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Quaternaire, 18, (1), 2007, p. 35-53

WHAT IS THE BOUNDARY FOR THE PERIOD AND ? THE CONTRIBUTION OF TURNOVER PATTERNS IN LARGE MAMMALIAN COMPLEXES FROM NORTH-WESTERN MEDITERRANEAN TO THE DEBATE Ⅲ

Maria Rita PALOMBO*

ABSTRACT

Assuming that the Quaternary has to be recognized as a formal chronostratigraphic/geochronological unit (having a Sub-/Sub- rank, as recommended by the International Commission on (ICS), or better a / Period rank, as suggested by several scientists), what boundary should be chosen? Should the lower boundary of the Quaternary coincide with the base of the (2.6 Ma) as proposed by the ICS? If so, should the Quaternary and Pleistocene lower boundaries be the same or should be different? To contribute to the debate, the large mammal record from the North-Western Mediterranean region have been revised in order to correlate the diversity and structural dynamics of reconstructed faunal complexes with the changes in environmental conditions occur- ring from the Middle to the . According to the results obtained, two major faunal renewals are detectable at the transition from the early to middle Villafranchian [~2.7-2.5 Ma, about at the of the transition from the Middle ( Stage) to the Late Pliocene (Gelasian Stage)], and from the middle to late Villafranchian (~2.0-~1.9 Ma, shortly before the official Plio-Pleistocene boundary). The faunal renewal from the early (V1) to the middle (V2) Villafranchian faunal complexes (that means from the MN16a “zone”/Triversa FU to MN16b “zone”/Montopoli FU) is linked to the Middle Plio- cene worsening, in turn related to the onset of bipolar glaciations followed by glacial- cycles of moderate amplitude (orbital pe- riodicity of 41 ka). The resulting increase in aridity and more intense seasonality caused the disappearance of several forest-dwelling taxa, especially small and arboreal-scansorial taxa, whereas new large grazers, mixed feeders or even browsers appeared. This renewal (al- ready called the “Equus- ”) can be regarded as a true turnover phase, due to the high percentage of last and new appearances, and to the important ecological structural changes in faunal complexes, involving mainly the guild. These faunal changes indicate that forests or woodlands gradually gave way to more open environments (including Artemisia steppe) alternating with warm-temperate deciduous forests. More- over, this event can be considered as the starting point for a dispersal phase leading to a progressive standing richness increase during the following Pliocene (middle Villafranchian, V3). Around 2.0-1.8 Ma (late Villafranchian, V4), despite the of some small browsing and grazing ruminants, diversity notably increased due to the progressive appearance of a number of carnivores. Indeed, the so-called “-event” involved several large and small Carnivora, such as the powerful scavenger Pachycrocuta brevirostris, the jaguar-like Panthera gombazsoegensis,andcoo- perative foraging canids. On the other hand, minor phyletic adjustments and some new appearances (especially grazers) affected herbivore guild. This relatively long dispersal phase, and correlated moderate turnover pulses, seems to be less important than the early/middle Villafranchian renewal phase, especially as far as and the Italian peninsula are concerned. As a result, taking into account the importance of faunal renewal at the Middle to Late Pliocene transition, it seems more reasonable to extend the base of the Pleistocene downwards from 1.81 Ma (official Plio/Pleistocene boundary) to 2.6 Ma (base of Pliocene Gelasian Stage). Accordingly, the base of the Gelasian seems to be the most appropriate lower boundary for both the Quaternary Period and Pleistocene Epoch.

Key-words: Quaternary, Pleistocene, Large mammals, North Western Mediterranean.

VERSION FRANÇAISE ABRÉGÉE

QUELLE LIMITE POUR LE QUATERNAIRE ET LE PLÉISTOCÈNE ? L’APPORT DE L’ÉTUDE DU RENOUVELLEMENT DES FAUNES À GRANDS MAMMIFÈRES DE LA MÉDITERRANÉE NORD OCCIDENTALE DURANT LE PLIOCÈNE MOYEN ET SUPÉRIEUR ET LE PLÉISTOCÈNE INFÉRIEUR INTRODUCTION La plupart des chercheurs conviennent que le Quaternaire devrait être reconnu comme une unité chronostratigraphique/géochronologique formalisée, Sub-Erathème/Sub-Ere, comme cela a été recommandé par la Commission Internationale pour la Stratigraphie (ICS) (cf. Clague, 2005, 2006) ou mieux Système / Période, comme suggéré par plusieurs chercheurs. Mais, il n’existe pas encore d’accord au sujet de cette unité. La limite inférieure du Quaternaire devrait-elle coïncider avec la base de l’étage Gélasien (2.6 Ma), comme cela a été proposé par l’ICS ? Si oui, les limites in- férieures du Quaternaire et du Pléistocène devraient-elles coïncider ou bien devraient-elles être différentes ?

* Dipartimento di Scienze della Terra, Università “La Sapienza”, CNR – Istituto di Geologia Ambientale e Geoingegneria, Piazzale A. Moro, 5 – 00185 ROMA, . E-mail : [email protected]

Manuscrit reçu le 08/07/2006, accepté le 09/10/2006 36

Pour contribuer au débat et en rappelant que le « Pléistocène » et le Quaternaire ont été créés en s’appuyant sur des donnés soit paléontologi- ques, soit climatiques (ex. Desnoyers, 1829 ; Lyell, 1833, 1839 ; Reboul, 1833 ; Agassiz, 1840 ; Forbes, 1846), les faunes à grands mammifères de la région méditerranéenne nord-occidentale ont été révisées dans le but d’envisager quels ont été les changements les plus importants des complexes fauniques (fluctuations de la diversité et changement de la structure) qui se sont produits durant le Pliocène moyen et supérieur et le Pléistocène in- férieur, lorsque d’importants changements climatiques ont modifié l’environnement. Le renouvellement des faunes et de la structure des paléocommunautés et leurs rapports avec les changements globaux du climat ont été considérés. En particulier, la dynamique des deux plus importants « turnovers » du Villafranchien, l’“elephant-Equus event” (Lindsay et al.,1980) (qui s’est déroulé grosso modo entre la fin du Zancléen et le début du Gélasien), et le « wolf event » (Azzaroli, 1983 ; Palmqvist, 1999 ; Sardella & Palombo, 2007), auparavant placé au début du Pléistocène, a été analysée dans le but d’envisager lequel des deux était le plus remarquable, en préci- sant si et de quelle façon le climat et les changements de l’environnement avaient entraîné le renouvellement des faunes. En effet, écologistes et également évolutionnistes ont débattu depuis longtemps du rôle que les changements du climat ont et ont eu sur l’évo- lution de la faune, et il semble que nous n’ayons pas encore trouvé d’accord. Les modèles les plus importants – tel que le « Stationary model »(Ro- senzweig, 1975) et les théories qui privilégient le rôle de l’environnent (Vrba, 1992, 1995 ; Brett & Baird, 1995), ou par contre les modèles et les théories qui regardent comme plus important la compétition intra- et inter-spécifique (Red Queen Hypothesis, Van Vallen, 1973 ; Bell, 1982 ; Pro- thero 2004) ; ou, enfin les hypothèses dont la vision est un peu plus complexe (“Coevolutionary disequilibrium Model”, Graham & Lundelius, 1984) ou stochastique (Court Jester Hypothesis, Barnosky 2001) – semblent être à la fois confirmés ou réfutés par les donnés paléontologiques. D’autre part, si le climat et les changements de l’environnement ont causé le renouvellement des faunes, soit par migration, soit par apparition et ex- tinction, les variations dans la structure des paléocommunautés devraient être en accord avec ces changements du climat. Dans ce but, nous avons analysé les turnovers et les variations en richesse, diversité et structure écologique, des complexes faunistiques à grands mammifères du Pliocène moyen et supérieur et du Pléistocène inférieur de la zone méditerranéenne nord occidentale.

