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The site of Coste San Giacomo (Early Pleistocene, central Italy):Palaeoenvironmental analysis and biochronological overview

Luca Bellucci a,*, Ilaria Mazzini b, Giancarlo Scardia c, Luciano Bruni a, Fabio Parenti a,Aldo Giacomo Segre a, Eugenia Segre Naldini a, Raffaele Sardella d

a Istituto Italiano di Paleontologia Umana, Piazza Mincio 2, I-00198 Roma, Italyb IGAG-CNR, Via Salaria Km 29.3, CP 10, Monterotondo Staz., I-00016 Roma, Italyc INGV, Sezione di Milano-Pavia, via Bassini 15, I-20133 Milano, ItalydDipartimento di Scienze della Terra, “Sapienza” e Università di Roma, P.le Aldo Moro 5, I-00185 Roma, Italy

a r t i c l e i n f o

Article history:Available online 15 April 2011

a b s t r a c t

Facies and ostracod analyses have been performed on a continental core drilled at Coste San Giacomo(Anagni, central Italy), where a middle Villafranchian faunal assemblage was first discovered in 1978. Thecore intercepted the palaeontological level and penetrated the underlying sedimentary succession,previously largely unknown, for a total sediment recovery of 40 m. In addition, new field surveys led tothe discovery of Hippopotamus sp. remains at the faunal site, thus pre-dating the dispersal of this largeungulate into Europe to the middle Villafranchian. The new sedimentological and palaeoecological dataallowed to define a palaeoenvironment mainly ascribable to an alluvial plain, characterized by a marshevolving into a floodplain with overbank deposits and a sand-bed fluvial-channel. This scenario issupported by the reassessed Coste San Giacomo faunal assemblage, consistent with running and/or clearwaters as well as prairies and grasslands, under mild climatic conditions.

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1. Introduction

The PlioceneePleistocene (PiacenzianeGelasian) boundary,constrained at 2.588 Ma (Rio et al., 1994; Gibbard et al., 2010) andapproximated by the GausseMatuyama polarity reversal(2.581 Ma; Lourens et al., 2005), straddles a global cooling trendbetween marine isotope stage (MIS) G2 to 100 (Lisiecki and Raymo,2005) and culminating with the onset of obliquity-driven glacial/interglacial cycles typical of the Early Pleistocene (Shackleton,1995). This global cooling trend is temporally associated with thedemise of Pliocene ecosystems and the spread of fauna and floraassociations typical of the Early Pleistocene.

As summarized by Rook and Martinez Navarro (2010), theearlyemiddle Villafranchian mammal turnover, characterized bythe dispersal in Europe of species adapted to open environmentssuch as elephants and horses [the so-called “elephant-Equus event”of Lindsay et al., 1980; see also Azzaroli, 1977], took place broadly atthis time. The use of the “elephant-Equus event” to mark theearlyemiddle Villafranchian turnover is however questioned by the

recent finding of modern monodactyl horses and elephants(Mammuthus) in at least two early Villafranchian localities ofEurope, i.e. in the Dacian Basin of Romania (Radulescu and Samson,2001; Lister et al., 2005) and at Vialette in France (Lacombat et al.,2008).

The fossiliferous sites of the Anagni basin (central Italy; Fig. 1)provide data of particular interest to elucidate the relationshipbetween the “elephant-Equus event” and the earlyemiddle Villa-franchian turnover. The sites of Coste San Giacomo, Fontana Ace-tosa (this latter also known as Acqua Acetosa), and Valle Catenaccio(Fig. 1) have been studied since the end of the 1970s by researchersof the Istituto Italiano di Paleontologia Umana (IsIPU) in Rome(Biddittu et al., 1979; Biddittu and Segre, 1982). The Coste SanGiacomo site (CSG) was discovered during a survey carried out in1978 along the Fosso delle Mole valley and its terraces (Fig. 2). In1985, 1989, and 1990 trenches were excavated at the base ofa terrace, finding a laterally traceable level with fossil vertebrates inthe yellow sands thereby exposed. Correlative sandy/clayeydeposits with fossil vertebrates were discovered in the same area atValle Catenaccio (VC) and Fontana Acetosa (FA). Finally, in 2009 theIsIPU promoted the drilling of a 40 m-long core with the aim ofinvestigating the depositional environment of this part of theAnagni basin and to provide a new chronology for the CSG fossil

* Corresponding author.E-mail address: lucabellucci@isipu.org (L. Bellucci).

