Trevor H. Worthy

Dating the late prehistoric dispersal of Polynesians to New Zealand using the commensal Pacific rat

The pristine island ecosystems of East Polynesia were among the last places on Earth settled by prehistoric people, and their colonization triggered a devastating transformation. Overhunting contributed to widespread faunal extinctions and the decline of marine megafauna, fires destroyed lowland forests, and the introduction of the omnivorous Pacific rat (Rattus exulans) led to a new wave of predation on the biota. East Polynesian islands preserve exceptionally detailed records of the initial prehistoric impacts on highly vulnerable ecosystems, but nearly all such studies are clouded by persistent controversies over the timing of initial human colonization, which has resulted in proposed settlement chronologies varying from ≈200 B.C. to 1000 A.D. or younger. Such differences underpin radically divergent interpretations of human dispersal from West Polynesia and of ecological and social transformation in East Polynesia and ultimately obfuscate the timing and patterns of this process. Using New Zealand as an example, we provide a reliable approach for accurately dating initial human colonization on Pacific islands by radiocarbon dating the arrival of the Pacific rat. Radiocarbon dates on distinctive rat-gnawed seeds and rat bones show that the Pacific rat was introduced to both main islands of New Zealand ≈1280 A.D., a millennium later than previously assumed. This matches with the earliest-dated archaeological sites, human-induced faunal extinctions, and deforestation, implying there was no long period of invisibility in either the archaeological or palaeoecological records.

A working list of breeding bird species of the New Zealand region at first human contact

Abstract We present an annotated working list of the bird species breeding in New Zealand during the late Pleistocene and Holocene, up to the time of human contact. New Zealand is defined as including the three main islands and the surrounding smaller islands, plus outlying island groups from Norfolk Island in the northwest, the Kermadec, Chatham, Bounty, Antipodes, Campbell, Auckland, Snares, to Macquarie Islands, but excluding islands south of Macquarie Island and the Ross Dependency. Inclusions or exclusions of species from the list were based on specified criteria. We include only species with a breeding population and not vagrants that occur in New Zealand but which breed elsewhere. Species with validly published names were included if there was fossil evidence for a breeding population before human contact. Species with a breeding population at the time of European contact were included unless contrary evidence from the fossil record indicates that they actually colonised after human settlement. Species without a fossil record were included if a breeding population exists on a relatively undisturbed island within the New Zealand archipelago as defined above. Species now present on the main islands were excluded if they are absent from all well‐documented fossil faunas. Species were excluded from the breeding fauna and treated as vagrants where sustained breeding has not been demonstrated. The phylogenetic species concept is applied both to fossil and to living taxa. The late Quaternary fossil record of birds in New Zealand is excellent, and the contribution of extinct taxa to the total list is understood at least as well as that of the surviving taxa. Many taxa presently recognised at subspecific level are treated here as full species. Twelve extinct species whose former presence is known from fossil evidence, but for which no description has been published, are listed under informal species designations. Taxonomic considerations limited the extent to which the main list could reflect present understanding of the diversity of the avifauna; some undescribed species are at present subsumed under one species name. Where previous taxonomic publications provide precedence, available names at the species‐level have been used. A supplementary hypothetical species list includes all nomenclatural changes signalled in extensive annotations to the main list. In this list we accept 245 species in 110 genera representing 46 families; 176 species were endemic to the archipelago. Preliminary biogeographic analyses based on the composition of the supplementary list show that there were four separate regional faunas: a northern subtropical fauna (Norfolk, Kermadecs); the major fauna of the main islands (North, South, Stewart, and offshore islands); a Chathams fauna (Chatham Islands only); and a subantarctic fauna on the southern islands. Species with wider distributions formed link groups. The origin and compositions of the regional avifaunas and their endemic species differ with their geographic position, climate, and proximity to source faunas. Instances of speciation in groups such as the Coenocoiypha snipe and Petroica flycatchers, and adaptive radiations in groups including moa and acanthisittid wrens, show that there are many avenues for research on the rate of evolution in island and mainland populations of New Zealand birds and that there are large gaps in knowledge of even common taxa. A brief case study demonstrates the inadequacies of using species lists that do not include Holocene fossil species. Species‐area curves based on the total fauna differ substantially from those developed in previous studies based on incomplete, or biased, lists. Pleistocene glaciations caused the pattern of distribution of species on the main islands to change in concert with vegetation changes. Other possible effects include the elimination of warm climate species early in the cooling phase more than 1 million years ago, the speciation in groups including waders and parrots as new habitats (e.g., braided riverbeds and alpine areas) appeared, and the appearance regularly during the Pleistocene of islands that were potential staging points for colonisation of the Chatham Islands. For at least the past 100 000 years, until 2000 years ago, the fauna appears to have been very stable in composition, despite strong cyclic fluctuations in climate and vegetation. The effects of extinctions within the past 2000 years on the composition of the present fauna include the elimination of most of the endemic taxa from all but the subantarctic faunas. Only 169 species of the original late Holocene breeding fauna survive. The extinctions have resulted in a strong bias towards marine and coastal taxa in the present avifauna, in contrast to the balanced representation of terrestrial and marine species in the Pleistocene and Holocene fauna. The importance of systematic studies and the determination of the status of island populations to conservation and basic ornithological research is emphasised. The systematic status of many New Zealand birds is poorly known at present.

