European Geologist Journal 48
Pikermi: a classical European fossil mammal geotope in the spotlight
by Socrates Roussiakis1, Panagiotis Filis1, Stamatina Sklavounou1, Ioannis Giaourtsakis2, Nikos Kargopoulos1 and George Theodorou1
1 Department of Historical Geology and Palaeontology, Faculty of Geology and Geoenvironment, National and Kapodistrian University of Athens, Panepistimiopolis, 15784 Athens, Greece
2 Section of Paleontology and Geobiology, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Richard-Wagner-Str. 10, 80333 Munich, Germany
Contact: srousiak@geol.uoa.gr
Abstract
The renowned Pikermian fauna has long served as a reference for the systematic, biostratigraphic and paleoecological study of Late Miocene Eurasian mammals. The classical locality of Pikermi has been extensively excavated since the mid-19th century, with the latest series of systematic excavations organised by the National and Kapodistrian University of Athens. The preservation and promotion of the locality is of paramount importance, not only for its scientific context, but also for its historical significance and educational value for the paleontological heritage of Greece and Eurasia. In this article we discuss the timeline of fieldwork and research at the locality, as well as the steps currently taken in order to preserve and explore Pikermi as an internationally acclaimed geotope.
Introduction
Pikermi (Attica, Greece) is one of the oldest known and most celebrated fossiliferous localities of the Eurasian Late Miocene. Numerous excavations have been conducted since the mid-19th century, revealing a rich and diverse vertebrate fauna of Turolian age. Pikermi is considered as one of the key reference localities of the European continental Upper Miocene (e.g. Bernor et al., 1996 and references therein) due to the diversity of its faunal composition and the fact that it represents the type locality of several Turolian vertebrate genera and species. The significant paleoecological context of the locality has led to the establishment of the term “Pikermian biome”. From both the wealth of the paleontological knowledge accumulated and the historical significance of such a long running excavation locality, it is apparent that the renowned Pikermi geotope must remain a focus of conservation efforts, allowing opportunities for the continuation of the fieldwork and its promotion as a prime destination of geotourism.
Geology
The fossiliferous locality of Pikermi is placed within the Mesogea Basin, one of the three major hydrographic basins of Attica, close to the municipality of Pikermi and ca. 20 km east of the city of Athens. The Mesogea Basin is surrounded by Mount Pentelikon to the north and Mount Hymettus to the west, as well as by the Koropi Hills to the south and the Euboic Gulf to the east. The basin’s hydrographic system consists of numerous streams originating from Pentelikon and Hymettus Mountains that flow from the higher northern and western altitudes towards the southern lowlands and then to the east. These streams gradually merge into the main Megalo Rema stream, which drains into the Euboic Gulf. One of the main tributaries of the Megalo Rema stream is the Valanaris, and it is along the banks of this tributary that most of the fossiliferous sites have been discovered.
The Mesogea Basin developed during the Late Miocene by activation of a major detachment fault, which separated carbonates of the Internal Hellenides from Mesozoic metamorphic rocks. The Upper Miocene sediments of the Mesogea Basin can be divided into the terrestrial to fluvial Pikermi Formation and the palustrine to lacustrine Rafina Formation (Böhme et al., 2017). The Pikermi Formation represents an up to 30-m-thick sequence of predominantly reddish silts with subordinate clastic channels of conglomerates and sandstones, which has yielded rich terrestrial vertebrate fauna. The Pikermi Formation rests discordantly above a lower limestone unit with palustrine to lacustrine marls and coals, and is concordantly overlain by the Rafina Formation, which is composed of palustrine to lacustrine clay, coal, and platy limestone. The Pikermi Formation can be further subdivided into two members. The lower Red Conglomeratic Member is characterised by an alternation of red silts with a weak pedogenic overprint and debris flow deposits. It is within the lower Red Conglomeratic Member that most historical and recent excavations took place. The stratigraphically younger upper fluvio-alluvial Chomateri Member represents an alternation of reddish to yellowish silts with fluvial channels and channel-fill trains and corresponds to the eponymous excavation site of Chomateri (Böhme et al., 2017).
Timeline of the excavations
The fossiliferous locality of Pikermi was discovered by the renowned Scottish historian and philhellene George Finley in 1836, during a tour he had undertaken in the Mesogea region of Attica with the hope of discovering remains of the temples of the Brauronian Artemis and the Oropian Amphiaraos. While prospecting the area, Finley noticed the unusual accumulation of bones inside a steep bank of red clay that had been washed away by a torrent that descended from Mount Pentelicon and was known to the locals as the stream of Pikermi. The peasants of the neighbourhood, who were acquainted with the spot, called these remains Hellenic bones (κόκκαλα ελληνικά). A few weeks later, Finlay read a note concerning his discovery at the newly established Physiographic Society of Athens, and donated his findings to the collections of the society, which later became part of the University of Athens. The society encouraged Finley to continue the exploration of the site, and he carried on with some additional excavations in collaboration with the distinguished German ornithologist Anton von Lindermayer, a founding member of the society.
