By Stamatis Kalogiannis
Much is known about the mammalian diversity of Greece during the last ice age; mammoths, wooly rhinos, cave bears, elephants, lions, hyenas and leopards would have been common across the Greek ice age landscape, with the Pleistocene megafauna of the country being reminiscent to the megafauna now ruling the African savannahs or the plains of the Indian subcontinent. The Pleistocene epoch is also a significant time of rapid human evolution, dispersal and cultural development, with both Neanderthals and modern humans occupying parts of mainland and insular Greece. Findings suggest Neanderthals first inhabited Southern Greece about 200,000 years ago, although there is fossil evidence suggesting human habitation by archaic hominid species dating much earlier.
Chapter 1: The Quaternary Period
The Quaternary is a geological time of the Cenozoic Era that spans from 2.58 million years ago to the present. It is divided into two epochs, namely the Pleistocene (2.58mya to 11.7kya) and the Holocene (11.7kya to today).
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| Map of the world during the Last Glacial Maximum, showing reduced sea levels (© NOAA) |
Greece in the Pleistocene
The geography of Greece during the Pleistocene would have been somewhat different, particularly at the coasts, where the lower sea-level would lead to less and larger islands and more terrestrial surface. The entirety of the Cyclades, for example, formed a single large piece of land during the middle Pleistocene (0.6mya), while the surface of Crete was slightly larger. Several islands of the Ionian and Aegean sea would be connected to the mainland (e.g. Euboea, Corfu) or, together with other nearby islands, would form single larger islands (e.g. Kefallonia and Zakynthos). Several islands east of the mid-Aegean trench were connected to what is now the mainland of Turkey (e.g. Chios, Lesvos) up until the end of the last glacial period. Furthermore, some of the major gulfs (e.g. Ambracian gulf, Pagasetic gulf) did not exist until the late Pleistocene. In general, the only major geographic difference would have been a lowered sea-level by more than 100 m. Glaciers were formed in the mountainous areas of mainland Greece, such as in the Pindus mountain range, and the mountains Ida and Lefka Ori on Crete.
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| Approximate map of Greece during the Middle Pleistocene. Note changes in sea level. |
When it comes to vegetation, a handful of studies provide an insight into the flora of some Pleistocene localities in Greece. Papadopoulou et al. (2018) examined pollen from a Lower Pleistocene lacustrine sedimentary sequence in Sousaki basin, eastern Corinth, southern Greece. The study revealed a Mediterranean type of vegetation with altitudinal zonation, where Pinus and Quercus dominated along other arboreal and non-arboreal plants. Rare taxa that are not found in southern Europe today were also present between 2.8 and 1.5mya. The study also found a rather stable, temperate or subtropical climate, with minor fluctuation between glacial/interglacial time periods. Another study of the pollen record in the Copais basin, Southern Greece revealed various vegetation variations attributed to climatic changes throughout the Pleistocene (Okuda 2008). The most persistent species were Quercus, Pinus and other temperate trees, as well as various steppe elements, such as Ephedra, Artemisia, Chenopodiaceae and Poaceae. Various species of aquatic plants also thrived in the banks of lake Copais, such as Typha and Myriophyllum. Ntinou (2020) studied wood charcoal from the late Pleistocene in the Klissoura cave in the Argolis, Peloponnese, revealing distinct phases of vegetation that correlate with the chronological framework of the site and the climatic events of the Pleistocene. The study showed an assemblage of flora composed by thermophilous Olea and Quercus during the last interglacial, followed by open Amygdalus woodlands under increasingly drier conditions in the last interglacial. Juniperus woodlands prevailed in colder/drier periods, while more humid conditions favored Quercus woodland. Other taxa identified are typical Mediterranean species, such as Pistacia, Pinus, Laurus nobilis, Prunus, Rhamnus and others. Another study by Gerasimidis et al. (2009) examined the pollen record from the area of Epirus (NW Greece), covering the Pleistocene epoch up until the late Holocene. The study showed fluctuation according to the glacial/interglacial timeline, with open steppe prevailing during the glacial periods. Arboreal species were only firmly present, and certain microenvironments characterized by favorable conditions were present in the mountainous regions. During the interglacial periods, the vegetation was drastically altered and woodland prevailed. It consisted of deciduous broadleaves appearing as mixed Quercus forests, while the mountainous vegetation was composed by Fagus, Pinus and Abies. Along these, plant species like Pistacia and Phillyrea showed that Mediterranean vegetation developed in certain localities.
