Fossil vertebrates from southern Zealandia: taonga of international significance

ABSTRACT

Vertebrate fossils from Aotearoa New Zealand have revealed the global significance of Zealandia on the origins of modern birds, the history of cetaceans during major climatic events of the Cenozoic and the evolution of cartilaginous and ray-finned fish. Internationally important collections of vertebrate fossils are housed in collections across Aotearoa and have attracted researchers from around the world studying evolution, biogeography and climate change. This special issue of the Journal of the Royal Society of New Zealand celebrates the vertebrate fossils of Aotearoa by showcasing taonga (treasures) that are significant to global and local vertebrate history.

KEYWORDS:

• Cetaceans
• penguins
• fish
• New Zealand

This special issue of the Journal of the Royal Society of New Zealand celebrates the fossil record of Aotearoa New Zealand and the continuing contributions of Zealandia to global knowledge of vertebrate diversity and evolution. Subphylum Vertebrata is our own relatively small, yet endlessly fascinating, branch of the tree of life (Bar-On et al. 2018). Many of the major anatomical changes and high-level diversification events along this branch had occurred well before the time when Zealandia began rifting away from the rest of Gondwana (Benton 1989; Donoghue and Keating 2014; Strogen et al. 2023). Ray-finned, lobe-finned and cartilaginous fishes had all arisen within the Palaeozoic, and terrestrial vertebrates had long-since diversified into all major recognisable clades including amphibians, crocodilians, birds, lepidosaurs and mammals. The basement rocks that Zealandia brought along with it when it separated from the rest of Gondwana in the late Mesozoic captured fossil evidence of some of these early events in vertebrate history (Strogen et al. 2023). Over the remainder of the Mesozoic and across the Cenozoic, however, the vertebrate biota on land and in the oceans would be radically reshaped. Major ecological transitions would give rise to endothermic marine hunters (e.g. whales and dolphins, penguins and seals). New forms of flying vertebrates would emerge and many formerly-volant clades would disperse to islands and have descendants who are now iconic for being increasingly cursorial (i.e. pekapeka, New Zealand lesser short-tailed bat) to entirely flightless (i.e. kākāpō) (Fordyce 1980; Ksepka et al. 2012; Worthy et al. 2013; Kear et al. 2017). The sediments that accumulated on Zealandia as it drifted towards the Pacific Ocean are an important archive that has captured some of the best evidence in the world of major changes to the vertebrate biota during the latest Cretaceous and across the Cenozoic.

As a result, the fossil vertebrate record of Zealandia has provided insights into globally important patterns in biodiversity, especially for marine clades. For example, the earliest fossil penguin Waimanu tuatahi, discovered in Palaeocene sediments of southern Marlborough, is one of the oldest known fossils representing the modern radiation of birds (i.e. the group of dinosaurs that survived the end Cretaceous extinction event) and is thus vital in many phylogenetic age calibrations (Slack et al. 2006). Well-preserved teeth and vertebrae from the shark Carcharocles ( = Otodus) angustidens discovered in Late Oligocene sediments of North Otago have helped reveal the origins of mega-toothed sharks such as Otodus megalodon (Gottfried and Fordyce 2001). An extinct family of toothed whales (Waipatiidae), also discovered in Late Oligocene sediments across North Otago and South Canterbury, has provided new understanding about the evolutionary origins of some of today’s very rare river dolphins (Tanaka and Fordyce 2015). New Zealand’s fossil record has been developed over more than 150 years of discovery and research and there are now several internationally important taxonomic collections distributed across the country. Many of the discoveries highlighted in this special issue are from the collections of the University of Otago Geology Museum, which is one of the oldest palaeontological research collections in the country.

The earliest developments of the fossil record for Aotearoa New Zealand were made by nineteenth Century luminaries such as Walter Mantell, James Hector, Alexander McKay and Frederick Hutton. The early to middle twentieth Century saw new generations of palaeontologists greatly expanding the diversity of the fossil fauna and flora of New Zealand, including Frederick Chapman (fossil fish), William Benham (fossil cetaceans), Brian Marples (fossil penguins) and Patrick Marshall (molluscs). Patrick Marshall was appointed lecturer in Geology at the University of Otago in 1901, and was succeeded in 1916 by Noel Benson, who became head of a new and separate Geology Department. Both Marshall and Benson had wide interests, including palaeontology. Other palaeontologists included John Douglas (Doug) Campbell and Robert (Bob) Carter. Ewan Fordyce joined the Department of Geology in 1982 and, with generations of students, developed an almost 40-year programme collecting and describing late Cretaceous and Cenozoic vertebrates, mostly from Otago and South Canterbury. Ewan Fordyce was also instrumental in setting up the Vanished World Centre and fostering an awareness of the rich fossil heritage of North Otago which ultimately led to the UNESCO accreditation of the Waitaki Whitestone Geopark. Daphne Lee joined the department in 1988 and has focused her work on living and Cenozoic marine invertebrates, palaeobotany, and the freshwater biota ranging from diatoms to insects and fish preserved in Miocene lakes in Otago, including the well-known Foulden Maar.

