The North Otago Vanished World trail has been created by local people with help from Otago University paleontologist, Ewan Fordyce. It allows public access to fossil sites, extinct vol­canoes and other major landforms that reveal the ancient history of the region. The sites range from Waianakarua to Oamaru on the coast, to inland Duntroon. You simply buy a Vanished World Fos­sil Trail brochure and guide yourself around.

At the Vanished World Centre at Duntroon (the old grocery store), there are more extensive dis­plays and kids can have a crack at chiselling fos­sils out of rocks. The centre is largely run by local women, including farmer Alison Simpson. Some of the whale fossils the area is known for were found on her farm; as sheep rub against rock walls they eventually dislodge embedded brachiopods. She brings them to the centre to give to school children who have never seen a brachiopod, or a fossil.

Some of the 19 Vanished World locations are impressive. While there aren’t any dramatic moun­tains, the drama is incised into the land. Streams, some of them no longer existing, have cut valleys, leaving curiously wrought limestone cliffs.

Any rocks of sedimentary origin may contain fossils, but some locations around the country are better than others. Most sandstones around Auckland’s Waitemata Harbour, for instance, contain few fossils. Coastal cliffs are generally the best location for finding fossils, but they can also be found in the banks of streams, road cuttings, or anywhere where there is exposed, clean, soft rock. Softer rock also makes it easier to recover the fossil.

The west coast of the North Island from Port Waikato to Wanganui has numerous fos­sil localities, apart from those places where volcanic rocks have spilled out onto the coast (as at Mts Karioi and Taranaki). For instance, at Kiritehere Beach south of Marakopa and west of Waitomo, every second rock on the beach is crammed with Mesozoic bivalve shells. But fos­sils are rare in greywacke, so the main ranges, Wellington and most of the Southern Alps have limited offerings.

However, the Wairarapa coast around Castle-point is worth exploring, as is much of the east coast of the South Island, as far north as Cape Campbell in Marlborough and down to Amberley. Further south, between South Canterbury and Nugget Point, there are many fossiliferous sedi­mentary rocks. For instance, many of the rocks on the exposed stony beach just a few kilometres south of Oamaru contain fossil material, while the cliffs at the north end of the beach contain a stra­tum jammed with brachiopods. Plenty of mollus­can fossils can also be found in adjoining rocks.

Inland from Oamaru and Waimate, fossils can be found in limestone and other sedimentary rocks, as well as at Clifden in western Southland and in the cliffs along the western end of Te Wae­wae Bay. Fossilised plant remains are common at Curio Bay, near the southernmost point of the South Island. At the other end of New Zealand, very recent (perhaps only 20,000-year-old) sub-fossil flax snails can be picked up on the sand dunes behind Cape Maria Van Diemen.

Fossils are almost everywhere!

Penguins are particularly important in studying the evolution of birds because, being flightless swimmers, they have heavy bones that persist well as fossils. Most flighted birds have very thin bones to reduce weight, which are easily destroyed in the turbulent workings of fossil beds. There are very few bird bones older than 65 million years, although quite a few bird footprints are known from the Late Creta­ceous. Also, because penguins are marine, their bones have a better chance of getting into sedimentary rocks laid down in the ocean than the bones of your average sparrow.

Penguins are a Southern hemisphere group and New Zealand’s fossil penguin record is second to none. It was only about three years ago that a largely intact skeleton was discovered by Junior Naturalists in Kawhia Harbour.

The oldest penguin fossils anywhere in the world were described in 2006 from the Waipara area of north Canterbury. Two new species were named and placed in a new genus, Waimanu (wai: water, manu: bird). These metre-tall birds have skeletal differences that set them apart from modern penguins but they are clearly ancestors. Waimanu looked rather like a shag, with a long slim bill—longer than in present-day pen­guins—and powerful, flattened wing bones that suggest they were used for swimming underwater. The fossils have been accurately dated at 58–61 million years old.

The dating of this find is crucial because the earlier we date penguin fossils, the further back we set the clock on the evolution of all birds. Skeletal characters can be scored and analysed to yield phylogenetic trees depicting relationships among different groups of birds, and DNA sequences can be compared to produce the same sort of information. This can then be analysed to give information about the times that groups of birds appeared.