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assemblage. The core recovered a previously unknown strati-graphic succession, which is object of a multidisciplinary studyincluding facies, ostracods, pollen, and palaeomagnetic analyses. Inthis paper, sedimentological and palaeontological data from thecore are presented and discussed together with a preliminaryreappraisal of the CSG faunal assemblage.

CSG represents a crucial site to understand the palae-oenvironmental and faunal changes in Italy during the EarlyPleistocene (Gelasian sensu Gibbard et al., 2010), just before thedispersal events that led into Europe African taxa such as, amongothers, Homo sp., Megantereon whitei, and Theropithecus sp.(O’Regan et al., in press).

2. Geological setting

The Coste San Giacomo site is located close to Anagni, w50 kmsoutheast of Rome (central Italy). The Anagni basin, covering anarea of w20 km2, is a deeply faulted, extensional depressionproduced during the initial phases of the neotectonic evolution ofthe Apennines. The basin, bounded by horsts of Mesozoic toMiocene rocks (Segre and Ascenzi, 1984; Carrara et al., 1995;Ascenzi et al., 1996; Segre, 2004), largely developed between theLate Pliocene and the earlier part of the Middle Pleistocene (Carraraet al., 1995; Galadini and Messina, 2004), and was affected byregional volcanic activity of the Alban Hills, Ernici, and Rocca-monfina volcanoes since w0.7 Ma (e.g. Giannetti, 2001; Peccerillo,2005; Rouchon et al., 2008) (Fig. 1). To the southeast, the Anagnibasin is bounded by the Sgurgola-Ferentino bedrock ridge (Albertiet al., 1975), which could have acted as a dam for lacustrine sedi-mentation during the Early Pleistocene (Muttoni et al., 2009)(Fig. 1). These lacustrine-alluvial sediments were covered by trav-ertine (Segre and Ascenzi, 1984) and by Middle Pleistocene pyro-clastics, dated at Fontana Ranuccio between 0.528Ma and 0.487Ma(KeAr dating, Biddittu et al., 1979) and attributed to the Alban Hillsmagmatic district (w0.7e0.02 Ma; Peccerillo, 2005).

3. The Coste San Giacomo 1 core

The Coste San Giacomo 1 core (CSG1) was drilled in September2009 at the site with coordinates N41�45021.700 E13�05049.400

(WGS84 reference system), 206 m above sea level (Fig. 3). The corepenetrated 40 m of sediments, but experienced an overall expan-sion of w10% during drilling operations, reaching a total thicknessof 43.4 m. Depths reported in Fig. 3 have not been corrected for theexpansion and reflect the actual measured length of the core. Coredescription and facies analysis were performed by taking intoaccount sediment texture, structure, colour, weathering, verticallithofacies variation, and the occurrence of accessory features suchas roots, organic matter, wood fragments, fossils and bioturbation.Sand texture and colour were determined by means of a 0.5 4sediment comparator (Udden-Wentworth grain-size classificationscheme) and the Munsell Soil Color Chart, respectively. CaCO3content was qualitatively evaluated in field with a w5% HCl solu-tion, but no remarkable variations (e.g. depletion) were observedthroughout the core.

Core segments do not show any pervasive sediment disturbance(e.g. concave-downward warping or flowin structures), except foroccasional fluidization of some sandy layers. Planar-parallel lami-nations in the sediment show a gentle tilt of w15e20�, perhapsproduced by post-depositional tectonic activity.

The palaeoenvironmental interpretation of the CSG1 core wascarried out by integrating information from facies analysis andmicropalaeontological content (ostracodes andcharophytes). A totalof 180 standard (w10 cm3) samples was taken every 20 cmthroughout core. The samples have beendisaggregated in 5%dilutedhydrogen peroxide, wet-sieved through a 65 mm and 125 mm meshand oven-dried. Ostracod valves and carapaces (1 individual ¼ 1carapace or 1 valve) were identified under a stereoscopic binocularmicroscope and classified according to the taxonomical scheme ofMeisch (2000). The derived auto-ecological preferences are listed inTable 1.

