to a major, short cli-matic pulse named the Initial Eocene Thermal Maximum(IETM; Koch et al. 1992; Gingerich 2003). In Europe, the MDEis detected by comparing fossil mammal localities from discon-tinuous deposits (karstic or isolated fluvial outcrops; Russell1964; Estravis 1992; Smith and Smith 1996; Hooker 1996). Thescattered position of the European sites hinders their correlationand dating. Moreover, these European mammalian faunas showstriking compositional differences between northern and south-ern provinces, impeding the long-distance comparison and corre-lations (Marandat 1997, Smith 2000). It is therefore interesting tofind faunal links between northern and southern European mam-malian faunas across the PEb in well-correlated stratigraphicsettings.Two particular European sections, Tremp in Spain (Southernprovince) and Dormaal in Belgium (Northern province) showfavorable conditions towards this goal. Micromammal assem-blages from continental sediments in both areas can be directly(south-Pyrenean Basin) or indirectly (Belgian Basin) correlatedwith marine deposits and with the Carbon Isotope Excursion(CIE) (Lopez-Martinez et al. 1995, 1996; Lopez-Martinez andPelaez-Campomanes 1998; 1999; Steurbaut et al. 1999; Pujalteet al. 2003; Steurbaut et al. 2003; Schmitz and Pujalte 2003).This event marked by a rapid decrease in