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Island Weirdness #37 — Natunaornis gigoura

The islands of Fiji are located in the South Pacific, a couple of thousand kilometers east of Australia and northeast of New Zealand. Formed via volcanic activity, the over 300 islands making up the archipelago had no native land mammals for most of their history, leading to birds, reptiles, and amphibians taking up the large animal niches in the ecosystem.

Subfossil remains of a unique mix of species have been found on Viti Levu, the largest of the Fijian islands — including a flightless megapode, a sylviornithid, a big frog, a giant iguana, a terrestrial crocodilian, and a meolaniid tortoise.

One of the most surprising discoveries, however, was actually a pigeon.

Natunaornis gigoura was by far the biggest pigeon known from any Pacific island, and one of the largest pigeons to ever live, being almost the same size as the Mauritian dodo at around 0.9m tall (3′). But unlike its distant cousin it still looked very much like a scaled-up normal pigeon, probably resembling a giant version of the closely related modern crowned pigeons.

It had reduced wings and strong legs, indicating it was flightless, and an unspecialized beak that suggests it was a generalist forager eating fallen fruit, seeds, and invertebrates from the forest floor.

Natunaornis existed well into the Holocene, but like many other island dwellers it was severely affected by the arrival of humans. Austronesian peoples reached Fiji somewhere between 3500 BCE and 1000 BCE, and it’s likely that a combination of hunting and predation from introduced mammals rapidly killed off the giant pigeons along with all the other large native species.

Island Weirdness #36 — Haast’s Eagle

Before the arrival of humans in New Zealand, the only predator of the native giant flightless birds was Haast’s eagle (Hieraaetus moorei), an enormous species of raptor from the South Island.

With the slightly larger females reaching lengths of around 1.4m (4’7″) and hefty body weights of 15kg (33lbs), it was the largest eagle known to have ever lived, and one of the largest of all birds of prey. Yet its wings were actually proportionally short for its size, spanning about 2.5m (8’2″), giving it less ability to soar but much better maneuverability when flying in the thick vegetation of scrubland and forests.

Its closest living relatives are the much smaller Australian little eagle and the Palearctic booted eagle, which its lineage split from sometime in the Pleistocene — meaning that it must have evolved to be so huge incredibly quickly.

At its size and weight when striking it would have hit its prey with a force equivalent to a falling cinder block, and with no major competitors it could have fed from a single large kill for many days.

As apex predators Haast’s eagles would also have never been particularly numerous, and their population was very sensitive to the availability of their prey species.

Unfortunately the early Māori people also found the large flightless birds like the moa to be delicious easy meals, and by the early 1400s the eagle had disappeared alongside its main food sources. Legends about a giant human-eating bird called the pouakai are thought to be based on folk memory of Haast’s eagle, and it may well have occasionally preyed on the settlers during the short time it coexisted with them.

Island Weirdness #35 — Flightless Giants

With the lack of large terrestrial mammals in New Zealand, birds were free to exploit the “big herbivore” niches in the ecosystem — and the giant moa were the ultimate result.

Closely related to modern South American tinamous, the ancestors of moa were small flying birds that arrived in New Zealand sometime in the early Cenozoic. At the time of the Miocene St Bathans fossil deposits they were already large and flightless, and by the Holocene they had grown truly enormous.

Uniquely they completely lost their wings, not even having the tiny vestigial bones seen in other large flightless birds.

A stylized illustration of an extinct giant flightless bird. It has a tiny head with a downward-curving beak, a long neck, no wings at all, and long chunky legs. — Dinornis robustus

The South Island giant moa (Dinornis robustus) was the largest of them all, with females standing almost 2m tall at the back (6’6″) and able to reach their heads up to heights of around 3.6m (11’10”). It had a long neck, a relatively tiny head with a curved beak, and large powerful legs — and preserved hair-like body feathers show that it was reddish-brown in color.

It also had some of the most extreme sexual dimorphism seen in any bird species, with the males being significantly smaller than the females at only about 1.2m tall (3’11”). This seems to have been the result of scaling-up smaller differences in body size from their ancestors.

A stylized illustration of an extinct flightless bird. It has a triangular downward curving beak, a long neck, small wings, and short stout legs. — Aptornis defossor

The adzebills were another odd group of big flightless birds whose ancestors also date back to sometime before the St Bathans deposits. They had large downward-curving beaks, short strong legs, and highly reduced wings that were smaller proportionally than those of the dodo.

They were less common than the moa, found only the drier forested parts of the lowlands, and based on isotope analysis of their bones they seem to have been predators hunting invertebrates, reptiles, and smaller birds.

When their remains were first discovered they were even thought to be a type of moa, but later studies (including recovered ancient DNA) have shown they were actually gruiformes, with their closest living relatives being either the South American trumpeters or the African flufftails.

The South Island adzebill (Aptornis defossor) was the slightly larger of the two species known from the Holocene, reaching sizes of about 0.8-1m tall (2’8″-3’3″).

The ancestors of the Māori people arrived in New Zealand around the year 1300, and sadly within about a century a combination of human hunting pressure and predation by introduced mammals sent both the moa and adzebills into total extinction.