Overall, it seems that the vegetation of Greece during the earlier Quaternary was largely composed of common modern species and was well-diversified, with temperate and subtropical species. There seems to be some degree of oscillation among glacial and interglacial time periods, with the abundance of certain vegetation types also varying according to latitude. Short-term climatic variations would surely play an important role too. The southern part of Greece was not affected much by the glacial periods, as open woodland composed by Quercus, Juniperus, Olea and other, similar evergreen trees was retained throughout the epoch and is still prevailing today. In addition, azonal vegetation with Cyperaceae and Typhaceae and riparian forests composed by Platanus, Liquidambar and Alnus existed across river banks and lakes. Mixed broad-leaved temperate forests with Acer, Fagus, Corylus, Juglans, Tilia, Ulmus and other forest elements along the ever-present Quercus were predominant in low altitudes. Open habitats, particularly steppes consisting of grasses (Poaceae), Artemisia and Ephedra were present to some degree during glacial periods in Southern Greece. Conifer forests with Cedrus, Tsuga and Pinus were also present, especially at the higher altitudes. In Northern Greece, similar forests would prevail during the interglacial time periods. Open steppes with Artemisia, Chenopodiaceae, Poaceae and Asteraceae, however, were likely much more widespread than in other parts of the country, due to drier and colder conditions. These open habitats would largely replace woodland cover during the glacial periods. Forests during the glacial periods of Northern Greece were composed by Quercus, Pinus and the well-distributed fir trees (Abies). Furthermore, typical thermoxeric Mediterranean broad-leaved maquis with Arbutus, Pistacia, Phillyrea and Quercus occurred in low elevations throughout the country during the interglacials, although it was likely not as widespread as it is today.
The fauna of Greece during the Pleistocene contained an extraordinary amount of megafauna. Dozens of studies have focused on mammalian fossil findings excavated from several different sites across the country, especially from caves. Some remarkable species are represented by Proboscidea (e.g. Elephas antiquus), Rhinocerotidae (e.g. Coelodonta antiquitatis, Stephanorhinus hemitoechus), Equids (e.g. Equus hemionus), Bovids (e.g. Bison schoetensacki) and several carnivores, such as felids (e.g. Homotherium, Panthera pardus spelaea, Panthera leo, Lynx lynx), spotted hyenas (Crocuta crocuta) and bears (e.g. Ursus spelaea). Many of the modern mammals present in Greece were also abundant in the Pleistocene of the country, such as red deer, roe deer, balkan chamois, wild boar, gray wolves and brown bears.
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| Artistic reconstruction of the open steppes that prevailed during the epoch. A similar scenery was likely present in Northern Greece during the Last Glacial Maximum. © Mauricio Antón |
Chapter 2: The Pleistocene herpetofauna of Greece
There is very limited research on fossilized reptiles and amphibians from Greece, with most of it focusing on the Neogene period. A handful of studies mention dozens of taxa from Pleistocene sites. Bufonidae, Rana sp., Hyla sp., Salamandridae, Testudinidae, Lacertidae, Ophiomorus sp., Pseudopus sp. and Colubrinae have been excavated from a site in Kaiafas, Peloponnese (Villa et al. 2020, Delfino & Georgalis 2022), pointing to a species composition similar to the herpetofauna present in the area today. Pleistocene chelonian remains from two sites in the Peloponnese (Franchthi cave & Megalopolis) have been identified as European Pond Terrapin Emys orbicularis, Balkan Terrapin Mauremys rivulata and Hermann’s Tortoise Testudo hermanni (Vlachos & Delfino 2016), all species being present in the Peloponnese today. Extinct from the island today, an endemic land tortoise subspecies, Testudo marginata cretensis, has been described from Pleistocene cave deposits in Crete. The validity of the subspecies, supposedly larger than extant T. marginata in the Greek mainland, has been refuted by additional material (Vlachos 2022). The same author also presents further chelonian fossils from Crete, specifically some fragments attributed to Mauremys cf. rivulata found in the same caves. Balkan Terrapins still exist on Crete today. Monitor lizard fossils assigned to the genus Varanus have been found in a Middle Pleistocene site in Athens (Tourkovounia) (Georgalis et al. 2017). The latter findings are considered to be the youngest European varanid fossils, indicating that the family went extinct from Europe much later than previously thought, more than 5 million years after colonizing the region during the Miocene. The Tourkovounia