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Impact of Early and Middle Pleistocene major climatic events on the palaeoecology of Southern European ungulates
No full textThe Early and Middle Pleistocene were characterised by two major climatic events: the onset of the Quaternary glaciations and the Early-Middle Pleistocene Transition (EMPT) with glacial cycles changing their periodicity. The present study reviews recent research on the palaeoecological adaptations of Pleistocene ungulates from Mediterranean Europe following these global climatic changes, through an examination of dental wear patterns and hypsodonty indices of 27 fossil taxa from 4 key localities. Ungulates from Coste San Giacomo (2.1 Ma) adopted a wide range of feeding behaviours suggesting the presence of heterogeneous environments in the region. Following the gradual deterioration of climatic conditions and drier habitats ungulates display narrower diet ranges with no incidence of obligated browsers as attested at Olivola (~1.8 Ma). The diffusion of open habitats from the Early Pleistocene onwards is also reflected by the reduction of brachydont taxa. Discrepancy between dental mesowear and microwear patterns of Vallparadís Estació (~1.0–0.6 Ma) and Fontana Ranuccio (0.4 Ma) ungulates points to an increase in seasonality during the EMPT and after its consolidation. All examined taxa display dietary plasticity through the Early and Middle Pleistocene with even specialised groups, such as equids, showing a certain flexibility in their diet
Palaeoecological and palaeoenvironmental reconstruction of the Mediterranean Europe during the Early and Middle Pleistocene based on fossil ungulates dietary adaptations
Full text linkIl Pleistocene Inferiore e il Pleistocene Medio sono stati caratterizzati da due grandi eventi climatici: l’inizio dei cicli glaciali del Quaternario che hanno instaurato un graduale trend verso climi più freddi e aridi, e la transizione del Pleistocene Medio (Early-Middle Pleistocene Transition) con il passaggio da cicli glaciali regolati da una periodicità di 41 kyr a cicli con periodicità di 100 kyr. Entrambi gli eventi hanno avuto grandi conseguenze sugli ecosistemi terrestri dell’Emisfero boreale, portando in Europa meridionale alla progressiva scomparsa degli ambienti tipicamente subtropicali del Neogene superiore, sostituiti da habitat sempre più aridi e aperti. La risposta degli organismi terrestri a questi cambiamenti climatici è importante per comprendere come variazioni del clima presenti e future, possono influenzare gli habitat della regione del Mediterraneo.
Dall'inizio del cenozoico, i mammiferi si sono evoluti e diversificati per occupare una grande varietà di nicchie ecologiche in ambienti che vanno dalla tundra ai deserti, dalle steppe alle foreste tropicali. Tra i grandi mammiferi moderni, gli ungulati erbivori sono particolarmente suscettibili ai cambi di vegetazione in quanto la loro dieta è intrinsecamente legata alla disponibilità di risorse vegetali. Le abitudini alimentari degli ungulati fossili rappresentano quindi un'importante fonte di informazioni riguardo la struttura degli habitat del passato e la loro evoluzione a seguito di variazioni climatiche.
In questa tesi, le condizioni paleoambientali di quattro siti del Pleistocene Inferiore e Medio della penisola italiana e della penisola iberica, vengono analizzate e ricostruite mediante l'altezza della corona dei molari (ipsodontia) e i pattern di usura dentaria di artiodattili e perissodattili fossili. Dall'esame delle diete a adattamenti alimentari di questi gruppi di ungulati, è stato possibile acquisire anche nuove conoscenze sulla ripartizione delle nicchie ecologiche e sui meccanismi di sfruttamento delle risorse adottati da questi mammiferi durante il Pleistocene. È stato inoltre sviluppato e testato un nuovo strumento per lo studio delle tracce di microusura presenti sullo smalto dei denti.
