Twenty million years ago, Lake Manuherikia covered much of the Maniototo Plains of Central Otago. At 5,600 sq km this lake was nine times the size of Lake Taupō, extending all the way from the Waitaki River to the Nevis Valley south of Queenstown.
Although we don’t know how long the lake remained, we know it was there in the early Miocene (about 16 to 19 million years ago). We also know it was surrounded by rich subtropical vegetation.
The edges of the lake were fringed with ferns and swamps. After the lake dried up, its bed became a fossil-rich layer of sediments. During the last 20 years palaeontologists have found fossil plants, fish, birds and other animals in the clay and mudstone of the Manuherikia lake sediments.
This video shows how the land we now call New Zealand was transformed over a period of 40 million years between the Paleocene Period (c60 million years ago) and the Miocene Period (c20 million years ago).
St Bathans Crocodile
Crocodilia
New Zealand once had a 3 metre-long crocodile that was about the size of northern Australia’s living freshwater crocodile (Crocodylus johnstoni). Crocodiles were probably the most significant predator at St Bathans.
The presence of a crocodile in Zealandia was first identified from a bone found by palaeobotanist Dr Mike Pole at St Bathans in 1987.Since the team of palaeontogists has been working at St Bathans, nearly 200 crocodile bones and teeth have been recovered from four sites. However, the bones confirming the exact type of crocodile have so far proved elusive. Although several skull and limb bones have been recovered, these have all belonged to different animals.
These crocodiles were covered in bony projections called osteoderms and they had robust limbs. Their lower jaw was shaped unlike any other crocodile, suggesting that they had short, deep faces. There may have even been more than one type of crocodile in Lake Manuherikia.
These crocodiles have no obvious relation to crocodile fossils found in the South West Pacific or Australia. It’s possible that, like the tuatara, they date back to the ancient continent of Gondwana.
Mata Creek Goby
Mataichthys bictenatus
By far the most common animal fossils preserved in the deposits are fish. Most of the fossils are backbones.
The remains of skull bones and several thousand tiny ear bones, called otoliths, have also been preserved. Fourteen species of fish have been described, all of which belong to families still living in Aotearoa New Zealand today.
Most of the species are in the families that includes whitebait (Galaxiidae) and gobies (Eleotridae) but at least two types of grayling (Retropinnidae) have been found. This proves that most of the freshwater fish families living around Aotearoa New Zealand and southern Australia today were established between 19 and16 million years ago. Most fish species were larger than their living relatives.
Schwarzhans W, Scofield RP, Tennyson AJD, Worthy JP, Worthy TH. 2012. Fish Remains, Mostly Otoliths, from the Non-Marine Early Miocene of Otago, New Zealand. Acta Palaeontologica Polonica 57: 319–350.
St Bathans Kiwi
Proapteryx micromeros
A tiny species of kiwi that may have been able to fly has been identified from three bones.
The St Bathans Kiwi was smaller than any living species of kiwi, with a leg bone (femur) that was shorter and about half the diameter of a Little Spotted Kiwi leg bone (the smallest modern kiwi).
The genus name Proapteryx comes from Latin and means before (pro) Kiwi (Apteryx), indicating that this species precedes modern kiwi in the geological record. The species name micromeros comes from the Latin micro meaning small and meros meaning thigh.
Palaeontologists believe the presence of a small, slender-legged kiwi in Aotearoa New Zealand as much as 20 million years ago indicates that kiwi and their nearest relatives (the gigantic elephant birds of Madagascar) evolved from a small-bodied and possibly flying ancestor.
This bird was probably about the size of a pigeon. It would have weighed between 280 and 380 grams, about a third the weight of the living Little Spotted Kiwi.
Worthy. TH, Worthy JP, Tennyson AJD, Salisbury SW, Hand SJ, Scofield RP. 2013. Miocene fossils show that kiwi (Apteryx, Apterygidae) are probably not phyletic dwarves. Paleornithological Research 2013 – Proceedings of the 8th International Meeting of the Society of Avian Paleontology and Evolution: 63–80.
