Tag: new caledonia

Island Weirdness #39 — Mekosuchus inexpectatus

Along with their weird giant birds, the islands of New Caledonia were also home to a small crocodilian unlike any alive today.

It was one of the last known members of a lineage of crocodiles known as the mekosuchines, which originated in Australia during the early Eocene about 50 million years ago and later island-hopped out into the South Pacific — mostly around the Coral Sea, but with some making it as far as New Zealand. By the start of the Holocene, about 12,000 years ago, they’d already declined and disappeared from the vast majority of their range, with only a few isolated island species remaining.

Named Mekosuchus inexpectatus, the New Caledonian mekosuchine was only about 2m long (6’6″), just slightly bigger than the modern dwarf crocodile. It was much more terrestrial than living crocs, spending most of its time on land, and it had teeth in the back of its jaws that were specialized for crushing, suggesting it mainly preyed on hard-shelled invertebrates such as snails and crabs.

Based on its limbs anatomy it may also have been able to climb trees. Although this idea was ridiculed when it was originally suggested back in the 1990s, a more recent discovery has shown that modern crocs can actually climb trees too.

Like with many other Holocene island species, the extinction of Mekosuchus inexpectatus seems to be directly linked to the arrival of humans, who reached New Caledonia around 1500 BCE.

Bones in archaeological kitchen waste sites show that the settlers actively hunted and ate Mekosuchus, but dating of the last known remains is uncertain. The most generous estimate is actually as recent as about 300 CE, so much like Sylviornis these small land crocs may have persisted for some time before finally going extinct.

Island Weirdness #38 — Sylviornis neocaledoniae

Between Australia and Fiji lie the islands of New Caledonia, an archipelago at the northern end of the mostly-submerged continent of Zealandia. Having split away from Australia at the end of the Cretaceous, 66 million years ago, New Caledonia’s Cenozoic isolation has resulted in the islands acting as a refugium for a number of “living fossil” lineages, including the kagu, a small nautilius, and the “primitive” flowering plant Amborella.

One of the strangest residents of these islands was Sylviornis neocaledoniae, a huge flightless bird standing around 0.75m tall (2’6″) and measuring about 1.7m long (5’7″). Initially mistaken for a ratite, it was later found to be a cousin of the galliforms, the group that contains modern chickens, turkeys, pheasants, quail, megapodes, and curassows.

Sylviornis had a massive skull with a large deep beak, topped with a bony crest, along with reduced wings and stout legs. It also had no wishbone, extra tail vertebrae, and a ribcage and pelvis that looked more like a non-avian dinosaur.

It was probably a slow-moving herbivore, browsing on plant matter and digging up roots and tubers with its beak and feet.

Thousands of subfossil remains of Sylviornis individuals have been found, but a large proportion of them are all juveniles, suggesting that this species’ reproductive strategy was to have large numbers of young at a time. It also seems to have had a surprisingly short lifespan for its size — just 5-7 years.

New Caledonia was first settled by humans around 1500 BCE, and it’s likely that Sylviornis was hunted by both them and the invasive mammals they brought along like dogs, pigs, and rats.

The folklore of the Kanak people features stories of a large flightless bird known as the du, described as being reddish-colored with a star-shaped crest, so it’s possible Sylviornis actually persisted alongside the new arrivals for some time — but eventually the environmental disruption was too much for these odd primitive dino-chickens, and they were gone.