MATÉRIAUX ET MÉTHODE Les listes fauniques de 112 faunes locales (LFAs) d’Espagne, de France et d’Italie, les plus riches ou les plus irréfutables au point de vue chronologique, ont été révisées aussi bien que la taxonomie et la distribution chronologique des espèces (fig. 1, tab. 1 et 2). Des complexes faunisti- ques proches des « paléocommunautés » ont été déterminés également à l’aide d’analyses multivariées (analyses de cluster), permettant de recon- naître des complexes fauniques (FCs) cohérents au point de vue chronologique et écologique (biochrones). Ces complexes peuvent être regardés comme des « block of coordinated stasis »(sensu Brett & Baird 1995 ; Bret et al., 1996), puisqu’on assume que, pendant le temps qu’ils renferment, aucun turnover ne se produisit (cf. Palombo, 2005, sous presse et références bibliographiques citées). Les méthodes de Harper (1975) et Foote (2000) ont été utilisées pour calculer la richesse standardisée et la diversité, celles de Torre et al. (1999) et Foote (2000) pour calculer l’index de turnover entre deux FCs successives et les taux d’apparition et d’extinction dans chaque FC respectivement.

RÉSULTATS L’analyse de similitude montre l’évidence d’une séparation plus importante entre le LFAs du Villafranchien inférieur et moyen qu’entre celles du Villafranchien moyen et supérieur. Les valeurs des indices de turnover calculés à la transition entre deux FCs successives confirment le caractère progressif du renouvellement qui se développe durant le Pliocène supérieur. Les taux d’apparition et d’extinction soulignent d’un côté ce turnover, et de l’autre mettent en évi- dence la phase de dispersion qui se déroule pendant le Pliocène supérieur (bien que d’une façon différente en chaque région), lorsque les nouvelles apparitions sont toujours plus nombreuses que les . En revanche, une phase de disparitions progressives et de réduction de la biodiversité caractérise le Pléistocène inférieur. Cette tendance est confirmée par les fluctuations de la diversité et de la richesse qui augmentent durant le Pliocène final, atteignant leur maximum au début du Pléistocène inférieur. En ce qui concerne l’habitat, les taxons qui préfèrent un milieu forestier, bien que plus nombreux en Italie qu’en Espagne, diminuèrent du- rant le Pliocène et le Pléistocène inférieur. Parmi les , on peut remarquer la diminution des brouteurs, lorsque les « mixed-feeders »de- viennent plus nombreux, peut-être à cause d’une fragmentation plus importante du milieu. Le début du Pliocène moyen est marqué aussi par la disparition des taxons de petite taille et l’apparition de mammifères de grande taille.

DISCUSSION D’après les résultats obtenus, durant le Pliocène moyen et supérieur et le Pléistocène inférieur, les renouvellements majeurs sont détectables à la transition entre les complexes fauniques du Villafranchian inférieur (V1 FC) et du Villafranchien moyen ancien (V2 FC) (~2.7-2.5 Ma), et entre le complexes du Villafranchien moyen (V3 FC) et supérieur (V4 FC) (~2.0-1,9 Ma). Le premier peut être mis en relation avec le début des glacia- tions bipolaires, suivi par des cycles glaciaire/interglaciaire d’amplitude modérée (périodicité orbitale de 41 ka), qui favorisent des variations du climat et du milieu. La saisonnalité plus marquée et une augmentation de l’aridité causent la disparition de plusieurs taxons de milieu forestier, des petits carnivores et des espèces « scansorial » ou arboricoles, alors que des herbivores de grande taille, « mixed-feeders » ou bien brouteurs, appa- raissent. Ce renouvellement (“elephant-Equus event” Lindsay et al., 1980) peut être considéré comme un vrai turnover, et marque aussi un change- ment de la structure des complexes fauniques, qui affecte surtout la guilde des herbivores/frugivores. De plus, cet événement peut être considéré comme le point de départ de la phase de dispersion qui mène à une augmentation progressive de la richesse pendant le Pliocène supérieur (Villafran- chien moyen,V3 FC, et début du Villafranchien supérieur, V4 FC). En effet, au début du Pléistocène inférieur, en dépit de l’extinction de quelques broyeurs ou tondeurs d’herbe de taille moyenne, la diversité acquiert son maximum en raison de l’apparition progressive pendant le Pliocène supé- rieur de plusieurs carnivores (“wolf event”, Azzaroli, 1983 ; Palmqvist et al., 1999 ; mais voir aussi Sardella & Palombo, 2007), tel que des canidés solitaires ou chassant en groupes, et Pachycrocuta brevirostris et Panthera gombazsoegensis. Une situation équivalente (un turnover suivi par une phase de dispersion), mais beaucoup plus accentuée, caractérise aussi le turnover de la fin du Pléistocène inférieur (Palombo et al., 2005 ; Palombo & Valli, 2005 avec références). Ces deux turnovers sont précédés par une phase plus ou moins prolongée de réduction de la diversité, pendant la- quelle les extinctions prévalent (Palombo, 2005, 2007). Il semble que les turnovers les plus importants se produisent d’une façon cyclique et qu’ils marquent le début d’une période caractérisée d’abord par la prévalence des apparitions de nouveaux taxons, puis par une réduction de la diversité. Les plus importants changements de faune semblent être déclenchés ou favorisés par les variations les plus importantes du climat et de la végétation, lorsque la structure des communautés va être aussi bâtie progressivement par la compétition intra- et inter-guilds.

CONCLUSION Le renouvellement faunique qui se réalise au passage entre Villafranchien inférieur et moyen (Pliocène moyen et supérieur) semble être plus important que la restructuration du début du Pléistocène inférieur. En réalité, le renouvellement qui marque le passage entre Villafranchien moyen et supérieur arrive au cours du Pliocène tardif. En outre, le turnover au passage Pliocène moyen– Pliocène supérieur (début du Gélasien) marque le début d’un cycle de renouvellement faunique qui se terminera à la fin du Pléistocène inférieur. Les données relatives aux faunes à mammifères de la zone méditerranéenne nord occidentale indiquent donc que le Gélasien pourrait être considéré comme le premier étage du Pléistocène et le début du Quaternaire.

Mots-clés : Quaternaire, Pléistocène, Grands mammifères, zone méditerranéenne nord occidentale. 37