St Bathans Adzebill
Aptornis proasciarostratus
Adzebills are a bizarre group of recently extinct, flightless birds that were only found in Aotearoa New Zealand. These fossils confirm that adzebills have lived in Aotearoa New Zealand for at least 20 million years.
The palaeontologists believe the nearest relatives of adzebills are tiny African birds called flufftails. The St Bathans Adzebill was slightly smaller than the two recently extinct adzebill species.
The St Bathans Adzebill was described from two distinctive backbones. Four other bone fragments found at the same site are believed to be from the same species. The species name proasciarostratus comes from the Latin words pro meaning before, ascia meaning adze and rostratus meaning beaked.
Worthy TH, Tennyson AJD, Scofield RP. 2011. Fossils reveal an early Miocene presence of the aberrant gruiform Aves: Aptornithidae in New Zealand. Journal of Ornithology. 152: 669–680.
St Bathans Shelduck
Miotadorna sanctibathansi
This large duck was similar to the Paradise Shelduck found in Aotearoa New Zealand today but it was not a direct ancestor.
The name Miotadorna is based on the palaeontologists’ conclusion that the species is a Miocene shelduck related to Tadorna (the genus that includes the Paradise Shelduck). The species name reflects that the bird used to live around the old gold mining town of St Bathans, near the fossil sites.
The St Bathans Shelduck is the largest duck found in the fossil sites. There are also at least two as-yet undescribed species of geese which may be related to the recently extinct New Zealand Goose (Cnemiornis).
Worthy TH, Tennyson AJD, Jones C, McNamara JA, Douglas BJ. 2007. Miocene waterfowl and other birds from central Otago, New Zealand. Journal of Systematic Palaeontology 5: 1–39.
Manuherikia Duck
Manuherikia lacustrina
The Common Manuherikia Duck was a diving duck a bit smaller than an Australasian Shoveler. It had large salt glands that show it could live in saline water as well as the freshwater Lake Manuherikia.
Manuherikia lacustrina was the commonest bird in Lake Manuherikia and was about the size of the modern Grey Duck found in Aotearoa New Zealand today.
Worthy TH, Tennyson AJD, Jones C, McNamara JA, Douglas BJ. 2007. Miocene waterfowl and other birds from central Otago, New Zealand. Journal of Systematic Palaeontology. 5(1): 1–39.
St Bathans Goose
Waterfowl found at St Bathans includes six duck species and two unnamed geese. These have been mainly identified from the size and form of their upper wing bones (humeri).
The closest relative of both goose species appears to be Australia's Cape Barren Goose.
Worthy TH, Tennyson AJD, Jones C, McNamara JA, Douglas BJ. 2007. Miocene waterfowl and other birds from central Otago, New Zealand. Journal of Systematic Palaeontology. 5(1): 1–39.
Bartle's Bittern
Pikaihao bartlei
A tiny bittern, the size of the extinct New Zealand Bittern, probably haunted the reeds around the lakebed.
Bartle’s Bittern was a small bittern species possibly related to little bitterns (Ixobrychus) and was much smaller than the St Bathans Heron (Matuku otagense) that it lived alongside.
The genus name Pikaihao is based on Māori words meaning a small fisherman. The species name bartlei honours J A (Sandy) Bartle, retired curator of birds at the Museum of New Zealand Te Papa Tongarewa.
St Bathans False Flamingo
Palaelodus aotearoa
This goose-sized bird, described from two fossil leg bones, was a member of an extinct group called the palaelodids. These were slender birds with long, thin legs and a long neck. Like their close relatives, flamingos, they fed in shallow water but they had a straight bill and not the distinctive bill of flamingos.
Until the fossils were found at St Bathans, the group was only known in North and South America, Europe, Egypt and Australia. Some palaeontologists believe Palaelodus could swim under water, chasing prey. But it’s more likely that they browsed for food while swimming or standing in shallow water.
Compared to its Northern Hemisphere relatives, Palaelodus aotearoa was medium-sized, slightly smaller than the older Palaelodus wilsoni from South Australia. Compared to other members of the group, the New Zealand bird had stouter legs.