HOLOCENE–LATE PLEISTOCENE

MIDDLE PLEISTOCENE

Colluvial, alluvial, “terra rossa”, upper travertine deposits

Pedogenized pyroclastics, lacustrinedeposits and travertine

Alban Hills pyroclastic flowand Ernici volcanics

Marsh and fluvial deposits

Gavignano tectonic facies megaconglomerates

CM - Colle MarinoCSG - Coste San GiacomoFA - Fontana AcquacetosaFR - Fontana RanuccioVC - Valle Catenaccio

Thrusts

Faults

EARLY PLEISTOCENE (GELASIAN)

PLIOCENE

Bedrock

Tectonics Sites

Late Miocene turbidites

Middle Miocene marineepilitoral limestones

N

P

N

Cretaceous to early Mioceneplatform limestones

N

P

N

Plio-Pleistocene basinsReliefs > 500 m

Anagni basin

0N

2km

N

P

N

i

0N

HOLOCEN

MIDDLE

EARLY P

PLIOCEN

Bedrock

Tectonics

Plio-PleiReliefs

Anagni

Montelanico

Anagni

L. Canterno

Mts. Lepini (Ausoni)

Villamagna

Gavignano

FRCM

FA

Sgurgola

Morolo

Ferentino

CSGVC

Montelanico R.

Sacco R.

Sacco R.

Mts. Simbruini (Ernici)

P a d u n i

Fig. 1. Geological map of the Anagni basin with the faunal sites discussed in text: Coste San Giacomo (CSG), Fontana Acetosa (FA), Fontana Ranuccio (FR), and Valle Catenaccio (VC).

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In the CSG1 core, 4 major facies associations (Fig. 3) pertainingto a continental environment mainly ascribable to an alluvial plaindepositional system have been identified.

3.1. Marsh facies association

3.1.1. DescriptionThis facies association consists of a 20-m-thick vertical stack of

laminated, fine-grained deposits with interbedded sand layers andorganic-rich intervals (lignite and gyttja). The fine-graineddeposits, mainly silty clay, are characterized by faint, cm-thick,planar-parallel lamination and display a dominant grey colourwith bluish (5PB 5-6/1, 10B 4/1) to greenish (10G 4-5/1, 5GY 5-6/1)hues. Sand layers are usually normal-graded or massive and showa thinning-upward trend through all the facies association. Someinverse-graded sand layers are observed near the bottom of thefacies association. Lignite and organic-rich intervals range inthickness from w0.5 to w2 m and seem to occur in a cyclical waythrough all the facies association. CaCO3 nodules are observed invery few layers. In addition to wood fragments and vegetationremains, the fossil content includes freshwater ostracods andcharophytes (Characeae gyrogonites). Ostracods have been recov-ered from several intervals within this facies association (Fig. 3). Insamples from assemblages A and B (Fig. 3), respectively at27.85e27.80 m and 25.10e25.05 m, only juvenile forms of Candonasp. juv. occur (Fig. 4f). The sample at 19.30e19.15 m (Fig. 3,assemblage C) bears the richest and most diversified fauna of thecore, with Ilyocypris gibba (Fig. 4a), Herpetocypris reptans, Potamo-cypris zschokkei, Candona candida, and juvenile forms of noded

Cyprideis torosa. At 18.60e18.55 m, (Fig. 3, assemblage D) twospecies of Mixtacandona and Potamocypris sp. juvenile forms areobserved. Finally, in the assemblage E (17.95e17.60 m; Fig. 3)Cyclocypris ovum and fragments of Candonidae and H. reptans aredocumented together with gyrogonites of the Characee group.

This facies association is observed in the core interval39.60e17.60 m (Fig. 3).

3.1.2. InterpretationThe occurrence of laminated, fine-grained deposits points to

settling as main depositional process. The vertical thickness of thisfacies association suggests a long-standing water body, where thecyclic occurrence of vegetal remains and organic-rich intervals mayreflects variations in thewater depth. The bluish to greyish hues arecharacteristic of oxygen depletion and waterlogged conditions but,however, the preservation of primary sedimentary features (e.g.lamination) and the lack of mottling rule out remarkable pedogenicprocesses. The occurrence of rare layers with CaCO3 nodulesmay beascribed to groundwater level oscillations. Moving throughout thefacies association, the ostracod assemblages depict slightly differentenvironmental conditions, mainly in the uppermost part of thefacies association. Juvenile forms of Candona sp. juv. (Fig. 3, assem-blages A and B) suggest a stressed environment, while the assem-blage with I. gibba, H. reptans, P. zschokkei, and C. candida (Fig. 3,assemblage C) is typical of shallow, slowly flowing water witha clayey substrate. Juvenile forms of noded C. torosa indicate a slightsalinity in the water body. The occurrence of Mixtacandona (Fig. 3,assemblage D) points to the vent of interstitial waters (Rogulj et al.,1994), while the Potamocypris sp. juvenile forms are common in

Fig. 2. a) General overview of the CSG site (arrow corresponds to location of CSG section); b) the CSG section in 1990.