1 - INTRODUCTION In point of fact, the Gelasian corresponds to the be- ginning of significant evolution not only of Earth cli- In the revised geological time scale (Gradstein et al., matic system but also of the biosphere. As a matter of 2004), it has been propose to extend the Sys- fact, during the Pliocene and Pleistocene, large mam- tem (Period) up to the , de facto deleting the mal species and “palaeocommunities” have turned over “Quaternary”. Actually, when in 1985 the Plio-Pleisto- several , moreover a plentiful literature debates cene boundary was formally defined (Aguirre & Pasini, whether these taxonomical and structural changes in 1985), the status of the Quaternary within the the course of time are more greatly influenced by biotic chronostratigraphical scale remained undefined and interactions (for instance Prothero, 1999, 2004), or by later was never formally resolved. Pillans (1998, 2004) random perturbations to the physical environment (for proposed the Quaternary should be redefined as a Sub- instance “Court Jester hypotheses”, Barnosky, 2001). system (Subperiod) of the extended Neogene System Actually several models have been proposed that (Period), and that its base be defined at the base of the emphasised the role of density-dependent factors Pliocene Gelasian Stage at 2.6 Ma, opening a new de- (Rosenzweig 1975) or changes in the physical environ- bate (e.g. Ogg, 2004; Pillans & Naish, 2004; Clague, ment (Vrba, 1992, 1995, 2000; Brett & Baird, 1995). 2005, 2006). In point of fact, paleontological and On the other hand, following to the “Red Queen hy- climatic peculiarities of the “Quaternary” were pothesis”– in this Macroevolutionary (Van Valen, recognized since the beginning of the 19th century (e.g. 1973) and Microevolutionary (Bell, 1982) sense, Desnoyers, 1829; Lyell, 1833, 1839; Reboul, 1833; changes in equilibrium may be due to the internal dy- Agassiz, 1840; Forbes, 1846) and “Quaternary” has namics of competitive relationships, and do not neces- been traditionally considered to be an interval of sarily predict a close interdependence between major climate worsening during which climate had oscilla- climatic changes and evolutionary events. Actually, ting extremes. Currently a formal decision on the due the fact that climate change removes keystone spe- “Quaternary” status is pending. Anyhow, assuming cies causing changes in interactions between species that the Quaternary is to be recognized as a formal and the restructuring of ecosystems (“Coevolutionary chronostratigraphic/geochronological unit (having a disequilibrium Model” by Graham & Lundelius, Sub-Erathem/Sub-Era rank, as recommended by the 1984), the internal dynamics of competitive relation- International Commission on Stratigraphy (ICS), or ships might also have played an important role in mam- better a System/ Period rank, as suggested by several malian fauna evolution (see e.g. Alroy et al., 2000; scientists), what boundary should be chosen? Should Prothero, 2004). As regards to the Plio-Pleistocene the lower boundary of the Quaternary coincide with the boundary and taking into account the climatic changes base of the Gelasian Stage (2.6 Ma) as proposed by the characterizing the Pliocene and those at the beginning ICS? If so, should the Quaternary and Pleistocene of the Pleistocene, when, and for what reason were lower boundaries be the same or should be different? faunal communities most significantly reconstructed? According to the ICS proposal (Clague, 2005, 2006), In the middle latitudes of the North , the first the base of the Quaternary becomes 2.6 Ma, but the major influx of ice-rafted debris around the base of the Pleistocene remains at 1.8 Ma, as ratified in Gauss/Matuyama boundary coincided with a profound 1985 (Aguirre & Pasini, 1985). On the other hand, it is change in the Eurasian flora assemblage and with a re- worth mentioning that the base of the Gelasian cor- organisation of mammalian communities. This impor- responds to the beginning of significant global tant biotic event, linked to the Middle changes: for instance the first major influx of ice-rafted worsening, in turn related to the onset of bipolar glacia- debris, in the middle latitudes of the North Atlantic, or tions, has been already recognized (the so-called “ele- the onset of extensive deposition in China around phant-Equus event” Lindsay et al., 1980; Steininger the Gauss/Matuyama boundary (marine isotopic stage et al., 1985; Azzaroli et al., 1988), and has been chosen MIS104, Ding et al., 1997; Shackleton, 1997; Par- as the boundary between the early and middle tridge, 1997a, b; and reference therein) coincided with Villafranchian (Caloi & Palombo 1996). The profuse a profound change in the Eurasian flora and faunal as- changes in flora and fauna during this event have semblages (for instance Zagwijn, 1974; Grichuk, 1997; prompted several authors to propose placing the Lindsay et al., 1980; Steininger et al., 1985; Azzaroli et Plio-Pleistocene boundary here (cf. inter alios Alberdi al., 1988). Shackleton (1997, p. 34) pointed out that the et al., 1997; Kolfschoten & Gibbard, 1998; Suc et al., lower part of the proposed Upper Pliocene Gelasian 1997 and the references therein). Stage approximates the culmination of a of cy- After the Middle Pliocene climate worsening, in the cles over which the intensity of the glaciations gra- time span included between the Reunion normal ma- dually increases (“glacial” stages 104, 102 and 100 gnetic episode and the Olduvai magnetostratigraphic represent clearly defined events; they are succeeded by event, a slight decrease in temperature altered the vege- less well-defined fluctuations). Accordingly, since the tation, at least in the Western Mediterranean area, global change that occurred at MIS 104, several au- giving rise to more open environments (Suc et al., thors have considered the lower boundary of the 1995; Torre et al., 2001). Moreover, at the transition Gelasian Stage as a more appropriate lower boundary from the middle to the late Villafranchian (~2.0-1.9 Ma) for the Pleistocene Period. a further faunal renewal can be detected, involving the 38 39 W-Wc = miscellaneous woodland; ene. Azzaroli, 1992; Di Stefano & Petronio, 1998, 2003; Pfeiffer, d Mediterranean-type vegetation; inter alios land, milieu à végétation de méditerranéen boisée ; W-Wc = des forêts rts aussi bien que des milieux ouverts peu boisés ou au bord des deux ; r. -like group (see Dama -like » est assez discutée (voir inter alios Azzaroli, 1992 ; Di Stefano & Petronio, 1998, 2003 ; Middle Pliocene to the Early Pleistoc Dama Gr = tondeurs d’herbe; Fr = Frugivores; Om = omnivores; C = carnivores. ; t habiter des shrublands ou des milieux boisés ouve sed woodland; Wc = open woodland, bushland and woode , 2006 for a discussion). stern Mediterranean, dating from the et al. e rapportées au groupe génériquement nommé « savane ; W = des forêts plus ou moins fermée ; Wc = des forêts ouvertes, bush rranéenne nord occidentale durant le Pliocène et le Pléistocène inférieu and, as well as in more open landscapes, or at the edge of both; shionships of the Plio-Pleistocene belonging to the so-called r à tondeur d’herbe avec la saison ou occasionnellement Gr = grazer; Fr = Frugivore; Om = omnivore; C = carnivores. ubiquistes à large valence écologique, qui peuven cervidés de taille moyenne du Plio-Pléistocèn Biochronological range of selected Carnivora and Primata of the North-We : Pfeiffer, 1999, 2005 ; Croitor, 2001, 2005 ; Croitor & Bonifay, 2002 ; van der Made, 1999 ; Valli et al, 2006). Wc-O, O-Wc = flexible taxa,Feeding which behaviour: can Br live = in browser; shrublandBody B-G or mass: = open BM1 mixed-feeder woodl I =(*) <10 Authors disagree kg; on BM2 tassonomy, =10-60 systematic and1999, kg; phylogenetical 2005; BM3=60-200 rela Croitor, kg; 2001, BM4 2005; =200-1000 Croitor kg; & BM5= Bonifay, >1000 2002; kg. van der Made, 1999; Valli Tab.1 : Chronologie des principaux Carnivores et de la zone médite Masse corporelle : BM1 =(*) <10 L’appartenance générique kg des ; BM2 =10-60 kg ; Kg BM3=60-200 ; BM4 =200-1000 kg ; BM5 = >1000 kg. claires et boisées ;Diète Wc-O, : O-Wc Br = = taxons brouteur; B-G = animaux qui changent de brouteu Habitat. Taxa inhabiting: O = open environments, g rassland, steppe or ; W = forests and clo Tab. 1 Habitat. Taxons habitant : O = des environnements ouverts, , steppe ou 40 41 ly Pleistocene. ne inférieur. a and Artiodactyla of the North-Western Mediterranean, dating from the Middle Pliocene to the Ear s et Artiodactyles de la zone méditerranéenne nord occidentale durant le Pliocène et le Pléistocè Biochronological range of selected Perissodactyl : Tab. 2 Abbreviations as in Tab. 1 Tab. 2 : Chronologie des principaux Périssodactyle 42 dispersal of a canid closely related to etruscus site, and/or recovered from the same stratigraphic hori- (the already called “wolf-event”, first defined by zon; 20 from Spain, 46 from France, 46 from Italy) Azzaroli, 1983, but see Palmqvist et al., 1999; Sardella ranging in from the Pliocene to the Middle Pleisto- & Palombo, in press for a discussion). This event was cene ( to early Aurelian land mammal ages, supposed to be connected with the climatic changes oc- LMAs, sensu Gliozzi et al.,1997; Palombo, 2004, curring at the end of the Pliocene and regarded as a 2005) have been selected because of their unusually signal of the transition to the Pleistocene. complete faunal record, their richness, or because they Thus the question is: what was the most important are the only representatives of a biochron. Selected faunal turnover? Is it the Middle to Late Pliocene re- Ruscinian (MN14-15) and Galerian plus Aurelian newal or the Late Pliocene to Early Pleistocene one? LFAs have been considered for comparison purpose. To contribute to the debate, the large mammal fossil Similarities have been evaluated based on the Jac- records from North-Western Mediterranean region quard binary coefficient, and of cluster analysis per- have been revised in order to analyse the diversity and formed using the UPGMA method (NTSYS-PC structural dynamics of reconstructed faunal complexes programme, version 2.0, Rohlf, 1998). According to in the light of the changes in environmental conditions this method, each member of a cluster has equal weight occurring from the Middle Pliocene to the Early at all levels of clustering (cfr. Hazel, 1970; Shi, 1993). Pleistocene. Taxa occurring in a very few faunas are not relevant for this type of quantitative analysis, even if characteristic of a well-defined span of time. The cophenetic correla- 2 - MATERIAL AND METHODS tion coefficient (CCC) was computed as a measure of Biochronological ranges of 149 Pliocene and Early distortion (Farris, 1969). Preference was shown for Pleistocene taxa, whether commonly found at Spanish, the Q-Mode dendrogram, particularly suitable in French and Italian sites or having a particular biochronologically-oriented studies (Hazel, 1970). biochronological significance, have been revised and carefully reassessed (tab.1 and 2). 2.2 - BIOCHRONOGICAL SETTING