site has provided various other valuable findings from the Pleistocene, such as Elaphe cf. quatuorlineata, Zamenis situla, Scolecophidia and some amphibians. On the topic of large lizards, anguids of the genus Pseudopus are well-represented by Cenozoic fossils in Europe, with two species known to have persisted into the Quaternary; Pseudopus pannonicus & P. apodus (Klembara et al. 2010). The former is not known from the Pleistocene of Greece so far, though the Pseudopus sp. fossil identified by Villa et al. (2020) in the Peloponnese is not unlikely to belong to P. pannonicus. The species appears to have gone extinct in the Middle Pleistocene, when it was gradually replaced by the closely related P. apodus at the eastern part of its range. When it comes to skinks, an Ablepharus kitaibelii fossil from the Pleistocene/Holocene of a cave in Attica is the only known fossil of the species, complementing the aforementioned Ophiomorus sp. fossil from Kaiafas. Pleistocene amphibians are represented by a number of species throughout many sites in Southern Greece. Pelobates, Bufotes, Bufo, Rana, Pelophylax and Hyla are the most common taxa (Georgalis & Delfino 2022a), implying no changes in the composition of amphibians in mainland Greece since the Pleistocene.
Fossils from the ‘Bate cave’ on the island of Crete dating to the Late Pleistocene have been identified as the following taxa; Bufo cf. viridis, Testudo marginata cretensis, Lacerta cf. erhardii and Coluber cf. gemonensis (Kotsakis 1977). With the exception of the land tortoise, the rest of the species currently occur on Crete - Lacerta erhardii likely corresponds to the endemic Podarcis cretensis. Fossils of the genus Natrix have been found in the Gerani cave of Crete, likely from the extant N. tessellata currently present on the island (Georgalis & Delfino 2022b). This small faunal assemblage may indicate a climate similar to the modern climate of present-day Crete. In addition, a Discoglossus sp. fossil is reported from the Sitia formation of Crete (Kotsakis 1982), a Western Mediterranean genus not present in the fossil record of Greece. The identification has been questioned by many, due to Discoglossus being similar to Latonia, a genus present in abundance in the Pliocene of Greece. No Pleistocene fossils of Latonia exist, though the genus may have survived into the Quaternary on Crete. Last, a large lizard tibia, placed by various authors in the genus Uromastyx or Agama, is reported from the Late Pleistocene of Simonelli cave in Crete (Mangili 1980), but its identification remains a subject of debate. In Chios, indeterminable Lacertidae, Natricinae, and Colubrinae, ‘oriental vipers’ probably in the genus Montivipera, Eryx jaculus and a supposed Naja fossil are reported from a Middle Pleistocene site in Latomi (Schneider 1975). The identification of the latter has been rejected by some authors.
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| Pseudopus apodus (© Plato Stefanopoulos) |
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| Hyla arborea (© Stamatis Kalogiannis) |
In the rest of Europe, the largest part of fossil herpetofaunal material is composed by extant taxa still present within European territory. This phenomenon is known as the ‘Herpetofaunal Stability Hypothesis’, a theory suggesting that herpetofauna has remained taxonomically and geographically stable throughout the Quaternary. The theory can also be applied to Pleistocene Greece, as only a handful of ‘exotic’ and extinct species exist in the country’s fossil record from that epoch. Few exotic taxa are known from the Pleistocene of other European countries too. In the Iberian peninsula, fossils of the anguid lizards Dopasia and Ragesaurus medasensis have been found in the Early Pleistocene of the mainland and the Medes islands. In addition, Agamidae, Pseudopus pannonicus, Mabuya sp., Scolecophidia, oriental vipers and extinct geckos are known to have existed in Spain until the Early Pleistocene (Blain et al. 2016). An extinct allocaudate species, Albanerpeton pannonicus, is known to have survived until the Early Pleistocene of Rivoli Veronese, Northern Italy. The species was the last member of the salamander-like order Allocaudata and likely became extinct when the first major glaciation event made the area unsuitable, with A. pannonicus being unable to migrate further southwards (Villa et al. 2018). A few more extinct amphibians are reported in the Pleistocene of Europe; Pliobatrachus cf. langhae from the Middle Pleistocene of Germany, Mioproteus wezei from the Middle Pleistocene of Central Europe and Parahynobius sp. from the Early Pleistocene of the Carpathian basin (Ivanov 2007). It seems that the extinction of amphibian taxa in Europe during the early Quaternary was probably caused by changes in climate.
