Thursday, 6 October 2011

On the Origins Of The Mysterious South American Bird, The Hoatzin

The holotype fossils of Namibiavis senutae, the supposed
African ancestor of the South American Hoatzin
The hoatzin (Opisthocomus hoatzin) is a very strange bird that lives in the jungles of the continent of South America. With its blood red eye and feathered crest, it is rather reptilian. The strange thing is that this bird is not like any other avians on the continent. Its origins are very mysterious. It is more physically similar to the African cockatoos and turacos. This implies that it had prehistoric origins, but the creature itself is a very poor flyer, capable only of short wing-assisted hops and flutters.

The morphology and the theory contradict one another. What is also interesting is that this creature has a completely herbivorous diet. Most birds, even fruit feeders, often partake of insects and birds of prey of course feed primarily on live animals or carrion. The hoatzin's diet is more like that of a mammal. However a team of German, French and Brazilian scientists have discovered fossil evidence which sheds light upon this biological mystery.

They described a new species of prehistoric avian which lived in Namibia around 17 million years ago. This creature, named Namibiavis senutae, consisted of upper arm and shoulder girdle bones, and has a very interesting morphology. It was very similar to a series of 23 million year old bones from a fossil site in south east Brazil, which belonged to the oldest known hoatzin on Earth. The similarity between the bones, but the geographical difference, shows that the hoatzin may very well have have had African origins.

23 million years ago, Africa and South America were already separated by the Atlantic ocean. The question is how the ancestors of the hoatzin could have crossed the ocean? Gerald Mayr, an ornithologist on the research team, has a theory. Storms often cause large chunks of mangrove swamp to break away from the African coast and float across the to Americas, often carrying native species with it. In fact we believe this was how simians originated in the New World.

As a flightless bird, the hoatzin and its ancestors would have been trapped, yet somehow they survived the journey across. They are large enough to have food and water reserves for such an expedition. Due to the Cenozoic ocean currents and wind directions, a journey across the Atlantic was only probable in a westerly direction. The scientists claim, therefore, that 'South America's most enigmatic bird' has its origins outside of South America in Africa.