For instance, storks and penguins are related groups, and if the oldest penguins are 61 million years old, then storks and penguins must have diverged prior to that time. And if the DNA of modern storks and penguins diverges by 30 per cent, how long ago must rooks and falcons have been separate if their DNA is 40 per cent different? Combining data from these fossil penguins with sequence information strongly suggests that new groups of birds were arising as long ago as 98 million years, far back in the Cretaceous.

This view is at variance with the ideas of some who think that most birds were wiped out by the KT (Cretaceous-Ceno­zoic) extinction and that modern birds only began to radiate in the Cenozoic. Jeffrey Stilwell and his team from Monash University in Victoria recently found penguin-like birds that could possibly be even older in Takitika Grit on the Chathams. Older fossil penguins will push back the date of bird radiation even further into the Cretaceous. The study of fossil penguins is having unexpectedly wide ramifications!

On 24 november 1998, Hamish Campbell was carrying out field work beside Titiroa Stream on the eastern side of the lower Mataura River in South­land when he discovered a rock that showed a mould of fossil material. The mould (65 x 55 mm) was ornamented with coarse ridges, which initially looked like something from an ammonite shell. Further investigation showed that it wasn’t an ammonite, mollusc or brachiopod, or indeed any other sort of invertebrate.

Vexed, he took the fragment to Ewan Fordyce, who suggested it was similar to ornamented dermal bones of Palaeozoic and Mesozoic amphibians. A cast of the speci­men was sent to specialist paleontologist Anne Warren, of La Trobe University in Victoria. She identified it as about a quarter of the underside of the left clavicle (collar bone) of a 2 m salamander-like amphibian known as a stereospondyl. Fossil pollen and fossil leaf material collected nearby dated the surrounding rock to the Early Triassic, some 250 million years ago.

That date makes this the oldest terrestrial fossil in the country and the most convincing evidence to date of the presence of these large, ancient amphibians in New Zea­land—although at this time these rocks were part of Gond­wanaland. This sort of amphibian was among the very earli­est four-limbed vertebrates (tetrapods) to waddle onto land.

Stereospondyl amphibians first appeared in the late Devonian and survived in Gondwanaland until the Early Cretaceous. In the Palaeozoic they were mostly terrestrial but Mesozoic stereospondyls were aquatic, and some species attained the size of large crocodiles. Important Mesozoic finds of stereospondyls have been made in eastern Australia, so it is likely that this species was similar.

The Australian forms had a large head with upward-facing eyes, a large mouth with many needle-like teeth, rather short legs and a sprawling gait. The jaws may have been capable of fast snapping, but they would not have been particularly strong. Perhaps the Mataura fossil represents an ambush-predator that lay in wait in the water to snaffle prey that came sufficiently close. Possibly the animal also fed on land, although it could only have done so in damp environments where its skin would not dry out.

There has been brief mention of “labyrinthodont” teeth (an earlier name for stereospondyls) from two marine Triassic localities elsewhere within New Zealand (Nugget Point and Nelson) but the identity of those fossils is uncertain. Ichthyo­saurs, for example, occur in the New Zealand marine Triassic and are known to have teeth with labyrinthine or deeply in-folded and intricate enamel. Until Campbell’s discovery in that Southland stream, there was no particular reason to expect stereospondyl amphibians ever existed in New Zealand.

The largest reptile fossil so far discovered in New Zealand­ and it is substantially complete—is a marine plesiosaur recently given the name of Kaiwhekea katiki by Ewan Fordyce. It was discovered in 1983 by an amateur fossil collector at Shag Point, on the coast north of Dunedin, but was described and named only in 2002. The 7 m skeleton was excavated by a team from the University of Otago in a month-long operation and the remains are now on loan for display at Otago Museum. Many of the bones had dissolved as acidic groundwater penetrated cracks in the concretion, but casts of their shapes were well preserved in the rocks, and the skeleton was largely articulated. Only the front flippers are missing.