A lot of Pleistocene fossils from Europe come from extant European species that show few changes in distribution. Some taxa used to have a broader distribution over the continent; for example Mauremys and Blanus fossils were found in Italy (Delfino & Bailon 2000), Pelodytes punctatus and Natrix tessellata/maura were found in Britain (Holman 1993) and Bufotes viridis s.l. was found in Spain (Blain et al. 2016). The composition of species in various Pleistocene sites can also give an insight into the climate and habitats of an area during the time. A study (Jovanović et al. 2020) on Late Pleistocene fossil finds from cave deposits in Serbia shows that the herpetofauna mainly consisted of Rana temporaria, Zootoca vivipara, Lacerta agilis, Anguis fragilis, Vipera berus, Vipera ammodytes and Zamenis longissimus, distinguished in three chronocultural phases; Mousterian (160,000-40,000 years BP), Aurignacian (43,000-26,000 years BP) and Gravettian (33,000-21,000 years BP). As found, the Gravettian phase presents the lowest diversity of species, coinciding with the last Glacial Maximum, along with the appearance of more cold-tolerant alpine species. During the Aurignacian, species diversity indicates a cooling climate and a high degree of environmental humidity, generating a landscape dominated by humid grasslands and scrubs. The composition of species during the Mousterian shows warmer, temperate conditions. Nose-horned viper Vipera ammodytes was only found to occur in the Mousterian period. The presence of Zamenis longissimus throughout all three time periods may indicate the survival of woodland even during the colder periods of the Late Pleistocene.
Phylogeography and Pleistocene biogeography
Recent phylogenetic studies have also revealed high genetic diversification patterns during the glacial/interglacial intervals of the Pleistocene in Europe by examining the mitochondrial genome of different herpetofauna species. The genus Vipera has been widely studied in this regard, with its modern distribution being a perfect example of how species may have been affected by the Pleistocene glaciation events. Some European vipers are considered ‘glacial relics’ - a population of a cold-adapted taxon that has been left behind after the last ice age. Such a case is the Balkan Adder Vipera berus bosniensis, a species known to inhabit cold mountainous areas of the Balkan peninsula. During the glacial periods, adders would be widespread throughout the suitable lowland plains of the region. In progressively warmer conditions during the interglacial periods, however, they would retreat to the higher altitudes where they favored lower temperatures. In modern times, the populations of Vipera berus s.l. in Europe correspond to three clades, which were probably separated into three geographically isolated groups sometime in the Lower Pleistocene. From these, only the Northern clade remains widespread throughout Europe, ranging from Great Britain to Russia and as far north as Fennoscandia. A study using mtDNA sequence data revealed that the clade likely retreated to the Carpathian region during the ice ages, from where it re-colonised the rest of Northern Europe after the cold periods ended (Ursenbacher et al. 2006). The warmer climate of Southern Europe (Italy and the Balkans) did not allow the other two clades to leave the mountains after the LGM, ‘trapping’ them in higher altitudes. Consequently, Balkan adders only occur as relict populations at the northernmost mountains of Greece, such as in the Rhodope mountain range. The other montane, cold-adapted herpetofauna species of Greece likely had similar distribution patterns during the glacial maxima. Phylogenetic analyses of the Alpine Newt Ichthyosaura alpestris revealed 5 distinct clades, with extensive divergence in the eastern clades implying great isolation in multiple glacial refugia in Central and Southeast Europe (Sotiropoulos et al. 2007). The results showed that Western and Northern Europe was colonized from the marginal refugial populations, which remained in Southeast Europe shifting their ranges upwards to higher altitudes. Lacerta agilis and Rana temporaria, currently inhabiting the mountains in the northern parts of Greece, might have followed a similar pattern. Hence, these taxa can be considered ‘glacial relics’ in the country, and were likely present in lowland habitats during the ice age.
