Cécile Blondel’s research while affiliated with Université de Poitiers and other places

The Oligocene–Miocene transition witnessed great environmental and faunal changes, spanning from late Oligocene to early Miocene (MP28–MN3). Its drivers and consequences on mammals are, however, poorly understood. Rhinocerotoids are among the most affected taxa, reflected by great taxonomical and morphological changes. However, potential associated changes in ecology have not been explored. Here, we investigated the palaeoecology of 10 rhinocerotid species coming from 15 localities across Western Europe and ranging from MP28 to MN3. We explored evolutionary trends for diet, physiology and habitat via dental wear, hypoplasia, body mass and stable isotopy. All rhinocerotids studied were C3 feeders, whether browsing or mixed-feeding, but clear dietary differences were observed at some localities and between Oligocene and Miocene rhinocerotids. The prevalence of hypoplasia was low (less than 10%) to moderate (less than 20%), but there were great differences by loci, species and localities. Body mass covaried with hypoplasia prevalence, suggesting that larger species might be more susceptible to stresses and environmental changes. We reconstructed similar warm conditions at all localities except Gaimersheim, but found greater variations in precipitation. Indeed, a clear shift in δ¹³C values was noticed at the end of the Oligocene, consistent with climatic and vegetation changes reported at that time.

Cet article décrit du matériel dentaire et postcrânien inédit d’artiodactyles et de périssodactyles issu du gisement de Valbro (Phosphorites du Quercy, France). Il s’agit de la cinquième contribution sur ce gise- ment. Ce paléokarst a livré 14 taxons d’euongulés avec, parmi les artiodactyles, le dichobunidé Dichobune fraasi, un entélodontidé Entelodon sp., les cainothériidés Paroxacron valdense, Plesiomeryx cadurcensis, Ple. huerzeleri et Caenomeryx cf. procommunis, les gelocidés Gelocus communis et Pseudogelocus scotti et le bachitheriidé cf. Bachitherium sp. ; et parmi les périssodactyles, les paléothériidés Plagiolophus ministri et Pl. minor, les rhinocérotidés Ronzotherium filholi et Epiaceratherium magnum et l’eggysodontidé Eggysodon osborni. L’association de ces espèces permet de confirmer un âge Oligocène inférieur (Rupélien), proche du niveau-repère MP22, et permet de proposer une liste faunique de 72 taxons de vertébrés. Parmi les vertébrés de Valbro, les euongulés représentent un des groupes les plus diversifiés et constituent le plus gros contingent de spécimens. Cette abondance, due essentiellement aux très nombreux restes de cai- nothériidés retrouvés au sein du gisement, est comparable à celle des rongeurs. Par comparaison avec les sites européens contemporains, la faune d’artiodactyles et de périssodactyles de Valbro est parmi les plus diversifiées d’Europe occidentale. This manuscript describes unpublished dental and postcranial material of artiodactyls and perissodactyls from the Valbro deposits (Phosphorites from Quercy, France). It is the fifth contribution on this site. This paleokarst yielded 14 euungulate taxa with, among the artiodactyls, the dichobunid Dichobune fraasi, the entelodontid Entelodon sp., the cainotheriids Paroxacron valdense, Plesiomeryx cadurcensis, Ple. huer- zeleri and Caenomeryx cf. procommunis, the gelocids Gelocus communis and Pseudogelocus scotti and the bachitheriid cf. Bachitherium sp.; and among the perissodactyls, the palaeotheriids Plagiolophus ministri and Pl. minor, the rhinocerotids Ronzotherium filholi and Epiaceratherium magnum and the eggysodontid Eggysodon osborni. The association of these species confirms an early Oligocene age (Rupelian), close to the MP22 reference level, and allows us to propose a faunal list of 72 vertebrate taxa. Among the Valbro vertebrates, euongulates are one of the most diverse groups and constitute the largest specimen collec- tion. This abundance is essentially due to the large number of cainotheriid remains found in the deposit, and is comparable to that of rodents. Compared with contemporary European sites, the artiodactyl and perissodactyl fauna from Valbro is among the most diversified in western Europe.