2.1 - FAUNAL COMPLEX DETECTION The Plio-Pleistocene biochronology of large mam- mals from North-Western Mediterranean region has To better outline the chronological distribution of been re-assessed taking into account the results of simi- species in the NW Mediterranean region, it is impera- larity analysis as well as the regional data supplied by tive to define a common chronological framework the empirical documentation of the stratigraphical matching Spanish, French and Italian local ranges of in local sections. From the Pliocene to biochronological schemes (MN, MNQ, MmQ and the Early Pleistocene, the following FCs have been FUs) already erected on the basis of selected considered (fig. 1): palaeobioevents, as well as on the evolutionary stage - R= Ruscinian, including the Early Pliocene LFAs displayed by taxa belonging to a well-defined phyletic already ascribed to MN14-15. We have chosen to lineage or on typical taxa associations (Mein, 1975, consider these faunas as a group due to the very poor 1990, 1998; Azzaroli, 1977, 1982; Guérin, 1982, 1990; fossil record of French and Italian LFAs belonging Agustí, 1986; Bruijn et al., 1992; Agustí et al., 1987, respectively to MN14 and MN15 “zones”. 2001; Gliozzi et al., 1997; van Dam, 2001; Palombo, 2005). - V1= Villafranchian 1, corresponding to the Middle Disparities among Spanish, France and Italian fossil Pliocene LFAs already ascribed to MN16a or records increase the well-known difficulties in esta- Triversa FU (early Villafranchian sensu Palombo et blishing correlations among local faunal complexes al., 2003). (FCs) (Palombo, 2005; Palombo & Sardella, 2007). - V2= Villafranchian 2, including the early Late Plio- Moreover, the comparison is often problematic be- cene LFAs ascribed to MN16b or Montopoli FU cause of the actual disparities in the composition of lo- (early middle Villafranchian sensu Caloi & cal faunal assemblages (LFAs) (due to discontinuities Palombo, 1996). in the stratigraphic record, to taphonomical biases, and - V3= Villafranchian 3, to which the Late Pliocene to the fact that only a small part of the whole fossil re- LFAs such as the Spanish and French LFAs belon- cord is actually known), the uncertain of ging to MN17 and the Italian ones already attributed some classic LFAs (see for instance Pastre, 2004) as to “Saint Vallier”/Collepardo and Costa San well as different opinions regarding the taxonomic Giacomo FUs have been ascribed. We have chosen to determinations of some taxa. include the latter FU in this faunal complex, Given these considerations, to re-assess the Middle although in the Costa San Giacomo LFA (Italy) a Pliocene-Early Pleistocene mammalian complexes of true “Canis”ofC. etruscus group lowest occurred the NW Mediterranean region, a multivariate analysis side by side with typical middle Villafranchian taxa has also been performed. 112 LFAs (lists of the species (Rook & Torre, 1996) due to The compositional af- identified from the fossil remains retrieved at a given finity shown by these FUs. 43

taxa, together with a stock of Villafranchian faunal elements. Such LFAs have been considered as “tran- sitional faunas” in previous works (Bonifay 1978; Azzaroli et al., 1988 and references there in) or as Epivillafranchian faunas (cf. Kahlke, 2005) or as representative, as far as Italy is concerned, to the be- ginning of the Galerian MA. G1 includes the LFAs referable to MmQ2 (here MmQ2b), MNQ20 “zone” and Colle Curti FU. As suggested by the “minimum census technique” (Rosenzweig & Taylor, 1980; Stucky, 1990), ‘range- through’ or Lazarus taxa (Barry et al., 1995; Maas et al., 1995) have been assumed to occur in intervals where they were actually not found, provided that they can be identified in preceding and successive intervals.

2.3 - FAUNAL COMPLEX CHARACTERISATION

Three main approaches have been used to explore the palaeoclimatic significance of faunal evolutionary changes: shifts in diversity; shifts in origination/immi- gration and extinction rates (turnover, dispersal, ex- tinction phases); shifts in relative abundance of specific ecological categories.

