G. Ficcarelli

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.

Taxonomic remarks on the South American Mastodons referred to Haplomastodon and Cuvieronius

New mastodon finds collected in the Province of Carchi (Northern Ecuador) give further evidence that in South America Haplomastodon and Cuvieronius are monospecific. Of all the specific names referred to the genus Haplomastodon, only chimborazi must be considered valid as it alone was based on significant diagnostic material. As far as the genus Cuvieronius is concerned a new type species, Cuvieronius tarijensis, is proposed as the type specimen of Cuvieronius hyodon likely belongs to Haplomastodon.

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.

New Haplomastodon findsfrom the Late Pleistocene of northern Ecuador

Abstract New mastodon remains were collected in the Carchi Province, northern Ecuador. The levels from which the fauna was collected are referred to the Late Pleistocene (Late Lujanian Mammal Age). On the basis of this fossil material, we conclude that probably only one species of Haplomastodon was present in Ecuador, most of tropical South America, and temperate southwestern Brazil. At the present state of knowledge we feel it convenient to classify the different Haplomastodon demes of this faunal province as Haplomastodon ex gr. waringi ( Holland , 1920 ).

Cesi, an early Middle Pleistocene site in the Colfiorito Basin (Umbro-Marchean Apennine), central Italy

Near the village of Cesi, at the head of the Chienti River, in the Colfiorito Basin (Umbro-Marchean Apennines, central Italy), fluvio-lacustrine deposits have yielded mammal fossil remains. The results of a multidisciplinary investigation indicate that the vertebrate-bearing sediments date about 700 ka and accordingly provide a fossil assemblage for the Middle–Late Galerian. Palynological investigations carried out from sediments underlying the fossiliferous level suggest predominantly cold and dry conditions, whereas the fauna suggests a slight climatic amelioration towards cool and moist conditions in the uppermost part of the sequence.

FOSSIL ELEPHANTS FROM BUIA (NORTHERN AFAR DEPRESSION, ERITREA) WITH REMARKS ON THE SYSTEMATICS OF ELEPHAS RECKI (PROBOSCIDEA, ELEPHANTIDAE)

Abstract A succession of five fossiliferous levels near Buia in the northern Danakil (Afar) Depression of Eritrea has produced an abundant early Pleistocene fauna including a ca. 1.0 Ma cranium of Homo. Elephas is well represented at many sites; with one exception the entire Buia Elephas sample represents a relatively derived member of the Elephas recki lineage. Univariate and multivariate analysis of dental characters demonstrates that the Buia sample is intermediate between E. recki ileretensis (Koobi Fora, Ileret) and E. r. recki (Beds 3 and 4 at Olduvai). The biologic reality of the separation of E. recki into five chronologically successive subspecies is questionable. Our analysis supports the hypothesis that E. r. ileretensis and E. r. recki form a single phyletic lineage.

PALEOMAGNETIC AND PALYNOLOGIC INVESTIGATIONS IN THE UPPER VALDARNO BASIN (CENTRAL ITALY): CALIBRATION OF AN EARLY VILLAFRANCHIAN FAUNA

The silty clays embedding an early Villafranchian mammal fauna of the Triversa faunal unit (f.u.) have been paleomagnetically and palynologically studied in a continuous sequence exposed in the Santa Barbara quarry.The study has allowed to date the earliest occurrence in Italy of a faunal assemblage of this unit and to define the corresponding climatic conditions. The sampled section has provided a magnetic polarity sequence of the late Gauss,where the fossiliferous layer fits the Kaena reversed interval.Its age of ca. 3.1 Ma,during subtropical climate conditions correlatable to the Reuverian of Netherlands, suggests an older age for the beginning of the Villafranchian, possibly associated to a more dramatic scenario able to trigger the faunal turnover.

Stratigraphy and paleontology of upper Pleistocene deposits in the interandean depression, northern Ecuador

Abstract In the Interandean Depression of northern Ecuador (Carchi Province), more than 50 m of pyroclastic and windblown deposits (Cangahua Formation) were deposited during the cold phases of the Quaternary, interrupted many times by the development of evolved paleosoils during interstadials. The deposition occurred during downcutting if the plateau and covered existing morphologic irregularities. The upper part of the Cangahua Formation includes three fossiliferous horizons that contain fauna of Lujanian Mammal Age. On the basis of geomorphologic, sedimentologic, and paleontologic evidence, the upper part of the Cangahua is referred to the latest Pleistocene. After this, a renewed phase of downcutting began, reflecting early Holocene climatic amelioration.

A new vertebrate fossiliferous site from the Late Quaternary at San José on the north coast of Ecuador: preliminary note

A new fossiliferous site is described south of Manta on the north coast of Ecuador. Estuarine sediments overlying Quaternary terraced deposits contain abundant vertebrate remains belonging to the following taxa: Eremotherium cf. laurillardi or E. rusconii, Haplomastodon chimborazi, and Geochelone s.l. On the basis of geological context and the fossil assemblage, a probable Early Holocene age is suggested, although a latest Pleistocene age cannot be ruled out. This discovery will provide crucial new information to enhance knowledge of the geologic and faunistic evolution of the area.