Early Pleistocene enamel proteome from Dmanisi resolves Stephanorhinus phylogeny.

The sequencing of ancient DNA has enabled the reconstruction of speciation, migration and admixture events for extinct taxa1. However, the irreversible post-mortem degradation2 of ancient DNA has so far limited its recovery-outside permafrost areas-to specimens that are not older than approximately 0.5 million years (Myr)3. By contrast, tandem mass spectrometry has enabled the sequencing of approximately 1.5-Myr-old collagen type I4, and suggested the presence of protein residues in fossils of the Cretaceous period5-although with limited phylogenetic use6. In the absence of molecular evidence, the speciation of several extinct species of the Early and Middle Pleistocene epoch remains contentious. Here we address the phylogenetic relationships of the Eurasian Rhinocerotidae of the Pleistocene epoch7-9, using the proteome of dental enamel from a Stephanorhinus tooth that is approximately 1.77-Myr old, recovered from the archaeological site of Dmanisi (South Caucasus, Georgia)10. Molecular phylogenetic analyses place this Stephanorhinus as a sister group to the clade formed by the woolly rhinoceros (Coelodonta antiquitatis) and Merck's rhinoceros (Stephanorhinus kirchbergensis). We show that Coelodonta evolved from an early Stephanorhinus lineage, and that this latter genus includes at least two distinct evolutionary lines. The genus Stephanorhinus is therefore currently paraphyletic, and its systematic revision is needed. We demonstrate that sequencing the proteome of Early Pleistocene dental enamel overcomes the limitations of phylogenetic inference based on ancient collagen or DNA. Our approach also provides additional information about the sex and taxonomic assignment of other specimens from Dmanisi. Our findings reveal that proteomic investigation of ancient dental enamel-which is the hardest tissue in vertebrates11, and is highly abundant in the fossil record-can push the reconstruction of molecular evolution further back into the Early Pleistocene epoch, beyond the currently known limits of ancient DNA preservation.

Insights into the lower torso in late Miocene hominoid Oreopithecus bambolii.

Oreopithecus bambolii (8.3-6.7 million years old) is the latest known hominoid from Europe, dating to approximately the divergence time of the Pan-hominin lineages. Despite being the most complete nonhominin hominoid in the fossil record, the O. bambolii skeleton IGF 11778 has been, for decades, at the center of intense debate regarding the species' locomotor behavior, phylogenetic position, insular paleoenvironment, and utility as a model for early hominin anatomy. Here we investigate features of the IGF 11778 pelvis and lumbar region based on torso preparations and supplemented by other O. bambolii material. We correct several crucial interpretations relating to the IGF 11778 anterior inferior iliac spine and lumbar vertebrae structure and identifications. We find that features of the early hominin Ardipithecus ramidus torso that are argued to have permitted both lordosis and pelvic stabilization during upright walking are not present in O. bambolii However, O. bambolii also lacks the complete reorganization for torso stiffness seen in extant great apes (i.e., living members of the Hominidae), and is more similar to large hylobatids in certain aspects of torso form. We discuss the major implications of the O. bambolii lower torso anatomy and how O. bambolii informs scenarios of hominoid evolution.

Zoogeographic significance of Dmanisi large mammal assemblage.

