Dolphin Fossil Missing Link

Dolphin Fossil Missing LinkWhile the terrible events surrounding the dolphin slaughter in Japan continues, in New Zealand, a dolphin fossil has uncovered a missing link in dolphin evolution. The fossil entitled ‘Papahu taitapu’ was found in the area of Cape Farewell in the upper South Island of New Zealand. The name ‘Papahu’ comes from the Maori name for dolphin, with ‘taitapu’ translating as the title for the area in question.

Dr Gabriel Aguirre and Professor Ewan Fordyce have just released a report on Papahu in the Journal of Vertebrate Paleontology. Papahu lived 19-22 million years ago, it was one of the few dolphins to be living at the start of the Miocene era. Therefore it lived at the same time as prehistoric dogs, horses and bears and at the time when the sabre tooth cat was a common creature. Around this age most of New Zealand was underwater and the seas were much shallower. These waters that were home to the Papahu, were also shared with baleen whales and penguins. Dr Aguirre reports that the area was experiencing a period of global warmth with temperatures around the southern part of New Zealand at about 64 degrees fahrenheit, significantly warmer than those seas today.

Professor Fordyce states that the South Island has been a particularly fruitful place for fossils in recent times. In the Miocene period the sea around the South Island reached half a mile further inland than it does today. Thus there is a lot of limestone and other soft rocks in areas that used to be covered by the sea. These ancient dolphins would have sunk to the seafloor when they died and become embedded in the rock. Over time these rocks have eroded to reveal their fossils. Because of New Zealand’s latent discovery, in terms of exploration, these pieces are still being uncovered.  Researchers are continually finding new dolphin fossils along with other marine animals that fill in the missing links and further understanding in how these creatures evolved.

The fossil is composed of a skull and jawbone, as well as a couple of extra pieces. The jawbone is noted to have distinct conical teeth making it recognisable as belonging to a particular group that dolphins and toothed whales evolved from. Dr Aguirre reports that the skull is slightly wider than modern dolphins, and not as highly domed. The Papahu would have been about 2 meters long, the same size as its modern counterparts. Study of the skull and delicate ear canals has revealed that the dolphin could communicate through high-pitched sound. It also used this feature to hunt for prey in the opaque water.

The discovery is a new milestone in the heritage of dolphins as it is aiding scientists with the transition between modern forms and the archaic models. Dr Aguirre was able to use the distinct elements of the skull to identify it as an entirely new, different from all previous uncovered fossils. Professor Fordyce said they compared the fossil with modern dolphin skulls and other previously discovered artefacts and they found that ” it belongs in a diverse and structurally variable group of ancient dolphins that evolved and spread worldwide 19 million to 35 million years ago.”  The dolphin fossil thus provides another missing link in the chain from the modern dolphin to its prehistoric ancestor.

It is still unknown why the Papahu and other prehistoric forms of dolphin and whale died out.

By Sara Watson

Sources:

University of Otago
Otago Daily Times
International Business Times
NZ Herald
Britannica

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