Pliocene Research Articles

Rise and fall of Pliocene free-living corals in the Caribbean

Climate change is currently having an impact on shallow-water corals, and global circulation models predict that levels of p CO 2 and temperature will rise within the next century above anything recorded for at least the past 650 k.y. The Pliocene Epoch is a recent, albeit imperfect, geologic analog for such conditions in the Caribbean. Diverse communities of free-living solitary and flabelo-meandroid (FSFM) corals inhabited shallow nearshore to deeper oligophotic habitats of the Pliocene. FSFM corals were well suited to the low-angle depositional profiles, increased productivity, increased sedimentation, and warmer temperatures of the Pliocene. Origination rates of FSFM coral species between 8 and 4 Ma are roughly double other zooxanthellate corals. FSFM corals underwent abrupt extinction between 2 and 1 Ma, as environmental conditions changed and suitable habitat was eliminated. The evolutionary bottleneck of Pliocene–Pleistocene extinctions and relic steep-margined Pleistocene topography may leave modern faunas vulnerable as we return to Pliocene-like conditions.

New records of the fur seal Callorhinus (Carnivora: Otariidae) from the Plio-Pleistocene Rio Dell Formation of Northern California and comments on otariid dental evolution

ABSTRACT New fossils representing two species of the fur seal Callorhinus are reported from the uppermost Pliocene to lower Pleistocene Rio Dell Formation of northern California. The finds include latest Pliocene–earliest Pleistocene dentaries and postcrania of Callorhinus gilmorei, and a partial dentary of early Pleistocene age identified as Callorhinus sp. The aforementioned material is ascribed to C. gilmorei due to the incipient single-rooted condition of the p1–2, retention of double-rooted p3–m1, and overall small size. The dentary identified as Callorhinus sp. exhibits a more derived pattern of tooth morphology, including single-rooted p1–p4 (and double-rooted m1), larger size than C. gilmorei, and in the size range of extant Callorhinus ursinus (which typically exhibit fused roots on all postcanine teeth). Fusion of postcanine roots began with the p2 and continued posteriorly, and is likely an adaptation to accommodate crowded teeth anteriorly in the jaws. Callorhinus gilmorei has previously been reported from the upper Pliocene of southern California and Japan, and this new record extends the range of this taxon further north in the Northeast Pacific. Callorhinus sp. is the most complete pinniped fossil to be described from the early Pleistocene of the Northeast Pacific. The wide biogeographic range of Callorhinus during the Pliocene and Pleistocene documents the persistence of this taxon, potentially as a Pliocene-Holocene anagenetic lineage. This highlights the antiquity of the Callorhinus lineage, which has persisted in the Northeast Pacific since the Pliocene, establishing it as the oldest and earliest diverging crown otariid.

Are there pre-Quaternary geological analogues for a future greenhouse warming?

Given the inherent uncertainties in predicting how climate and environments will respond to anthropogenic emissions of greenhouse gases, it would be beneficial to society if science could identify geological analogues to the human race's current grand climate experiment. This has been a focus of the geological and palaeoclimate communities over the last 30 years, with many scientific papers claiming that intervals in Earth history can be used as an analogue for future climate change. Using a coupled ocean-atmosphere modelling approach, we test this assertion for the most probable pre-Quaternary candidates of the last 100 million years: the Mid- and Late Cretaceous, the Palaeocene-Eocene Thermal Maximum (PETM), the Early Eocene, as well as warm intervals within the Miocene and Pliocene epochs. These intervals fail as true direct analogues since they either represent equilibrium climate states to a long-term CO(2) forcing--whereas anthropogenic emissions of greenhouse gases provide a progressive (transient) forcing on climate--or the sensitivity of the climate system itself to CO(2) was different. While no close geological analogue exists, past warm intervals in Earth history provide a unique opportunity to investigate processes that operated during warm (high CO(2)) climate states. Palaeoclimate and environmental reconstruction/modelling are facilitating the assessment and calculation of the response of global temperatures to increasing CO(2) concentrations in the longer term (multiple centuries); this is now referred to as the Earth System Sensitivity, which is critical in identifying CO(2) thresholds in the atmosphere that must not be crossed to avoid dangerous levels of climate change in the long term. Palaeoclimatology also provides a unique and independent way to evaluate the qualities of climate and Earth system models used to predict future climate.