Island Weirdness #34 — Heracles inexpectatus

New Zealand is probably one of the most famous modern examples of a unique island ecosystem, having been isolated for the last 80 million years. Lacking any living terrestrial mammals, birds instead became the dominant land animals, adapting to a wide range of niches and evolving unusual flightless forms like the modern kiwi and kākāpō.

The St Bathans fossil site on the South Island dates to the early Miocene, about 19 to 16 million years ago, just after a period known as the “Oligocene drowning” when large portions of the landmass were underwater. It gives us a glimpse of an ancient version of New Zealand when the ecosystem was recovering and rapidly diversifying in a then-subtropical climate, and has produced a wide range of new fossil species (including a mysterious mammal).

One of the most recent discoveries from the site is Heracles inexpectatus, a close relative of the modern New Zealand parrots — but significantly larger than any living species, estimated to have stood almost 1m tall (3’3″). Known from just a few leg bones, the fossils were so big that they initially weren’t even recognized as belonging to a parrot, instead being mistaken for a large eagle before their true nature was realized.

At such a size it would likely have been flightless, although it may have still been capable of climbing trees and gliding. Much like the modern kea it was probably an omnivore, using its large curved beak and powerful crunching bite to eat pretty much whatever it wanted.

By the late Miocene, around 13 million years ago, New Zealand’s climate rapidly shifted cooler and drier, and the tropical forests were quickly replaced with temperate ones. This changing habitat may have been too much too fast for the giant parrots to deal with, and they went extinct alongside many of the other St Bathans species.

Island Weirdness #33 — Big Pigs & Tiny Buffalo

Located on the Pacific Ring of Fire, the islands of the Philippines were formed by volcanic activity at the junction between several tectonic plates. Most of the 7461 islands that make up the archipelago have never been connected to any other landmass, leading to a huge number of unique endemic species evolving from whatever managed to arrive via ocean rafting events.

A stylized illustration of an extinct giant pig. It has four long thick tusks and long legs.. — Celebochoerus cagayanensis

Celebochoerus cagayanensis was a giant species of pig, known from the island of Luzon. Living around 800,000 years ago in the mid-Pleistocene, it had enormous tusks and stood around 1m tall at the shoulder (3’3″) — similar in size to the very largest modern pigs, the African giant forest hogs.

The giant forest hogs are also some of its closest living relatives, along with the river pigs, and back in the Miocene and Pliocene similar pigs were present in Asia. Celebochoerus‘ ancestors probably arrived in the Philippines from Taiwan, and eventually spread onwards to the Indonesian island of Sulawesi to the south, where another species of Celebochoerus existed.

A stylized illustration of an extinct dwarf water buffalo. it has short curved horns, drooping ears, and a chunky body. — Bubalus cebuenesis

In contrast to the huge pigs of Luzon, the Cebu tamaraw (Bubalus cebuensis) was a particularly tiny species of wild cattle related to modern water buffalo. Just 75cm at the shoulder (2’6″), it was an example of insular dwarfism even smaller than the modern tamaraw which still survives on the island of Mindoro.

The spotty fossil record of these animals makes it difficult to determine when they disappeared, but it’s likely that they went extinct sometime around the arrival of early humans about 700,000 years ago.

Island Weirdness #32 — Tiny Elephants On Parade Part 3: More Indonesia

It’s finally time for part 2 of the Island Weirdness series!

(If you haven’t seen the previous installments, I suggest starting back at the beginning here.)

We left off last time with the dwarf stegodontids of Flores, but other Indonesian islands also had their own populations of unusually small elephant-relatives — so here’s a few more to start off this month!

A stylized illustration of an extinct dwarf elephant. It has long straight tusks and small ears. — Sinomastodon bumiajuensis

Sinomastodon bumiajuensis lived on the island of Java during the early Pleistocene, about 2-1.5 million years ago. It stood around 2m tall at the shoulder (6’6″), less than half the size of most other Sinomastodon species from mainland Asia. Although it looked convergently similar to modern elephants it was actually a member of the gomphotheres, much more closely related to the weird “shovel-tuskers” than to any living species.

A stylized illustration of an extinct dwarf elephant. It has long gently curving tusks and proportionalyl short legs. — Stegodon semedoensis

Stegodon semedoensis, also from the early Pleistocene of Java about 1.5 million years ago, is only known from a few isolated molar teeth — but the size of those teeth suggest it was one of the smallest known pygmy stegodontids. It was probably no more than 1.2m at the shoulder (3’11”), comparable in size to its close relative Stegodon sondaari over on Flores.

A stylized illustration of an extinct dwarf elephant. It has four straight tusks, two longer ones in its upper jaw and two shorter ones in its lower jaw. — Elephas celebensis

Meanwhile on Sulawesi, Elephas celebensis (sometimes called Stegoloxodon celebensis) was an actual true elephant closely related to the modern Asian elephant. Living during the late Pliocene and early Pleistocene, between about 2.5 million and 800,000 years ago, it was only 1.5m tall (5′) and had a second set of tusks in its lower jaw, a “primitive” feature retained from the gomphothere-like ancestors of modern elephants.