We undertake a comparative mammalian zoogeographic analysis with the aim of revealing the extent to which the Dmanisi Early Pleistocene large mammal assemblage resembles, at the genus level, African, Arabian, and Eurasian localities of similar age. The inclusion of Old World Pliocene and Pleistocene mammalian faunas provides us with insights into the provincial origins of specific mammalian taxa and permits us to assess the relative affiliation of the Dmanisi mammalian faunas to other faunas in the Old World. Our analysis also allows us to consider hypotheses about the timing and direction of zoogeographic connections between western Eurasia and Africa during the Early Pleistocene. We utilize multiple zoogeographic analytical tools as a cross-comparison of Dmanisi with 42 other Eurasian and African mammalian-bearing localities between 2.7 and 0.7 Ma. Overall, we find that Dmanisi compares most closely with a subgroup of Greek, Italian, and Spanish localities that are slightly younger than Dmanisi itself. This could suggest a progressive dispersal from East to West of the large mammal communities during the late Early Pleistocene and the first occurrence at Dmanisi, and then later in Western Europe, of some taxa such as Stephanorhinus ex gr. etruscus-hundsheimensis, Equus altidens, Bison georgicus, Soergelia minor, Megantereon whitei, Canis borjgali, Canis (Xenocyon) lycaonoides. Dmanisi's habitats included drier areas, probably of open wooded savannah and grassland and by mountainous to semiarid rocky terrain. There is evidence that Dmanisi records short intervals of increased aridity in the middle part of the succession contemporaneous with the occurrence of Homo.

A comparative study of the Early Pleistocene carnivore guild from Dmanisi (Georgia).

The carnivore guild of the Early Pleistocene site of Dmanisi is among the most diverse of the Early Pleistocene of the entire Old World. It includes 14 carnivoran taxa: Homotherium latidens, Megantereon whitei, Panthera onca georgica, Acinonyx pardinensis, Lynx issiodorensis; Pachycrocuta brevirostris; Canis (Xenocyon) lycaonoides, Canis borjgali, Vulpes alopecoides; Ursus etruscus; Lutra sp., Martes sp., Meles sp., and Pannonictis sp. The analysis of this rich carnivore guild was carried out under different methodological approaches to compare the assemblage with other chronological coeval European, Asian, and African sites from a paleobiological perspective. To achieve the goal, we used a permutational hierarchical method called boostrapping cluster analysis based on taxonomic absence/presence matrices (at both generic and specific level) and on ecological matrices (considering dietary preferences/hunting strategies of each carnivoran) and carried out Mantels tests assessing magnitude of time, space, ecology, and taxonomy as source of difference between guilds. Our results suggest a close similarity among the Dmanisi carnivore assemblage and other guilds recorded from European late Villafranchian sites such as Pirro Nord, Venta Micena, and Apollonia 1 and, in a lesser extent, to European Epivillafranchian sites as Vallonnet, Untermassfeld, or the Vallparadís Section. Early to Middle Pleistocene Asian carnivore assemblages display several similarities with the Dmanisi guild mainly in the record and diversity of felid and the canid ecomorphotypes. Eastern African sites such as Olduvai and Omo, as well as South African sites, display a lower similarity with the studied sample, basically for the most diverse hyenid taphocoenoses. To sum up, the present study suggests a close similarity between the Dmanisi carnivore guild and other European Late Early Pleistocene assemblages without close parallels with African or Asian assemblages.

The Dmanisi Equus: Systematics, biogeography, and paleoecology.

The Equus datum has been established as a geochronologic 'instantaneous' migratory event of a North American Equus species into Eurasia at the beginning of the Pleistocene (2.58 Ma). A remarkable radiation of Equus followed across Eurasia and Africa. Dmanisi includes excellent remains of Equus, well calibrated between 1.85 and 1.76 Ma. Our morphologic and morphometric analyses of the augmented Dmanisi Equus sample support the co-occurrence of Equus stenonis and Equus altidens in the sequence. Dmanisi E. stenonis is found to be morphologically similar to the European E. stenonis populations and represents the best well-dated easternmost occurrence of this species in Eurasia. The Dmanisi E. altidens represents the oldest well-calibrated occurrence of this species in Western Eurasia. Our analyses demonstrate that E. altidens extended its range westward from west Asia to Greece, Germany, Italy, Spain, and possibly France. Our results do not support distinguishing multiple subspecies of E. altidens, including E. altidens altidens, E. altidens granatensis and E. stenonis mygdoniensis. The Dmanisi cranial and postcranial samples exhibit morphologies close both to extant hemiones and zebras. Equus altidens is believed to have been well adapted to newly emergent arid environments in western Eurasia during the late Early and early Middle Pleistocene. The first occurrence of E. altidens at Dmanisi marks an important turnover in the horse communities of the late Early Pleistocene, with a dispersion of this species from West Asia to West Europe ca. 1.8 Ma.