A Bavarian soldier, who presumably participated in these excavations, collected some specimens, thinking the calcite crystals formed inside the cavities of the fossilised bones as being diamonds. Upon his return to Munich, the soldier presented these specimens to the distinguished professor of zoology Andreas Wagner. Wagner disproved the soldier’s hopes about diamonds, but acknowledged the scientific value of the specimens, securing them for the collections of the Bavarian Academy of Sciences by paying a sizeable compensation. Among the scanty material, he instantly recognised the maxilla of a primate, which he subsequently described as a new genus and species, Mesopithecus pentelicus (Wagner, 1839). This was one of the first fossilised primate specimens to be ever discovered, thus attracting immediately significant interest from the scientific community. In 1848, Wagner studied some additional material from Pikermi send to him by Anton von Lindermayer. During the winter of 1852-1853 new excavations were organised at Pikermi by the German naturalist Johannes Rudolf Roth, and the results were jointly published by Roth and Wagner (1854).
In 1853, Hercules Mitsopoulos, professor of natural sciences at the University of Athens, led the first excavations carried out by a Greek team. In 1854, the physician Aristeides Chairetis undertook a minor excavation and sent some material to the Natural History Museum of Paris, which became the subject of an announcement by renowned zoologist Georges Louis Duvernoy at the French Academy of Sciences.
Duvernoy’s announcement, in conjunction with the scientific results presented by Roth & Wager (1854), stimulated the Academy of Sciences of Paris to provide the generous financial means to support a series of extensive excavations at Pikermi under the direction of the geologist and palaeontologist Jean Albert Gaudry during the winter of 1855-56 and the summer of 1860. The scientific results were documented by Gaudry in his monumental monograph “Animaux fossiles et géologie de l’Attique” (Gaudry, 1862-1867). Gaudry described and illustrated in great detail the diverse fossil species of the Pikermian fauna (Figure 1). In addition, Gaudry was one of the first paleontologists to apply phylogenetic trees to assess the systematic affinities between fossil forms, taking also their stratigraphical position into account. Even today, Gaudry’s monograph remains influential for the comparative study and systematic evaluation of the Late Miocene mammalian faunas in the Old World.
Figure 1: The classical reconstruction of the Late Miocene cercopithecid monkey Mesopithecus pentelicus from Pikermi by Albert Gaudry (1862-67).
Moderate fieldwork activity continued during the 1880s and 1890s, with some excavations led by Wilhelm Dames for the Natural History Museum of Berlin in 1882, by Melchior Neumayer and Leopold von Tausch for the Paleontological Institute of the University of Vienna in 1885, by the Prince of Orleans in 1888, and by Michalet from Dijon in 1895. In addition, several occasional minor excavations by amateur naturalists, fossil dealers, and material exchange between museums and institutions distributed fossil specimens from Pikermi throughout the world.
The turn of the century signalled one of the major excavation campaigns in the area, organised by Arthur Smith Woodward for the British Museum of Natural History, and Τheodore Skouphos for the University of Athens (Woodward, 1901). During the following years, Skouphos continued the excavations in Pikermi, further enriching the paleontological collections of the University of Athens. The last of the major historical campaigns was conducted during 1912 by Othenio Abel under the auspices of the Academy of Sciences of Vienna (Abel, 1922).
After a hiatus of over half a century, activity resumed in 1971 with the discovery of a new fossiliferous site in the area named “Chomateri”. Several systematic excavations were carried out between 1972 and 1980, led by Nikolaos Symeonidis from the National and Kapodistrian University of Athens (NKUA) in collaboration with Friedrich Bachmayer and Helmut Zapfe from the Natural History Museum of Vienna (Symeonidis et al., 1973).
In 2008, fieldwork began anew in Pikermi, with a series of systematic excavations under the direction of Prof. George Theodorou from the National and Kapodistrian University of Athens (Theodorou et al., 2010). Several new and prolific fossiliferous sites have been revealed, namely Pikermi Valley 1-3 (PV 1-3). The excavations continue to be carried out annually, with more than 2000 new specimens collected during these latest campaigns (Figures 2 and 3).
Figure 2: On the left, a typical fossiliferous bone assemblage at the PV1 site, with in situ articulated fore- and hind limbs of three-toed hipparionin equids. On the right, excavation of proboscidean limb bones at the PV1 site (NKUA expeditions).
Figure 3: Cranium of the Late Miocene cercopithecid monkey Mesopithecus pentelicus from Pikermi in preparation (NKUA expedition 2018).
Faunal context and paleoecological remarks
The several hundred studies accompanying the long line of fieldwork activity in the locality have revealed a rich and diverse mammalian fauna with representatives of most macromammalian groups that inhabited Greece during the Late Miocene (Bernor et al., 1996; Theodorou et al., 2010; and references therein). Among the most frequent mammalian representatives are three-toed hipparionini horses, numerous bovid species, as well as three rhinocerotid and four giraffid species. Carnivores exhibit a remarkable diversity of eighteen different species including representatives of the families Felidae, Hyaenidae, Mustelidae, Ursidae and Ailuridae. Proboscideans, primates, hyracoids, suids, cervids, chalicotheriids, hystricids, murids and insectivores are also encountered in various degrees of frequency. Complementing the fauna list of mammalian taxa, there is also a small number of avian and reptilian taxa (Figures 4–6).