Dopo il passaggio dal Pliocene al Pleistocene, la regione centrale della penisola italiana è stata caratterizzata da ambienti molto eterogenei con la presenza sia da zone umide/paludose, foreste e praterie aperte. In questo contesto le numerose specie di ungulati simpatrici adottavano un ampio range di abitudini alimentari come riscontrato nelle faune fossili del sito di Coste San Giacomo (2.1 Ma; Anagni, penisola italiana centrale). In questa località taxa di taglia più piccola mostrano morfologie e pattern di usura dentaria tipica di brucatori con una dieta più selettiva, mentre animali di dimensioni maggiori risultano avere uno spettro di adattamenti più ampio con taxa brucatori, pascolatori o a dieta mista. Con il progressivo sviluppo del trend verso climi più freddi e più aridi, si osserva una propagazione degli ambienti aperti nella penisola. A seguito della transizione tra Gelasiano e Calabriano gli ungulati fossili mostrano un range più ristretto di abitudini alimentari come attestato nella località del Pleistocene Inferiore (~ 1.8 Ma) di Olivola (Aulla, penisola italiana centrale). In questo sito la maggior parte dei taxa mostra gradi di usura dentaria riconducibili a una dieta mista con l'assenza di ungulati strettamente brucatori. I cervidi in particolare che durante il Gelasiano consumavano prevalentemente risorse vegetali tenere e poco abrasive in ambienti boschivi, durante il Calabriano modificano le loro abitudini alimentari includendo il consumo di piante più abrasive per trarre vantaggio dalla diffusione di ambienti più aperti.
Le praterie aperte erano ancora l'elemento dominante degli ambienti dell'Europa meridionale durante il tardo Pleistocene Inferiore. A seguito del MIS 22, e del così detto "0.9 Ma event", si registra un incremento della stagionalità nella regione del Mediterraneo come attestato dall'alto numero di ungulati a dieta mista stagionale presenti nel livello EVT7 della sezione di Vallparadís (bacino di Vallès-Penedès, penisola iberica NE). Questa intensificazione della stagionalità potrebbe aver portato a considerevoli cambiamenti periodici della qualità di risorse vegetali disponibili. In questo scenario è possibile che i mammiferi erbivori tendessero ad ampliare il proprio dietary breadth includendo più tipologie di piante (più e meno abrasive) nella propria dieta. Una marcata stagionalità ha rappresentato un elemento chiave anche per gli ecosistemi della penisola italiana dopo la fase terminale della transizione del Pleistocene Medio. Questi ambienti che in Italia Centrale (Fontana Ranuccio, bacino di Anagni) hanno agito come habitat-rifugio per popolazioni di ominidi fossili, erano caratterizzati da ambienti eterogenei che spaziavano da foreste a spazi più aperti come comprovato dalla relativa abbondanza di cervidi brucatori e dalla presenza di taxa con una dieta molto o fortemente ricca di piante erbacee. La discrepanza osservata tra i risultati ottenuti dei pattern di usura dentari a lungo e breve termine nelle popolazioni di uro fossile (Bos primigenius) suggeriscono che una forte stagionalità con rigidi periodi avversi potrebbe aver spinto questi grandi animali a nutrirsi periodicamente anche di risorse vegetali sub-ottimali rispetto alla loro dieta abituale.
Utilizzando alcuni dei dati raccolti durante il progetto di ricerca, è stato inoltre sviluppato un programma open access (MicroWeaR) per migliorare la metodologia corrente di analisi dei pattern di microusura dentaria. Il software, scritto in linguaggio di programmazione R, è un tool liberamente scaricabile che permette di quantificare e classificare in modo semi-automatico le tracce microscopiche di usura. Il programma è stato testato su foto di superfici dentarie appartenenti a due mammiferi erbivori fossili (un cervide e un primate) ottenute con uno stereomicroscopio e un microscopio elettronico a scansione. I risultati ottenuti dall'analisi effettuata con MicroWeaR sono consistenti con quelli acquisiti tramite utilizzo di altri software di elaborazione di immagini. MicroWeaR rappresenta quindi un valido strumento per uno studio rapido e preciso delle abitudini alimentari di taxa fossili.The Early and Middle Pleistocene were characterised by two major climatic events: the onset of the Quaternary glacial cycles which led to a gradual trend towards cooler and more arid conditions and the Early-Middle Pleistocene Transition (EMPT) with cycles changing from a 41 kyr to 100 kyr periodicity. Both events had great consequences on Northern Hemisphere terrestrial ecosystems, and in Southern Europe, led to the progressive disappearance of the late Neogene subtropical environments and to the spread of more arid open habitats. The response of past biota to these climatic changes is important to understand how present and future climate shifts can affect the structure of Mediterranean habitats.