Worthy TH, Tennyson AJD, Jones C, McNamara JA, Douglas BJ. 2007. Miocene waterfowl and other birds from central Otago, New Zealand. Journal of Systematic Palaeontology 5: 1–39.
New Zealand Lake-wanderer
Hakawai melvelli
Shorebirds are a diverse group, which includes gulls and the migratory godwits that visit our shores each year from their Arctic breeding grounds. Fossils of wading birds have been found at St Bathans. These prehistoric birds had ancient and mysterious origins.
The proportions of the wing bones of the New Zealand Lake-wanderer indicate that it was a good flier and, as some of bones were from young birds, that these birds bred locally rather than being migrants from elsewhere.
This small wading bird was similar in size to a male Australian Plains-wanderer (Pedionomus torquatus) and it probably weighed between 50 and 60 grams. Features of the bones place Hakawai melvelli in a group of wading birds that includes both the Australian Plains-wanderer (Pedionomidae) and the group of South American seedsnipe (Thinocoridae).
The Plains-wanderer may be its closest relative, but the bird is sufficiently distinct that it may deserve to be placed in its own family.
The genus name is based on the mythical Hakawai of Māori legend. The species name honours New Zealand-based ornithologist David Melville for his efforts to advance shorebird conservation locally and globally.
Sansom’s Plover
Neilus sansomae
This small starling-sized wading bird foraged on the lake shore. Its bones are fairly rare in the St Bathans sediments, making it difficult to determine much about the bird’s ecology. It may have weighed 88 to 98 grams. Some of the fossils were from younger birds, indicating that the birds were not migrants but bred here.
Neilus sansomae was probably the ancestor of a group of wading birds that includes the sheathbills of the Antarctic and subantarctic islands and the Magellanic Plover of South America. Although much smaller than the two species of living sheathbill, features of the bones suggest Neilus may have been a closer relative of sheathbills than the Magellanic Plover.
The genus name is after Neilus who was, in Greek mythology, the father of Chiona. This refers to Sansom’s Plover being the ancestor of the sheathbills in the genus Chionis. Neilus comes from the Greek word meaning river valley, so it also describes the site where the fossils were found.
The species name honours Southland ornithologist Olga Sansom (1900–1989) who, along with her daughter Maida Barlow, studied shorebirds in southern Aotearoa New Zealand.
St Bathans Diving-petrel
Pelecanoides miokuaka
Although St Bathans was a freshwater lake it was clearly not far from the sea as several marine shells and the bones of a seabird have been found in the lake.
Pelecanoides miokuaka is the oldest known member of the marine diving-petrels. The species was described from a partial upper wing bone found at St Bathans. The only other fossil diving-petrel described (the South African species P. cymatotrypetes of the Early Pliocene) is 10 to 15 million years younger.
The genus name is that of the living diving-petrels. The species name miokuaka comes from the Māori name for diving-petrels (kuaka) combined with mio that denotes it is from the Miocene.
Worthy TH, Tennyson AJD, Jones C, McNamara JA, Douglas BJ. 2007. Miocene waterfowl and other birds from central Otago, New Zealand. Journal of Systematic Palaeontology 5: 1–39.
St Bathans Pigeon
Rupephaps taketake
The St Bathans Pigeon was slightly smaller than a New Zealand Pigeon (kererū). It was more closely related species in Australia and Melanesia that to the living New Zealand Pigeon.
The genus name comes from rupe, a Māori and Polynesian name for pigeons, and phaps, a Greek noun for wild pigeon. The species name taketake is from a Māori word meaning ancient or original.
Worthy TH, Hand SJ; Worthy JP; Tennyson AJD, Scofield RP. 2009. A large fruit pigeon (Columbidae) from the Early Miocene of New Zealand. Auk 126: 649-656.
Zealandian Dove
Deliaphaps zealandiensis
A second species of pigeon, Deliaphaps lived in Aotearoa New Zealand during the early Miocene.
