Lorenzo Rook

BIOCHRONOLOGY OF SELECTED MAMMALS, MOLLUSCS AND OSTRACODS FROM THE MIDDLE PLIOCENE TO THE LATE PLEISTOCENE IN ITALY. THE STATE OF THE ART

The Authors have elaborated four range charts of mammalian (large and micro), molluscs and fresh-water and brackish ostracodes faunas, for the selected Plio-Pleistocene fossiliferous localities of the Italy. A new Mammal Age (Aurelian) correlatable to late Middle and Late Pleistocene has been defined. Inside this age two Faunal Units (Torre in Pietra and Vitinia) have been defined as characteristic for Early and Middle Aurelian, while no gisements have been chosen for the late Aurelian. Biochronological units are calibrated on magnetostratigraphic and isotopic scales and by radiometric datings.

A one-million-year-old Homo cranium from the Danakil (Afar) Depression of Eritrea

One of the most contentious topics in the study of human evolution is that of the time, place and mode of origin of Homo sapiens. The discovery in the Northern Danakil (Afar) Depression, Eritrea, of a well-preserved Homo cranium with a mixture of characters typical of H. erectus and H. sapiens contributes significantly to this debate. The cranium was found in a succession of fluvio-deltaic and lacustrine deposits and is associated with a rich mammalian fauna of early to early-middle Pleistocene age. A magnetostratigraphic survey indicates two reversed and two normal magnetozones. The layer in which the cranium was found is near the top of the lower normal magnetozone, which is identified as the Jaramillo subchron. Consequently, the human remains can be dated at ∼1 million years before present.

The Early Messinian Velona basin (Siena, central Italy): paleoenvironmental and paleobiogeographical reconstructions

Abstract A multi-disciplinary study of the basal lacustrine succession of the Velona basin (Tuscany, central Italy) provides informations about the paleoenvironmental and paleogeographical evolution of a post-collisional basin located in the Mediterranean area. Detailed sedimentological, paleontological (molluscs, ostracods, mammals, charophytes and pollen) and geochemical analyses on biogenic carbonates were carried out on a 66-m-thick muddy–sandy succession. Integrating the vertical distribution of selected species of ostracods and molluscs with the range of the mammal assemblage it has been possible to correlate the basal succession of the Velona basin to the Early Messinian (pre-evaporitic) corresponding to the lower part of the MN 13 zone. The basal portion of the Velona filling deposits corresponds to an unstable shallow lacustrine/marshy environment, rich in aquatic vegetation, surrounded by swamps dominated by Taxodiaceae and uplands dominated by warm temperate deciduous forests. Waters were generally brackish (oligo/mesohaline), alternating with hypohaline episodes. Salinity changes recorded by the faunal assemblages do not parallel with changes in the geochemical signatures in ostracod shells and charophyte gyrogonites. Geochemistry of biogenic carbonates points to an athalassic origin of the water salinity probably linked to the dissolution of the Triassic evaporites of the basement. Thus, the absence of connections between the Velona basin and the Mediterranean Sea during Early Messinian is confirmed. Ostracods, molluscs and mammals show a central European paleobiogeographical affinity, showing that, at the time of deposition of the Velona filling deposit, the endemic Tusco-Sardinian paleobioprovince was already disrupted and the northwards connections were noticeable. On the other hand, ostracods do not show any paleobiogeographic affinity with the ostracod assemblages of the Paratethyan realm, suggesting that no links between Mediterranean and Paratethys were present at that time.

LATE PLEISTOCENE SURVIVAL OF THE SABER-TOOTHED CAT HOMOTHERIUM IN NORTHWESTERN EUROPE

Saber-toothed cats (Machairodontinae) were wide-spread, top predators of the Pleistocene terrestrial ecosystem. In Europe, they previously were known only from the early and middle Pleistocene (Adam, 1961; Turner and Anton, 1997), and their fossils are always extremely rare. The previous youngest record was from Steinheim a/d Murr, Germany, where an upper canine of Homotherium was found in a stratum dated to ca. 0.3 Ma (Adam, 1961). In this paper, we describe a well-preserved den- tary of Homotherium latidens dated by 14 C to be late Pleisto-

Last Glacial mammals in South America: a new scenario from the Tarija Basin (Bolivia)