The Oligocene-Miocene transition witnessed great environmental and faunal changes, spanning from late Oligocene to early Miocene (MP28-MN3). Its drivers and consequences on mammals are however poorly understood. Rhinocerotoids are among the most affected taxa, reflected by great taxonomical and morphological changes. However, potential associated changes in ecology have not been explored. Here, we investigated the paleoecology of 10 rhinocerotid species coming from 15 localities across Western Europe and ranging from MP28 to MN3. We explored evolutionary trends for diet, physiology, and habitat via dental wear, hypoplasia, body mass, and stable isotopy. All rhinocerotids studied were C3 feeders, whether browsing or mixed-feeding, but clear dietary differences were observed at some localities and between Oligocene and Miocene rhinocerotids. The prevalence of hypoplasia was low (< 10 %) to moderate (< 20 %), but there were great differences by loci, species, and localities. Body mass co-variated with hypoplasia prevalence, suggesting that larger species might be more susceptible to stresses and environmental changes. We reconstructed similar warm conditions at all localities except Gaimersheim, but found greater variations in precipitation. Indeed, a clear shift in δ ¹³ C values was noticed at the end of the Oligocene, consistent with climatic and vegetation changes reported at that time.

The Ulm-Westtangente locality has yielded the most abundant vertebrate fauna from the Aquitanian stage in Germany. Its dating to the Mammal Neogene Zone 2a, a turnover in Cenozoic climate, makes it a crucial source for the understanding of faunal, paleoecological and paleoenvironmental specifics of the European Aquitanian. However, while most taxa from Ulm-Westtangente have been studied, little to no research has been conducted on the large herbivores, particularly on the two rhinocerotids Mesaceratherium paulhiacense and Protaceratherium minutum. Here, we used a multi-proxy approach to investigate the paleoecology of these two species. The remains of the smaller species P. minutum (438 to 685 kg) are twice as abundant as those of the larger M. paulhiacense (1389 to 2327 kg), but both display a similar age structure (~ 10% of juveniles, 20% of subadults and 70% of adults), mortality curves, and mild prevalence of hypoplasia (~ 17%). Results from dental mesowear, microwear, and carbon isotopes indicate different feeding preferences: both were C3 feeders but M. paulhiacense had a more abrasive diet and was probably a mixed feeder. Our study on rhinocerotids also yielded new paleoenvironmental insights, such as the mean annual temperature (15.8 °C) and precipitation (317 mm/year) suggesting rather warm and dry conditions.

The locality of Ulm-Westtangente yielded the richest vertebrate fauna from the Aquitanian of Germany. Its dating to the Mammal Neogene Zone 2a, a turnover in Cenozoic climate, makes it a crucial source for the understanding of faunal, palaeoecological and palaeoenvironmental specifics of the European Aquitanian. However, if most taxa from Ulm-Westtangente have been studied, very little to nothing has been done on the large herbivores and notably on the two rhinocerotids Mesaceratherium paulhiacense and Protaceratherium minutum . Here, we used a multi-proxy approach to investigate the paleoecology of these two species. The remains of the smaller species P. minutum (442 to 667 kg) are twice as abundant as those of the larger M. paulhiacense (1687 to 2576 kg), but both display a similar age structure (∼ 10 % of juveniles, 20 % of subadults and 70 % of adults), mortality curves, and mild prevalence of hypoplasia (∼ 17 %). Results from dental mesowear, microwear, and carbon isotopes indicate different feeding preferences: both were C3 feeders but M. paulhiacense had a more abrasive diet and was probably a mixed feeder. Our study on rhinocerotids also yielded new paleoenvironmental insights, such as the mean annual temperature (15.8 °C) and precipitation (317 mm/year) suggesting rather warm and dry conditions. Statements and Declarations The authors have no relevant financial or non-financial interests to disclose. This study was funded by a post doctoral fellowship of the Alexander von Humboldt Foundation (Germany).