Paleoecology, biochronology, and paleobiogeography of Eurasian Rhinocerotidae during the Early Pleistocene: The contribution of the fossil material from Dmanisi (Georgia, Southern Caucasus).

Rhinocerotidae represents a common element in the Eurasian Pleistocene faunas. Origin, dispersal route, and biochronology of several species are still poorly understood due to gaps in the fossil record, in particular from central Eurasia. A remarkable collection of rhinoceros remains was recovered from the Early Pleistocene site of Dmanisi (Georgia). This collection is unique for the Early Pleistocene Rhinocerotidae records due to its abundance in remains, its age (ca 1.8 Ma) and geographic position (between Eastern and Western Eurasia). Two crania, which display some different morphological traits, are assigned to two different morphotypes and investigated by means of geometric morphometrics using landmarks and semilandmarks. Shapes in lateral and dorsal views of different Rhinocerotini species are compared with the studied crania to infer paleoecological information. The shape in the lateral view reflects ecological niche, in particular feeding type from browsing to grazing, and it also represent taxonomic discrimination. Morphotypes 1 and 2 from Dmanisi fall in two different clusters, corresponding to two different species, notably in lateral view. The results suggest a niche partitioning during the Early Pleistocene of Dmanisi between a browse-dominated and a grass-dominated mixed feeders, or possibly the presence of two ecomorphotypes of the same species. A comprehensive update of the Early Pleistocene occurrences of Eurasian Rhinocerotidae is reported in the discussion on the paleoecology of the extinct Northern Eurasian rhinocerotines.

A 450 million years long latitudinal gradient in age-dependent extinction.

Leigh Van Valen famously stated that under constant conditions extinction probability is independent of species age. To test this 'law of constant extinction', we developed a new method using deep learning to infer age-dependent extinction and analysed 450 myr of marine life across 21 invertebrate clades. We show that extinction rate significantly decreases with age in > 90% of the cases, indicating that most species died out soon after their appearance while those which survived experienced ever decreasing extinction risk. This age-dependent extinction pattern is stronger towards the Equator and holds true when the potential effects of mass extinctions and taxonomic inflation are accounted for. These results suggest that the effect of biological interactions on age-dependent extinction rate is more intense towards the tropics. We propose that the latitudinal diversity gradient and selection at the species level account for this exceptional, yet little recognised, macroevolutionary and macroecological pattern.

Understanding climate's influence on the extinction of Oreopithecus (late Miocene, Tusco-Sardinian paleobioprovince, Italy).

Despite its long history of scientific study, the causes underlying the extinction of the insular hominoid Oreopithecus bambolii are still a matter of ongoing debate. While some authors consider intense tectonism and invading species the cause of its extinction ca. 6.7 Ma, others propose climatic change as the main contributing factor. We rely on long-term patterns of tooth wear and hypsodonty of the Baccinello and Fiume Santo herbivore-faunas to reconstruct changes in habitat prior to, during and after the extinction. While a mosaic of habitats was represented in Baccinello V1 (as shown by a record of browsers, mixed feeders and species engaged in grazing), more closed forests (higher proportion of browsers, shortage of mixed feeders and lack of grazers) characterised Baccinello V2. Finally, there was a partial loss of canopy cover and development of open-patches and low-abrasive grasses in Baccinello V3 (as denoted by new records of taxa involved in grazing)-although still dominated by a forested habitat (since browse was a component in all diets). Our results provide evidence for two perceptible shifts in climate, one between 8.1 and 7.1 Ma and other ca. 6.7 Ma, though this latter was not drastic enough to lead to intensive forest loss, substantially alter the local vegetation or affect Oreopithecus lifestyle-especially if considering the growing evidence of its versatile diet. Although the disappearance of Oreopithecus is complex, our data reject the hypothesis of environmental change as the main factor in the extinction of Oreopithecus and Maremma fauna. When our results are analysed together with other evidence, faunal interaction and predation by invading species from mainland Europe seems to be the most parsimonious explanation for this extinction event. This contrasts with European hominoid extinctions that were associated with major climatic shifts that led to environmental uniformity and restriction of the preferred habitats of Miocene apes.

