Oldest fossil tropicbird found in New Zealand

Researchers from Canterbury Museum and Senckenberg Museum in Frankfurt, Germany, have discovered near Waipara/North Canterbury (on New Zealand’s South Island), what is probably the oldest example of a relative of today’s tropicbirds.

Fossil bones of Australornis lovei. Abbreviations: cbp – crista bicipitalis; 
cdp – crista deltopectoralis; csc – cotyla scapularis; csr – capital shaft ridge; 
fah – facies articularis humeralis; msc – scar for musculus scapulohumeralis cranialis;
 prj – projection formed by facies articularis clavicularis; tbd – tuberculum dorsale 
[Credit: G Mayr & RP Scofield]

The fossil bones were found by an amateur palaeontologist, Leigh Love, in the Waipara Greensand, in strata that are about 60 million years old. Mr Love made headlines last year when a fossil he found nearby was recognised by the same team as belonging to an unknown group of flying seabirds and was named Australornis lovei.

Today tropicbirds inhabit the warm waters of the tropical and sub-tropical oceans. The red-tailed tropicbird breeds in New Zealand only in the Kermadec Islands, ranging south to Northland and occasionally further south in the summer. This fossil shows that in the tropical early Paleocene period – just after the event that caused the extinction of dinosaurs - tropicbirds inhabited the waters surrounding the whole of Zealandia (the ancient sub-continent New Zealand was once part of).

Artist's impression of Australornis lovei 
[Credit: Derek Onley]

Until the discovery of this fossil, all other reported fossil tropicbirds finds were in the northern hemisphere and it had been assumed that tropicbirds had spread from Laurasia, the northern supercontinent neighbour of Gondwana.

“The new fossil is an exciting find as it helps our understanding of how tropicbirds evolved. This fossil can be directly linked to fossil finds of previously unknown origins: the first from the late Cretaceous period (about 70 million years ago) which was found in New Jersey, USA and several fossils from the late Paleocene period (about 58 million years ago) found in Morocco and central Asia,” says Dr Paul Scofield, Senior Curator Natural History at Canterbury Museum and Adjunct Professor of Paleontology at the University of Canterbury, a co-author of the study.

Dr Gerald Mayr, Curator of Birds at Senckenberg Museum says: “The discovery of this fragmentary fossil give us the earliest insight into the evolution of one of the most enigmatic lineages of seabirds”.

Dr Scofield and Dr Mayr have published their research findings in the Journal of Vertebrate Paleontology.

Source: Canterbury Museum [December 03, 2015]