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| Post-glacial re-colonization routes of the adder in Europe, based on Ursenbacher et al. (2006) |
The phylogeography of widespread reptile species in Greece can also provide valuable info about the colonization patterns of European herpetofauna, highlighting the importance of Greece as a glacial refugium. Mainland Greece and the various islands (e.g. Cyclades) acted as refugia for the Caspian whip snake Dolichophis caspius during the ice age, which was seemingly confined to the southern Balkans during the time. Post-glacial dispersal to the north led to the colonization of Central and Eastern Europe out of the peninsula (Nagy et al. 2010). Although it seems that the species survived in southern refugia during cold intervals, with the Peloponnese being an excellent refuge for European reptiles and hosting lots of suitable grassland habitat (see Chapter 3), the absence of D. caspius from the peninsula remains a mystery. A similar southwards isolation during the Last Glacial Maximum was followed by the Four-lined snake, which, as shown by the fossil record, was more widespread before the Pleistocene (Kornilios et al. 2013). With the glacial events of the epoch, the species retreated to the southern areas of the Balkan and Apennine peninsulas where it remains until today. Contrary to Dolichophis caspius, however, the four-lined snake subsequently failed to re-colonise Central Europe during the Holocene but has successfully occupied most of the Greek mainland. Although the reason behind the species failing to reach its historical range after the ice age is unclear, competition by similar colubrid species or a climate unlike that of the Neogene period are some likely explanations. Aesculapian Snakes Zamenis longissimus also colonized much of Europe from their refugia in the southern peninsulas of the continent after the LGM (Musilova et al. 2010), now being widespread throughout the continent.
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| Left: Male of Podarcis peloponnesiacus (© Stamatis Kalogiannis), Right: Phylogenetic tree showing divergence times (© Kiourtsoglou et al. 2021) |
Lower sea level during the Pleistocene allowed herpetofaunal species to colonize several of the Aegean and Ionian islands. In Crete, the phylogeography and colonization patterns of 4 snake species were studied, revealing three distinct ‘paths’ (Kyriazi et al. 2013). The oldest pattern was that of the Cat Snake Telescopus fallax, which likely reached the island from Anatolia via a land bridge during the Messinian, followed by the Dice Snake Natrix tessellata, reaching Crete with trans-marine dispersal from Turkey at the Pliocene-Pleistocene boundary. More recently, Balkan Whip Snake Hierophis gemonensis and Leopard Snake Zamenis situla likely colonized Crete by crossing the sea from the Peloponnese during the Pleistocene, with in-between islands serving as stepping stones. The role of the Peloponnese during the early Quaternary is significant, as it is among the most notable ice age refugia of Europe. This can be seen in the high abundance of Pleistocene fossils and the presence of glacial relics at the mountains of the peninsula. Such relics are the Smooth Snake Coronella austriaca and the Alpine Newt Ichthyosaura alpestris found at the higher altitudes of the Central Peloponnese, which retreated to the area during the last ice age and were later isolated there. The southern geographic location of the peninsula would have resulted in a mostly temperate climate, as shown by the Mediterranean vegetation identified from Palaeolithic wood charcoal in a cave of the Argolis prefecture (Ntinou 2020). The species composition reported in Villa et al. (2020) from Kaiafas, consisting of three anurans, one salamander, one testudine, at least five lizards and one snake, also shows a very rich herpetofauna.
