In 2011, Alastair Johnson was hunting for fossils on a remote beach in Taranaki. Three-million-year-old fossil oysters and scallops are common here, but remains of vertebrates are much rarer. On this occasion, something magical appeared out of the rock – the most complete fossil albatross skull ever found. Curator of vertebrates Alan Tennyson tells us more.
Hunting for fossils: A variable exercise
Hunting for fossils takes skill, time, patience, and sometimes – strength.
When scouring the beaches, eroded bone seen on the surface of a rock is often a useful clue as to what might lie inside, but it is still almost impossible to know what’s actually contained in the rock.
Revealing the contents of such rocks is a lengthy and arduous process. Sometimes you have to lug boulders kilometres to a vehicle in order to get them to a preparation lab.
The rewards of such an exercise are variable. Numerous times crushed fragments of an undiagnostic bone appear as the rock is meticulously chipped away in a cloud of dust.
However, on rare occasions, something magical appears.
This was the case when a peculiar and beautifully preserved albatross skull appeared before Alastair Johnson’s eyes.
The skull arrives at Te Papa
After Te Papa acquired Alastair’s albatross skull in 2015, it received a bit of finishing work from expert preparator Al Mannering, before I was then able to compare it closely with other skulls in our collection.
A new species
It was clearly an albatross skull, but two unusual things were immediately apparent: it was very small (smaller than the skulls of all living albatrosses) and its beak was oddly thin (other albatrosses have a broader, more rounded beak).
Gerald Mayr, from the Senckenberg Research Institute and Natural History Museum Frankfurt, and I compared the skull with those of all living and extinct albatross taxa.
We concluded that the size of the new fossil was not so unusual in albatross history – some long extinct albatrosses ranging in age from the Eocene to the Miocene epochs were similarly small.
However, the narrow bill was unique among all known albatrosses, both living and extinct.
What has caused the difference in size and beaks?
So why were some albatrosses smaller in the past and why did some have such narrow beaks?
In our new article, we suggest that albatrosses evolved from smaller relatives, so we might expect some ancient albatrosses to be smaller than the modern ones which can have wingspans up to 3meters wide.
Beaks based on diet
Most albatrosses are predominantly squid eaters, but they also take fish, crustaceans, and various other invertebrates.
Usually, narrow beaks in seabirds are found in fish-eaters such as shearwaters, shags, razorbills, and some penguins (such as king penguins). Based on this information, we think that the Taranaki albatross was mainly a fish-eater.
We can only speculate as to why small fish-eating kinds of albatrosses are no longer alive today but competition with a wide range of other seabirds in this size range, such as shags and gannets may be an answer.
We predict that further fossil discoveries are likely to find that narrow-billed albatrosses were more abundant in the past, and that fish-eating was a more common feeding method for ancestral albatrosses.
What have we named the new species?
Given how distinctive the new skull is, we have named it as a new genus and species Aldiomedes angustirostris: The taxon is named in honor of the fossil’s finder Alastair (‘Al’) Johnson; the second part of the name refers 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.