Since the beginning of the Cenozoic era, mammals evolved and diversified to occupy a variety of ecological niches in different environments spanning from the cold tundra to arid deserts, from steppes to rainforests. In modern terrestrial large mammals, herbivorous ungulates are particularly susceptible to vegetation change as their feeding behaviours are intrinsically linked to plant resource availability. Dietary adaptations of fossil ungulates thus represent an important source of information about past habitats and their evolution following climatic variations.
In this dissertation, palaeoenvironmental conditions of four Early and Middle Pleistocene sites of the Italian and Iberian Peninsula are reconstructed by means of molar crown height (hypsodonty) and dental wear patterns of fossil artiodactyls and perissodactyls. By examining ungulate dietary proclivities, new insights on the niche partitioning and resource exploitation mechanisms of this group during the Pleistocene are also provided. Moreover, a new tool to investigate dental microwear patterns in fossil taxa is here tested and described.
After the Plio/Pleistocene transition, heterogeneous environments characterised the Central Italian Peninsula, with the occurrence of wetlands, closed canopies and open grasslands. In this context, numerous ungulates could live in sympatric conditions by adopting a wide range of feeding behaviours as reported from the Early Pleistocene fossil assemblage of Coste San Giacomo (2.1 Ma; Anagni, Central Italian Peninsula). Smaller taxa were generally selective feeders while larger animals had more diverse dietary adaptations spanning from browsers to mixed feeders to grazers. As the trend towards cooler and more arid climates continued, open landscapes spread further in the peninsula. Following the Gelasian/Calabrian transition, fossil ungulates display a narrower range of feeding behaviours as attested in the Early Pleistocene (~ 1.8 Ma) locality of Olivola (Aulla, Central Italian Peninsula). In this site, most taxa display a mixed diet with no occurrence of strict browsing signals. Cervids in particular during the Gelasian consumed predominantly soft plant resources in wooded environments, but during the Calabrian shifted their diet to include more abrasive items taking advantage of the diffusion of more open habitats.
Open grasslands were still a dominant element of the Southern European environments during the late Early Pleistocene. After MIS 22, the so-called "0.9 Ma event", an increase in seasonality is recorded in Mediterranean Europe as attested by the high number of seasonal mixed feeders in layer EVT7 from the Vallparadís Section (Vallès-Penedès Basin, NE Iberian Peninsula). This increment of seasonality may have led to considerable periodic changes in the quality of food items available to herbivores which in adverse seasons widened their dietary breadth feeding on both soft and more abrasive plant resources. Seasonality also played a key role in shaping the ecosystems of the Italian Peninsula after the end of the EMPT, which acted as refugium habitats for archaic human populations. In the Middle Pleistocene site of Fontana Ranuccio (Anagni basin, Central Italian Peninsula), the relative abundance of browsing cervids and the presence of taxa with a grass-rich mixed or grazing diet point to heterogeneous environments spanning from forests to more open landscapes. The pronounced discrepancy between long-term and short-term dental wear patterns of the large aurochs Bos primigenius suggests the occurrence of marked seasonality with harsh adverse periods in which this species was forced to feed even on sub-optimal food items.
Using the collected dental microwear data, an open access program to improve current 2D microwear analysis has been designed. The software written in R environment is a free tool, MicroWeaR, which allows for a semi-automatic quantification and classification of microwear features. The program has been tested on pictures of two fossil herbivorous mammals (a cervid and a primate) taken with a stereomicroscope and a scanning electron microscope. Results are consistent with those obtained with other image processing software, thus MicroWeaR represents a robust program for precise and cheaper dental microwear analysis, and a valid tool to investigate dietary behaviours of fossil taxa
Paleoenvironments and climatic changes in the Italian peninsula during the early pleistocene. Evidence from dental wear patterns of the ungulate community of coste San Giacomo
No full textQuaternary glacial/interglacial alternations, influenced by orbital obliquity cycles with a 41-ka long periodicity, started in the northern hemisphere around 2.6 Ma ago. Such alternations affected the
terrestrial ecosystems, especially those of the Mediterranean region, with changes in the floristic communities and the dispersal and radiation of a number of large mammal open dwellers. Analyses of tooth
wear patterns of ungulates from the Early Pleistocene site of Coste San Giacomo allow for a more objective reconstruction on the paleoenvironments and the climate in the Italian Peninsula during this