What did it look like? Plesiosaurs have been described as a hefty snake threaded through a turtle. Kaiwhekea probably swam quite rapidly, a bit like a sea lion, using its well-developed flippers. It had a long slim neck with a narrow head, but the neck was probably not especially flexible. The mouth contained 86 even, small to medium-sized teeth in the top jaw and 84 in the lower. It had large, powerful jaw muscles. Prey was likely to have been soft-bodied, such as squid: In fact its name is derived from Maori: kai (to eat) and whekea (squid). Being a reptile, it would have been air-breathing and laid a clutch of eggs ashore like a turtle or crocodile.

The fossil was found in a large concretion in silty sandstone of the Katiki Formation. Surrounding fossils, especially foraminifera, suggest it perished some 70 million years ago in a sheltered embayment or a marine estuary. Was it stuck in the mud, or left behind by a retreating tide? Perhaps it was a female seeking the safety of an estuary to lay eggs?

Plesiosaurs first appeared in the Triassic 215 million years ago and a few survived to the KT extinction 65 million years ago. Although this New Zealand species has been placed in its own genus, it seems to belong to a family that was best known from the Jurassic of the North­ern hemisphere.

Other Zealandian plesiosaurs are known from Mangahouanga Stream (Tuarangisaurus, Mauisaurus), Joan Wiffen’s site in inland Hawke’s Bay, and from north Canterbury between Amberley and Kaikoura. Most of these other plesiosaurs belong to a different group known as elasmo­saurs, which had extremely long necks. Because it is rare to find sub­stantially intact skeletons, it is difficult to assign species with certainty, but it seems likely that 4–8 species of plesiosaur once lived here.

Another marine reptile group well-represented in New Zealand rocks are mosasaurs, large lizard-like creatures that were able swimmers and active predators. Four or five species have been described from Hawke’s Bay and a similar number from Canterbury, but the same caveats around species numbers apply. One of the more recent Canterbury specimens is a 5 m individual from the Waipara area. Unlike most other reptiles, mosasaur relatives survived the KT extinction to give rise to modern lizards and crocodiles.

Fossils of ichthyosaurs (literally fish-lizards), another extinct group of marine reptiles that resembled dolphins, have been found at Mt Potts in inland Canterbury, at Tinui in southern Wairarapa, in Southland, at Kawhia, near Kiritehere west of Waitomo and, most recently, north-east of Dargaville.

As is soften the case in paleontology, the most intriguing fossil find of recent years is tiny in size and looks insignificant. In 1978, a deposit containing fossils was discovered near St Bathans in Central Otago. Most fossiliferous deposits are laid down in the sea, but not this one. In the Early Miocene (16–19 million years ago) this area was the bed of a 5500 sq km lake and the deposit contains freshwater organisms and small bones from a range of ter­restrial creatures. These include lizards, bats, a crocodile, a relative of the tuatara, at least 24 types of birds, and three bones from one or more species of tiny mammal.

A mammal? New Zealand has always been touted as the land that had no native land mammals apart from bats, where all crea­tures developed entirely naive toward mammalian predators. All such dogma is thrown into question by this discovery.

Two of the bones found are from the jaw of this mammal and the third is the head of a right femur. The team who have done the work—led by Trevor Worthy, a New Zealand paleobiologist and cav­er—have decided to treat the bones as belonging to a single spe­cies. The femur fragment comes from an adult animal and is about 4 mm in length, the partial jaws about 5 mm. Fortuitously, jaw bones are among the most useful bones for identifying mammals. This animal seems to have had one incisor, one canine and two double‑rooted premolar teeth, although only the empty sockets are preserved. There may have been molars further back but that part of the jaw has not been found. Compared with other mam­mals from Australia—where there are extensive mammalian fossils of similar age—these bones differ from all marsupials and bats and all placental mammals.

Interpreting the fragments of finds like this requires a good deal of scientific rigour. Indeed, to give readers a taste of the original paper, “the material… is from a basal mammal probably more derived than morganuconodontans and more primitive than multituberculates and trechnotheres and which is not a monotreme or an eutriconodon­tan”. The structure of the bones rules out either a proficient swimmer or flier. Hence the authors conclude that there was another long-surviving mammalian ghost lineage on the New Zealand archipelago and that it was a survivor from Mesozoic times along with leiopelma­tid frogs and tuatara, etc. It was therefore a Gondwanan entity.