More fossil material will need to be found to establish its relationships to modern birds. However, scientists believe it is most closely related to the Living Samoan Tooth-billed Pigeon (Didunculus), the giant Papuan Crowned Pigeons (Goura), the Nicobar Pigeon (Caloenas) and the extinct Dodo.
De Pietri VL, Scofield RP, Tennyson AJD, Hand SJ, Worthy, TH. 2009. The diversity of early Miocene pigeons (Columbidae) in New Zealand. Proceedings of the 9th International Meeting of the Society of Avian Paleontology and Evolution. Contribuciones del Museo Argentino de Ciencias Naturales 7: 49–68.
Squawkzilla the Giant Parrot
Heracles inexpectatus
In 2008, a pair of very large bird leg bones was discovered at St Bathans. Palaeontologists initially thought the bones were from a giant eagle, but then realised they were from the largest parrot ever found.
This one metre-high giant parrot probably couldn’t fly and although mainly a vegetarian, it may also have eaten meat. The native kea, which are parrots, are known to attack sheep and they are much smaller than this monster bird.
The palaeontologists formally named it Heracles inexpectatus, Heracles after the powerful hero of Greek mythology and inexpectatus to reflect the surprising nature of the discovery. They nicknamed it Squawkzilla. These giant parrots may have weighed as much as 7 kg, more than double that of the unusually heavy kākāpō, also a parrot.
Worthy TH, Hand SJ, Archer M, Scofield RP and De Pietri VL. 2019. Evidence for a giant parrot from the Early Miocene of New Zealand. Biology Letters 15: 20190467.
St Bathans Tuatara
Sphenodontia
The tuatara is the sole living relative of an ancient race of lizard-like reptiles called the Rhynchocephalia that lived for at least 240 million years. From just a few fossil fragments scientists can tell that the relatives of the tuatara have long been in Aotearoa New Zealand.
The tuatara is sometimes called a living dinosaur but this isn’t factually correct. The tuatara’s ancestors lived amongst the dinosaurs but were small lizard-like reptiles. However modern birds are more closely related to the giant dinosaurs than the tuatara.
Although tuatara look like lizards, the similarity is superficial. The group has several characteristics that make it unique among reptiles. The tuatara has a third eye on the top of the head. The eye isn’t used to see but is sensitive to light and is believed to help the tuatara judge the time of day or season.
Tuatara also have two parallel rows of teeth in their upper jaw. The lower jaw fits into the gap between the rows to produce a special grinding and sawing motion to crush their prey. This feature can be seen in the fossil.
While there haven’t been enough bones found to give it a formal name, scientists are confident that it confirms relatives of the tuatara have been in Aotearoa New Zealand for at least 16 million years.
Lee's Parrot
Nelepsittacus daphneleeae
Lee's Parrot is one of three smaller parrot species also found at St Bathans. These three birds were all from a single genus, Nelepsittacus.
The name recognises that these ancient parrots are the ancestors of the modern genus Nestor (the kaka and Kea). The name is derived from Greek mythology, a combination of Neleus, the father of Nestor and psittakos (Greek for parrot).
The St Bathans fossil parrots confirm the presence of the family Strigopidae in Aotearoa New Zealand for at least 20 million years. The lineage leading to the Kākāpō had apparently already diverged before this date, as there haven’t been any bones of a Kākāpō-like fossil found at St Bathans.
After Squawkzilla, Lee's Parrot is the largest and the rarest of the four parrot species described from Bathans. Lee’s Parrot was just a little smaller than the living kaka.
Worthy TH, Tennyson AJD, Scofield RP. 2011. An early Miocene diversity of parrots (Aves, Strigopidae, Nestorinae) from New Zealand. Journal of Vertebrate Paleontology 31: 1102–1116.
The Waddling Mouse
This is an unnamed fossil species believed to be an extinct primitive land-dwelling mouse-sized mammal. It is known from just a few tiny teeth and a fragment of a limb bone.
This mammal may be a late surviving ancient species that might only be distantly related to living mammals. The discovery and publication of this find in 2007 caused a sensation.