The chronology, sedimentary history, and paleoecology of the Tarija Basin (Bolivia), one of the richest Pleistocene mammalian sites in South America, are revised here based on a multidisciplinary study, including stratigraphy, sedimentology, geomorphology, paleontology, isotope geochemistry, and 14C geochronology. Previous studies have indicated a Middle Pleistocene age for this classic locality. We have been able to obtain a series of 14C dates encompassing all the fossil-bearing sequences previously studied in the Tarija Basin. The dated layers range in age from about 44,000 to 21,000 radiocarbon years before present (BP), indicating that the Tarija fauna is much younger than previously thought. Glacial advances correlated to marine isotopic stages (MIS) 4 and 2 (ca. 62 and 20 ka BP, respectively) are also documented at the base and at the very top of the Tarija–Padcaya succession, respectively, indicating that the Bolivian Altiplano was not dry but sustained an ice cap during the Last Glacial Maximum. The results of this multidisciplinary study enable us to redefine the chronological limits of the Tarija sequence and of its faunal assemblage and to shift this paleontological, paleoclimatological, and paleoecological framework to the time interval from MIS 4 to MIS 2.

Modern macaque dietary heterogeneity assessed using stable isotope analysis of hair and bone.

Dietary variability might have been a major factor in the dispersal and subsequent persistence of the genus Macaca in both tropical and temperate areas. Macaques are found from northern Africa to Japan, yet there have been few systematic attempts to compare diets between different modern populations. Here we have taken a direct approach and sampled museum-curated tissues (hair and bone) of Macaca mulatta (rhesus macaques) for carbon and nitrogen stable isotope dietary analyses. Samples from India, Vietnam, and Burma (Myanmar) were taken, representing both tropical and temperate populations. The delta(13)C values obtained from hair show that the temperate macaques, particularly those from Uttar Pradesh, have a delta(13)C signature that indicates at least some use of C(4) resources, while the tropical individuals have a C(3)-based diet. However, delta(13)C values from bone bioapatite indicate a C(3)-based diet for all specimens and they do not show the C(4) usage seen in the hair of some animals, possibly because bone represents a much longer turnover period than that of hair. The results of delta(15)N analyses grouped animals by geographic region of origin, which may be related to local soil nitrogen values. The greatest variation in delta(15)N values was seen in the specimens from Burma, which may be partly due to seasonality, as specimens were collected at different times of year. We also investigated the relationship between the hair, bone collagen, and bone bioapatite delta(13)C results, and found that they are highly correlated, and that one tissue can be used to extrapolate results for another. However, our results also suggest that hair may pick up discrete feeding traces (such as seasonal usage), which are lost when only bone collagen and bioapatite are examined. This has important implications for dietary reconstructions of archaeological and paleontological populations.

MicroCT Scan in paleobiology: application to the study of dental tissues

State of the art in paleoanthropological and paleoprimatological research foresees the use of advanced non-destructive investigative approaches. Microcomputed tomography (microCT) is a fundamental tool, since it offers the opportunity to get high quality morphological information with high spatial resolution. We carried out the set-up of an experimental microCT system able to examine paleobiological samples. The equipment can operate on small objects (size up to 3 cm) with a nominal spatial resolution of 30 μm, allowing their 3D volume reconstruction and morphometric analysis. This approach represents a forefront technique in paleobiological studies, successfully employed only in a limited number of advanced research centers. A specific program of microCT analysis has been planned on a sample of human and non-human fossil primate dentitions, in order to assess the specific nature of a number of tooth lesions (e.g. caries versus abrasion). This currently in progress experimental activity represents the first step for the set-up of a research center specifically devoted to the realization of advanced studies in the field of archaeo-paleobiology.