Figure 4: Faunal diversity at the Late Miocene locality of Pikermi.
Figure 5: Cranium and associated mandible of the Late Miocene bone-cracking hyaenid Adcrocuta eximia from Pikermi (NKUA collections).
Figure 6: Cranium of the Late Miocene tandem-horned rhinocerotid Diceros neumayri from Pikermi (NKUA collections).
Recent paleoecological reconstructions, based on a variety of methodologies -including sediment analysis, palynology, isotope analysis, magnetostratigraphy, and evaluation of the potential dietary preferences of the fossil taxa – suggested a savannah habitat for the Pikermian fauna that ranged around the wooded grassland to woodland transition (Böhme et al., 2017).
Current fieldwork activity is focused on the PV1 site, but imminent objectives of the project include the annual continuation of the excavations, with an expansion to other sites including PV3 and Chomateri, as well as the thorough preparation of the material and its scientific evaluation. The detailed study of the newly excavated material is essential for improving the understanding of the taphonomical, biogeographical and paleoecological context of the locality, as well as for the evaluation of the systematic affinities and phylogenetic position of the Pikermian taxa. Of particular interest is the acquisition of high resolution stratigraphical and taphonomical data in order to refine the local stratigraphy by assessing the number of the fossiliferous levels and documenting their exact faunal content (Theodorou and Nicolaides, 1988).
Present and future perspectives
Recent excavations of the National and Kapodistrian University of Athens led to the discovery of a large collection of vertebrate fossil specimens, which is currently housed in the Rafina-Pikermi Municipality’s Urban Planning Building. This facility includes a small fossil preparation laboratory, a fossil repository, and an exhibition hall with representative fossil specimens and selected animal reconstructions (Figure 7). Since its establishment this exhibition has attracted the public and also media attention, and has been heavily visited by schools, non-profit societies and individual visitors.
Figure 7: Views of the current paleontological exhibition in Pikermi.
Promoting Pikermi as a renowned geotope well outside the limits of the scientific community remains a primary objective. The proposed establishment of a protected geopark in the area, with multidisciplinary and educational context, is considered of paramount importance. The geopark concept has been successfully applied both domestically and internationally, highlighting the geological and paleontological heritage through educational and experiential activities, promoting public environmental awareness, and encouraging the development of a sustainable form of geotourism for the local communities. Some examples of this well-functioning geopark model, which is also supported by the United Nations Educational, Scientific and Cultural Organization (UNESCO, unesco.org) include: the petrified forest on Lesvos Island UGGp (UNESCO Global Geopark), Sitia UGGp, and Psiloritis UGGp in Greece; Swabian Alb UGGp in Germany; Conca de Tremp-Montsec UGGp in Spain; Stonehammer UGGp in Canada; Danxiashan UGGp and Zigong UGGp in China and many more. The renowned Pikermi locality meets UNESCO’s criteria and is a suitable candidate for inclusion in the Global Geoparks Network (GGN). Such an important step, if supported by public authorities, local communities, and private sponsors, can lead to the development of sustainable geotourism in Pikermi, taking also into account the short distance from Athens, a city that attracts millions of visitors every year for its unique monuments and cultural heritage.
The discussed scheme involves the transfer of the collected material and existing infrastructure to a larger and more suitable permanent museum facility. The recruitment of specialised scientific staff is also compulsory to facilitate the implementation of the museological arrangement and presentations, as well as the indispensable fossil preparation equipment and laboratory. Furthermore, a notable proposal concerns the restructuring of certain excavation sites into an area accessible to the public, where visitors may observe the paleontological fieldwork experience and the material itself as it is discovered in situ.
The ultimate goal of this endeavour is to bridge the specialised scientific interest of the locality with the wider appeal of geotourism, combining the ecological implications emerging from the fieldwork research with current environmental issues and diversity conservation efforts. All of these aspects may be achieved through guided tours and excursions, professionally designed educational programs and experiential activities for children and adults, lectures and workshops, as well as continued collaboration with other universities and research institutions.
Acknowledgments
We would like to thank all of the participants of the latest excavations in Pikermi, as well as the personnel of the Municipality of Rafina-Pikermi for their continued assistance. The fieldwork campaigns from 2009 to 2019 were supported by the Municipality of Rafina-Pikermi, several private sponsors, and the NKUA-Special Account Research Grant project no. 70/3/12977.
References
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Bernor, R.L., Solounias, N., Swischer, C.C., Van Couvering, J.A. 1996. The corellation of three classical “pikermian” mammal faunas – Maragheh, Samos and Pikermi -with the European MN Unit System. In: Bernor, R.L., Fahlbusch, V., Mittman, H.-W (Eds.), The Evolution of Western Eurasian Neogene Mammal Faunas, Columbia University Press, New York. p. 137–154.
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