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| Hierophis gemonensis, one of Crete's four snakes, colonized the island during the Pleistocene (© Plato Stefanopoulos) |
Most of the modern herpetofaunal taxa colonized Greece during the Miocene-Pliocene timespan, but especially during the Messinian Salinity Crisis (MSC) that occurred during the Messinian (5.96-5.33mya), when the desiccation of the Mediterranean sea allowed several biota to migrate between three continents. Nevertheless, some species are recent additions to the herpetofauna assemblage of the region. The genus Malpolon is represented by two species around the Mediterranean coast; Malpolon monspessulanus in the west and M. insignitus in the east. Divergence between them is estimated to have taken place around 3.5-6 million years ago in the Maghreb desert, from where the two clades spread to a westwards direction into the Iberian peninsula and an eastwards direction into Anatolia, respectively. Although the exact chronology of this event is unclear, mtDNA data place it at around 83,000-168,000 years ago for the western species, though Pliocene fossils from Iberia may indicate an earlier entrance into SW Europe, during the MSC. The species may have subsequently gone extinct from Europe during the first glaciation events. The exact time period of expansion of the eastern species into the Balkan peninsula is unknown, but likely happened very recently, sometime in the Plio-Pleistocene. This is evident in: a) The almost complete absence of Malpolon fossils from the Balkans, b) The absence of Malpolon insignitus from Aegean islands that were separated from continental Eurasia before the Pleistocene (e.g. Cyclades) and c) The ecology of the genus as largely thermophilous snakes that would likely not thrive during the glacial events in the Balkans. Very few fossils of Malpolon exist from Eastern Europe, particularly in the Late Pliocene of Romania and Greece. It is not unlikely that Malpolon reached the region during the MSC or sometime in the Pliocene, but similarly to Iberia, went extinct or was much scarcer during the Pleistocene. This hypothesis might suggest two distinct colonizations of the area, with the second one resulting in the modern populations. One can only speculate about the biogeography of the species, and further phylogenetic research is required in order to determine the chronology of its ‘invasion’ in Southeastern Europe.
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| Malpolon isnignitus is one of the most succesful Greek snakes (© Stamatis Kalogiannis) |
The presence of monitor lizards well into the Pleistocene of Southern Greece is remarkable and raises questions about their extinction. The first appearance of the family in the fossil record of Europe takes place during the Eocene. These Paleogene varanids probably went extinct at the end of the Eocene, appearing again after the early Miocene. During that time, representatives of the genus Varanus are reported from sites in Samos (V. amnhophilis) and Attica (V. marathonensis). Monitor lizards then become progressively scarcer during the Pliocene, with the last occurrence outside Greece being reported from the Late Pliocene of Hungary. The finds from the Middle Pleistocene of Attica are the youngest varanid fossils from Europe and presumably originate from a smaller descendant of V. marathonensis. The smaller size might be an adaptation in response to changes in climate, particularly colder conditions during the first glaciation events of the Pleistocene. These major climatic fluctuations during the glacial periods along with low genetic diversity may have ultimately led to the extinction of the taxon in Greece, as monitor lizards are known to be largely thermophilous animals adapted to living in tropical and subtropical regions. Another hypothesis would be that monitor lizards were hunted to extinction by early humans during the Middle-Late Pleistocene, although there is no fossil material showing cut marks or other evidence of harvesting. Furthermore, several other exotic reptile lineages are known to have lived during the Miocene-Pliocene of Greece. Such taxa are Cordylidae, Agamidae, Crocodylia, Elapidae (e.g. Naja romani in the Late Miocene) and Pythonidae (e.g. Python euboicus in the Early Miocene), all going extinct before the Plio-Pleistocene transition. The presence of these taxa indicate a warm, tropical or subtropical climate during the early Neogene of Greece. Progressively cooling conditions shortly before the Quaternary is the best explanation for their extinction.
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| Holotype of 'Varanus amhnophilis', currently considered a synonym of V. marathonensis (© Conrad et al. 2012) |
Chapter 3: Herpetofauna composition and habitat diversity
The Pleistocene vegetation reported for three areas throughout mainland Greece (Peloponnese, Central Greece and Epirus) generally agrees with the composition of herpetofaunal species during the same period. Based on both phylogenetic data of herpetofauna and data regarding Pleistocene plant assemblages, significant variations of species and habitat diversity would occur between glacial/interglacial time periods. Gerasimidis et al. (2009) highlighted the abundance of open steppes and grasslands in the ice age of NW Greece. The occurrence of such habitats can also be supported by the presence of various grazers and browsers, such as deer, ibex, rhinos, bison, aurochs and wild horses. This type of habitat would likely be inhabited by Northern European herpetofauna species retreating southwards, seeking warmer climatic conditions. Such species occur today in alpine meadows and other mountain habitats of N Greece. Pollen studies from the Pleistocene of the Peloponnese peninsula and the Copais basin (Urban & Fuchs 2005, Okuda et al. 2008, Papadopoulou et al. 2018) show the significant presence of steppe-like grasslands in Southern Greece too. The diversity of herpetofauna species at southern grassland habitats might have consisted of typical grassland-dwellers, such as the Caspian Whip Snake Dolichophis caspius, which would retreat towards southern refugia during glacial periods. Deciduous and evergreen forests were also abundant throughout the country, with several temperate species like beech trees, conifers and oaks prevailing in both Southern and Northern Greece during interglacial periods (Gerasimidis et al. 2009, Papadopoulou et al. 2018). Temperate woodland species like Aesculapian Snakes Zamenis longissimus would occupy such forests. Furthermore, the presence of typical wetland reptiles and dozens of amphibians throughout the Pleistocene fossil record of Greece points toward the abundance of ecosystems characterized by the presence of many water bodies, such as lakes and rivers, which were covered by riparian forest species like Platanus and aquatic plants like Typhaceae. Last, numerous Mediterranean species in Pleistocene fossil assemblages of Southern Greece may indicate a temperate - Mediterranean type of climate at the southernmost parts of the country, at least during the interglacial periods. Pleistocene vegetation studies confirm this, as species like Pistacia and Olea, typical of the thermo-Mediterranean maquis were found to occur.