Extreme reversed sexual size dimorphism in the extinct New Zealand moa Dinornis

The ratite moa (Aves; Dinornithiformes) were massive graviportal browsers weighing up to 250 kg (ref. 1) that dominated the New Zealand biota until their extinction approximately 500 yr ago. Despite an extensive Quaternary fossil record, moa taxonomy remains problematic and currently 11 species are recognized. Three Dinornis species were found throughout New Zealand and differed markedly in size (1–2 m height at back) and mass (from ∼34 to 242 kg). Surprisingly, ancient mitochondrial DNA sequences show that the three species were genetically indistinguishable within each island, but formed separate North and South Island clades. Here we show, using the first sex-linked nuclear sequences from an extinct species, that on each island the three morphological forms actually represent just one species, whose size varied markedly according to sex and habitat. The largest females in this example of extreme reversed sexual size dimorphism were about 280% the weight and 150% the height of the largest males, which is unprecedented among birds and terrestrial mammals. The combination of molecular and palaeontological data highlights the difficulties of analysing extinct groups, even those with detailed fossil records.

The evolutionary history of the extinct ratite moa and New Zealand Neogene paleogeography

The ratite moa (Aves: Dinornithiformes) were a speciose group of massive graviportal avian herbivores that dominated the New Zealand (NZ) ecosystem until their extinction ≈600 years ago. The phylogeny and evolutionary history of this morphologically diverse order has remained controversial since their initial description in 1839. We synthesize mitochondrial phylogenetic information from 263 subfossil moa specimens from across NZ with morphological, ecological, and new geological data to create the first comprehensive phylogeny, taxonomy, and evolutionary timeframe for all of the species of an extinct order. We also present an important new geological/paleogeographical model of late Cenozoic NZ, which suggests that terrestrial biota on the North and South Island landmasses were isolated for most of the past 20–30 Ma. The data reveal that the patterns of genetic diversity within and between different moa clades reflect a complex history following a major marine transgression in the Oligocene, affected by marine barriers, tectonic activity, and glacial cycles. Surprisingly, the remarkable morphological radiation of moa appears to have occurred much more recently than previous early Miocene (ca. 15 Ma) estimates, and was coincident with the accelerated uplift of the Southern Alps just ca. 5–8.5 Ma. Together with recent fossil evidence, these data suggest that the recent evolutionary history of nearly all of the iconic NZ terrestrial biota occurred principally on just the South Island.

Miocene mammal reveals a Mesozoic ghost lineage on insular New Zealand, southwest Pacific

New Zealand (NZ) has long been upheld as the archetypical example of a land where the biota evolved without nonvolant terrestrial mammals. Their absence before human arrival is mysterious, because NZ was still attached to East Antarctica in the Early Cretaceous when a variety of terrestrial mammals occupied the adjacent Australian portion of Gondwana. Here we report discovery of a nonvolant mammal from Miocene (19–16 Ma) sediments of the Manuherikia Group near St Bathans (SB) in Central Otago, South Island, NZ. A partial relatively plesiomorphic femur and two autapomorphically specialized partial mandibles represent at least one mouse-sized mammal of unknown relationships. The material implies the existence of one or more ghost lineages, at least one of which (based on the relatively plesiomorphic partial femur) spanned the Middle Miocene to at least the Early Cretaceous, probably before the time of divergence of marsupials and placentals >125 Ma. Its presence in NZ in the Middle Miocene and apparent absence from Australia and other adjacent landmasses at this time appear to reflect a Gondwanan vicariant event and imply persistence of emergent land during the Oligocene marine transgression of NZ. Nonvolant terrestrial mammals disappeared from NZ some time since the Middle Miocene, possibly because of late Neogene climatic cooling.

Miocene waterfowl and other birds from central Otago, New Zealand

Synopsis Abundant fossil bird bones from the lower Bannockburn Formation, Manuherikia Group, an Early‐Middle Miocene lacustrine deposit, 16–19 Ma, from Otago in New Zealand, reveal the “St Bathans Fauna” (new name), a first Tertiary avifauna of land and freshwater birds from New Zealand. At least 23 species of birds are represented by bones, and probable moa, Aves: Dinornithiformes, by eggshell. Anatids dominate the fauna with four genera and five species described as new: a sixth and largest anatid species is represented by just one bone. This is the most diverse Early‐Middle Miocene duck fauna known worldwide. Among ducks, two species of dendrochenines are most numerous in the fauna, but a tadornine is common as well. A diving petrel (Pelecanoididae: Pelecanoides) is described, so extending the geological range of this genus worldwide from the Pliocene to the Middle Miocene, at least. The remaining 16 taxa are left undescribed but include: a large species of gull (Laridae); two small waders (Charadriiformes, genus indet.), the size of Charadrius bicinctus and Calidris ruficollis, respectively; a gruiform represented by one specimen similar to Aptornis; abundant rail (Rallidae) bones, including a common flightless rail and a rarer slightly larger taxon, about the size of Gallirallus philippensis; an ?eagle (Accipitridae); a pigeon (Columbidae); three parrots (Psittacidae); an owlet nightjar (Aegothelidae: Aegotheles sp.); a swiftlet (Apodidae: Collocalia sp.); and three passerine taxa, of which the largest is a member of the Cracticidae. The absence of some waterbirds, such as anserines (including swans), grebes (Podicipedidae) and shags (Phalacrocoracidae), among the abundant bones, indicates their probable absence from New Zealand in the Early‐Middle Miocene.