epoch. Our results show that this area was composed by a mosaic of biomes, in particular by steppe and woodlands/wetlands. Evidence of such heterogeneity is provided by the wide spectrum of feeding behaviours found among the numerous ungulate herbivores here recorded, with cervids (Axis cf. lyra, Croizetoceros cf. ramosus and Eucladoceros sp.) exhibiting browser diets, most of the bovids (Gazella
borbonica and Leptobos sp. and Gallogoral meneghinii) being intermediate feeders and the equid Equus stenonis showing a strict grazer behaviour. These results provide new insights for a timing of changing
ecosystems in Southern Europe and reveal the environmental legacy of this global climatic shift, which is essential for understanding the early occupation of Homo in Europe. Thus, our data provide new evidence that such an environmental heterogeneity and a wide spectrum of available food resources could have been the main factors favouring the settlement of early species of Homo in this area
The role of climate change in the extinction of the last wild equids of Europe : palaeoecology of Equus ferus and Equus hydruntinus during the Last Glacial Period
Full text linkAltres ajuts: European Union "NextGenerationEU / PRTR" programThe last European wild equids -Equus ferus and Equus hydruntinus- were among the large mammals (or megafauna) that became extinct during the Late Quaternary Extinction Event disappearing from Europe during the Holocene. The role that the combined action of the major climatic changes of the Pleistocene/Holocene Transition and the human activities played in their extinction is not fully understood. The reduction of steppe-like biomes in Europe following the increase of mean global temperatures during the Holocene is usually regarded as the main event that triggered their disappearance, as both equids display typical morphological adaptations for open grasslands and grass eating. However, E. ferus and E. hydruntinus are found, often even co-occurring, in both warm and cold phases of the Late Pleistocene. Thus, the investigation of their niche occupation can help decipher whether their ecology and specialised dietary adaptations were the main reason of their decline following the early Holocene global warming. Here we investigate the feeding strategies of the two equids by studying their long- and short-term dietary adaptations through examination of their patterns of dental wear. As expected, dental mesowear points to a highly abrasive diet concordant with a grazing feeding behaviour for both E. ferus and E. hydruntinus which is consistent with their specialised morphological adaptations for open habitats. In contrast, dental microwear suggests a somewhat degree of plasticity in diets, as both species display microscopic features commonly recorded in modern mixed feeders. Such a flexibility may be the reason for which they could have persisted even when open grasslands were not the dominant landscape. Our findings provide a new line of evidence supporting the idea that human activities (e.g., competition with the first domestic forms brought from Eurasia and Africa) may have played a larger role in the extinction of some megafauna groups than climate change per se
New data on the Middle Pleistocene small mammal fauna from the Homo bearing site of Fontana Ranuccio (Anagni Basin, Central Italy)
Full text linkThe scanty small mammals material of the Middle Pleistocene Fontana Ranuccio site is characterized by the presence of six spe-cies belonging to three order: Eulipotyphla, Lagomorpha, and Rodentia. The small mammal fossils evidence from Fontana Ranuccio, instead the scarce number of specimens, indicates that the site is characterized by a warm and wooded environment with subordinate grassland
MicroWeaR
No full textMicroWeaR is a package to examine and score microwear scars in a semi-automatic way
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Downsizing in the Late Pleistocene: Sus scrofa (Suidae, Mammalia) in the Apulian peninsula (Southern Italy)
No full textThe extant wild boar Sus scrofa has one of the largest geographical ranges of all mammals, and from its appearance in the late Early Pleistocene (Epivillafranchian) it is also widely represented in the European fossil record. There is a general consensus in recognizing that early wild boars are larger than Late Pleistocene specimens, but no agreement exists neither on the chronology of this transition, nor if only one occurred. From the end of 1800s, the Apulian peninsula (Southern Italy) represented a key region to study Mediterranean Quaternary paleoenvironmental dynamics. This territory is rich in mammal remains, often associated to lithic tools and human remains. Consequently, this region has a remarkable research tradition, which constitutes a solid background to test S. scrofa size variability through time. Here, the wild boar craniodental material from several late Middle and Late Pleistocene sites (Aurelian assemblages) of Apulia is presented for the first time. The studied sample includes specimens from different localities with well-documented palaeobiological, biochronological, and geo-archaeological data (e.g., Grotta Romanelli, Melpignano, and Avetrana). The results support that S. scrofa populations underwent a size reduction during the early Late Pleistocene. The biochronological and paleoenvironmental implications of this bioevent are discussed in the broad scenario of Aurelian faunal impoverishment, when other long-lasting species such as the straight-tusked elephant and the hippo disappeared from the region