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Fig. 3. The Coste San Giacomo 1 core. From left to the right: facies association, lithology, sedimentary features, and ostracod associations. On the right, the location of the core siteand the physical correlation of CSG1 core with the CGS faunal site are shown. The area and the level where the CSG fauna was collected are displayed in grey. Bones recovered in theCSG1 core at the depth interval of 4.90e5.10 m have the same elevation as the CSG fauna. FR1 and FR2 are respectively the Fontana Ranuccio 1 and Fontana Ranuccio 2 cores (SegreNaldini et al., 2009; Muttoni et al., 2009).

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slowly flowing streams. C. ovum together with fragments of Can-donidae and H. reptans (Fig. 3, assemblage E) suggests a permanentwater body with muddy floor and rich vegetation. H. reptans isknown to feed preferably on old Chara (macroalgae) (Meisch, 2000)and gyrogonites of the Characee group have been found in associa-tion with H. reptans. Gyrogonites also indicate a permanent waterbody with clear, shallow waters. Auto-ecological data suggest

standing to slowly flowing, shallow-water conditions and recordalso episodes of low salinity in the order of w5& of NaCl. Lowsalinity episodes can be ascribed to a negative hydrologic balance inclosed basin settings, where water flows in during floods and isremoved by evaporation (e.g. Langbein, 1961; Anadón et al., 1994).

As a whole, this facies association is interpreted as a marsh,likely related to an aggrading floodplain.

Table 1Auto-ecological preferences of the determined ostracod species (fromMeisch, 2000 and Frenzel et al., 2010). Candona sp. juv., Potamocypris sp. and Pseudocandona sp. juv. arenot included in the list.

Taxon Salinity Temperature Habitat Substrate

Candona candida Freshwater to aeoligohaline Oligothermophilic Endobenthic SedimentCandonopsis kingslei Freshwater to aeoligohaline Thermoeuryplastic Endobenthic MudCyclocypris ovum Freshwater to aeoligohaline Thermoeuryplastic Nectobenthic SedimentCyprideis torosa Holeuryhaline Polythermophylic Endoeepibenthic Sediment (mud)Herpetocypris reptans Freshwater to beoligohaline Thermoeuryplastic Endoeepibenthic phytal MudIlyocypris gibba Freshwater to aeoligohaline Meso-polythermophilic Nectobenthic SedimentMixtacandona laisi Freshwater HyporheicMixtacandona tabacauri Freshwater HyporheicPotamocypris zschokkei Freshwater Cold stenothermal Stygophilic Fine mudPseudocandona eremita Freshwater StygobiticPseudocandona rostrata Freshwater Cold stenothermal Stygophilic

Fig. 4. Most common ostracod taxa recovered from the CSG sediment core. Scale bars ¼ 200 mm, except otherwise stated. a) Ilyocypris gibba (Ramdohr, 1808), RV, sample19.30e19.25; b) Pseudocandona sp. juv., sample 5.55e5.50; c) Mixtacandona laisi (Klie, 1938), LV, sample 15.00e15.05, scale bar ¼ 100 mm; d) Pseudocandona eremita (Veidovsky,1882), LV, sample 15.00e15.05; e) Candonopsis kingslei (Brady and Robertson, 1870), carapace, sample 15.00e15.05; f) Candona sp. juv., sample 27.85e27.80, scale bar ¼ 100 mm.

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3.2. Near-shore facies association

3.2.1. DescriptionThis association is w5-m-thick and consists of calcareous

medium- to coarse-grained sand and silt, massive or locallyarranged in fining-upward cycles, with embedded siliciclastic siltyclay or silty sand and organic-rich layers. The silty matrix in sandlayers is generally abundant, but the original content could havebeen strongly influenced by fluidization during drilling. Cementa-tion occurs only in few horizons and it is weak and sparse. Colour ismainly white (2.5Y 8/1, 5Y 8/1, 5PB 8/1), ranging from moreoxidized (10YR 5/4, 2.5Y 6/6) to more reduced conditions (5G 6/1,10GY, 5PB 6/1, 5Y 4-6/3). This facies association provided to belargely barren, except at interval 15.90e13.40 m (Fig. 3, assemblageF) where Mixtacandona laisi (Fig. 4c,d), Mixtacandona tabacauri,Candonopsis kingslei (Fig. 4e), and Pseudocandona eremita (Fig. 4d)were observed.

