GEORGE LYRAS


Faculty of Geology and Geoenvironment
University of Athens

research

Brain Evolution

[Zodiolestes AMNH-New York ]


Soft tissues usually do not fossilize, yet there is fossil evidence about the brain. This is because the brain is protected within the neurocranium, a hard bone structure that is often preserved as fossil, and which in addition gets a lot of attention during paleontological excavations and subsequent conservation. Particularly in the case of mammals, the brain almost entirely fills the neurocranium, so the casts of the brain cavity (endocranial casts or endocasts) reveal most of the features of the external brain anatomy. Although paleoneurological data are limited to the external anatomy of the brain, they are the only direct evidence about the brains of the past. The use of only living species to reveal the evolutionary history of the brain has its limitations, due to the danger of so-called Scalae Naturae (pseudo-evolutionary sequences) in which a living species is regarded as representative of the ancestral stage of another species. To avoid the effects of parallelisms, the contribution of the fossil record is crucial. Where comparative neurology tries to reveal the evolution of the brain by comparing brains only of living animals, paleoneurology does so by observations on fossil brains. As Tilly Edinger noted, "paleoneurology introduced to comparative neurology a fourth dimension: time".


of Mice and Mammoths


During the Plio-Pleistocene many islands of the World were inhabited by endemic mammals of mainland origin. Today, most of these island endemics are extinct and are known to us only by their fossil remains. The insular mammals present unique adaptations to the island environment compared to their mainland relatives, such as smaller size and robust and short limbs. In collaboration with Mark Lomolino, Dov Sax, Maria Rita Palombo and Alexandra van der Geer we investigated the importance of body size changes in insular mammals. The project was entitled of Mice and Mammoths.


Island biodiversity and cultural evolution


The project investigated the impact of natural and anthropogenic changes to the insular environments and the importance of those changes to human culture. It was a multidisciplinary project, drawing on the expertise of an international team of scientists from different fields: Geosciences, Life Sciences and Humanities. The project is entitled Island biodiversity and cultural evolution.

In order to carry out the project, we selected islands from three different areas: the Eastern Mediterranean Sea (Crete, Karpathos and Cyprus), the Indian Ocean (Madagascar and Mauritius) and the western Pacific Ocean (Philippines: Luzon and Masbate). These areas have a different geologic, biogeographic and ethnographic background. Furthermore, these islands were colonized by humans during different periods in history (ranging from 800,000 years ago till the 17th century.)


Pleistocene Faunas

[Canis AMPG-Athens]


In collaboration with Athanasios Athanassiou, John de Vos and Alexandra van der Geer we investigated some of the Pleistocene mainland localities of Greece. In addition, together with the artist Alexis Vlachos we made reconstructions of fossil mammals from that period.

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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