Systematic and biostratigraphic significance of a chinchillid rodent from the Pliocene of eastern Argentina

Fil: Rasia, Luciano Luis. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Division Paleontologia Vertebrados; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina

Radiation-induced signals of gypsum crystals analysed by ESR and TL techniques applied to dating

Natural crystals of terrestrial gypsum were investigated concerning the radiation effects on Electron spin resonance (ESR) and Thermoluminescence (TL) properties and their application for geological dating. ESR signals of Fe 3+, Mn 2+, G1 ( SO 3 - , g = 2.003) and G2 ( SO 4 - , g ∥ = 2.018 g ⊥ = 2.009 ) centers were observed. The thermal stability and dose response of the ESR signals were found to be suitable for an age determination using a signal at g = 2.009. The intensity of this center increased with γ-radiation and the additive dose method for this ESR center yielded accumulated dose GD of 67.4 ± 10.1 Gy. Using U, Th and K contents plus the cosmic-ray contribution, a dose rate of 1.92 ± 0.22 mGy/year has been obtained. We have determined the ESR age of the gypsums to be (35 ± 4) × 10 3 years. TL peaks at 157 and 278 °C were observed. By using initial rise method the thermal activation energy of 278 °C TL peak was found to be underestimated, probably due to the thermal quenching. Activation energies and frequency factors obtained by the method of varying the heating rate indicate lifetime of 4.09 × 10 7 years (at 15 °C) for 278 °C peak. The additive dose method applied to this TL peak yielded GD of 75 ± 11 Gy. The corresponding TL age using the 278 °C TL peak was found to be (39 ± 5) × 10 3 years for gypsum sample. The TL age of this sample is consistent with the ESR age within experimental error limits. The obtained ESR and TL ages are not consistent with the expectations of geologists. This contradiction is probably due to the repeatedly recrystallisation of gypsum samples under the environmental conditions after their formation in the upper Miocene–Pliocene Epoch.

A new Drynaria (Polypodiaceae) from the Upper Pliocene of Southwest China

A polypodiaceous fern, Drynaria callispora sp. nov., is described from the upper Pliocene Sanying Formation in western Yunnan Province, southwestern China. This species with well-preserved pinnae and in situ spores is the first convincing Drynaria fossil record. Detailed morphological investigation reveals that D. callispora is characterized by 1) pinnatifid fronds with entire-margined pinnae having straight or zigzag secondary veins; 2) finer venation showing void quadrangular areoles, but occasionally with one unbranched veinlet; 3) one row of circular sori on each side of the strong primary vein; and 4) in situ spores with verrucate exospores elliptical in polar view and bean-shaped in equatorial view. A morphological comparison shows that D. callispora is significantly different from all the fossil species previously identified as drynarioids. A phylogenetic analysis of D. callispora supports that the fossil is closely related to D. sinica Diels and D. mollis Bedd., two extant species distributing in the Himalayas. The discovery of the new fern indicates that the genus Drynaria became diversified in its modern distribution region no later than the late Pliocene and had retained a similar ecology to that of many modern drynarioid ferns ever since.

NEOTECTONIC FEATURES AND MOVEMENT IN THE EAST CHINA SEA

Since late Pliocene,neotectonic movement in the East China Sea has been intensified,and the most obvious features of the neotectonic movement include faults,folds,magmatic intrusion and eruption,seafloor hydrothermal activities,and coastal changes,etc.The neotectonic movement is characteriged by vertical large-scale block-faulting,in an oscillating and episodic manner.Regional difference of neotectonic movement is apparent and shows continuity to cerlain extent in some areas.Meantime,the neotectonic movement occurs in NE(or NEE)～NNE direction along the continent margin,and includes two parts:the eastern belt along the Okinawa Trough and the western belt along the western border of the East China Sea shelf,which extends from—Shanghai,to Zhejiang,Fujian,and Guangdong offshore regions.A tranquil zone of neotectonic movement occurs between the two belts.Neotectonic movement is mainly characterized by faulting,seismic activities,and large-amplitude block-faulting in the western belt;but more intensified in the eastern belt.It includes not only faulting,frequently earthgualce activities,and large-amplitude block-faulting,but also folding,large-scale intrusion and eruption of magmatic rocks,and seafloor hydrothermal activities.Intensive neotectonic movement in the East China Sea owes its origin to the intensitied trough extension in Quaternary,as one of the features of the active subduction of the Pacitic plate.