Palaeoenvironments of the MIS 15 site of Cava di Breccia - Casal Selce 2 (central Italian Peninsula) and niche occupation of fossil ungulates during Middle Pleistocene interglacials
No full textThe Ponte Galeria area within the city of Rome has yielded numerous fossiliferous localities that represent a reference point for the study of the European Middle Pleistocene ecosystems. Within Ponte Galeria a rich collection of fossil mammals has been unearthed from Cava di Breccia–Casal Selce 2 (MIS 15) thus the site represents an optimal laboratory to investigate the palaeoenvironments of a defined territory during the Middle Pleistocene. We investigate the feeding behaviours of the ungulate community of Cava di Breccia–Casal Selce 2 to reconstruct the MIS 15 habitats and also compare the data with those of the nearby site of Fontana Ranuccio (MIS 11) which shares similar faunal composition with Cava di Breccia–Casal Selce 2 to test if ungulates occupied the same niches during two different interglacials. Open habitats with scattered woodlands characterised the Ponte Galeria area during MIS 15, whereas woodlands were more widespread during MIS 11 at Fontana Ranuccio. Ungulates display similar diets in both localities, suggesting that cervids, large bovids and equids adopted the same niche partitioning strategies during both interglacials
Resource and niche differentiation mechanisms by sympatric early pleistocene ungulates. The case study of Coste San Giacomo
Full text linkResource competition and niche partitioning among the exceptionally high number of sympatric ungulates of the Early Pleistocene site of Coste San Giacomo (Central Italy) is here examined through the
study of their dietary proclivities and body size. The main aim of this study is to investigate the niche differentiation mechanisms that let the fossil ungulates coexist in the same region. We also provide
information about the complementarity of two different methodologies that observe diet variation at a different time scales (inner and outer mesowear) in the study of dental wear patterns of fossil ungulates.
Results from analyses of dental wear degree and body masses predictions show that a wide range of feeding behaviours were adopted by the taxonomical groups (i.e., cervids, bovids and equids) in order to
avoid competition. Among larger ungulates diet ranges from strict browsing (Eucladoceros sp., Gazellospira torticornis), to mixed feeding (Gallogoral meneghinii, Leptobos sp.) to pure grazing (Equus stenonis), whereas smaller taxa are more selective feeders (Axis cf. lyra, Croizetoceros cf. ramosus) with only one exception (Gazella borbonica). When taxa with the same feeding behaviour occurred in the same habitat, competition was minimised by differences in body size
Testing Equid Body Mass Estimate Equations on Modern Zebras-With Implications to Understanding the Relationship of Body Size, Diet, and Habitats of Equus in the Pleistocene of Europe
Full text linkThe monodactyl horses of the genus Equus originated in North America during the Pliocene, and from the beginning of the Pleistocene, they have been an essential part of the large ungulate communities of Europe, North America and Africa. Understanding how body size of Equus species evolved and varied in relation to changes in environments and diet thus forms an important part of understanding the dynamics of ungulate body size variation in relation to Pleistocene paleoenvironmental changes. Here we test previously published body mass estimation equations for the family Equidae by investigating how accurately different skeletal and dental measurements estimate the mean body mass (and body mass range) reported for extant Grevy's zebra (Equus grevyi) and Burchell's zebra (Equus quagga). Based on these tests and information on how frequently skeletal elements occur in the fossil record, we construct a hierarchy of best practices for the selection of body mass estimation equations in Equus. As a case study, we explore body size variation in Pleistocene European Equus paleopopulations in relation to diet and vegetation structure in their paleoenvironments. We show a relationship between diet and body size in Equus: very large-sized species tend to have more browse-dominated diets than small and medium-sized species, and paleovegetation proxies indicate on average more open and grass-rich paleoenvironments for small-sized, grazing species of Equus. When more than one species of Equus co-occur sympatrically, the larger species tend to be less abundant and have more browse-dominated diets than the smaller species. We suggest that body size variation in Pleistocene Equus was driven by a combined effect of resource quality and availability, partitioning of habitats and resources between species, and the effect of environmental openness and group size on the body size of individuals.Peer reviewe
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