This facies association is observed from the core’s bottom to39.60 m and in the interval 17.60e12.70 m (Fig. 3).

3.2.2. InterpretationThe interpretation of this facies association is not straightfor-

ward, as its sediments experienced strong fluidization and partialrecovery during drilling operations. The texture of calcareoussediments and the occurrence of organic matter may reflecta context of shallow-water conditions, with large biochemicalproduction of calcareous concretions and organic matter fromshore vegetation (e.g. Magny, 1992; Gierlowski-Kordesch, 1998).Medium- to coarse-grained sizes can be ascribed to high-energywave dynamics (Magny, 1992) or, more likely, to post-depositional mechanical weathering produced by root action andalternating dry (subaerial exposure)/waterlogged conditions(Gierlowski-Kordesch, 1998 and references therein). Colour varia-tions in the facies association may support this interpretation, aspoint to the presence of iron in both oxidized and reduced statusdue to periodical waterlogging (Retallack, 2001). Local fining-upward trends may represent gradual transgressive events due tothe water level rise. The ostracod assemblage is typical of intersti-tial habitat and could point to the proximity of a spring (Dole-Olivier et al., 1993; Mößlacher et al., 1996). The occurrence ofC. kingslei (partly epigean form) together with hypogean formsindicates mixed communities, which must move with hydrologicalvariations, being unable to survive desiccation.

Taking into account the aforementioned features and thevertical relationship with the other facies associations (sections 3.1and 3.3), this facies association is interpreted as a near-shoreenvironment of a still-water body (marsh).

3.3. Floodplain facies association

3.3.1. DescriptionDominant fine-grained, laminated sediments with few inverse-

graded or massive sand layers compose this facies association,together with accessory features such as CaCO3 nodules, rootlets,and very small fragments of organic material. Lamination andCaCO3 nodules are frequent throughout the facies association.Colour mainly ranges from greenish/bluish grey (10BG 5/1, 10Y 5/1,10B 6/1,10G 4/1) and olive (5Y 6/3, 2.5Y 6/8), with few layers havingmore yellowish hues (2.5Y 7/4, 2.5Y 6/3). Upward, in a virtualcoarsening trend, the succession pass to normal-graded, medium-to fine-grained, thin-bedded silty sand, locally arranged into sandto silt fining-upward sequences, with sharp base and CaCO3nodules in the silt layer. Ostracods have been recovered in theupper part of the facies association. The assemblage is made up ofPseudocandona rostrata with subordinate Candonopsis juv. in the

assemblage G (Fig. 3) and Pseudocandona sp. juv. (Fig. 4b), Candonasp. juv., Mixtacandona juv. in the assemblage H (Fig. 3).

At the whole, this facies association is observed from 12.70 to5.10 m (Fig. 3).

3.3.2. InterpretationThe occurrence of fine-grained, laminated deposits point to

settling as main depositional process, while the few sand layersreflects short-lived, moderate-energy events. CaCO3 nodules,rootlets, and the organic material mark alternating phases ofwaterlogging and subaerial exposure. All these features point toa floodplain deposit. This interpretation is supported by theoccurrence of P. rostrata (Fig. 3, assemblage G), a cold stenothermalspecies, rheotolerant and stygophilic, which lives in both perma-nent and temporary small water bodies. Upward, the thin alter-nation of normal-graded sand and silt reflects a change insedimentation style, with an increase of short-lived, moderate-energy events, tentatively ascribable to a crevasse splay(6.55e5.10 m; Fig. 3). The occurrence of Pseudocandona sp. juv.,Candona sp. juv., and Mixtacandona juv. (Fig. 3, assemblage H) stillindicates a temporary water body influenced by interstitial waters.

3.4. Fluvial-channel facies association

3.4.1. DescriptionThis facies association is w5-m-thick and consists of a vertical

stack of amalgamated, moderately sorted, normal-graded, fine-grained sands. Sedimentary structures include massive sand layers,as well as ripple cross-lamination and horizontal planar bedding.The sand stack has a lower erosional boundary and displaysa fining-upward trend, gradually evolving into massive or locallylaminated clayey silt with CaCO3 nodules and rootlets. Colourtypically ranges from yellow to olive hues (2.5Y 7/3, 5Y 6/3). Thisfacies association is barren of ostracods, but several vertebratefragments were observed at 5.10e4.90m, resting onto the erosionalsurface.