Pliocene climate change of the Southwest Pacific and the impact of ocean gateways

The transition from the early Pliocene “Warmhouse” towards the present “Icehouse” climate and the role of Gateway dynamics are intensively debated. Both, the constrictions of the Central American Seaway and the Indonesian Gateway affected ocean circulation and climate during the Pliocene epoch. Here, we use combined δ18O and Mg/Ca ratios of planktonic foraminifera (marine protozoa) from surface and subsurface levels to reconstruct the thermal structure and changes in salinities from the Southwest Pacific Deep Sea Drilling Project (DSDP) Site 590B from 6.5 to 2.5Ma. Our data suggest a gradual cooling of ~2°C and freshening of the sea surface during ~4.6–4Ma with an increased meridional temperature gradient between the West Pacific Warm Pool and the Southwest Pacific when the closing of the Central American Seaway reached a critical threshold. After ~3.5Ma, the restricted Indonesian Gateway might have amplified the East Australian Current, allowing enhanced heat transport towards the Southwest Pacific with reduced meridional temperature gradients when the global climate gradually cooled. At the same time our data suggest a cooling and freshening of Subantarctic Mode Water (SAMW) or/and an increased northward flow of SAMW towards Site 590B, possibly a first step towards the present Antarctic Frontal System.

Eruptive and sedimentary evolution of the Pliocene Grad Volcanic Field, North-east Slovenia

Middle to Upper Pliocene (~ 3 Ma) Grad Volcanic Field (SW Pannonian basin system) encompasses an area of about 3 km 2, of which some 1.7 km 2 belong to the outcropping volcanics. Pyroclastic and syn-eruptively reworked volcaniclastic deposits are the most widespread in occurrence. Remains of an autobrecciated lava flow, a residual neck and their peperites are partially reworked by a large debris flow. Volcanic activity occurred in a continental depositional environment dominated by alluvial fan and braided river systems. Streams draining from the north-west to the south-east were infilling a rapidly subsiding Radgona Depression. The style of volcanic activity was mainly explosive and was reinforced by hydrovolcanic processes. Three volcanic centres probably existed, and they migrated spatially and temporally from the north to the south over a distance of some 5.6 km. The rocks of the northernmost volcanic centre are fairly eroded and contain abundant, up to 10 cm sized lherzolite xenoliths. The largest crater developed about 2.5 km to the south. From an early maar stage, a tuff-cone, and subsequently, a tuff-ring evolved. The crater was filled with eroded pyroclastic material and stream load. A new vent became active some 500 m to the south. Initial stage was mainly magmatic and produced pyroclastic flow and fall deposits. Late-stage eruptions were predominantly hydrovolcanic (phreatomagmatic and phreatic), and built up a small tuff-cone having some 300 m in diameter. Trachybasaltic and subordinate basanitic magmas erupting in the Grad Volcanic Field are geochemically distinguishable from the neighbouring occurrences in the South Styrian Basin and the South Burgenland Swell. Relatively lower abundance of TiO 2, MgO, Sc, V and Cu, and higher abundance of MnO, P 2O 5, Zn, Sr, Zr, Hf, Nb, Ba, Ta and U indicate somewhat different source and/or evolutionary pattern.

THE CONTROLLING FACTORS ANALYSIS OF QIONGDONGNAN SLOPE DEEPWATER CHANNELS AND ITS SIGNIFICANCE TO THE HYDROCARBON EXPLORATION

We studied controlling factors and significance of channels developed in Pliocene and Pleistocene of Qiongdongnan slope area based on the global sea level fluctuation,climate change,sediment supply and seafloor topography.The controlling factors of Pliocene channel are mainly sediment supply,including sediments from Red River and Hainan Island,the tectonics is the key induced factor,and the formation of this channel has close relation with the large-scale slump developed in Yinggehai basin in early Pliocene period.We worked out the formation model of the Pleistonce channel,and found that the large-scale sea level drop during the last glacial maximum was the controlling factor of this channel,and the tectonics induced the minor mountain rivers in the mid-south peninsula that fed the west South China Sea slope directly,resulting in the formation of this channel.The development of deepwater channel had instructions to the global sea level fluctuation,sediment supply and sequence stratigraphy interpretation of the slope area.The deepwater channel could be a good reservoir in the deepwater area and thus of great significance to the deepwater exploration.

