Evolutionary dead-end for toothed birds

2013-01-08 14:45

Toothed birds were an evolutionary dead end. (Stephanie Abramowicz)

Dane McDonald

Cape Town - A newly discovered bird fossil has shed light on the dynamics of the evolutionary process. Sulcavis geeorum was discovered in the Liaoning Province of China.

Fossil dating suggests that it lived during the Early Cretaceous between 121 and 125 million years ago. S geeorum forms part of an early group of birds called enantiornithines which are the only known birds to have developed a variety of tooth structures.

Scientists are still puzzled as to why they died out at the end of the Cretaceous period. Jingmai O’Connor, lead author of the study published in the Journal of Vertebrate Palaeontology, suggests that “maybe differences in diet played a part”.

Dr Jurie van den Heever from the Palaeontology Research Group at Stellenbosch University agrees that the diversity of the enantiornithines is not clearly understood. “One often sees early diversity in a group which later settles into a less diverse pattern of evolution,” he told News24.

In the case of the enantiornithines, diversity was lessened with extinction of species like S geeorum.

“It’s almost as if various anatomical options were initially tried and later reduced to the more viable adaptations,” said van den Heever. SA does not have any bird fossils from the Cretaceous period. Despite having an extensive fossil record the terrestrial deposits of the Cretaceous have mostly been eroded and now lies below the sea.

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- News24