A sphenodontine (Rhynchocephalia) from the Miocene of New Zealand and palaeobiogeography of the tuatara (Sphenodon)

Jaws and dentition closely resembling those of the extant tuatara (Sphenodon) are described from the Manuherikia Group (Early Miocene; 19–16 million years ago, Mya) of Central Otago, New Zealand. This material is significant in bridging a gap of nearly 70 million years in the rhynchocephalian fossil record between the Late Pleistocene of New Zealand and the Late Cretaceous of Argentina. It provides the first pre-Pleistocene record of Rhynchocephalia in New Zealand, a finding consistent with the view that the ancestors of Sphenodon have been on the landmass since it separated from the rest of Gondwana 82–60 Mya. However, if New Zealand was completely submerged near the Oligo-Miocene boundary (25–22 Mya), as recently suggested, an ancestral sphenodontine would need to have colonized the re-emergent landmass via ocean rafting from a currently unrecorded and now extinct Miocene population. Although an Early Miocene record does not preclude that possibility, it substantially reduces the temporal window of opportunity. Irrespective of pre-Miocene biogeographic history, this material also provides the first direct evidence that the ancestors of the tuatara, an animal often perceived as unsophisticated, survived in New Zealand despite substantial local climatic and environmental changes.

Quaternary fossil faunas from caves in Takaka Valley and on Takaka Hill, northwest Nelson, South Island, New Zealand

The late Quaternary fossil vertebrate faunas from 43 caves in Oligocene limestones and Ordovician marbles in the Takaka Valley and on Takaka Hill, northwest Nelson, New Zealand, are described and discussed. Depositional environments are described and interpreted. Major sites, including Ngarua Cave, Hawkes Cave, Kairuru Cave, Hobsons Tomo, and Irvines Tomo are described in detail. Many sites on Takaka Hill have been damaged by casual collectors since their discovery around 1900. Most sites were pitfall traps, but some deposits had been redistributed by water. Two deposits were attributed to an accumulation of material from pellets ejected by laughing owls (Sceloglaux albifacies), and of these the spectacularly rich Predator Cave site provided a large sample of small vertebrates. The fossil faunas included 42 species of land snails, three species of leiopelmatid frog, a tuatara, three species of geckoes, one or more species of skink, at least 58 (including two introduced) species of bird, three species of b...

Quaternary fossil faunas, overlapping taphonomies, and palaeofaunal reconstruction in North Canterbury, South Island, New Zealand

This paper describes the late Quaternary fossil fauna from the area within a 10 km radius of Waikari, North Canterbury, New Zealand. Fossils from a pitfall deposit (Waikari Cave), ten predator sites attributed to laughing owls Sceloglaux albifacies (notably Ardenest, Gowan Hills Owl site, and P. Lambs Owl site), five swamp sites (notably Pyramid Valley and Glencrieff), and three archaeological sites, contributed most of the data. A few specimens came from coalluvial deposits in rock shelters. A small fauna is described from alluvial deposits along Home Creek, near Waipara. The age of these faunas includes the Late Pleistocene (Otira Glacial) for the Home Creek fauna, Late Glacial — early Holocene for Glencrieff, and Late Holocene for Pyramid Valley swamp, Waikari Cave, and all predator sites. Some of the predator sites accumulated fauna until late in the nineteenth century. The total avian fauna for the Waikari region (including Glenmark) comprises 65 indigenous and 4 introduced species of birds. In addi...

Quaternary fossil faunas from caves in the Punakaiki area, West Coast, South Island, New Zealand

The late Quaternary fossil vertebrate faunas from 42 caves in Oligocene limestones of the Barrytown Syncline, Westland, New Zealand, are described and discussed. The depositional environments in cave sites in the area are described and interpreted. Several major sites, including Metro Cave, Madonna Cave, and Te Ana Titi, are described in detail. The Hermits Cave deposit is probably derived from pellets ejected by laughing owls (Sceloglaux albifacies) at one of their roost sites. Radiocarbon dating shows that the faunas were laid down at various times during the past 25,000 years. A date of 25,070 years is the oldest so far obtained from any cave fossil in New Zealand. The fossil fauna consisted of 50 species of bird, three frogs, one skink, one gecko, one tuatara, and two or possibly three bats. They comprised two distinct faunal assemblages. A glacial fauna, dating from the last (Otira) Glaciation and Late Glacial periods, between 10,000 and 25,000 radiocarbon years ago, contained taxa typical of Holoce...