Numerical taxonomy of Palaeocarya (Juglandaceae) from the Mangbang Formation of West Yunnan, China

Specimens of Palaeocarya (Juglandaceae) were collected from the upper Pliocene of western Yunnan Province, which is a new geographical and age range record of engelhardioid winged fruits in China. A numerical taxonomic investigation based on 14 morphological characters of fossil and extant specimens of engelhardioid winged fruits in China was conducted using multivariate methods. Phenetic clustering shows that there are four morphotypical groups which we assign to four species. Two groups are assigned to the previously described fossil species, Palaeocarya guangxiensis Li Hao-Min et Chen Yun-Fa, 2003 and Palaeocarya koreanica (Oishi) Manchester, 1987. Two new species are recognized, Palaeocarya yunnanensis and Palaeocarya longialata. These Neogene Engelhardieae fruits provide fossil data for understanding the origin and evolution of the Engelhardia species that now inhabit South China.

Compressional Pilocene and compressional-transpressional Pliocene states of stress, southern Chilean Andes (38-42º30'S).

Las rocas intrusivas y los sedimentos mioceno-pliocenos y pleistocenos de la Depresion Central y de la Cordillera Principal entre los 38 y 42o30'S, han sido afectados por deformacion fragil tanto de caracter local como regional. El estudio de la geometria y cinematica de microfallas y el analisis de los tensores desviatoricos permitieron establecer los estados de esfuerzo a la escala regional. Se determinaron dos eventos tectonicos: 1- un evento plioceno, de tipo compresivo uniaxial, pre-Cuaternario y generalizado en toda la zona estudiada, con una direccion de esfuerzo principal s1 cercana a E-W; 2- un evento pleistoceno, con una particion de los esfuerzos, caracterizado en la zona de ante-arco por una compresion con una direccion de esfuerzo principal s1 NNE-SSW a N-S, y en la zona de intra-arco por una transgresion dextral con una direccion de esfuerzo principal s1 NE-SW.

MARINE PALEOENVIRONMENTS OF MIOCENE-PLIOCENE FORMATIONS OF NORTH-CENTRAL FALCON STATE, VENEZUELA

Research Article| July 01, 2010 MARINE PALEOENVIRONMENTS OF MIOCENE–PLIOCENE FORMATIONS OF NORTH-CENTRAL FALCÓN STATE, VENEZUELA Carly J. Smith; Carly J. Smith 1Department of Earth and Environment, Florida International University, Miami, FL 33199, USA Search for other works by this author on: GSW Google Scholar Laurel S. Collins; Laurel S. Collins 4 1Department of Earth and Environment, Florida International University, Miami, FL 33199, USA 4Correspondence author. E-mail: collinsl@fiu.edu Search for other works by this author on: GSW Google Scholar Carlos Jaramillo; Carlos Jaramillo 2Smithsonian Tropical Research Institute, Balboa, Republic of Panama Search for other works by this author on: GSW Google Scholar Luiz I. Quiroz Luiz I. Quiroz 3Department of Geological Sciences, University of Saskatchewan, Saskatoon, Canada Search for other works by this author on: GSW Google Scholar Journal of Foraminiferal Research (2010) 40 (3): 266–282. https://doi.org/10.2113/gsjfr.40.3.266 Article history received: 28 Apr 2009 accepted: 26 Oct 2009 first online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Carly J. Smith, Laurel S. Collins, Carlos Jaramillo, Luiz I. Quiroz; MARINE PALEOENVIRONMENTS OF MIOCENE–PLIOCENE FORMATIONS OF NORTH-CENTRAL FALCÓN STATE, VENEZUELA. Journal of Foraminiferal Research 2010;; 40 (3): 266–282. doi: https://doi.org/10.2113/gsjfr.40.3.266 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyJournal of Foraminiferal Research Search Advanced Search Abstract Late middle Miocene to middle or late Pliocene benthic foraminifera from north-central Falcón State, northwestern Venezuela, were used in determinations of the marine paleoenvironments of the Urumaco, Codore, Caujarao, La Vela and San Gregorio formations. From 121 collected samples, 31 that included a total of 126 taxa were applied to paleoenvironmental interpretations, and 20 well-preserved foraminiferal samples were analyzed with cluster analysis. In the Urumaco region, the upper middle to upper Miocene Urumaco Formation, which alternates among continental, marginal marine, and marine facies, was predominantly inner shelf, and the taxa and very low diversities suggest highly variable, low-salinity conditions. Foraminifera of the upper Miocene–middle Pliocene Chiguaje Member of the overlying Codore Formation indicate a deepening from inner to deeper-middle shelf. The middle to upper Pliocene San Gregorio Formation varies from estuarine in the lower Vergel Member to inner shelf in the overlying Cocuiza Member. In the Coro–La Vela region to the northeast, paleobathymetries are deeper, fluctuating from middle- to outer-neritic depths in the upper Miocene Taratara Member of the Caujarao Formation, and middle-neritic depths in the conformably overlying upper Miocene, basal part of the La Vela Formation. The relatively stable water depths of the Caujarao and lower La Vela formations support deposition on a stable marine platform. Overall, the shallower facies in the west and deeper facies in the east agree with the interpretation of an eastward progression of inversion of the Falcón basin from Miocene to Pliocene time. The middle Miocene–Pliocene shelf sequences of Falcón are compared to other formations of Venezuela and Colombia with similar paleoenvironments. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Evolution of karst in Messinian gypsum (Monferrato, Northern Italy)

