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Image: Charles J. Sharp [CC BY-SA 4.0 ]
About 136,000 years ago, a bird unable to fly was extinct.
The bird was resident on the Aldabra atoll, in the Indian Ocean, whose fauna and flora had been wiped out when the island had been completely flooded by the sea.
Scientists from the University of Portsmouth and the Natural History Museum said that the bird had managed to come back from the dead.
This is thanks to a rare event called iterative evolution, in which the evolutionary process of the same ancestor is repeated at different times in history.
In this case, the white-throated rattle – a bird native to Madagascar – had evolved to become unable to fly on different occasions, separated by a few thousand years.
About 100,000 years ago, the sea level was lowered due to glaciation, allowing the island of Aldabra to re-exist. The rails, which migrated to other islands, including Mauritius and Reunion, also landed at Aldabra.
Aldabra, then rid of its predators, allowed the rail to evolve and become unable to fly due to the lack of threats on the island. You can still find the last surviving track colony on the island today.
The researchers in the study, who published their findings in the Zoological Journal of the Linnaean Society, studied rail fossils before and after flooding. They found that the bones of the wing were in an advanced state of loss of flight, while the ankle bones showed signs indicating that it was evolving towards a loss of capacity.
"These unique fossils provide irrefutable evidence that a member of the railroad family colonized the atoll, probably from Madagascar, and became unable to fly at every opportunity," said the researcher. senior Julian Hume in a statement.
"The fossil evidence presented here is unique with respect to rails, and embodies the ability of these birds to successfully colonize isolated islands and to develop the absence of flight over and over."
David Martill, a co-author of the study, said that they knew of no other example of rattles or birds in general, who introduced the phenomenon of iterative evolution. Sabretooths, with their awesome teeth, have benefited from this process during the course of history.
"Only Aldabra, which has the oldest paleontological record of all oceanic islands in the Indian Ocean region, has fossil evidence demonstrating the effects of sea level change on extinction phenomena. and recolonization, "he added.
"The conditions were such at Aldabra, the most important being the absence of terrestrial predators and competing mammals, which allowed a rail to evolve autonomously in the face of theft on every occasion."
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