2.3.1 - Diversity and Richness Richness (herein considered as a proxy of the γ diver- sity, which measures the overall diversity for different ecosystems within a region, Whittaker, 1972) can be measured by the total number of taxa actually or poten- tially occurring in each biochronological interval. Ne- vertheless, the richness of a single time interval may be overestimated when first local appearances have been considered as occurring at the beginning of the interval and the taxa that disappeared as persistent up to the end Fig. 1: Biochronological scheme of Spain, French and Italian faunal complexes. of it, whereas they might not actually overlap in time. Fig. 1 : Schéma biochronologique des complexes faunistiques In order to reduce this bias, and since taxonomic diver- d’Espagne, de France et d’Italie. sity relates to origination/immigration and extinc- tion/emigration rates, data have been analysed using - V4= Villafranchian 4, including the latest Pliocene the methodology developed by Foote (2000) calcula- and earliest Pleistocene LFAs (early late Villafran- ting “Total Diversity” and “Estimated mean standing chian sensu Gliozzi et al., 1997). We choose to in- diversity” as well as “Diversity minus singletons”. clude in the same FC the assemblages previously [“Total Diversity” (Ntot)=NFL +NbL +NFt +Nbt;and referred to Olivola and Tasso FUs (Azzaroli et al., “Estimated mean standing diversity” (Nemd)=Ntot – 1988; Gliozzi et al., 1997) for two reasons: the scan- No/2–Ne/2; “Diversity minus singletons” (NDmS)=+ tiness of French and Spanish fossil record in this in- NbL +NFt +Nbt;whereNo (Number of originations) = terval (roughly corresponding to MNQ18 and NFL +NFt;Ne (Number of extinctions) = NFL +NbL; MmQ-1 ), and the compositional affinities NFL = taxa that exist only in the interval; NbL =taxathat shown by the latest Pliocene-earliest Pleistocene originate before the interval but go extinct within it; Italian LFAs (Palombo, 2005). NFt = taxa that originate in the interval and persist be- - V5= Villafranchian 5, including the Early Pleisto- yond it; Nbt = taxa that originate before the interval and cene renewed LFAs referred to Farneta and Pirro persist beyond it]. FUs, and to MNQ 19 and MNQ2 (herein MNQ2 a) Moreover, it is possible to standardise the number of “zones”. Even in this case, we group together diffe- taxa that potentially occur at a given time interval by rent LFAs not only due to the paucity of the fossil re- considering species richness at the midpoint of each cord in some regions, but for the substantially simi- time interval as standing richness value calculated ac- lar composition. cording to Harper’s method (Harper, 1975) [Standing - G1= Galerian 1, including the late Early Pleistocene Richness (Nsr) = Nbda + Nrt + ½ (Nf + Nl– No) where LFAs. They are characterised by a few “Galerian” Nsr = number of taxa that potentially occur at a given 44 time interval, Nbda = number of species present be- Herbivores were separated into grazers (Gr, concen- fore-during and after the faunal unit, Nrt = number of trating feeding on grasses and sedges), browsers (Br, species present before and after but not in the faunal concentrating feeding on leaves, seeds, shoots, etc., unit, Nf = number of first appearances, Nl = number of with a reduced amount of grasses), and mixed-feeders last appearances, No = number of taxa confined in the (MF, taxa which on a seasonal, regional or occasional interval]. basis, eat grass or leaves, bark, seeds, etc. indiffe- rently). The trophic categories of frugivores (Fr) and 2.3.2 - Faunal Renewal omnivores (Om) have been considered as a single group. Carnivora consuming more than 10% of flesh Actually, species richness patterns strictly relate to are included in “Carnivores” (C). origination and extinction rates, thus richness changes and turnover patterns are closely connected. Increases Three major ecological habitat groups were retained or decreases in richness indicate respectively dispersal encompassing taxa inhabiting: 1) forests and closed or extinction events, whereas a change in taxonomical woodland (W); open woodland, bushland and wooded composition between two successive biochrons can be Mediterranean-type vegetation (Wc); miscellaneous regarded as a true faunal turnover when changes in spe- woodland (W-Wc); 2) open environments, , cies composition result from the concurrent extinction steppe or savanna (O); as well as 3) more flexible taxa, of existing species and replacement by the immigra- which can live in shrubland or open woodland, or even tion/origination of new species. Both and in more than one landscape or at the edge of two immigration have been treated as first appearances different ones (Wc-O, O-Wc). (= ‘lowest occurrences’ in the local stratigraphic suc- Body mass, the most useful describer of species cession) and extinctions or migration as last appea- adaptations in fossil species, was considered a proxy of rances (= ‘highest occurrences’ in the local strati- body size, according to Gingerich et al., (1982). Body graphic succession) (cf. Palombo, 2005 for a discus- mass was estimated using different allometric equa- sion). To compute origination and extinction rates, a tions, tested as the most adequate for each taxon (see taxon is assumed to have originated within the Palombo, in press; Palombo & Giovinazzo, 2007). biochron where it is first observed, while a taxon is as- The following categories have been utilised: BM1 = sumed to have become extinct within its last observed <10 kg; BM2 =10-60 kg; BM3=60-200 kg; BM4 = 200-1000 kg; BM5= >1000 kg. biochron. Per-taxon rates of origination (ORpt)andex- tinction (ERpt) are calculated as ORpt =(NFL + Palaeosynecological analysis was based on the rela- ∆ ∆ NFt)/Ntot/ t,andERpt =(NFL + NbL)/Ntot/ t following tive abundance of ecological categories for each faunal Foote (2000) (∆t=span of time). complex. Faunal renewals can also be estimated from the num- ber of extinctions and new occurrences at the end of a biochron and at the beginning of the successive one. 3 - RESULTS Turnover indices (TI) are calculated using the first ap- pearance (FA) and last appearance (LA) percentages (% FA = FA / RM x 100) (% LA = LA / RM × 100) that 3.1 - SIMILARITY have normalised the LA and FA using a running mean [RM = N – (FA + LO) / 2], as in Torre et al. (1999) [TI = Clustering of the entire dataset based on species oc- (% FA + % LA) / 2]. Using this method, faunal com- currence from the Pliocene to the middle Pleistocene plexes have been considered as “blocks of coordinated (fig. 2) clearly divides local faunal assemblages (LFAs) stasis” (sensu Brett et al., 1995, 1996); thus taxa were into two main groups: cluster A with Pliocene-Early assumed to be present during the whole time span cor- Pleistocene LFAs (from the Ruscinian up to the late responding to the biochron in which they first /last ap- Villafranchian, pre-Jaramillo event) and cluster B with peared (even if this was not necessarily true). Middle Pleistocene LFAs (Galerian and early Aurelian sensu Gliozzi et al., 1997; but see Palombo, 2005). 2.3.3 - Taxon-Free Characterisation of Faunal However, the Italian LFAs correlated with the Complexes Jaramillo event (early Galerian, sensu Gliozzi et al., 1997) fall within the group made up of the “late “Palaeocommunity” types were established, assi- Villafranchian” Spanish and French LFAs highlighting gning species to several ecological categories by means the main gap separate that occurs between the Italian of feeding behaviour, preferred habitat and body mass “archaic” and “modern” fauna (cf. Palombo, 2005). (Taxon-free characterization, Damuth, 1992). Within cluster A, two sub-clusters can be detected:

Feeding behaviour has been inferred on the basis of the first, A1, includes in separate groups the Ruscinian skull and mandible morphology, the extension of mas- (A11) and the early Villafranchian (A12)LFAs;the ticator muscle insertions, hypsodonty index, relative (A2) includes the middle-late Villafranchian dimensions of premolar and molar rows, occipital bone ones. The gap dividing A1 from A2 is definitely more and condylus inclination, apophysis of dorsal vertebra important than the separation between middle (A211) length and inclination, etc. (see Palombo, in press and and late (A212) Villafranchian LFAs. It is worth men- references there in). tioning that the latest Villafranchian LFAs (as well as 45