In the Tertiary Basin of Piedmont (Northern Italy) a 100-150 m thick Messinian sedimentary succession crops out, composed of pre-evaporitic clays, gypsum beds and post-evaporitic lacustrine-marine fine-grained sediments. In the Monferrato area the thickness of the evaporite sequence is highly variable (0-140 m) due to an important erosion surface formed at the end of the evaporite cycle and carved in the gypsum beds. Epigenic caves probably formed during this short intra-Messinian phase of emersion. Cave sediments contain benthonic and planctonic foraminiferal associations ranging in age from Burdigalian to Upper Pliocene. These sediments have probably been deposited in recent times, although it cannot be completely ruled out that they accumulated in caves developed in Upper Messinian times. The formation of the most important caves of this area probably started at the end of the Messinian under epigenic conditions. Possibly, those inherited caves enlarged slowly during the Quaternary in an intrastratal and confined hypogene karst system.

The Upper Pliocene avifauna of Ahl al Oughlam, Morocco. Systematics and biogeography. In Proceedings of the VII International Meeting of the Society of Avian Paleontology and Evolution, ed. W.E. Boles and T.H. Worthy

The Upper Pliocene avifauna of Ahl al Oughlam, Morocco. Systematics and biogeography. In Proceedings of the VII International Meeting of the Society of Avian Paleontology and Evolution, ed. W.E. Boles and T.H. Worthy

Workshop on Pliocene Climate

The warm Pliocene epoch (5–3 million years ago) is often cited as a good analog for the near future climate because of its striking resemblance to the predictions of the “Intergovernmental Panel on Climate Change” for the next decades. Indeed, relative to today, during the Pliocene epoch, surface temperatures were 3–4°C warmer, sea level was about 5–40 meters higher, atmospheric CO2 concentrations were relatively similar or slightly higher (~400 ± 50 ppmv), and ice sheets were restrained to Antarctica. However, since 3.0 Ma ago, the Earth’s climate has undergone a major transition from a warm and relatively stable state towards cold conditions marked by amplified glacial/interglacial cycles and widespread ice sheets in the Northern Hemisphere (NHG), and to a lesser extent over Antarctica. The causes and consequences of this global climate transition— driving warm periods to “icehouse” conditions marked by “Quaternary-style” glacial/interglacial cycles—are still uncertain. Yet, they may include the interaction of several mechanisms tied to oceanic and atmospheric circulations, tectonic-, greenhouse gases-, and biological activity, biogeo

Workshop on Pliocene Climate

No abstract available. <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.9.11.2010" target="_blank">10.2204/iodp.sd.9.11.2010</a>

EVALUATING REPETITION IN SEDIMENTARY SUCCESSIONS USING HIGH RESOLUTION INTEGRATED STRATIGRAPHY: AN EXAMPLE IN THE LOWER PLIOCENE SEQUENCE OF ODP HOLE 975B

The Lower Pliocene succession recovered at ODP Hole 975B (Balearic Basin, western Mediterranean) displays a sudden increase in sedimentation rate, in disagreement with the lithological homogeneity that characterizes the succession. The present study, consisting of a high resolution stratigraphic analysis, demonstrates that the succession is affected by repetition. The section has been astrochronologically constrained through integration of detailed biostratigraphy and cyclostratigraphy, which permitted a precise evaluation of the length and duration of the duplicated interval. This result demonstrates the efficacy of integrated stratigraphy in solving wide-range geological problems.

