Preserved Feeding Apparatus on Palaeogene Fossils Shows Pelican Beak is Old Hat
A beautifully preserved fossil of the earliest known Pelican, a fossil dating from the Oligocene Epoch shows that Pelicans have had their unusual beaks and pouches for at least 30 million years. It seems that as far as the Pelican is concerned, if something isn’t broken it does not need fixing, the feeding apparatus of these birds seems unchanged for 30 million years. If an organism or a part of an organism remains unchanged for a very long period of time, scientists call this “evolutionary stasis”. It seems that the shape of the Pelican’s beak has remained unchanged for millions of years.
The significance of this fossil was not realised at the time of its discovery in finely grained limestone deposits in a region of south-eastern France (Luberon). It was only when a French scientist examined this specimen in a colleague’s collection that the importance of this fossil and its baring on bird evolution became clear.
Mr Tourment bought the ancient Pelican years ago from another collector who found it in the area in the 1980s; but its significance only became clear when Dr Louchart looked at it closely.
Dr. Louchart commented:
“I was surprised by the completeness and quality of preservation of this fossil. It is embedded in a very fine lacustrine limestone which preserves all the details.”
A 30 Million Year Old Bill
Picture Credit: A. Louchart
The picture shows the cervical neck vertebrae (neck bones), parts of the skull and the long beak of this prehistoric bird. The beak measures approximately 30 cm in length and the entire specimen is around 1.2 metres long from the tip of its beak to the tip of its tail, suggesting a very small Pelican, similar in size to the smallest extant Pelicans. However, scientists are not sure whether this is a fully grown specimen. They are confident however, that this fossil belongs in the genus Pelecanus (Pelicans) and the fossil shows morphological and anatomical differences between it and the seven living species of Pelican around today, to make the fossil a distinctive species.
Its well preserved beak contains a special joint within that allows its two parts to be extremely distended, opening up the pouch used to collect fish. So Pelicans had their pouches at least 30 million years ago.
Dr. Louchart stated:
“It is remarkably similar morphologically to the seven species of living Pelican, but its proportions differ slightly from all of them, so it probably represents a distinct species.”
The discovery has surprised the researchers, because it reveals just how little Pelicans have evolved over huge expanses of time. In the early Oligocene, fish existed (teleosts)that were similar in size and shape to the modern prey of today’s Pelicans. This suggests that Pelicans quickly evolved their huge beaks and have maintained them almost unchanged since because they are optimal for fish feeding.
However, it could also be that the giant beak has not evolved in the past 30 million years because of constraints imposed by flying.
The idea is that once Pelicans evolved bodies capable of flying with such a large beak, the beak itself couldn’t evolve further without compromising the birds’ ability to fly, essentially locking in its design.
Dr. Louchart added:
“It shows an example of stasis, or no morphological change, in the skeleton, although perhaps changes in other characteristics occurred, such as plumage or behaviour.”
Evolutionary stasis in higher vertebrates is quite rare, although the limited fossil record for most back-boned animals prevents a more complete examination of this phenomenon. Dr. Louchart concluded that few other flying animals appear to have survived unchanged for so long. The only other good example would be bats, these animals have a body shape that appears to have survived unaltered since the early Tertiary.