ALEXANDRA VAN DER GEER

Vertebrate Palaeontology

research interests

Paradolichopithecus

[Reconstruction of Paradolichopithecus. Drawing by A. Vlachos]


Paradolichopithecus is an extinct baboon-like monkey of Eurasia. It lived during the Pliocene, and got extinct in the early Pleistocene. Fossils were discovered in Spain, France, Roumania, Greece and China. Paradolichopithecus is closely related to macaques (Macaca), but has the size of a large baboon (Papio). The postcranial anatomy has some unique features, indicating a different life-style compared to macaques. The morphology of the astragalus (talus) deviates from that of similar sized baboons in the same way in which Australopithecus' astragalus differs from that of a large chimpanzee. In my view, this reflects a higher degree of terrestriality of Paradolichopithecus, possibly even higher than that of the gelada (Theropithecus), and likely included an increased degree of bipedal locomotion and posture. Astragali of trained japanese macaques appear to follow the same pattern. For a detailed study, see my pdf's, available from my Publications.


Insular Mammal Evolution

[An island dwarf (E. falconeri) compared to its mainland ancestor (E. antiquus)]


Evolution of animals on islands often follows a dramatically different course. Freed from the pressure of large mammalian carnivores, herbivores may soon suffer from overpopulation, leading to overgrazing, with an inevitable meltdown of their population as a result. Only the lucky ones that can adapt to new ecological niches have a change to survive. On an island the rule "To Adapt or To Die" is even stronger than on the mainland. The most bizarre island endemics are often the outcome. Not only herbivores have to undergo local evolution to escape certain death. Carnivores like wolves often become smaller and have to shift their normal prey range to a menu of small rabbit-like animals, crustaceans or birds. Unfortunately, most of the strange islanders are long extinct. The majority lived during the Miocene and Plio-Pleistocene periods. The study of their evolution can help us understand the long-term effects of habitat fragmentation, habitat loss and sea-level rises. My personal speciality are island deer, especially Hoplitomeryx, the Late Miocene early horned deer from the ancient island of Gargano (South Italy) and Candiacervus, the Pleistocene deer from Crete (Greece) (for our reconstruction, see also our poster for Weimar 2004.

Hoplitomeryx matthei (Cast based on holotype, stored at Naturalis, Leiden, NL)



Geology and South Asian Folklore

[Krishna's butterball at Mahabalipuram (Tamil Nadu); photograph Archaeological Survey of India, courtesy Kern Institute, Leiden (the Netherlands) ]


Geological phenomena in the landscape (eroded stones, mountains, giant steps, volcanoes) and fossils (petrified remains of life of the past) are often considered proofs of myths and legends. In Kathmandu valley (Nepal), plain stones represent the Matrikas (mother goddesses). They are attributed a soul, and are considered alive. More often, these stones (mani stones) are inscribed or adorned with a simple carving, e.g. of a lotus flower, and given to the mountain gods at chorten, small shrines or sometimes nothing more than a heap of such stones. Often these mani stones are lined up, and cross the landscape in the form of seemingly endless walls. Examples of eroded stones are Krishna’s butter ball near Mahabalipuram in Tamil Nadu, and a ring stone along the Sutlej river.

Ammonites, extinct carnivorous molluscs, are worshipped in India as symbols of the god Vishnu, based on their wheel-shaped form (chakra. There are many types of these so-called shalagramas, depending on the degree of preservation, color, shape etc. White fossil corals from Dvaraka, the submerged city of Krishna, also bear chakra markings, and are used as shalagrama. Evidence for nagas, a race of wise, mythical snakes, is found in the Himalayas, where fossil ammonites and fossil bones are abundantly found. These fossils are often pyritized or bearing calcite crystals, resembling sparkling jewels. Reports of naga palaces, shining with precious stones, may have been inspired by the spectacular Salt Range, where the sunlight is reflected by salt-crystals. Fossil sea urchins found in the Narmada Valley (Madhya Pradesh) are called five grooves (pancha khadda), obviously inspired by the five radiating ambulacral rays on the surface.

Abundant fossils are found on the surface in the Siwalik Hills, a range of Himalayan foothills, ranging from Pakistan to Myanmar. These fossils figure in local myths. In Pinjore Valley, they are remains of demonic rakshasas, killed by an epic hero. In the nearby former kingdom of Nahan, fossil elephant molars are considered heads of gods, obviously decapitated at some fight. Less than 50 kilometres away, the famous Kurukshetra plain was the stage for the epic battle as described in the Mahabharata. In my recent work on this subject, I make the link between the Pinjore and Nahan fossils, explained away as battle remains, and the battle of Kurukshetra. The plains of Kurukshetra are rich, too, in fossils, and more, archeological remains of Indus Valley settlements, such as Rakhigarhi, where ancient weaponry and pottery comes to the surface after rainfalls. The combined occurrence of bones and artifacts kept the memory of the battle alive.


Vishnu's chakra (disc) is represented by the shalagrama (ammonite) (from my ppt presentation at EASAS 2006)


Fossils are explained as epic battle remains in the Siwalik Hills (from my ppt presentation at EASAS 2006)



Plio-Pleistocene Faunas

[Canis AMPG-Athens]


An example of a Late Plio-Pleistocene (MN17) fauna is that of Vatera (Lesvos, Greece). These animals lived about 2 million years ago, when Lesvos was not yet an island, but part of Asia Minor. They form a typical mainland fauna, with sabre-toothed cats, large elephants, raccoon dogs and other animals that are not found on islands. The giant tortoises of Vatera were the last of their kind, and only some relict populations such giants managed to survive until today on remote islands. The fauna of Vatera is known from several other Eurasian localities as well. Eurasia at that time formed an extended ecosystem, ranging from Spain in the west to China in the east, and the Balkan peninsula in the south to northern France in the north. Our reconstructions of some of the animals of that period, painted by Alexis Vlachos (Athens), are based upon actual skeletons of these animals, combined with their most closely related living relatives.


Homotherium crenatidens (Drawing by Alexis Vlachos)

Equus stenonis (Drawing by Alexis Vlachos)

Mammuthus meridionalis (Drawing by Alexis Vlachos)

Anancus arvernensis (Drawing by Alexis Vlachos)



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