Influence of the post-Miocene tectonic activity on the geomorphology between Andes and Pampa Deprimida in the area of Provincia de La Pampa, Argentina

The genesis of the relief between the Andes and the Pampa Deprimida plain between 36° and 39°S has never been considered. The region is intermediate between two contrasting geomorphic styles, the meridian-oriented highs and depressions of the Sierras Pampeanas to the north and the eastwards sloping northern Patagonian mesetas to the south. From geophysical data, it coincides with an intermediate zone between a flat-slab subduction zone to the north and a normal subduction zone to the south. From west to east (68° to 64°W), four units follow each other: the easternmost portion of the Sub-Andean piedmont, the depression of the Río Chadileuvú, a Plateau, and a high scarp separating it from the Pampa Deprimida lowland. The Plateau is the southernmost portion of the Brazilian shield. Geomorphological and sedimentological analyses led us to the following conclusions: 1. the Andes uplift created a large piedmont reaching the Pampa Deprimida and including the Plateau which between the Pliocene and the Middle Pleistocene was shaped in a series of stepped levels covered by Andean fluvial sediments; 2. the meridian-oriented Rio Chadileuvú depression is of tectonic origin, younger than the Middle Pleistocene, and breaks the continuity between the piedmont and the Plateau: this depression could be an incipient foreland basin; 3. the eastern scarp is a fault scarp, probably Upper Pleistocene in age, due to a faster activity of the fault zone between the craton and the Macachín Trough. This young morphotectonic activity coincides with the change from a west–east Patagonian pattern to a north–south orientation of the relief typical of the Sierras Pampeanas, but younger than them. The river network was affected by this evolution. During the Upper Miocene, a palaeo-Río Negro flowed to the north–east, then shifted southwards. The Río Colorado entered the Pampa region during the Upper Pliocene creating a set of stepped fluvial accumulation terraces, while the piedmont was drained by eastward streams. Following the formation of the Chadileuvú depression, a north–south drainage, largely endoreic, replaced the Sub-Andean flows. A capture of the Río Chadileuvú by the Río Colorado is going on due to the incision of the Río Colorado in the south. The regional landscape is therefore directly related to Late Pleistocene tectonic activity, whereas climate changes explain the different sedimentary characteristics of the surficial deposits.

Mitochondrial phylogeography of the Bedriaga’s rock lizard, Archaeolacerta bedriagae (Reptilia: Lacertidae) endemic to Corsica and Sardinia

Archaeolacerta bedriagae is a rock-dwelling lizard endemic to the Corso-Sardinian insular system. We investigated the phylogeography of the species by using the mitochondrial ND4 and flanking tRNAs genes from 94 specimens belonging to 19 populations. Phylogenetic, Barrier, and SAMOVA analyses revealed a highly structured pattern characterized by two levels of discontinuities in the geographical distribution of mtDNA diversity: (i) a deep phylogeographic break in Northern Corsica between Lineage A, restricted to northernmost Corsica, and Lineage B widespread all over the remaining range of the species, and (ii) some minor phylogeographic discontinuities within lineage B, which is sub-structured into six closely related haplotype clades with remarkable concordance with geography. The first evolutionary event concerning the split between the two main lineages from an ancestral population occurred in the Upper Pliocene (5.87–3.68 mya), while the divergence within lineage B would have started from the Upper Pleistocene (2.5–1.6 mya), between Corsican and Sardinian populations. Somewhat later (1.7–1.1 mya), the Sardinian ancestral population underwent fragmentation into population groups inhabiting North, Central, and South Sardinia. As inferred from previous allozyme surveys, the divergence among population groups would be driven by allopatric fragmentation, while the discrepancy concerning the major partition into two lineages inferred from mtDNA but not apparent in analysis of allozymes needs further investigation.