A partial Homo pelvis from the Early Pleistocene of Eritrea.

Here we analyze 1.07-0.99 million-year-old pelvic remains UA 173/405 from Buia, Eritrea. Based on size metrics, UA 173/405 is likely associated with an already described pubic symphysis (UA 466) found nearby. The morphology of UA 173/405 was quantitatively characterized using three-dimensional landmark-based morphometrics and linear data. The Buia specimen falls within the range of variation of modern humans for all metrics investigated, making it unlikely that the shared last common ancestor of Late Pleistocene Homo species would have had an australopith-like pelvis. The discovery of UA 173/405 adds to the increasing number of fossils suggesting that the postcranial morphology of Homo erectus s.l. was variable and, in some cases, nearly indistinguishable from modern human morphology. This Eritrean fossil demonstrates that modern human-like pelvic morphology may have had origins in the Early Pleistocene, potentially within later African H. erectus.

Isotopic reconstructions of habitat change surrounding the extinction of Oreopithecus, the last European ape.

OBJECTIVE: Oreopithecus bambolii was the last hominoid to survive in Europe. The purpose of this investigation was to reconstruct, through stable isotope analyses, Oreopithecus' habitat, subsistence behavior, and changes in habitat that may have led to its extinction. METHODS: Carbon and oxygen stable isotopes from inorganic carbonate in tooth enamel from Oreopithecus and its contemporaneous faunas from localities in Tuscany and Sardinia were sampled. Also the fauna from localities in Tuscany shortly after Oreopithecus went extinct were sampled. RESULTS: Results indicated that Oreopithecus, compared with most modern hominoids, inhabited forests that probably had a more open canopy. At Tuscan localities, Oreopithecus yields some of the highest carbon isotope values but some of the lowest oxygen, suggesting a diet that may have included tubers or aquatic vegetation. Relatively higher oxygen values in Sardinia suggested that its diet included arboreal foods as well. Among modern and fossil hominoids, Oreopithecus only resembled chimpanzees living outside of rainforests. It also resembled Ardipithecus in carbon isotope values, suggesting possible similarities in feeding strategies concordant with shared skeletal features between Oreopithecus and early hominins. Isotope values from post-Oreopithecus faunas indicated a shift to more forested conditions, unlike other hominoid extinctions associated with loss of forest. CONCLUSIONS: Isotopic reconstructions of Oreopithecus' habitat and changes associated with its extinction indicated that its paleoecology was unique among hominoids. However, these reconstructions also suggested that like other hominoids, Oreopithecus was susceptible to changes in seasonality of precipitation, and it may have used wetlands as a buffer to seasonal regimes. Am J Phys Anthropol 160:254-271, 2016. © 2016 Wiley Periodicals, Inc.

The endocast of the one-million-year-old human cranium from Buia (UA 31), Danakil Eritrea.