Fig. 2: Dendogram for 112 Spanish (20) French (46), and Italian (46) local faunal assemblages (Q-mode) based on un-weighted data of 149 species. Cophenetic correlation coefficient = 0.9467. Spain: Layna = Layna-MN15; Villaroya = Villaroya MN16a; Helago = Huel-MN16b; La Puebla de Valverde = PVal-MN16b; Fonelas = Fone- las-MmQ1; Cueva Victoria = Cvict-MmQ2; Venta Micena; Venta del Moro = VentaMMmQ2; Quibas = Quibas-MmQ2; Barranco Leon = BLeon-MmQ2; Fuente Nueva 3 = FNueva-MmQ2; Ponton de la Oliva = POliva-MmQ2; Huescar = Huescar-MmQ3; Atapuerca TD4 = AtTD4-MmQ3; Atapuerca TD6 = AtTD6-MmQ3; Cullar de Baza = Cul- larBaza-MmQ4a; Torralba = Torr-MmQ4b; Ambrona = Ambr-MmQ4b; Atapuerca TD10= AtTD10-MmQ4b; La Solana del Zamborino = Sol- Zam-MmQ4b; El Congosto = Cong-MmQ4b France : Montpellier, yellow sands = Mont-14; Montpellier, Palais de Justice = Just-14; Celleneuve = Celle-14; Trévoux = Tré-14; Saint Lau- rent des Arbres = SLA-14; Perpignan = Perp-15; Autrice = Autr-15; Via- lette = Vial-16; Les Etuaires = Et-16; Chagny = Cha-16; Roca Neyra = Roc-17; Saint Vallier = StVal-17; Pardines = Pard-17; Saint Vidal = SVid-17; La Rochelambert = Lamb-17; Corneillet = Corn-17, Chilhac = Chil-17; Montoussé 5 = Mt5-18; Le Coupet = LCop-17; Senèze = Sen-18; Peyrrolles = Pey-19; Blassac la Gironde = Blas-19; Sartenette = Sart-20; Le Vallonet = Vallo-20; Sainzelles = Sz-20; Saint Prest = SPrest-20; Durfort = Durf-20; Sohleilac = Sol-21; L’Escale = Esc-22; Vergnac =Verg-22; Nautire = Naut-22; Céou-22; Caune de L’Arago, lo- wer complex = AraI; Caune de L’Arago, middle complex 1 =AraII; Caune de L’Arago, middle complex 2 = AraIII; Aldène = Ald-23; Burg-23; Montoussé 3 = Mt3-23; Lunel Viel = LunV-23; Combe-Grenal = CGren-23; Verchizeuil = Verz-23; Orgnac = Or3-24; Pech d’Aze = Az7-24; La Fage = Fag-24; Cedres =Cedr-24; Grotte du Lazaret = LazIII-24 Italy : Val di Pugna = Pugna-MN15; Ponzano di Magra =Ponz; Barga, Pieve Fosciana = Barga; Triversa = Tr; Gaville, Santa Barbara = Gav./Barb-Tr; Montopoli = Montop-Mo; Valle Catenaccio = V.Ca- ten.-Mo; Colle Pardo = C.Pardo-Mo; Costa San Giacomo = C.Giaco- mo-CsGTorre Picchio = T.Picchio-CsG; Quercia = Quercia-CsG; Olivola = Olivola-OT; Upper Valdarno (already ascribed to Olivola FU) = Valdarno1-OT; Poggio Rosso = PoggioRos-OT; Matassino = Matassi- no-OT; Casa Frata = CasaFrata-OT; Casa Sgherri = C.Sgherri-OT; Fael- la = Faella-OT; Fontana Acetosa = F.Acetosa-OT; Upper Valdarno (already ascribed to Tasso FU) = Valdarno2-OT; Bacino Tiberino = B.Tiberino-OT; Monte Riccio = Mt.Riccio-OT; Pantalla = Pantalla-OT; Mugello = Mugello-Fa; Val di Chiana = ValChiana-Fa; Selvella = Sel- vella-Fa; Pietrafitta = Pietrafita-Fa; Pirro Nord = Pirro-Pr; Colle Curti = C.Curti-CC; Cava Redicicoli = Redicicoli-Pr; Slivia = Slivia-Sl; Ponte Galeria 2 = P.Galeria-Sl; Pagliare di Sassa = Sassa-Sl; Valdemino = Val- demino-Is; Isernia La pineta = Isernia-Is; Cesi = Cesi-Is; Notarchirico = Notarch-Is; Venosa Loreto= Loreto-Fr; Fontana Ranuccio = Ranuc- cio-Fr; Visogliano = Visogliano-Fr; Sedia del Diavolo = S.Diavolo-TP; Torre in Pietra, lower level = T.Pietra-TP; Capri Quisisana = Ca- priQ-TP;Bucine = Bucine-TP; Torre in Pietra, upper level = T.Pie- tra2-TP; Campo Verde = Cverde-TP Tr = Triversa FU; Mo = Montopoli FU; CsG = Costa San Giacomo FU; OT = Olivola+Tasso FU; Fa = Farneta FU; Pr = Pirro FU; TP = Torre in Pietra FU. Fig. 2 : Classification hiérarchique (dendrogramme-Q) des 112 faunes locales espagnoles (20), françaises (46) et italiennes (46) du Pliocène et Pléistocène inférieur et moyen basée sur 149 espèces. CCC = 0,9467. 46 the Italian LFAs ascribed to Colle Curti FU) set sepa- It is worth noting that the declining in biodiversity at rately, confirming the renewal characterising the se- Middle (V1) to Late Pliocene (V2) transition is possi- cond part of the Early Pleistocene (A22). bly related to the dwindling of forest dwellers. This tendency is less evident or disagrees with the trends of Within cluster B, a gap clearly separates two other forest dwellers’N and Nsr (fig. 3) because of follow- groups: B (late Early Pleistocene and early Middle emd 1 ing Harper’s (1975) and Foote’s (2000) methods the Pleistocene, early Galerian and the most archaic mid- number of taxa confined in the interval are underesti- dle Galerian LFAs) and B (Middle Pleistocene, middle 2 mated. On the other hand, the high values of N ,N and late Galerian, early Aurelian LFAs). B subcluster tot emd 1 and Nsr characterising the North-western Mediterra- includes French LFAs which have been calibrated with nean region at the beginning of the Early Pleistocene the Jaramillo event or LFAs considered very close in were mainly related to the increase in ubiquitous taxa age to it (Huescar, Spain) as well as the Italian Ponte (fig. 3). Galeria LFA, probably because of the presence of ex- clusive taxa such as Hemibos galerianus (Martinez Navarro & Palombo, 2004) and of the long-surviving 3.3 - FAUNAL RENEWAL Villafranchian herbivores, such as the medium-sized cervids belonging to the “Pseudodama” group (but see The general trend shown from the Middle Pliocene to Di Stefano & Petronio, 2003). Interestingly, this the Early Pleistocene in biodiversity is confirmed by sub-cluster set together Italian and French localities trends in origin/extinction rates (fig. 4). At transition that in separate analyses set with the latest from the Middle to Late Pliocene (from V1 to V2), the Villafranchian and Galerian (early Middle Pleistocene) number of last appearances was greatly enhanced, LFAs respectively. This fact highlight the “transi- leading to a moderate extinction phase that mainly in- tional” character of latest Early Pleistocene LFAs volved forest dwelling taxa (fig. 5), followed by a dis- confirmed by the persistence of several Villafranchian persal period, during which first appearances (open taxa together with new taxa that will survive until the landscape dwelling and, subordinately, ubiquitous following middle Pleistocene. taxa, fig. 5) clearly prevailed. On the whole, the results obtained seem to indicate For most of the Early Pleistocene extinctions, once that, although the heterogeneity of the fossil record in again prevailed. This period was followed by a new dis- each region does not enable us carry out analyses on the persal phase at the transition to the middle Pleistocene, basis of a comparable number of LFAs for each interval leading to the increase in diversity mentioned above (for instance, large mammalian faunas are poorly re- (fig.3,4). presented in the Ruscinian fossil record of Italy and the The trend in turnover indexes calculated at the transi- late Villafranchian record of Spain and France), the tion between two successive biochrons (fig. 6) shows main clusters emphasise on the significance of the mid- two important faunal renewals at the early to middle dle to late Pliocene faunal reconstruction. Villafranchian (V1 toV2+V3) (first mainly involving forest dwellers and later ubiquitous taxa), and at the early to the middle Galerian (sensu Gliozzi et al., 1997) 3.2 - DIVERSITY AND RICHNESS (G1-G2) transition. The highest turnover indexes cor- respond to extinction bioevents characterising the Early Pleistocene (V4 and V5) and especially concern The trend of total diversity (Ntot), measured on the ubiquitous taxa (fig. 6). basis of species occurrences in the faunal complexes Accordingly, four different phases ensued in a rather defined above (fig. 3), reveals that periods of lower cyclical way: an “extinction” phase took place during diversity alternating phases of an average species in- the Early and Middle Pliocene (Ruscinian and early crease occurred throughout the whole Plio-Pleisto- Villafranchian), followed by a dispersal phase during cene. A decrease in N characterised the transition tot the Late Pliocene (middle and Earliest Villafranchian); from the Middle to Late Pliocene (early, V1-MN16a, to a new extinction phase took place during the ensuing middle, V2-MN16b, Villafranchian). The following in- early Pleistocene, even if the faunal complexes crease in number of species during the Late Pliocene (V5-G1) were relatively static. At the transition to the (middle Villafranchian, V3-MN17) was more gradual Middle Pleistocene new appearances again prevailed. and was eventually completed at the beginning of the Early Pleistocene (early late Villafranchian, V4), when a peak in Nemd and Nsr can also be detected (fig. 3). 3.4 - CHANGES IN ECOLOGICAL STRUCTURE During the following Early Pleistocene (latest OVER TIME Villafranchian-Early Galerian sensu Gliozzi et al., 1997, V4-G1), richness decreased reaching a minimum Even if faunal renewal is related to extinctions, origi- at the end of the Early Pleistocene. This late Early nation/immigration and local evolution affecting fau- Pleistocene negative peak was followed by a signifi- nal richness, it does not always imply structural cant increase in the number of species at the transition reconstruction of mammal communities. Changes in to the Middle Pleistocene (middle Galerian sensu community structure can, however, be detected during Gliozzi et al., 1997, G2). the whole time-span examined here. 47