A stylized illustration of an extinct dwarf elephant. It has long curving tusks and small ears. — Stegodon sompoensis

At the same time Sulawesi also had yet another small stegodontid, Stegodon sompoensis, also around 1.5m tall.

Both of these dwarfs lived alongside a larger Stegodon species, as well as giant tortoises and large-tusked pigs.

The cooling climate of the Pleistocene and dropping sea levels eventually connected the islands of western Indonesia to the Sundaland landmass of mainland Asia. Influxes of new predators and competitors — and early humans — probably drove these endemic small elephants to extinction.

Rostropycnodus

The extinct pycnodonts were a group of mostly circular-shaped fish, convergently similar to modern reef fish like marine angelfish or butterflyfish – but some of them developed much much weirder appearances.

Rostropycnodus gayeti here was one of the especially odd-looking forms, known from the mid-Cretaceous of Lebanon about 100-95 million years ago.

It had an elongated snout with the upper jaw longer than the lower, a pointed spiky horn on its forehead, and a massive pectoral region that bulged out at the front of its body. Meanwhile its pectoral fins were modified into big immobile spines, and its pelvic fins were highly reduced and positioned beneath another set of large spines.

And it was tiny, only about 5.5cm long ~(2″).

It would have been a slow swimmer, relying on its spikiness to deter larger predators, and it’s currently unclear what it ate with its unusual spiny snout. Many other pycnodonts had mouths full of round crushing teeth, but Rostropycnodus’ jaws seem to have been mostly toothless – so perhaps it used its snout to probe around in cracks or sediment for small soft-bodied invertebrates.

Kalligrammatids

Did you know butterflies weren’t the first insects to look like butterflies?

Lepidopterans (the group of insects containing moths and butterflies) have been around since the Late Triassic – but it wasn’t until the diversification of flowering plants during the Cretaceous that recognizable moths would have evolved, and true butterflies didn’t actually appear until the early Cenozoic.

Before then, back in the mid-Jurassic about 165 million years ago, a completely different group of insects convergently evolved remarkably butterfly-like features such as large colorful scaled wings and long sucking proboscises.

Known as the kalligrammatids, these insects were giant members of the lacewing group, related to modern forms like antlions and owlflies. But unlike their predatory relatives the kalligrammatids were specialized pollinators, possibly having a mutualistic relationship with the flower-like cones of bennettitales or the pollination drops of some types of conifers. They seem to have originated in China and were found across Asia and Europe by the Late Jurassic, but a few fossils from South America suggest they were even more widespread and may just have a poor fossil record.

They reached wingspans of up to 16cm (~6″), comparable to some of the largest modern butterflies, and often sported conspicuous anti-predator markings on their wings such as stripes and eyespots – so it’s not surprising that they’re often nicknamed the “butterflies of the Jurassic”.

Rather ironically, the extinction of the kalligrammatids was probably linked to the rise of the flowering plants that the true butterflies would later be so dependent on. As flowers diversified and plants like the bennettitales declined, the kalligrammatids dwindled and disappeared, with the last known fossil record coming from the mid-Cretaceous of Brazil about 113 million years ago.

But while they were around, I do wonder if they also exhibited some similar behaviors – such as mud-puddling for extra nutrients, and specifically the habit of drinking the tears of larger animals that we see in some species. Perhaps some non-avian dinosaurs like this Dilong occasionally put up with kalligrammatids sitting on their faces!

Antilohyrax

This is not a deer.

In Africa during the Eocene and Oligocene, the main terrestrial herbivores were a different type of mammal entirely: hyraxes, the close relatives of elephants and manatees. Although their only modern representatives are small climbing rodent-like animals, hyraxes were once a much more diverse and widespread group, filling a variety of ecological niches and ranging from the size of rats up to the size of rhinos.

Antilohyrax pectidens was a mid-sized example of these diverse hyraxes, standing about 50cm tall at the shoulder (1′8″) and living around 34-28 million years ago in Egypt. It had a deer-like snout and long slender limbs adapted for running and leaping, with leg bones incredibly similar in size and proportion to modern springbok.

Its incisor teeth were comb-shaped and resembled those of colugos, so it was probably a similar sort of selective browser eating soft leaves and shoots.

Leivanectes

Elasmosaurids are often depicted with noodly snake-like or swan-like necks, but they were probably actually quite stiff and inflexible in life. And while we know from fossilized gut contents that they ate relatively small prey like fish, crustaceans, and cephalopods, exactly how they used their distinctive long necks is still uncertain.

There’s some variation in the sizes and shapes of their teeth, so it’s likely each species was specialized for slightly different feeding styles – we’ve even found a filter-feeding one! – and the recently-named Leivanectes bernardoi here adds in a little more diversity, too.

Living about 115-112 million years ago during the mid-Cretaceous of Colombia, Leivanectes would have been fairly large at around 9m long (29′6″), slightly bigger than the other elasmosaurid species known from the same ancient marine deposits. It had a reduced number of teeth in its jaws, but these teeth were also proportionally larger, suggesting that it may have been tackling bigger tougher prey than its relatives.

Unfortunately it’s currently only known from a single partial skull, so we don’t have any other clues about its ecology.