This facies association occurs at the top of the core, from 5.10 to0.60 m (Fig. 3).

3.4.2. InterpretationThe general fining-upward trend, together with the occurrence

of traction structures, erosional surfaces, and reworked fragmentsof accessory features (in this case, bones) are characteristic ofa fluvial-channel deposit (e.g. Miall, 2006). The gradual upwardtransition to fine-grained deposits is interpreted as channel aban-donment, with sedimentary processes changing from traction tomainly settling. The occurrence of CaCO3 nodules and rootlets atthe top of the facies association points to subaerial exposure andweak weathering.

4. Mammal fauna

Biddittu et al. (1979) described the palaeontological sites of theAnagni basin and remarked on the occurrence of Villafranchianmammal assemblages at Coste San Giacomo (CSG), Valle Catenaccio(VC), and Fontana Acetosa (FA) (Fig. 1). The species reported fromFA are Mammuthus meridionalis, Hippopotamus sp., Stephanorhinusetruscus, Leptobos sp., Sus strozzi, Equus stenonis, Eucladoceros sp.,“Cervus philisi”, Megantereon cultridens, Pachycrocuta sp., Canis sp.,Lepus sp., and Testudo sp.

Only a few vertebrate remains have been found in the yellowsands at VC, namely Mammuthus sp., E. stenonis, Eucladoceros sp.,Gazella borbonica, Pachycrocuta sp., Castor fiber, Testudo sp., andEmys sp. (Cassoli and Segre Naldini, 1984, 1993; Segre Naldini andValli, 2004).

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A larger amount of fossils comes from the CSG site. Fossil boneswere collected from ground surface, where the fossil-bearingyellow sands are ploughed for agriculture. The surveys provideddiversified faunal assemblages that Biddittu et al. (1979) referred tothe middle Villafranchian because of the affinities of CSG faunawith that from Saint Vallier (France) (Viret, 1954; Guérin et al.,2004, and references therein).

In recent times an increasing number of localities with middleVillafranchian faunas has been discovered and studied (Varshets inBulgaria; Sesklo, Dafnero, Vatera, Volakas in Greece; Rook andMartinez Navarro, 2010, with references therein). Gliozzi et al.(1997) pointed out and updated the biochronology for

PlioePleistocene mammals of Italy and defined the Costa San Gia-como Faunal Unit (FU).

As Rook and Martinez Navarro (2010) summarized, the faunalcomposition ofmiddle Villafranchian units is characterized by someimportantfirst occurrences, including thoseof S. etruscus, E. stenonis,Sus cf. strozzii, the rupicaprine Gallogoral meneghinii, and the spiralhorned antelope Gazellospira torticornis. In addition, the firstoccurrence of Canis cf. C. etruscus, a carnivore very common in thelater faunal units, has particular biochronological relevance. Theoccurrence of Canis cf. C. etruscus in the CSG fauna (Rook and Torre,1996) suggested that the so-called “Wolf-event” of Azzaroli (1983)started earlier than originally assumed and cannot indicate the

Fig. 5. Selected fossil remains from the CSG site. a) Mammuthus meridionalis; b) Anancus arvernensis; c) Gazellospira torticornis; d) Gazella borbonica; e) Equus stenonis; f) Hippo-potamus sp. Scale bar ¼ 10 mm.

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PlioePleistocene transition (Palombo and Sardella, 2007). Finally,recent identification of Canis sp. in the early Villafranchian of Via-lette, indicates that thediffusionofwolf-like dogs across Eurasiawasa diachronous event (Lacombat et al., 2008; Sotnikova and Rook,2010). Besides the First Appearance Datum (FAD) of Canis cf.C. etruscus, the CSG faunal assemblage shows other peculiar featuresof biochronological value such as the occurrence of gazelle andantelopes (G. borbonica and G. torticornis), coexistence of Anancusarvernensis and M. meridionalis, and the Last Appearance Datum(LAD) of A. arvernensis.