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Fig. 3: Trends of diversity from the Middle Pliocene to the Early Pleistocene in the North-Western Mediterranean faunal complexes and in ecolo- gical categories established on the basis of the preferred habitat. Standing richness value calculated according to Harper’s method (1975) [Standing Richness (Nsr) = Nbda + Nrt + ½ (Nf + Nl– No) where Nsr = number of taxa that potentially occur at a given time interval, Nbda = number of species present before-during and after the faunal unit, Nrt = number of species present before and after but not in the faunal unit, Nf = number of first appearances, Nl = number of last appearances, No = number of taxa confined in the interval]. “Total Diversity”, “Estimated mean standing diversity” and “Diversity minus singletons”, calculated according to Foote’s (2000) method. [“Total Diver- sity” (Ntot)=NFL +NbL +NFt +Nbt; “Estimated mean standing diversity” (Nemd)=Ntot –No/2 – Ne/2; “Diversity minus singletons” (NDmS)=+ NbL +NFt +Nbt; where No (Number of originations)= NFL +NFt;Ne (Number of extinctions) = NFL +NbL;NFL = taxa that exist only in the interval; NbL = taxa that originate be- fore the interval but go extinct within it; NFt = taxa that originate in the interval and persist beyond it; Nbt = taxa that originate before the interval and persist beyond it]. Fig. 3 : Variation de la diversité des complexes fauniques de la zone méditerranéenne nord occidentale durant le Pliocène moyen et supérieur et le Pléis- tocène inférieur établie d’après l’habitat préféré. Valeur de la richesse standardisée calculée d’après la méthode de Harper (1975) [Richesse Debout (Nsr) = Nbda + Nrt + ½ (Nf + Nl – Aucun) où Nsr = nombre de taxons potentiellement présents durant l’intervalle de temps examiné, Nbda = nombre de taxons présents avant, pendant et après l’intervalle de temps examiné, Nrt = nombre de taxons présents avant et après mais pas dans l’intervalle de temps examiné, Nf = nombre de premières apparitions, Nl = nombre de dernières apparitions, No = nombre de taxons confinés dans l’intervalle].

Diversité totale, diversité moyenne estimée et Diversité moins singletons, calculées d’après la méthode de Foote (2000). [“Diversité totale” (Ntot)=NFL +

NbL +NFt +Nbt ; “diversité moyenne estimée” (Nemd)=Ntot –No/2 – Ne/2 ; “Diversité moins singletons” (NDmS)=+NbL +NFt +Nbt ;oùNo(Nombre d’appari- tions) = NFL +NFt ;Ne (Nombre d’extinctions) = NFL +NbL ;NFL = taxons qui existent seulement dans l’intervalle du temps examiné ; NbL = taxons qui sont présents avant l’intervalle de temps examiné mais qui disparaissent durant cet intervalle ; NFt = taxons présents dans l’intervalle de temps examiné et per- sistant dans l’intervalle suivant ; Nbt = taxons présents avant et après l’intervalle de temps examiné].

During the Middle Pliocene (early Villafranchian, Starting from the Late Pliocene until the Early Pleis- V1) distribution by habitat type for large mammals and tocene (middle and late Villafranchian, V2-V5), the by feeding behaviour for categories of herbivores did frequency of taxa inhabiting forest woodlands progres- not noticeably differ from that typically recorded in sively decreased, whereas taxa suggesting open modern forest or scrubland environments: forest- environments and more arid climatic conditions pro- dwellers dominated, and among the herbivores, brow- gressively augmented, especially during the Early sers attained their maximum percentage, along with the Pleistocene, reaching their maximum at the end of the trophic category of frugivores and omnivores (fig. 7). late Villafranchian (V5) (fig. 7). Actually, the late 48

Fig. 4: Trends in origination and extinction rates in the North-Wes- tern Mediterranean faunal complexes from the Middle Pliocene to the Early Pleistocene.

Origination (ORpt) and Extinction (ERpt) rates calculated according to ∆ Foote’s (2000) method (ORpt =(NFL +NFt)/Ntot/ t, and ERpt =(NFL + ∆ ∆ NbL)/Ntot/ t ; t = span of time). Fig. 4 : Taux d’apparition et d’extinction durant le Pliocène moyen et supérieur et le Pléistocène inférieur calculés à partir des complexes fauniques de la zone méditerranéenne nord occidentale.

Taux d’apparitions (ORpt) et d’ extinctions (ERpt) calculés d’après la méthode de Foote (2000) (ORpt =(NFL +NFt)/Ntot / t, et ERpt =(NFL +

NbL)/Ntot / t ; t = intervalle du temps).

Fig. 6: Faunal renewals from the Middle Pliocene to the Early Pleis- tocene of North-Western Mediterranean faunal complexes (above) and in the ecological categories established on the basis of the species’ preferred habitat (below). Turnover indices (TI) = (% FA + % LA) / 2; % FA = FA / RM x 100; % LA = LA / RM x 100; FA = first appearance; LA = last appearance;

RM (running mean) = Ntot – (FA + LA) / 2. Fig. 6 : Renouvellements des complexes fauniques de la zone méditer- ranéenne nord occidentale et des catégories écologiques établies d’a- près l’habitat préféré (en bas) durant le Pliocène moyen et supérieur et le Pléistocène inférieur Indices de renouvellement (TI) = (% FA + % LA) / 2 ; % FA = FA / RM x 100 ; % LA = LA / RM x 100 ; FA = première apparition ; LA = dernière

apparition ; RM (running mean) = Ntot – (FA + LA) / 2.

Early Pleistocene (V5) was the time span during which the lowest frequency of forest-dwelling taxa has been found. Moreover, starting from the Late Pliocene (V3), grazer frequency progressively increased, reaching its maximum during the latest Villafranchian (V5), when browsers reached their minimum. It is worth noting that mixed feeders were the domi- nant category, and reached their maximum at the begin- ning of the Late Pliocene, starting to decrease only at the beginning of the Middle Pleistocene (G2), when grazers slightly augmented along with open landscape and forest dwellers, possibly due to the occurrence of more diversified environments. A comparison of body mass categories (fig. 7) shows Fig. 5: Trends in origination and extinction rates (following Foote, an average decrease in small taxa (BM1 < 60 kg) from 2000), from the Middle Pliocene to the Early Pleistocene, in the eco- the early (V1) to middle Villafranchian (V2), when me- logical categories established on the basis of the preferred habitat of species characterising the North-Western Mediterranean faunal dium-sized species (BM3) became dominant. Medium- complexes. sized species were particularly frequent during the late Fig. 5 : Taux d’apparition et d’extinction estimés à partir des catégories Early Pleistocene (late Villafranchian, V4-V59), écologiques établies d’après l’habitat préféré par les taxons des com- plexes fauniques de la zone méditerranéenne nord occidentale durant le whereas larger mammals (BM4) and pachyderms Pliocène moyen et supérieur et le Pléistocène inférieur. (BM5) were especially frequent during the middle 49

Fig. 7: Bar charts of species frequency in each ecological category established on the basis of the species’ preferred habitat, feeding habit and body mass in the North-Western Mediterranean faunal complexes from the Middle Pliocene to the early Middle Pleistocene. Fig. 7 : Fréquence des espèces dans chaque catégorie écologique établie d’après l’habitat préféré, la diète, et la masse corporelle des complexe fauni- ques de la zone méditerranéenne nord occidentale durant le Pliocène moyen et supérieur et le Pléistocène inférieur.

