Alastair's albatross

In 2011, amateur fossil hunter Alastair Johnson found a rock containing an interesting skull on a South Taranaki beach. The difficult task of extracting the delicate bones from the rock was initially done by Dave ‘Pom’ Allen, with final preparation by Al Mannering. This work revealed the most complete fossil albatross skull found anywhere in the world. This holotype (and only known specimen) is now held at Te Papa (registration no. NMNZ S.046313).

Only one other fossil albatross species has been named from New Zealand – Brian Marples named a late Oligocene furcula bone from North Otago as Manu antiquus in 1946, however, this bone is no longer considered to be from an albatross.

Today, New Zealand is the global centre of diversity for albatrosses, but up until now the fossil history of New Zealand albatrosses had been unknown. The fossil is from the Pliocene epoch, about 3 million years ago. At this time it lived alongside larger albatrosses because their remains have been found in the same deposits.

Globally much older albatross fossils have been found, going back to the early Oligocene and possibly even the middle Eocene, and so it is likely that albatrosses lived in the New Zealand region well before the Pliocene period also.

Given how distinctive the new skull is, it was named as a new genus and species: Aldiomedes angustirostris. The genus is named in honour of Alastair (‘Al’) Johnson, with the second part of the name refering to ‘Diomedes’, the Greek mythological figure, after which the albatross family was named. The species epithet is derived from the Latin ‘angustus’ meaning narrow, and ‘rostrum’ meaning beak.

Identification

Comparing the unique specimen with skulls of living albatross species, the fossil is smaller and has an unusually narrow beak. The size of the species falls between the largest of the burrowing petrels (the Westland petrel and white-chinned petrel) and the smallest of the living albatrosses.

Some long extinct fossil albatross species were as small as Alastair’s albatross, which is not surprising if modern albatrosses evolved from smaller ancestors. However, the narrow beak is unique among albatrosses. This unusual shape means that the species is probably not closely related to any living albatross species. Long narrow beaks are found in fish-eating seabirds, and so Alastair’s albatross was probably a fish specialist too. Living albatrosses tend to be scavengers, particularly of squid. Why the species died out is uncertain, but a lot of other similar-sized fish eating seabirds, e.g. shags and gannets, were alive in the Pliocene epoch, and so perhaps fish specialising albatrosses were out-competed.

The skull is the only part of the species discovered so far, and so nothing is known about the rest of the skeleton.

Distribution and habitat

All we know about the past distribution of the species is that it lived in proto-Taranaki seas. As an albatross, no doubt it would have been capable of ranging many thousands of kilometres.

The fossil specimen probably died at sea and sank to the bottom of the ocean where it was buried by sediments, only to be uplifted later by tectonic movements.