OBJECTIVES: The Homo erectus-like cranium from Buia (UA 31) was found in the Eritrean Danakil depression and dated to 1 million years. Its outer morphology displays archaic traits, as well as distinctive and derived characters. The present study provides the description and metric comparison of its endocranial anatomy. MATERIALS AND METHODS: UA 31 was originally filled by a diffuse concretion. Following its removal and cleaning, the endocast (995 cc) was reconstructed after physical molding and digital scan. Its morphology is here compared with specimens belonging to different human taxa, taking into account endocranial metrics, cortical traits, and craniovascular features. RESULTS: The endocast is long and narrow when compared to the H. erectus/ergaster hypodigm, although its proportions are compatible with the morphology displayed by all archaic and medium-brained human species. The occipital areas display a pronounced bulging, the cerebellum is located in a posterior position, and the middle meningeal vessels are more developed in the posterior regions. These features are common among specimens attributed to H. erectus s.l., particularly the Middle Pleistocene endocasts from Zhoukoudian. The parietal lobes are markedly bossed. This lateral bulging is associated with the lower parietal circumvolutions, as in other archaic specimens. This pronounced parietal curvature is apparently due to a narrow cranial base, more than to wider parietal areas. CONCLUSIONS: The endocast of UA 31 shows a general plesiomorphic phenotype, with some individual features (e.g., dolichocephaly and rounded lower parietal areas) which confirm a remarkable degree of morphological variability within the H. erectus/ergaster hypodigm. Am J Phys Anthropol 160:458-468, 2016. © 2016 Wiley Periodicals, Inc.

First record of Mesopithecus (Cercopithecidae, Colobinae) from the Miocene of the Iberian Peninsula.

We report dental remains of the extinct colobine monkey Mesopithecus from the Turolian (MN13, Late Miocene, ca. 6.23 Ma) locality of Venta del Moro (Valencia, Spain). They include most of the deciduous dentition and the unerupted germs of the first molars of a single infantile individual, as well as two lower left lateral incisors from two additional individuals. On the basis of morphometric comparisons, mainly based on the M1s, these remains are attributed to the Late Miocene species Mesopithecus pentelicus. They represent a significant addition to the knowledge of the deciduous dentition of this taxon, much less well-known than the permanent dentition. Although this genus was widely distributed from the Late Miocene through the Pliocene across Europe, southwestern Asia, Pakistan, and China, until now its occurence in the Late Miocene of the Iberian Peninsula had not been documented conclusively. Hence, the reported remains considerably enlarge southwestwards the known geographic distribution of Mesopithecus. The presence of this genus at Venta del Moro must be understood within the framework of the significant faunal turnover that took place in European faunas during the latest Turolian (the second Messinian mammalian dispersal), which is further documented at this locality by the occurrence of other eastern immigrants. At the same time, the presence of M. pentelicus at this site agrees well with previous paleoenvironmental and sedimentological evidence, indicating a lacustrine depositional environment with strong hydrologic seasonality.

A thorny question: the taxonomic identity of the Pirro Nord cervical vertebrae revisited.

The past geographic distribution of the genus Theropithecus (Primates: Cercopithecidae) is mainly restricted to Africa. Outside that continent, the earliest reported records of this genus consist of a calcaneus of cf. Theropithecus sp. from 'Ubeidiya (Israel, 1.6-1.2 Ma [millions of years ago]), as well as three associated cervical vertebrae from Pirro Nord (Italy, 1.7-1.3 Ma) attributed to Theropithecus sp. The attribution of the Pirro Nord vertebrae to this genus has been disputed on morphometric grounds, although their assignment to a large-bodied cercopithecid has remained undisputed. Here we report unpublished cervical vertebral specimens with a similar morphology and, given their significance for the paleobiogeography of Theropithecus (purportedly representing its earliest European record), we re-evaluate their taxonomic attribution. In particular, we reconsider the possibility that they belong to another non-primate mammal recorded at this site. Based on both qualitative and metric morphological comparisons, we strongly favor an alternative attribution of the cervical vertebrae from Pirro Nord to the large porcupine Hystrix refossa, which is widely documented at the site by both dentognathic and other postcranial remains. We therefore conclude that the dispersal of Theropithecus out of Africa before ca. 1 Ma (when it is recorded by dental remains from Cueva Victoria, Spain) is currently based only on the calcaneus from 'Ubeidiya tentatively attributed to this genus.

The late Early Pleistocene human dental remains from Uadi Aalad and Mulhuli-Amo (Buia), Eritrean Danakil: macromorphology and microstructure.