Enigmatic Anthropoid or Misunderstood Ape

The phylogenetic status of Oreopithecus bambolii from the late Miocene of Italy has been a source of much debate since the species was first described in 1872. This observation in itself is hardly surprising, since most fossil primates known since the end of the last century have acquired a complicated history of ideas on their taxonomic and phylogenetic placement. What is so unusual about Oreopithecus,however, is that this debate has continued to the present, This chapter is dedicated to the memory of Johannes Hurzeler (1908–1995) whose profoundly important contribution to the study of Oreopithecus and the Baccinello faunas has influenced both of us to follow the same path. The “keeper of the abominable coalman” may no longer be with us, but his remarkable discoveries will undoubtedly continue to inspire and excite the imagination of future generations of vertebrate paleontologists. and there are no indications from the current literature that its phylogenetic status is close to being resolved (e.g., Delson, 1988; Harrison, 1991; Andrews, 1992; Begun, 1994). The problem is especially perplexing because Oreopithecus is one of the best-known fossil primates. It is easy to comprehend how researchers might have difficulties establishing the relationships of fossil taxa based on one or two isolated teeth or just a few jaw fragments, but Oreopithecus is known from an almost complete subadult skeleton, several partial skeletons, and dozens of relatively complete mandibles and crania. We find ourselves, therefore, in the uncomfortable position of not being able to rely on the excuse favored by most paleontologists in this situation, that the solution to the problem lies in finding more and better material. In the case of Oreopithecus we have all the material we need; the shortcomings are not in the available evidence, but in the way that we view it. So why is it that several generations of primate paleontologists have failed to agree on the evolutionary status of Oreopithecus? A review of the literature clearly shows that part of the problem is as much sociological as it is scientific, involving a complex interplay of different philosophies, politics, and personalities that are difficult to tease apart from the purely empirical evidence. The consequence of these and other contributing factors is that Oreopithecus is perceived to be an “enigmatic anthropoid” (Delson, 1987), one that does not readily conform to our expectations of extinct hominioids based on other lines of evidence. However, is it really that Oreopithecus represents a piece of the puzzle that does not fit, or is it simply because the limitations that we impose on our expectations of hominoid evolution are too narrow, and that Oreopithecus is being made to fit the wrong puzzle altogether? We suspect that it is the latter that represents the crux of the Oreopithecus problem. Of the various factors that have served to confound recent attempts to resolve the phylogenetic relations of Oreopithecus, three can be identified that we believe have had a particularly profound impact.

African Crocodylians in the Late Neogene of Europe: A Revision of Crocodylus Bambolii Ristori, 1890

Abstract Genus Crocodylus is considered to have originated in Africa during the Early Miocene but it is only in the Late Miocene that there are evidences of dispersal toward Europe, where tomistomines and the alligatoroid Diplocynodon were widespread since the Paleogene. Revision of the type material of Crocodylus bambolii Ristori, 1890, a Tortonian crocodylian from the renowned Oreopithecus localities in central Italy, excludes it from Diplocynodon. The morphology of the remains, combined with chronology and biogeography, confirms its identity as cf. Crocodylus. The validity of the species Crocodylus bambolii is however not supported by the available morphological characters so that a solid differential diagnosis cannot be realized. It is therefore here proposed to consider Crocodylus bambolii as a nomen dubium. The European Late Miocene distribution of short-snouted crocodylians sees only alligatoroids in western Europe and, curiously, only crocodylids in the Central Mediterranean area. The Tusco-Sardinian and the Apulo-Abruzzi paleobioprovinces, whose lands are nowadays part of the Italian peninsula, are apparently the only European areas inhabited by short-snouted crocodylids, which are at the same time among the last crocodylians of the continent. The isolated teeth from Fiume Santo and Scontrone, two localities of these palebioprovinces, are also not Diplocynodon-like, but further material is needed to identify their owners with confidence.

Hypothesis on the cause of extinction of the South American mastodonts

Abstract Paleontological, geomorphological and sedimentological investigations on the Cangahua Formation in the Interandean depression of Northern and Central Ecuador have provided information on the evolution of the Andean paleoenvironment during the Late Pleistocene. Pyroclastic and windblown sediments were deposited during cold and dry phases of the last glaciation, interrupted many times by the development of forest-steppe and steppe paleosoils during interstadials. An erosional phase which closed the Cangahua sedimentation was followed by the deposition of colluvial sediments, characterized by a high number of minor pedogenetic episodes. The colluviums are confidently referable to the Holocene. The upper part of the Cangahua Formation is rich in mammal fossils and is probably referable to the Last Glacial Maximum. The fossiliferous sequences suggest that mastodonts disappeared before mylodonts and equids. We hypothesize that the increased cold and aridity of the Last Glacial Maximum, which deeply affected the Cordillera, caused the extinction of most of the megafauna and the mastodonts seem to have been the most sensitive to the environmental degradation. The final history of South American mastodonts, represented by Haplomastodon and Stegomastodon, spans the latest Pleistocene and probably the earliest Holocene. Haplomastodon was dispersed in the highlands within the tropical belt and Stegomastodon in plains of the southernmost part of Brazil, in Paraguay, Uraguay, Argentine, central and northern Chile. Both Haplomastodon and Stegomastodon suffered the same negative effects of the Last Glacial Maximum when their habitats underwent intense desertifications under dry and cold conditions. They disappeared in a mosaic way in the course of the latest Pleistocene, the last representatives probably surviving in favorable restricted areas where however the considerably increased selective pressure was in the long run devastating. In our opinion the human impact was not a determinant in causing mastodont extinction.