Monday 8 October 2012

A Massive Blunder

Palaeontology is the fusion between geology and comparative anatomy. The geological side of things establishes the fossil's age and original environment; comparative anatomy places the creature in the tree of life with its exact role in evolution. A specimen can be accurately compared to similar skeletons and its closest relatives identified, but occasionally there are errors.

The fossilized skull of the 7 million year old fish
Arrhinolemur, originally misidentified as a lemur
Years ago, when analysis techniques involved only a magnifying glass and a good hand for drawing, mistakes were far more common. And there have been a number of spectacular blunders over the years.

Scientific names reflect the characteristics of the organism to which it is assigned. Arrhinolemur scalabrinii translates as 'Scalabrini's lemur without a nose.' Yet the only true part of this is the fact that it was discovered by one Pedro Scalabrini in 1898 in seven million year old rocks in South America. Scalabrini handed the specimen over to palaeontologist Florentino Ameghino, who identified the fossil as a unique species of lemur in its own special class, arrhinolemuroidea.

Around 50 years later, the American palaeontologist George Gaylord Simpson re-examined the remains and found that it was not a lemur, but a fish. Clearly, something had been missed in translation. The preserved skull had been mis-identified as a tree-dwelling, fur-covered primate. For some reason, the matter was left at that until 1986 when Alvaro Mones suggested that Arrhinolemur could be related to a group of freshwater fish known as the characidiformes.
Modern day characidiformes

The matter was finally resolved in 2010, when two Argentinian researchers used the original photos and drawings of the skull to study its relationship to the fish. They concluded that the remains after 114 years of skulking in the back of a dusty museum collection, labelled as a lemur, were in fact fish. 'It is the head of a small fish, only a couple of inches long, but it's difficult to tell what it may have grown to,' said consultant Brian Sidlauskas. 'Fish in that family can be two inches long or two feet long, and there are 150 to 200 species in the family, all indigenous to South America.'

It is unfortunate that the fish will be stuck with its misleading name as the rules of scientific nomenclature do not allow for any changes after a name has been officially assigned. Still, it is important to know exactly where a creature lies in the tree of life. Arrhinolemur is recognised for what it is. In fact one could say that now it sleeps with the fishes.