Speculative analysisFor a more detailed analysis, I divided some potential vegetation/herpetofauna relationship patterns during the Pleistocene of Greece, based on fossil evidence, phylogeography studies and vegetation data:
b) Mixed deciduous woodland with Quercus, Fagus, Ulmus, Corylus, Acer, Tilia and other arboreal species that replaced open grasslands in Northern Greece during the interglacial periods, or persisted throughout the epoch in lowland Southern Greece, due to warmer and more humid conditions. Inhabited by typical temperate continental species, such as Aesculapian Snake Zamenis longissimus, Smooth Snake Coronella austriaca, Green Lizard Lacerta viridis and Slow Worm Anguis fragilis s.l.
d) Mediterranean shrubland/woodland, like maquis, with Arbutus, Pistacia, Olea, Quercus, Juniperus, Phillyrea, Rhamnus and other evergreen species. Present throughout the country during interglacials, but especially in Southern Greece and the Aegean islands, covering small to large coastal areas. Inhabited by typical thermophilous and Mediterranean species, such as Glass Lizard Pseudopus apodus, Four-lined Snake Elaphe quatuorlineata, Balkan Whip Snake Hierophis gemonensis, Nose-Horned Viper Vipera ammodytes, Eurasian Blind Snake Xerotyphlops vermicularis and Marginated Tortoise Testudo marginata.
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| Potentially common habitats associated with herpetofauna during the Pleistocene. From top left to right, deciduous Fagus forest, deciduous Quercus forest, open grassland and inland wetland |
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| Zamenis longissimus in its forest habitat (© Plato Stefanopoulos) |
Closing remarks and acknowledgments
This is the first part of a two-part sequence of articles regarding the evolution of Greek and European herpetofauna throughout the Quaternary, that is, about 3 million years of genetic evolution, range expansions, extinctions, geographical events, climate changes and later, human-mediated translocations. With the first part covering the Pleistocene epoch, widely known as the ‘ice age’, the next part will be focusing on the Holocene - a time characterized by the extreme development of the human species. The first part is the product of days worth of literature review and years worth of theories and speculations about the Greek herpetofauna developed by our team. The goal is simply to educate. Special thanks to Plato Stefanopoulos and Charis Kouelis for providing some photographs, and to Georgios Georgalis for providing some valuable info and documents.
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[2] Okuda, M., Yasuda, Y., Setoguchi, T. 2008. Middle to Late Pleistocene vegetation history and dlimatic changes at Lake Kopais, Southeastern Greece. Boreas 30 73-82.
[3] Ntinou, M. 2020. Vegetation change in southeastern Greece during the Pleistocene. The wood charcoal record from Klissoura Cave 1 (Peloponnese, Greece). Quaternary International 593-594 (11).
[4] Gerasimidis, A., Panajiotidis, S., Fotiadis, G., Korakis, G. 2009. Review of the Late Quaternary vegetation history of Epirus (NW Greece). Phytologica Balcanica 15 19-27.
[5] Villa, A., Georgalis, G.L., Delfino, M. 2020. The latest early Pleistocene amphibians and reptiles from Kaiafas (Greece) and the first record of fossil Ophiomorus (Squamata, Scincidae). Geobios 62 79-90.
[6] Delfino, M., Georgalis, G.L. 2022a. The Fossil Record of Amphibians (Amphibia: Urodela and Anura) in Greece. Fossil Vertebrates of Greece 1 185-203.
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