‘Dwarf mammoths lived on Crete island’
A second hard look at a specimen at the natural history museum in London has led to the discovery of “dwarf mammoths” that lived on a Mediterranean island maybe 3.5 million years ago. Mammoths, prehistoric relatives of elephants, are generally considered among the largest animals, however this island version named Mammuthus creticus was only slightly over a meter tall. The fossil teeth re-examined were collected in 1904 on Crete island in Greece, in the Mediterranean region well-known among palaeontologists for its dwarfed versions of large animals.
“Dwarfism is a well-known evolutionary response of large mammals to island environments,” said lead researcher Dr Victoria Herridge.
“Our findings show that on Crete, island dwarfism occurred to an extreme degree, producing the smallest mammoth known so far.”
The oxymoron of “mini mammoths” presents a good case for the hypothesised “island rule” of evolution that says mammals isolated from original habitats evolve rapidly into dwarf or giant versions — large mammals dwarf and small ones evolve into giants.
But there is consensus that changing in size may not be a general rule of island evolution, rather simply adaptation during speciation for a number reasons. It is possible that dwarf mammoth was not a result of an imposing evolutionary rule but as Dr Shai Meiri, zoologist at Tel Aviv University not involved with new finding, suggests: “for fecundity selection (small elephant — more babies) on islands without predators and competitors”.
“So, elephants certainly dwarf on islands. Not all large mammals dwarf on islands, and especially there is little to suggest that small mammals increase in size. So dwarf mammoths? Sure. Island Rule? I’d say not so fast.”
For decades, the tooth fossil was believed to be from a dwarfed descendant of the continental straight-tusked elephant. The authors of the paper published in Proceedings of the Royal Society B identified the enamel on the fossil to be patterned with “equal size rings” typical of mammoths and inconsistent with those on dwarfed elephant teeth.
The authors collected another piece of evidence on their visit to the original fossil site in Crete; this time a piece of the upper arm bone — humerous. The fragment showed fused ends indicating that the bone had finished growing and belonged to an adult. From measurements of the bone they could reconstruct the animals size finding it to be approximately one meter tall, the size of a new born Asian elephant.
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