If mammals were here, how and when did they become extinct when other archaic organisms survived? Their demise cannot be blamed on the Oligocene immersion, because the fossils are younger than that and the dates are well-supported.

It has always seemed mysterious that terrestrial mammals are absent from New Zealand. At the time Zealandia broke off from Gondwana, mammals were widespread. How could a piece of land almost half the size of Australia break away and not carry any mam­mals aboard? Perhaps they were killed off along with other faunal elements (such as Causarinas and eucalypt-like trees) 14 million years ago in the Miocene when the climate cooled? Only the fossils can tell us, and they are in no hurry to divulge everything.

Although dinosour fossils from New Zealand are not spectacular or numerous, they continue to be uncovered at a steady pace. Since New Zealand Geographic last covered dinosaurs in a major article in 1993 (see issue 19), further bones have been found in Hawke’s Bay, as well as new discoveries at the Chathams and a single bone collected near Port Waikato. As with the amphibian and Miocene mammal fossils, meagre remains—usually just a fragment of a single bone—lead to glo­rious flights of inventiveness and extrapolation in working out what animal it came from.

In one of the more recent papers by Joan Wiffen and Ralph Molnar, a 380 mm shard of bone is identified as being part of the rib of a titanosaur rather than any other animal. As Joan (now 83 years old) explained to me, “That rib is fairly flat and when you extrapolate it into the necessary curve, you get a rib that is a metre long—quite a large animal, bigger than most dinosaurs. It probably came from something that was 10–14 metres long.” Deficiencies in this sort of material mean that only the broadest of inferred identifications is possible—certainly not to genus or species level.

Wiffen and Molnar determined that this rib belonged to a titanosaur, a group which included the largest dinosaurs. One of the biggest, the wonderfully named Seis­mosaurus, may have exceeded 40 m in length! Despite their size, titanosaurs had relatively small heads, and their teeth were always small and blunt—chewers of plant material rather than tearers of flesh. Fossilised dung associated with late Cretaceous titanosaurs has revealed a broad, unselective plant diet, from cycads and conifers to grasses, even ancient forms of rice and bamboo.

Titanosaurs had relatively short necks for sauropods, and their tails were whip-like, but not as long as a diplodocid tail. While the pelvis (hip area) was slimmer than in some sauropods, the pectoral (chest area) was much wider, giving them a uniquely broad stance. The fossilised trackways of titanosaurs are distinctly wider than other sauropods. Their forelimbs were also stocky but their rear limbs were longer. With a flexible spinal column, they were probably more agile than their cousins and better at rearing up. Skin impressions have indicated that a mosaic of small, bead-like scales around a larger scale provided armour of a sort.

A dramatic find in Auca Mahuevot, Patagonia, has revealed something of their behaviour. A large titanosaurid nesting ground was discovered bearing 11–12 cm eggs containing fossilised embryos, complete with skin impressions. Apparently several hundred females dug holes, laid their eggs and then buried them under dirt and vegetation. Herd behaviour of this sort may have been a defensive response to guard against large predators.

The titanosaurs were the last great group of sauropods before the KT extinction event, and were the dominant herbivores of 90–65 million years ago, replacing earlier sauropods that died out between the late Jurassic and the mid-Cretaceous Peri­ods. They were widespread, especially in the southern continents (then part of the supercontinent of Gondwana). Only Antarctica has failed to yield titanosaur remains. However, in the Late Cretaceous, Zealandia was adjacent to Antarctica and based in high polar latitudes. Although Earth’s climate was warmer than it is now, nights would still have been long and cold and it is a surprising environment to find large reptiles, given the preference of modern reptiles for warm climates. However, while Joan Wiffen has discovered dinosaur bones, she is not responsible for the climate information, and this has relevance beyond just her discoveries. Did some of our dinosaurs and marine reptiles survive amongst ice rather than just in the steamy forests of popular culture?

At the other end of the dinosaur size scale, Wiffen and team have also discovered evidence of a tiny ceratosaur that would fit inside a coconut—a creature that was a dinosaurian version of a small monkey! Doubtless we will continue to find a smattering of dinosaur bones, perhaps from more new locations.