Summarizing, the CSG faunal assemblage is definitely middleVillafranchian and characterized by the following taxa: Macacacf. M. sylvanus florentina COCCHI, A. arvernensis (CROIZET AND JOBERT),M. meridionalis NESTI, Stephanorhinus sp. KRETZOI, E. stenonis COCCHI,Axis lyra (¼ C. philisi SCHAUB), Eucladoceros cf. E. teguliensis(DUBOIS), Croizetoceros ramosus HEINTZ, Cervidae indet., Leptobossp., G. borbonica DEPÉRET, G. torticornis (AYMARD), Gazella sp., Caniscf. C. etruscus FALCONER, Vulpes cf. V. alopecoides MAJOR, Hyaenidae(possibly Chasmaporthetes HAY), Homotherium sp. and Hystrix cf.H. refossa GERVAIS, Talpa sp. LINNAEUS (Figs. 5 and 6).

During the survey attending the drilling activity some newmammal fossil remains were found in the field where most of theCSG FU bones were previously collected. Among them, an upperincisor referable to Hippopotamus sp. (Fig. 5f) is of particularinterest and adds a new element to the faunal list. The occurrenceof the hippo in late Villafranchian faunal assemblages (Olivola andTasso FUs; Gliozzi et al., 1997) has been recently questioned and theearliest presence of the taxon in Europe was then considered thatfrom Venta Micena (Spain), correlative to the Pirro Nord FU in Italy(Rook and Martinez Navarro, 2010, with references therein).

The FA faunal assemblage was previously considered late Vil-lafranchian in age due to the occurrence of Hippopotamus remains(teeth and fragments of limb bones). Thus the FA fossils wereconsidered slightly younger than CSG, despite the fact that corre-lation between the fossiliferous levels of CSG and the FA could besupported by field evidence. The new finding of Hippopotamus inCSG allows to refer also the FA assemblage to the middle Villa-franchian. Therefore the occurrence of Hippopotamus, reportedboth in CSG and FA assemblages, assume a remarkable

biochronological value. In addition, Reimann and Strauch (2008)reported the occurrence of a partial skull of hippo in a middleVillafranchian faunal assemblage from Elis (Peloponnesus, Greece),albeit these authors did not provide a faunal list.

Finally, the tooth from CSG confirms the presence of the hippo inthe middle Villafranchian in the Italian peninsula, thus demon-strating the diffusion into Europe of an African taxon. Therefore, thedispersal event of the hippo occurred earlier than previouslysupposed, pre-dating the dispersal of other African taxa during theEarly Pleistocene.

5. Discussion

The integration of facies analysis and palaeoecological infor-mation provided by ostracods and mammal fauna led to thepalaeoenvironmental reconstruction of the CSG site. The verticaldistribution of facies and ostracod associations points to anaggrading, low-energy environment, with slowly flowing, cold,shallow waters, largely ascribable to an alluvial plain. The w20-m-thick marshy succession suggests a long-standing, depressed areaof an alluvial plain, probably confined by the bedrock. The bedrockis presently exposed few hundreds meters far from the CSG1 site(Fig. 1) and, in a context of regional aggradation, the marshydepression could be originated by fluvial damming of a recess ora small tributary valley cut into the bedrock. This kind of marshyenvironment is marginal to the alluvial plain and is largely docu-mented at the foot of the Southern Alps (Ravazzi et al., 2005;Scardia et al., 2010) and the Berici-Euganean hills (e.g. Calderoniet al., 1996; Kaltenrieder et al., 2009; Monegato et al., in press).The marsh at CSG likely developed as a closed basin, where waterinflow mainly occurred during floods and was removed by evapo-ration. Large amounts of organic matter and lignite suggest generalhumid conditions, during which floods regularly provided water tothe marsh and vegetation proliferated along the margin. Episodicnegative balance between water inflow and evaporation may haveled to moderate salinity increase as documented by the occurrenceof noded specimens of C. torosa (Vesper,1972). Evolution in time ledthe marsh to be completely filled and to evolve into a low-energyfloodplain, with episodic floods and more frequent subaerialexposure. The last facies association in the CSG1 core registers theapproach of a sand-bed fluvial-channel, at the base of which boneslie as a lag. Although taphonomic analyses have not been per-formed yet, bones fragments recovered in the fluvial-channeldeposits would suggest a reworking by the water flow for theCSG faunal assemblage. The CSG1 succession ends with the gradualabandonment of the fluvial-channel.