When humans arrived in Aotearoa New Zealand, birds ruled and bats were the only land mammals. But the discovery of these fossils prove that that land mammals, other than bats, once lived in Zealandia. It suggest that our unique wildlife and plants evolved in the presence of such mammals.
Worthy TH. Tennyson AJD, Archer M, Musser AM, Hand SJ, Jones C, Douglas BJ McNamara, JA, Beck, RMD 2006. Miocene mammal reveals a Mesozoic ghost lineage on insular New Zealand, southwest Pacific. Proceedings of the National Academy of Sciences 103: 19419–19423.
The Giant Burrowing Bat
Vulcanops jennyworthyae
Burrowing bats (Mystacinidae) are now only found in Aotearoa New Zealand but they were once found throughout Gondwana. They are unique amongst bats, as they scurry about on all fours foraging for food on the forest floor and along tree branches.
The forest around Lake Manuherikia were once home to at least four different types of bats. A giant burrowing bat, three times the size of the bats now living in Aotearoa New Zealand, was the most bizarre.
This bat, which weighed about 40 grams, was named Vulcanops jennyworthyae, after Jenny Worthy, a vital member of the palaeontology team who sorted through thousands of fossil fragments to find the hidden treasures.
The genus name recognises Vulcan, the mythological Roman god of fire, referring to New Zealand's volcanic nature, but also to the historic Vulcan Hotel at St Bathans. Burrowing bats are related to vampire bats and other bats from South America.
Hand SJ, Worthy, TH, Archer M, Worthy JP, Tennyson AJD; Scofield RP. 2013. Miocene mystacinids (Chiroptera, Noctilionoidea) indicate a long history for endemic bats in New Zealand. Journal of Vertebrate Paleontology 33: 1442-1448.
Hand SJ, Lee DE, Worthy TH, Archer M, Worthy JP, Tennyson AJD, Salisbury SW, Scofield RP, Mildenhall DC. 2015. Miocene Fossils Reveal Ancient Roots for New Zealand's Endemic Mystacina (Chiroptera) and its Rainforest Habitat. PLoS ONE 10: e0128871
Worthy TH, Salisbury SW, De Pietri VL, Tennyson AJD, Scofield RP, Gunnell GF, Simmons NB, Archer M, Beck RMD. 2018. A new, large-bodied omnivorous bat (Noctilionoidea: Mystacinidae) reveals lost morphological and ecological diversity since the Miocene in New Zealand. Scientific Reports. 8: 235.
An Unnamed Swift
Apodidae
A small species of swift, known as a swiftlet, has been identified from several bones found at St Bathans.
Swifts are small aerial feeding birds. This one was similar in size and form to the swiftlets found in tropical southeast Asia, Indonesia, Melanesia, northern Australia and Polynesia such as this specimen. Swifts no longer breed in New Zealand, but two much larger species occasionally visit.
Livezey's Rail
Litorallus livezeyi
Livezey's Rail is one of two tiny rails found fossilised at St Bathans. Rails are a group of aquatic birds which include the Weka, Tākahe and Pūkeko. Many rail species have spread from continents to far-flung islands.
The St Bathans rail species were both tiny compared to many of today's rails. They had smaller wings and were flightless.
Livezey's rail was the more uncommon of the two species. Its genus name comes from a combination of the Latin litore, meaning shore and rallus for rail. The name refers to the fact that the fossils were mostly found in clay sediments indicating that these birds probably lived around the lake shore.
The species name acknowledges the late Bradley C Livezey (1954–2011) and his enormous contribution to understanding the evolution birds, particularly rails and the evolution of flightlessness.
Mather EK, Tennyson AJD; Scofield RP, De Pietri VL, Hand SJ. Archer M, Handley WD, Worthy TH. 2019. Flightless rails (Aves: Rallidae) from the early Miocene St Bathans Fauna, Otago, New Zealand. Journal of Systematic Palaeontology 17: 423–449.
The St Bathans Fossil Dig
Dr Paul Scofield, Canterbury Museum Senior Curator Natural History, discusses extracting fossils from a 20 million-year-old lake bed near St Bathans, Central Otago.