Fieldwork performed during the last 15 years in various Early Pleistocene East African sites has significantly enlarged the fossil record of Homo erectus sensu lato (s.l.). Additional evidence comes from the Danakil Depression of Eritrea, where over 200 late Early to early Middle Pleistocene sites have been identified within a ∼1000 m-thick sedimentary succession outcropping in the Dandiero Rift Basin, near Buia. Along with an adult cranium (UA 31), which displays a blend of H. erectus-like and derived morpho-architectural features and three pelvic remains, two isolated permanent incisors (UA 222 and UA 369) have also been recovered from the 1 Ma (millions of years ago) Homo-bearing outcrop of Uadi Aalad. Since 2010, our surveys have expanded to the nearby (4.7 km) site of Mulhuli-Amo (MA). This is a fossiliferous area that has been preliminarily surveyed because of its exceptional concentration of Acheulean stone tools. So far, the site has yielded 10 human remains, including the unworn crown of a lower permanent molar (MA 93). Using diverse analytical tools (including high resolution µCT and µMRI), we analysed the external and internal macromorphology and microstructure of the three specimens, and whenever possible compared the results with similar evidence from early Homo, H. erectus s.l., H. antecessor, H. heidelbergensis (from North Africa), Neanderthals and modern humans. We also assessed the UA 369 lower incisor from Uadi Aalad for root completion timing and showed that it compares well with data for root apex closure in modern human populations.

The morphology of Oreopithecus bambolii pollical distal phalanx.

Oreopithecus bambolii is a Late Miocene ape from Italy, first described in the late 19th century. Its interpretation is still highly controversial, especially in reference to its hand proportions and thumb morphology. In this study, the authors provide detailed descriptions of the available Oreopithecus pollical distal phalanx (PDP) specimens, as well as bivariate and multivariate morphometric analyses in comparison with humans, extant apes, selected anthropoid monkeys, and available Miocene PDP specimens. The multivariate results reveal two opposite poles on the hominoid PDP shape spectrum: on one side, a mediolaterally broad and dorsopalmarly short human PDP, and on the other side, the narrow and "conical" PDP of chimpanzees and orangutans. The authors contend that Oreopithecus exhibits intermediate PDP proportions that are largely primitive for hominoids because it shares morphological similarities with Proconsul. Furthermore, Oreopithecus displays a mediolaterally wide tuft for a hominoid, as well as a palmarly elevated attachment for a long tendon of a flexor muscle that is associated at its proximal edge with a proximal fossa and at its distal edge with an ungual fossa. These nonmetrical traits have been associated in humans with their capability to oppose and contact the proximal pads of the thumb and fingers, that is, pad-to-pad precision grasping. These traits reinforce previous studies that indicate a human-like thumb-to-hand length ratio compatible with pad-to-pad precision grasping in Oreopithecus. Although specific hand use is still unresolved in Oreopithecus, the results suggest enhanced manipulative skills (unrelated to stone tool-making) in this taxon relative to other (extant or fossil) hominoids.

Postcranial evidence from early Homo from Dmanisi, Georgia.

The Plio-Pleistocene site of Dmanisi, Georgia, has yielded a rich fossil and archaeological record documenting an early presence of the genus Homo outside Africa. Although the craniomandibular morphology of early Homo is well known as a result of finds from Dmanisi and African localities, data about its postcranial morphology are still relatively scarce. Here we describe newly excavated postcranial material from Dmanisi comprising a partial skeleton of an adolescent individual, associated with skull D2700/D2735, and the remains from three adult individuals. This material shows that the postcranial anatomy of the Dmanisi hominins has a surprising mosaic of primitive and derived features. The primitive features include a small body size, a low encephalization quotient and absence of humeral torsion; the derived features include modern-human-like body proportions and lower limb morphology indicative of the capability for long-distance travel. Thus, the earliest known hominins to have lived outside of Africa in the temperate zones of Eurasia did not yet display the full set of derived skeletal features.

Increase on environmental seasonality through the European Early Pleistocene inferred from dental enamel hypoplasia.

