Alexandra van der Geer

Searching for dwarf elephants on the island Naxos (Greece)

I am a palaeontologist, specialised in aspects of evolution and biogeography of mammals on islands worldwide with emphasis on the Mediterranean and Southeast Asia. Currently, I am studying evolutionary changes in introduced rats on islands and the impact of humans on island ecosystems through time.


Island biogeography; island biodiversity; insularity; mammals; vertebrate palaeontology; extinctions; palaeoecology; taxonomy


The evolution and extinction of insular mammals worldwide, past and present.

An important aspect of the evolution of insular mammals is body size evolution, which roughly means that large mammals become small (dwarfism) whereas small mammals become large (gigantism). Many exceptions are known, and the factors that dictate the direction of body size evolution depend not only on the ancestral taxon but also on the island, the climate and the rest of the fauna, in other words, on the context. The extinction of insular mammals is perhaps an even more interesting phenomenon and sadly enough, an ongoing problem we face today on islands worldwide. The drivers behind these extinctions, however, are not always clear or known.

Skull of a Pleistocene dwarf deer
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A selection of the topics I am working on currently.

Changing invaders

How introduced rats have changed during their colonization of Pacific islands. Humans have been transporting vertebrates to islands worldwide since prehistory, often with dramatic impact on native fauna. These introduced species appear to change very…
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Of Mice and Mammoth

Of mice and mammoth: toward a general theory of body size across space and time. Body size is one of the major factors dictating physiological and anatomical processes. The direction of body size evolution in a species depends on many factors, internal as…
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Animals in stone

Animals in stone- Indian fauna sculptured through time. The art history of South Asia covers a time span of roughly four and a half thousand years. During this period, a vast number of animal stone sculptures has been produced, ranging from the pre…
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  • Van der Geer, A.A.E., Lyras, G., MacPhee, R.D.E., Mitteroecker, P. (2018) From Jumbo to Dumbo: cranial shape changes in elephants and hippos during phyletic dwarfing. Evolutionary Biology 45 (3): 303-317. DOI: 10.1007/s11692-018-9451-1
  • Van der Geer, A.A.E. (2018) Uniformity in variety: antler morphology and evolution in a predator-free environment. Palaeontologia Electronica 21.1: 9A. DOI: 10.26879/834
  • Van der Geer, A.A.E., Lomolino, M., Lyras, G.A. (2018) On being the right size – do aliens follow the rules.Journal of Biogeography 45: 515-529. DOI: 10.1111/jbi.13159.
  • Van der Geer, A.A.E., van den Bergh, G., Lyras, G.A., Prasetyo, U.W., Due, R.A., Setiyabudi, E., Drinia, H.(2016)The effect of area and isolation on insular dwarf proboscideans. Journal of Biogeography 43:1656-1666. DOI: 10.1111/jbi.12743
  • Van der Geer, A., de Vos, J., Dermitzakis, M., Lyras, G. (2010) Evolution of Island Mammals: Adaptationand Extinction of Placental Mammals on Islands. Oxford, Wiley-Blackwell, ISBN 13-978-1-4051-9009-1.

All publications on Google Scholar


Past graduate courses: 'Evolutie van het paard' (Evolution of the horse) for students of Veterinary Medicine (Utrecht University); 2012, 2013, 2014, 2016.

Ongoing PhD Students: 

Pauline Basilia (Griffith University, Brisbane) "Beyond dwarfing: examining insular dwarfism of Stegodon fossil remains from Southeast Asia"

Anne-Jifke Haarsma (Radboud University, Nijmegen) "Habitat and diet segregation of pond bats"

Past PhD Students:

Leila D'Souza (2019; Bristol University, UK) "An endemic radiation of deer in the Late Pleistocene of Malta". External examiner.

Matthew Scarborough (2018; University of Cape Town, South Africa) "Insular adaptations in the appendicular skeleton of Sicilian and Maltese dwarf elephants". External examiner.

George Lyras (2007; University of Athens, Greece) "The evolution of the brain in Canidae (Mammalia: Carnivora)". Supervisor.