The locality of Ulm-Westtangente presents the richest vertebrate fauna from the early Miocene of Germany. Its dating to the Aquitanian, a turning point in Cenozoic climate, makes it interesting to understand the faunal, palaeoecological, and palaeoenvironmental context in Europe at that time. However, very little has been done concerning the large herbivores despite they are a good proxy for palaeoenvironments. Here we used a multiproxy approach to investigate the palaeoecology of the two rhinocerotids from Ulm-Westtangente: Mesaceratherium paulhiacense and Protaceratherium minutum. The dental remains of the smaller species, P. minutum (estimated body mass based on teeth: 442–667 kg), are twice as abundant (337 vs. 155) as that of the larger M. paulhiacense (1687–2576 kg), but they display a similar age structure with around 10% of juveniles, 20% of subadults, and 70% of adults. Dental wear (mesowear, microwear) and carbon isotopes indicate different feeding preferences for the two species: both were C3 feeders but M. paulhiacense had a more abrasive diet and was probably a mixed feeder inhabiting a wider range of habitats. Both species have similar mortality curves revealing four mortality peaks correlated with life stages and events: around birth, juvenile diseases, weaning, and sexual maturity. They are also similarly affected by enamel hypoplasias, with about 17% of teeth bearing at least one defect, but the most affected loci are species-dependent. The oxygen isotopes of the studied rhinocerotid sample also allow to infer the mean annual temperature (19.2 °C), confirming warm-temperate to subtropical conditions. Keywords: diet, palaeoenvironment, niche partioning, Freshwater Molasse Germany, Aquitanian

Several scenarios for the dispersal of Miocene hominids from Africa to Eurasia still coexist. The reason why it remains impossible to decide between these scenarios, and why some fundamental questions about the biogeographic history of Miocene hominids are so difficult to address, lies in a fragmented fossil record and uncertain dating. In order to overcome these problems and to measure the potential effect of climate on the dispersal of Miocene hominids, we use ecological niche models (ENM) based on palaeoclimatic reconstructions of Early, Middle and Late Miocene. Using ENM, we demonstrate that the Eurasian climate during the Lower Miocene was not compatible with the climatic conditions required for the installation of hominids living in East Africa at the same time. Consequently, while the connection between Africa and Eurasia was active since the Gomphoterium Datum Event (PDE, ca. 19 myr), the presence of hominids in Eurasia appears unlikely during Early Miocene. In the Middle Miocene, the long-term cooling following the Middle Miocene Climatic Optimum profoundly modified the Earth's climate, notably in Eurasia. South Asia and Southeast Asia, as well as the Mediterranean coastline, became suitable for the presence of Late Miocene East African hominids. Finally, we provide a case of ecological niche displacement. The estimated climatic niches for European hominids in the Middle Miocene are distinctly different from those of their Lower Miocene ancestors from East Africa. These arising taxa found in Europe did not simply 'track' their climatic niche, but adapted to the new climatic conditions of the European continent.

In order to understand mammalian evolution and compute a wide range of biodiversity indices, we commonly use the ‘bioregion’, a spatial division adapted to ecological and evolutionary constraints. While commonly conducted by neontologists, the establishment of bioregions in palaeontology is generally a secondary analysis, shaped on subjective time scales and areas specific to the investigated questions and groups. This heterogeneity, coupled with the scale‐dependency of biodiversity indices, prevents the clear identification of macroecological and macroevolutionary trends for large taxonomic groups like extinct mammals. Here we tackle this issue by providing a coherent framework for Neogene and Pleistocene mammals of the Old World following two steps: (1) a temporal scale adapted to mammalian evolutionary history (i.e. evolutionary fauna) is defined by poly‐cohort analysis; (2) bioregions are then computed for each evolutionary fauna by clustering, ordination and intermediate approaches at multiples spatial scales (i.e. continental to regional) for Eurasia and Africa. Additionally, providing a coherent framework for a wide range of mammalian datasets, our results show: (1) the synchronous emergence and fall of five mammalian evolutionary faunas identified at chronological scales varying from the epoch to the geological stage; (2) a transition from a longitudinal to a latitudinal biogeographical structuring between the Miocene and Pliocene, especially in Europe; (3) the long‐term affinity of southern Asian with African faunas, in sharp contrast with the modern Palaearctic bioregion extension; and (4) the establishment of a vast Mediterranean bioregion from fragmented areas in the Late Miocene to its full extent in the Pleistocene.