Articles in this special issue describe new fossil vertebrates from the taonga (treasured) collections of the University of Otago Geology Museum and the Museum of New Zealand Te Papa Tongarewa, and further contextualise the fossil vertebrate record of Aotearoa New Zealand in global patterns of biodiversity. Three articles are reviews concerning important aspects of New Zealand fossil vertebrates. Robinson et al. (2024) provide a compilation of all fossil vertebrate type specimens that are part of the University of Otago Geology Museum, a collection of global significance. The Geology Museum houses type specimens of twenty fish, seventeen cetaceans, six birds and three reptiles, revealing the diversity of life in Southern Zealandia during from the Late Cretaceous to the Pliocene. Tsai (2023) reviews the fossil record of early baleen whales (Mysticeti) to show the special importance that discoveries from Zealandia have had in our understanding of when and from where living whale species arose. Baleen whales are also the subject of a review by Boessenecker and Richards (2024), who discuss the importance of the New Zealand record of Eomysticetidae, the earliest toothless baleen whales.

Original research features in 10 papers providing descriptions, and paleobiological and functional analyses, of Zealandian vertebrates. Fossil cetaceans feature in four of these papers. Meekin et al. (2024) describe a new species of Oligocene odontocete with strangely procumbent teeth. Procumbent tusk-like teeth were also present in fossil dolphins described by Coste et al. (2023), who also evaluate the association between rostrum proportions and morphology of procumbent teeth in fossil and living tusked species. Corrie and Fordyce (2024) also devote their analyses to the teeth, this time on a specimen of New Zealand kekenodontid, late-surviving archaeocetes that persisted until the late Oligocene. Marx et al. (2024) apply geochemical analyses of strontium isotopes to shed light on a unique assemblage of Early Miocene baleen whales from New Zealand.

Three papers shed light on the fossil record of fish from New Zealand. Rust and Robinson (2023) expand our knowledge of an Eocene gemfish originally described by Chapman in the 1930s, by including new material which revealed the so far unknown skull and caudal morphology of the species. Gottfried and Tennyson (2023) describe a Pliocene boxfish from New Zealand, the first for the Southern Hemisphere. The presence of this tropical species in New Zealand sheds light on the diversity of fishes when Zealandia had warmer marine ecosystems. Ehret et al. (2023) present the first occurrences of Carcharodon planus and C. hubbelli in New Zealand, fossil relatives of the great white shark.

Finally, three papers investigate our fossil record of birds. Ksepka et al. (2023) describe a new albatross species which represents the first record of albatrosses for the Southern Hemisphere. Fleury et al. (2023) present the discovery of a well-preserved trackway of seven moa footprints from the Kyeburn River, Central Otago, representing the second earliest fossil record of moa in New Zealand. Ando et al. (2024) describe a new species of fossil penguin from the Oligocene of New Zealand, the earliest tiny penguin which was as small as the extant little blue penguin.

Aotearoa New Zealand has a rich heritage of fossil discovery. The taxonomic collections built from these discoveries are now part of the country’s internationally significant scientific infrastructure. This resource, as this special issue shows, underpins global research partnerships in the fields of evolution, biodiversity, biogeography, stratigraphy and climate change. Aotearoa New Zealand fossil collections have developed through the efforts of comparatively few people, like the intrepid Ewan Fordyce, and face different levels of precarity due to a decentralised resourcing model. Nevertheless, the boundless enthusiasm for fossil discovery in Aotearoa New Zealand and the broader significance of each fossil specimen explains the value with which the collections are held. This special issue honours the enduring interest of students, researchers, and the wider public in the New Zealand fossil record, and commends the network of kaitiaki (guardians) across New Zealand who have enabled the exciting fossil vertebrate research presented here.

Disclosure statement

No potential conflict of interest was reported by the author(s).