Pocket pachyderms - Dwarf island proboscideans 1

A selection of dwarf proboscideans from the Mediterranean islands, to scale.

In Ancient Greek mythology, it was said that a race of one-eyed giants known as cyclopes lived within the bowels of Mt Etna on the island of Sicily. Legendary hero and later king Odysseus and his crew incurred the wrath of a cyclopes, which was tricked and blinded in their attempt to escape. As with most stories there is usually a kernal of truth. Exploring Greeks and Romans described finding strange large skulls across various islands throughout the Mediterranean. Roughly twice the size of a human's skull, the most obvious feature was a central depression facing forwards. Over a century ago an Austrian palaeontologist Othenio Able was the first to connect the skulls of extinct dwarf elephants with the legendary monster. That single 'eye' was actually the large nasal opening, typical of all elephant skulls.

Although we know of elephants as the largest terrestrial animals alive today, in the past there were numerous examples of small elephants found restricted to small islands. The likely scenario was that elephants were either isolated or swam to the islands and, through the economics of energy, decreased in size over generations due to a limited food supply and lack of predation. This is the first post looking at three general regions noted for their pint-sized proboscideans. This one will cover those elephants that were the source of the cyclopes legend in the Mediterranean Sea.

During glacial periods sea levels drop as available water is locked up in vast ice sheets, while during warmer interglacials sea levels rise. Thus during these warmer periods islands are created when land bridges are submerged. The Mediterranean Sea is dotted with islands which have fluctuated between being connected and split from the mainland on and off throughout the Pleistocene. Fossils of several small proboscideans have been located on a number of these islands. Only two elephant genera are known from Pleistocene mainland Europe, and all insular species derive from either the European mainland straight-tusked elephant Palaeoloxodon antiquus or a mammoth, probably Mammuthus meridionalis.

Most dwarf elephants are generally considered as originating from the giant Palaeoloxodon. There are at least eight named species and possibly an additional seven more forms that were found on the islands around Italy, Malta, Crete, Cyclades, Dodecanese and Cyprus. Due to the cyclic nature of the islands forming and reconnecting with the mainland, some of the larger islands were colonised by different forms. Sicily has evidence of three separate colonisations of elephants. Some islands exhibit the most extreme insular dwarfing seen in proboscideans. The best known example is P. falconeri from Sicily and Malta, possibly the smallest known elephant. While males reached just short of a metre at the shoulder, the tuskless females were even more diminutive standing at a paltry 80 cms. They were roughly comparable to modern baby elephants in size, but not in shape. Sometimes referred to as dachshund-like, the tiny elephant had a short rounded skull, long torso and short legs. Even with the larger species, size reduction varied on parts of the body. Weight reduction in P. cypriotes was down to just 2% of the 10 tonne mainland species, but they retained molars 40% of the size of it's ancestor.

There is no obvious reason for the size of any dwarf elephant species, with the smallest and largest species being found on the same islands at different times, suggesting that surface area of islands is not a simple link. One possible suggestion was that sea levels were higher at different times creating smaller palaeo-islands and encouraging smaller elephants to adapt. A species on Tilos in the Dodecanese has been dated to 4000 BC (Holocene) and was the last elephant to survive in Europe.

Two mini-mammoths are also known from Mediterranean islands, however originally they were thought to be yet more island forms of Palaeoloxodon. A re-evaluation of the fossil material, in particular the teeth, to show that they were members of Mammuthus. The earlier Cretan species was less than half the size of the mammoth found on Sardinia, and comparable to the smallest Palaeoloxodon. There is some uncertainty of the age of M. creticus, and it is possible that it descended from an earlier Mammuthus species.