Federica Marcolini

PLIO-PLEISTOCENE FOSSIL VERTEBRATES OF MONTE TUTTAVISTA (OROSEI, EASTERN SARDINIA, ITALY), AN OVERVIEW

The preliminary results of the analisys of fossil vertebrate remains from 19 fissure fillings in the karst network at Monte Tuttavista (Orosei, NMoro) are reported. about 80 taxa, among fishes, amphibians, reptiles, birds and mammals have been recognised.These remains document the evolution of vertebrate assemblages in the Sardinian insular domain, during a time interval apparently spanning the Late Pliocene to Late Pleistocene or Holocene. A succession of at least four populating complexes has been identified which document the vertebrate colonisation phases from the Italian mainland and the following periods of insularity. Indeed, the occurrence of endemic taxa such as the murid Rhagapodemus minor , the primate Macaca cf. M. majori and the caprine Nesogoral , suggest some fissure fillings date to a phase close to the Plio/Pleistocene boundary since these taxa occur at the Sardinian locality Capo Figari I which has been dated to about 1.8 Ma. However, the presence of the hunting-hyaena Chasmaporthetes , never reported before in Sardinia, could suggest that the beginning of the vertebrate record of Monte Tuttavista is older, given that this carnivore is documented in European Middle Pliocene-Early Pleistocene localities. The vertebrate assemblages that document the most recent migratory phases in the karst network of Monte Tuttavista are characterised by the occurrence of the endemic megalocerine cervid Praemegaceros cazioti and the arvicolid Tyrrhenicola henseli which are comparable with those occurring in other Late Pleistocene and early Holocene Sardinian sites.

Mosaic evolution in first lower molars of Pliocene Ogmodontomys (Rodentia: Arvicolidae) from the Meade Basin of southwestern Kansas (USA)

Thirteen characters and four indices from nine stratigraphically superposed samples of Ogmodontomys first lower molars (m1s) from the Meade Basin of southwestern Kansas, spanning an interval of approximately 2.0 million years of the Early and Middle Pliocene, were measured and analyzed by a variety of statistical techniques. The proportion of enamel atolls on the m1 were also examined. There were no statistically significant changes in eight measurements and one index. Although statistically significant differences were found for five of the variables and three indices during the sampling period, two of these variables and the three indices were interpreted as displaying an overall pattern of stasis within which statistically significant changes occurred. Three occlusal measurements displayed directional trends. Two of these represented changes in widths of dentine fields between triangle pairs (T1-T2, T3-T4) and the third was the deepening of a buccal reentrant angle (BRA3), initially as the result of loss of the enamel atoll in the anteroconid between Fallen Angel B and Fox Canyon, presumably as the result of a speciation event from O. sawrockensis to O. poaphagus. A second significant deepening of BRA3 occurred during the late middle Blancan (Middle Pliocene), within the species O. poaphagus. Significant widening of the dentine field between T1-T2 also occurred at this time, whereas significant decrease of the field between T3-T4 occurred twice; once at the O. sawrockensis – O. poaphagus speciation event and once again from Deer Park to Paloma in O. poaphagus. When we include data from the Schmelzmuster (microhistological enamel banding pattern), the summary indicates a punctuated pattern of change in occlusal morphology and Schmelzmuster pattern, concentrated at the O. sawrockensis – O. poaphagus speciation event and again within O. poaphagus at various points in the Pliocene. The linea sinuosa (enamel-dentine junction), on the other hand, displays a more varied evolutionary pattern, with significant (though sometimes temporary) changes occurring throughout the history of both species. The most significant changes in m1 shape occur at the O. sawrockensis – O. poaphagus transition, but both phyletic change and “punctuated gradualism” (stairstep evolution) are also recorded in O. poaphagus.

Variation of the Schmelzmuster and Other Enamel Characters in Molars of the Primitive Pliocene Vole Ogmodontomys from Kansas