Villafranchian (V2) and the Galerian (G1-G2). These place during the latest Pliocene (middle to late trends substantially agree with environmental data. Villafranchian transition). As expected, more or less significant changes in faunal taxonomical composition (leading to biochron distinction) correspond to faunal structural reconstructions. 4 - DISCUSSION However, which among the above mentioned faunal As mentioned above, ecologists and evolutionists renewal was most affected by climatic and environ- have been concerned mainly with problems related to mental changes? The faunal renewal from the early to climatic influence on faunal renewal, and two central middle Villafranchian faunal complexes and the en- questions have been widely debated. Could progressive suing (V2 – V3) reorganisation of palaeocommunities changes in the composition of mammal faunal com- was probably driven by the Pliocene climate worse- plexes (fluctuations in biodiversity, biomass, changes ning, in turn related to the onset of bipolar glaciations in frequency between forest- or woodland-dwellers and changes in the periodicity and amplitude of the gla- and more open environment dwellers, of browsing, cial-interglacial cycles (orbital periodicity of 41 ka, grazing and mixed-feeder , etc.) be inter- deMenocal & Bloemendal, 1995). The resulting in- et preted as a response to climate changes (which in turn crease in aridity and more intense seasonality (Suc al., paralleled significant changes in temperature, moisture 1995) caused the disappearance of forest-dwelling and vegetational cover)? Are intrinsic biotic controls taxa, especially small carnivores and arboreal- more important than extrinsic environmental controls scansorial taxa, whereas new large grazers, mixed as regards faunal renewal? The results obtained support feeders or even browsers appeared. the argument that, in the North-western Mediterranean This renewal (already called “elephant-Equus region and during the time span considered here, the event”, Lindsay et al., 1980; Azzaroli, 1983; Azzaroli most important faunal renewals occurred at the transi- et al., 1988) can be considered as the starting point for a tion from the early to middle Villafranchian (Middle to dispersal phase leading to a progressive diversity in- Late Pliocene, ~2.7-2.5 Ma) and from the early to mid- crease during the following Pliocene and up to the be- dle Galerian, (latest Early to Middle Pleistocene ginning of the Early Pleistocene. These faunal changes ~1.1-0.7 Ma). A progressive faunal renewal also took indicate that forests or woodlands gradually gave way 50 to more open environments (including Artemisia change. This evidence of African immigration to steppe), alternating with warm-temperate deciduous southernmost stresses the importance of “out of forests. Indeed, from an ecological point of view, early ” migratory waves, taking place approximately Villafranchian faunal complexes developed in environ- around 1.6 /1.3 Ma (Martinez Navarro, in press). Sub- ments slightly resembling those of modern forests, sequently, the diversity dropped and a new faunal re- especially due to the relatively high frequency of newal took place at the end of the Early Pleistocene. frugivores and the presences of scansorial species (es- Actually, the so-called “Galerian mammal turnover pecially Carnivora), whereas the middle Villafranchian pulse” (Rodriguez et al., 2004) started approximately faunal complexes show more affinities with modern when glacial maxima attributed to massive Northern bush-woodland. The faunal renewal was primarily due Hemisphere ice sheets (Suc et al.,1995; Shackleton, to immigration, mainly from Eastern Europe, of large 1995) became more extreme, representing a major and medium-sized herbivores, both grazers and community reorganization in the Western Mediterra- mixed-feeders, but also very large browsers (such as a nean area (see e.g. Azanza et al., 1999, 2000, 2004; primitive Mammuthus), while evolutionary substitu- Palombo, 2005, in press and references therein; tions within surviving phyletic lineages were rather Palombo & Valli, 2005). negligible (tab. 1 and 2). The dispersion of incoming herbivores is consistent with the spread of grassland and Artemisia and Ephedra steppe during “glacial” 5 - CONCLUSION phases, while closed forests gave way to warm-tempe- rate deciduous or coniferous forests during the “inter- According to the results obtained, it seems that the glacial”, under more arid global conditions. Moreover, most important faunal renewals, due both to immigra- during the late Pliocene, the appearance of cooperative tions and extinctions, can be linked to major global cli- foraging ubiquitous canids and, perhaps, the powerful matic changes (noticeably cold-shift oscillations). scavenger hyaenid Pachycrocuta brevirostris, inhabi- These turnovers are preceded by more or less pro- ting more or less open environment, affected the longed phases during which diversity decreased, but guild. Indeed, the already-called “wolf- represent a starting point for a dispersal phase, leading event” (Azzaroli, 1983, 1995; Palmqvist et al., 1999), to a progressive enhancement of faunal diversity. possibly a more gradual phenomenon than previously Moreover, it seems that the most important turnovers believed, had already been completed at the beginning occurred in a quasi-cyclical way, each cycle corre- of the Early Pleistocene (Palombo, 2005; Sardella & sponding to a faunal reconstruction made up of a period Palombo, 2007). The latest Pliocene dispersal phase of prevailing appearances and by a successive phase of primarily involved carnivores, since among new taxa predominant extinctions, leading to a reduction in none belong to species which evolved in loco (tab. 2), diversity. whereas new appearances among herbivores were prin- The most important changes in faunas seem to be cipally linked to the origination of new species within triggered by important climatic and vegetational pre-existing phyletic lineages [such as Mammuthus, changes, whereas the structure of the communities to Equus, ,“Pseudodama”(=Axis Rusa be progressively reassessed by inter- and intra-guilds after Di Stefano & Petronio, 2003) and some Leptobos] competition. and subordinately to immigration of large ruminants As a result, what are the implications for “Quater- both browsers and mixed feeder (e.g Cervalces, nary” and Pleistocene boundaries? Actually, the faunal Praevibos)(tab.2). renewal from the early to the middle Villafranchian Accordingly, around 2.0-1.8 Ma (beginning of the (from V1-MN16a to V2-MN16b) can be correlated late Villafranchian), the diversity peaked, despite the with the beginning of significant evolution not only of extinction of some small browsing and grazing rumi- the Earth’s climatic system but also of the biosphere nants. The Early Pleistocene faunal reconstruction was corresponding to the dawn of the Gelasian. Moreover, possibly affected both by climatic worsening and mo- taking into account on the one hand that the transition dification of the internal dynamics of competitive rela- totheLatePliocenemarksthebeginningofamorepe- tionships, also depending on the disappearances of riod of increasing of faunal diversity coupled with some pre-existing key taxa and ensuing available changes in community structure, and that on the other empty niches (Walker & Valentine, 1984; Rosenzweig hand the tassonomical and structural changes charac- & McCord, 1991). During the late Early Pleistocene, terising the Early Pleistocene faunas, depend on the the drop in temperature, along with an increase in dry- previous dispersal phase, and correlated moderate turn- ness, undoubtedly led to the spread of wooded grass- over pulses, the middle to late Villafranchian transition land and savanna, especially in the southernmost seems to be less important than the early to middle region (for instance the Iberian and Italian peninsulas). Villafranchian renewal phase, as far as the North- The increase in grazers and the appearance of new taxa Western Mediterranean faunas are concerned. inhabiting , and among other of Accordingly, it seems more reasonable to extend the Theropithecus, a mixed feeder dwelling in base of the Pleistocene downwards from 1.81 Ma (offi- open landscapes (Martinez-Navarro et al., 2005; Rook cial Plio/Pleistocene boundary) to 2.6 Ma (base of Plio- et al., 2005), is consistent with this environmental cene Gelasian Stage). 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