A team of palaeontologists from the University of Canterbury, Canterbury Museum, GNS and the Senckenberg Research Institute and Museum in Germany, has discovered a remarkably intact fossil of one of the earliest ancestors of a group of birds now restricted to the tropics.
The team described the fossil finds in Alcheringa: An Australasian Journal of Palaeontology published last month.
Tropicbirds, now represented by only three living species, have a long fossil record spanning at least 62.5 million years, with the oldest described species being Clymenoptilon novaezealandicum, or Zealandian Tropicbird.
The specimen, boasting a nearly complete skull, wing, and pelvis among other elements, was collected from the Waipara Greensand, North Canterbury, and is estimated to be around 62 million years old. It is the second tropicbird found in the Waipara Greensand (the first one was a smaller, unnamed specimen described in 2016).
Leigh Love, who first only found its skull but fortunately, a month later, also the rest of the specimen, discovered the Zealandian Tropicbird. His son David helped him retrieve it. Leigh Love says, “He was 10 years old at the time and very keen to join me on some of my fossil hunting trips into the Waipara. On this occasion when we found the bones, he said he was both surprised and amazed that we had found a flying bird. For me it has been great watching the faces of children light up as a result of finding rare creatures preserved from our distant past”.
The Zealandian Tropicbird has features that distinguish it from all other known fossil tropicbirds and suggest it was, evolutionarily speaking, an ancestral form of tropicbird. Features of the skull, wing, and pelvis suggest it had different feeding/foraging habits from living and other extinct tropicbirds, but because the specimen has no legs, it is not possible to get a complete picture of its mode of life.
The age (about 62 million years) and ancestral characteristics of this newly described species suggest that tropicbirds may have originated in the Southern Hemisphere – up until now all other fossil species had been known from the Northern Hemisphere only. The presence of a second, smaller, species of tropicbird in the Waipara Greensand, together with that of a primitive bony-toothed bird, and multiple species of penguin, indicate that Zealandian shores were a hub for seabird diversification following the mass extinction event that famously caused the extinction of the dinosaurs 66 million years ago.
Vanesa De Pietri, Senior Research Fellow, University of Canterbury says, “The extinction of dinosaurs and other land and aquatic vertebrates 66 million years ago, left vacant a vast array of habitats that birds were able to conquer. Through all these bird fossils we are finding in the Waipara Greensand, many as old as 62.5 million years old, we know that Zealandian shores played a key role in the early evolutionary history of many seabirds. Worldwide, the fossil record of birds this age is poor, which makes these Canterbury finds so significant in understanding what was happening with birds during the first 5 million years following the extinction of the dinosaurs.”
Paul Scofield, Senior Curator Natural History, Canterbury Museum says, “The Waipara Greensand continues to produce remarkable fossils from the early stages of the evolution of modern birds. This latest find demonstrates that groups of birds once thought to have evolved in the Northern Hemisphere probably evolved in the seas around Zealandia. The nearest relatives of our new species are found in the deserts of Morocco, demonstrating that tropicbirds were a widespread group between 60 and 40 million years ago”.
Gerald Mayr, Vanesa L. De Pietri, Leigh Love, Al Mannering, Erica Crouch, Catherine Reid & R Paul Scofield. 2023. Partial skeleton from the Paleocene of New Zealand illuminates the early evolutionary history of the Phaethontiformes (tropicbirds), Alcheringa: An
Australasian Journal of Palaeontology, DOI: 10.1080/03115518.2023.2246528