An in-depth study of the Early Pleistocene European remains of Hippopotamus has allowed the first detailed description of the incidence and types of dental alterations related to palaeopathologies and potentially linked to climatic and environmental factors. The results of a long-term qualitative and quantitative assessment highlight the importance of nutrient deficiencies on the development of dental enamel hypoplasia in Hippopotamus. Glacial cyclicity and the resulting changes in humidity and plant community structure conditioned the local environments critical for the survival of this taxon. Two main intervals of putative constrained nutritionally restrictions were detected at ca. 1.8 Ma and ca. 0.86 Ma (i.e., MIS63 and MIS21, respectively). Statistical comparisons show an increase in the frequency of dental hypoplasia between these two chronological periods, thus reinforcing the idea of increased seasonality in the circum-Mediterranean environments during the Early Pleistocene.

The earliest Ethiopian wolf: implications for the species evolution and its future survival.

In 2017, a hemimandible (MW5-B208), corresponding to the Ethiopian wolf (Canis simensis), was found in a stratigraphically-controlled and radio-isotopically-dated sequence of the Melka Wakena paleoanthropological site-complex, on the Southeastern Ethiopian Highlands, ~ 2300 m above sea level. The specimen is the first and unique Pleistocene fossil of this species. Our data provide an unambiguous minimum age of 1.6-1.4 Ma for the species' presence in Africa and constitutes the first empirical evidence that supports molecular interpretations. Currently, C. simensis is one of the most endangered carnivore species of Africa. Bioclimate niche modeling applied to the time frame indicated by the fossil suggests that the lineage of the Ethiopian wolf faced severe survival challenges in the past, with consecutive drastic geographic range contractions during warmer periods. These models help to describe future scenarios for the survival of the species. Projections ranging from most pessimistic to most optimistic future climatic scenarios indicate significant reduction of the already-deteriorating territories suitable for the Ethiopian Wolf, increasing the threat to the specie's future survival. Additionally, the recovery of the Melka Wakena fossil underscores the importance of work outside the East African Rift System in research of early human origins and associated biodiversity on the African continent.

Carbon isotopic record of terrestrial ecosystems spanning the Late Miocene extinction of Oreopithecus bambolii, Baccinello Basin (Tuscany, Italy).

Oreopithecus bambolii is a Late Miocene hominoid with an extensive fossil record in the Baccinello Basin (Tuscany, Italy), and was the only western European hominoid to survive a major extinction event ca. 9.6 Ma (millions of years ago). Oreopithecus lived in the insular Tusco-Sardinian paleobioprovince, where it evolved many unique anatomical specializations that make it important for understanding the mechanisms and history of Late Miocene hominoid evolution. The eventual extinction of Oreopithecus and its associated fauna ca. 6.5 Ma has generally been attributed to interaction with species that arrived from continental Europe following tectonic collision of the Tusco-Sardinian province with mainland Italy, but palynological, paleontological, and sedimentological records indicate an environmental shift toward more variable climate across the extinction event. To explore the possibility of environmental change as a contributing factor in the extinction of Oreopithecus, we developed a stable carbon and oxygen isotope record from organic matter in paleosols from the Baccinello Basin. These data show very low temporal and spatial variability (indicating plant ecosystem stability through time and space) and provide no evidence for ecologically significant changes in floral composition spanning the extinction event, suggesting that environmental change was not an underlying cause for the extinction of Oreopithecus and its associated fauna. The carbon isotope values fall entirely within the range of isotopic variability for modern plants following the C(3) photosynthetic pathway (trees, shrubs, cool-season grasses), indicating that C(4) vegetation (warm-season grasses) was not an important component of biomass. When corrected for temporal variation in the carbon isotopic composition of atmospheric carbon dioxide, the paleosol carbon isotope values are consistent with predicted values based on modern plants and the Baccinello palynoflora, supporting the reliability of paleosol isotopic records as paleoecological proxies.