A peculiarity of the ostracod assemblage is the concomitantoccurrence of epibenthic and hyporheic to stygobitic species in theassemblages D, F, G, and H (Fig. 3). Typically, these species occur ininterstitial and groundwater habitats, springs and waters con-nected to springs, and some of them in a broad range of differentfreshwater ecosystems. The groundwater hosted in the Mesozoic toMiocene rocks forming the backbones of the Anagni basin (Fig. 1)potentially represents a specific habitat for such taxa and theiroccurrence in assemblages D and F (Fig. 3) may support the inter-pretation of a marshy depression confined between the bedrockand an aggrading alluvial plain. The occurrence of Mixtacandonajuv. in floodplain settings (Fig. 3, assemblage H) could also be linkedto local groundwater characteristics, to the existence of floodplainsprings and to the peculiar position of the water body within thefloodplain (Ward et al., 1998). Danielopol et al. (1997) studying theinterstitial fauna in the Danube Valley near Vienna, reported richostracod assemblages during spring and poor assemblages duringsummer and autumn, corresponding respectively to well oxygen-ated and hypoxic or anoxic sediment conditions.

Fig. 6. Selected fossil remains from the CSG site. a) Chasmaporthetes; b) Canis cf.C. etruscus; c) Homotherium sp.; d)Macaca cf.M. sylvanus florentina. Scale bar ¼ 10 mm.

L. Bellucci et al. / Quaternary International 267 (2012) 30e39 37

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Ascenzi (1993) reported Candona albicans from fine-graineddeposits exposed along the rivers’ banks in the study area, butthe age of these deposits seems presently to be younger than CSG,because of the different topographic elevation and the availablepalaeomagnetic constrains (Muttoni et al., 2009).

The occurrence of hippos agrees with flowing and/or clearwaters, as well as with the presence of plants and grasses. Hipposprobably lived in the alluvial plain, which was an important watersource for many species, while the occurrence of canids, hyaenids,large equids, and gazelles suggests the presence in the area ofprairies and grasslands. Such a scenario can be supported also bythe occurrence of M. meridionalis with a molar teeth patternadapted to grazing grass and other types of hard vegetation. Assuggested by different authors (Palmqvist et al., 2003; RussoErmolli et al., 2010), the living African hippo and also the Pleisto-cene Hippopotamus antiquus cannot be considered tout court asindicators of warm climate conditions, but its occurrence is suitableto mild conditions. At present, only general palaeoenvironmentalconsiderations can be provided by the vertebrate fossil recordfrom CSG.

6. Conclusions

Recent drilling and field activities at the CSG faunal siteprovided a new stratigraphic data and fossil bones. The CSG1 core,drilled few meters above the local base-level to a depth of 40 m,allowed to recover a previously unknown sedimentary succession.The vertebrate-bearing level, known previously from surfaceexposure, was detected in the CSG1 core at 5.10e4.90 m below theground level. The integration of facies analyses, micro- and macro-palaeontological observations has led to a more detailed inter-pretation of the palaeoenvironmental settings of the CSG area inthe very early Pleistocene, largely pointing to a low-energy alluvialplain with prairies and grasslands, fed by sand-bed rivers. Amongthe new findings, an upper incisor of Hippopotamus was collectedin the field. This record has a valuable biochronological impor-tance, and it enables pre-dating the occurrence of this taxon to anearlier moment of the Early Pleistocene, witnessing a dispersalevent from Africa into Europe more than 2 Ma ago. Palae-omagnetic and palaeobotanical analyses are in progress in orderto provide a more complete scenario with firm chronologicconstraints.

Acknowledgments

We wish to thank Annalisa Zarattini (Soprintendenza per i BeniArcheologici del Lazio) who authorized ongoing field activity,Pierluigi Friello for the technical assistance during the drillingwork, the Micropalaeontological Laboratory at Roma Tre Universityfor providing access to their facilities, and Sergio Lo Mastro (RomaTre University) for the SEM pictures. Italu Biddittu, Laura Bruni,Amalia Faraci, and Barbara Saracino helped during the differentsteps of the research. Mauro Cremaschi, Massimiliano Ghinassi,Giovanni Monegato, and Giovanni Muttoni are thanked for theuseful comments and discussions on the early versions of themanuscript. We want also to thank Roberto Chiararia, Director of“Convitto Nazionale Regina Margherita” of Anagni, for providingassistance and facilities.

Research was financially supported by Banca di Credito Cooper-ativo Anagni, byMIURGrants “Ricerca di Ateneo federato di Scienzee Tecnologia AST Sapienza 2007” (Project: “I mammiferi del Pleis-tocene Inferiore italiano: evoluzione, migrazioni, biocronologia”;Resp.: R. Sardella), by MIUR IsIPU “funding 2008e2010”.

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