Variation in enamel microhistology (the schmelzmuster) and other features were examined in adult Ogmodontomys poaphagus molars from the Meade Basin of southwestern Kansas. Measurements of total enamel thickness and thickness of tangential enamel were taken on individual triangles of first upper molar samples from the superposed Ripley B, Hornet and Rexroad 2A local faunas. Although thickness of total enamel layers and the tangential zone were not statistically different between triangles and sites, the quality of tangential enamel on the trailing edges increased, from incipient tangential and well-developed tangential enamel (Ripley B and Hornet) to solely well-developed tangential enamel (Rexroad 2A). The fundamental schmelzmuster of O. poaphagus is radial enamel on the leading edges and radial plus incipient or well-developed tangential enamel on the trailing edges. These results support the assertion that the schmelzmuster is a consistent and genetically controlled character mosaic, and confirm suggestions in the literature that Ogmodontomys is distinct from Mimomys. Paired sample Student’s t-tests of trailing/leading edge samples for each triangle were used to test for differentiation. Although the molars of Ogmodontomys poaphagus appear undifferentiated under the light microscope, and are indeed separable from the distinctly negatively differentiated molars of Mimomys by this technique, our results show that the M1s of O. poaphagus are slightly negatively differentiated, with various triangles being either undifferentiated or negatively differentiated. O. sawrockensis has a more primitive schmelzmuster than O. poaphagus, and the presence of discrete (primitive) lamellar enamel on the apices of at least one triangle in 55% of the sample from Fallen Angel B, combined with the absence of lamellar enamel in molars of O. poaphagus from Fox Canyon and all subsequent Ogmodontomys samples, conclusively demonstrates that the Fallen Angel B population of O. sawrockensis was not ancestral to O. poaphagus in the Meade Basin. A unique mosaic of dental and size features indicates that the early Blancan O. pipecreekensis from Indiana is a sister species to O. sawrockensis and not ancestral to O. poaphagus.

Five million years of pocket gopher history in the Meade Basin of southwestern Kansas and northwestern Oklahoma

ABSTRACT n The Meade Basin record of pocket gophers extends from the latest Miocene (Buis Ranch local fauna) to modern time. A primitive species with hypsodont but rooted cheek teeth, Pliogeomys buisi, characterizes the late Hemphillian. Another species of Pliogeomys, P. louderbachi, is described here as a new species from the early Blancan. It is intermediate in dental and mandibular morphology between Pliogeomys and Geomys. The Geomys minor (= G. smithi) lineage displays a stepped dwarfing trend prior to its extinction, whereas the G. jacobi lineage demonstrates an overall pattern of stasis in size. G. jacobi is replaced by G. quinni at the end of the Pliocene, within which there is a significant directional size increase. A late Pliocene immigrant, the new species G. floralindae, appears in the Sanders assemblage. It is briefly replaced by an indeterminate small species in the Nash 72 local fauna. G. tobinensis is found in the Cudahy local fauna. Morphologically modern G. bursarius appears in the Meade Basin during the early Rancholabrean. A small, primitive species, Geomys adamsi, appears only during the early Pliocene at Fox Canyon, and transient Thomomys appear at various times during the Pleistocene, both apparently during cold intervals. A phylogenetic analysis suggests two clades, one uniting Pliogeomys russelli and Geomys adamsi and another including the remaining Meade Basin geomyines. Enhanced species turnover and the last push for modern mandibular morphology is most pronounced in sediments younger than about 2.6 million years ago, corresponding to the first global cooling heralding the Pleistocene.

LATE MIDDLE PLEISTOCENE COOL NON-MARINE MOLLUSC AND SMALL MAMMAL FAUNAS FROM LIVORNO (ITALY)

New stratigraphic data (exposed sections and boreholes) allowed a detailed reconstruction of the northern sector of the Terrazzo di Livorno (Central Italy). A new unit, called Corea formation was discovered and correlated to marine isotope stage (MIS) 6 and to its transition to MIS 5. This formation comprises, at its base, fluvial gravels and sands followed by fine-grained alluvial plain deposits. Non-marine molluscs, small mammals and pollen allow a reconstruction of the environment present during the deposition of the alluvial plain deposits. The environment was mainly an open space, though sparse woodlands should have been present. The non-marine fauna shows features intermediate between typical interglacial and glacial assemblages described so far in Italy. Worth of note is the presence of Orcula dolium and Vallonia enniensis , which now inhabit northern Italy. These findings improve our knowledge on the biogeography of Quaternary non-marine faunas of Central Italy. Stable isotopes data on land snail shells, freshwater shells and pedogenic carbonates showed that climate conditions were cooler than today (possibly 1-2°C less) with a significant amount of C4 vegetation, in an environment with moderately dry conditions.

Testing evolutionary dynamics on first lower molars of Pliocene Ogmodontomys (Arvicolidae, Rodentia) from the Meade Basin of southwestern Kansas (USA): A landmark-based approach

Abstract Landmark- and semilandmark-based geometric morphometrics were used to explore morphological variation in the occlusal surface and linea sinuosa (enamel-dentine junction) of first lower molars (m1s) of Ogmodontomys sawrockensis and O. poaphagus from the Meade Basin in southwestern Kansas. Morphological differences between the two species were determined in an effort to explore interspecific variation and to test the power of landmark geometry of dental variation for species discrimination. Significant differences were found between O. sawrockensis and O. poaphagus in both occlusal surface and the linea sinuosa patterns. Multivariate tests demonstrate that the most significant morphological changes occurred at the presumed O. sawrockensis-O. poaphagus speciation event. An intraspecific multivariate analysis of O. poaphagus m1s, however, also identified directional evolutionary tendencies in shape of both the occlusal surface and linea sinuosa.