Much like Japan, ancient Flores had a succession of dwarf stegodontids – close relatives of modern elephants that were capable of island-hopping through Indonesia by swimming.
Stegodon sondaari lived on Flores during the Early Pleistocene, about 900,000 years ago, and was the size of a small water buffalo at just 1.2m (3′11″) tall at the shoulder. It was probably descended from the larger Stegodon trigonocephalus, known from Java, and it had proportionally short legs which may have been an adaptation to clambering over rough terrain and steep inclines.
Around 850,000 years ago Stegodon sondaari disappeared from Flores, probably due to a large volcanic eruption, but a new wave of stegodontids quickly recolonized the island. The mid-sized Stegodon florensis probably originated from either Java to the west or Sulawesi to the north, and eventually evolved into a new dwarfed subspecies.
Stegodon florensis insularis wasn’t quite as small as its predecessor, standing around 1.8m tall (5′10″). It probably didn’t shrink quite so much due to the existing presence of various predators on Flores, since it was likely the main prey of large Komodo dragons, it was hunted by Homo floresiensis, and it may also have been occasionally targeted by giant storks.
It seems to have disappeared around the same time as several other unique endemic species, between 50,000 and 20,000 years ago, due to either climate change, another volcanic eruption, or the arrival of modern humans – or perhaps a combination of all of those factors.
And that’s all for this month… but Island Weirdness will be back later for part 2, with more giants, more dwarfs, and so many elephants.
Standing at an adult height of about 1.1m tall (3′7″), they were smaller than any population of modern humans and are thought to represent an unusual case of insular dwarfism.
They also had much smaller brains than would be expected for their size, similarly to the miniature hippos of Madagascar, which was probably an energy-saving adaptation in an island environment with limited resources, since brains are metabolically expensive organs. An area of their brains associated with higher cognition was about the same size as in modern humans, however, so they weren’t necessarily less intelligent – stone tools and butchery marks on dwarf elephant bones suggest they were cooperatively hunting, and there’s also possible evidence of fire use for cooking.
It’s not clear exactly where they belong on the human family tree, and attempts at extracting DNA from the known remains have so far failed. They might be descendants of a population of Homo erectus who arrived on Flores about 1 million years ago, or they may even have been part of a much older unknown lineage that dispersed from Africa over 2 million years ago.
Although they were initially thought to have lived on Flores from 190,000 years ago up to about 12,000 years ago, more accurate dating of the cave where their skeletal remains were discovered suggests they actually disappeared about 50,000 years ago – about the same time that modern humans arrived on the island.
Indonesia is located at the junction between several tectonic plates, and as a result a large number of volcanic islands make up the region. While some of these islands have had land connections to Asia or Australia in the past, others are separated by deep ocean trenches and have been isolated with little movement of species between them.
Leptoptilos robustus was a huge stork, closely related to the living marabou and adjutants but estimated to have been at least 20% larger. It would have stood around 1.8m tall (5′10″) and had a chunkier build with unusually heavy thick-walled bones, suggesting it may have become functionally flightless. Only fragmentary arm bones were found, however, so its unknown whether its wings were reduced in size or not.
There were few large carnivorous mammals on Flores (possibly none), and Leptoptilos robustus would have had little competition for carrion and prey. It may even have filled an ecological niche similar to the giant Hatzegopteryx of Cretaceous Hațeg Island – a large terrestrial stalking predator eating any smaller animals unfortunate enough to fit into its mouth.
The known remains date to the Late Pleistocene, around 50,000 to 20,000 years ago, and this giant bird seems to have gone extinct sometime during that date range. It’s unclear what killed it off, but possible factors include a changing climate on the island, a major volcanic eruption, and the arrival of modern humans.
It was closely related to the dodo, although it wasn’t a direct descendant. Based on DNA studies their last common ancestor is estimated to have lived about 20 million years ago, so they must have each convergently evolved from separate pigeon lineages that arrived on each island at different times.
Standing 70-90cm tall (2′4″-2′11″), with males being larger than females, it had long legs, a long neck, and a slightly hooked beak with a black band described as resembling a widow’s peak. Its plumage was grey and brown, and it was reportedly aggressively territorial and capable of giving a strong bite.
It had large lumpy bony knobs on its wrist bones that were used as weapons to clobber each other while fighting. Due to this its wings were less reduced than the dodo, retaining stronger musculature, and it was apparently also capable of using them to create loud low-frequency sounds for communication – possibly in a similar manner to modern crested pigeons’ whistling wings.
The solitaire survived for longer than both its dodo cousin and the Réunion ibis, but only because its island was rarely visited by humans until the late 1600s. Once Rodrigues began to be exploited the story became the same as the other Mascarene islands: a combination of hunting, habitat destruction, and predation by invasive species rapidly dwindled its population. It likely went extinct sometime between the 1730s and 1750s, since an exhaustive search for a live specimen in 1755 failed to find a single bird.
The island of Réunion was formed southwest of Mauritius ony about 2-3 million years ago, and likewise developed its own vertebrate ecosystem from various birds, reptiles, and bats arriving via island hopping and rafting.
Accounts from the 1600s and 1700s of a white bird on the island known as the “Réunion solitaire” were for a long time thought to refer to a close relative of the dodo, but no dodo-like subfossil remains were ever found.
Eventually bones of a different type of bird were discovered: an ibis. Closely related to the African sacred ibis, Threskiornis solitarius was a similar size at about 65cm long (2′2″) but had a much chunkier build. Its beak was shorter and straighter than other ibises, and it had reduced flight capabilities – features that matched the old solitaire descriptions surprisingly well.
Its coloration was mostly white, merging into grey and yellow, and it had glossy or iridescent black ostrich-like plumes on its rear. It mainly lived in forests and used its beak to search through soft soil for invertebrates like worms and insects.
A combination of its island tameness and the fact that it was considered to be good eating resulted in it being heavily hunted during the 1600s, and along with pressure from invasive mammals – such as predation by cats and its eggs being eaten by pigs – it soon became a rare sight, found only in more remote highland areas of the island.
The last definite account of the Réunion ibis was in the early 1700s, and it was probably completely extinct within the first couple of decades of that century.
Along with its uniquebirds, Mauritius was also home to many endemic reptile species. In the absence of terrestrial mammals giant tortoises were the largest herbivores on the island, and various geckos, skinks, and snakes helped to fill out the rest of the vertebrate ecosystem.
Leiolopisma mauritiana was a very largeskink, one of the biggest ever known to have existed with a total length of around 80cm (2′7″). Its ancestors originated in Australasia, over 5600km away (~3500 miles) at least 3-4 million years ago – and they must have endured a particularly long ocean rafting journey without any island hopping stops, since none of the other islands along that route seem to have ever had populations of similar skinks.
It probably lived in rocky areas, possibly also being capable of digging burrows, and would have eaten an omnivorous diet of seeds, fruits, invertebrates, and smaller lizards and birds.
By the early 1600s it was already extinct, very soon after the arrival of humans, probably due to predation from invasive mammals like rats. However, its half-sized close relative Leiolopisma telfairii does still survive on rat-free Round Island a short distance to the north of Mauritius, and recent conservation efforts have been rebuilding its population and setting up new colonies on other nearby small islands.
The dodo wasn’t the only unique bird to evolve on Mauritius. While about eight other endemic bird species still survive today, there were at least twice that many before the arrival of humans in the late 1500s – including the broad-billed parrot Lophopsittacus mauritianus.
Also referred to as the “Indian raven” in historical accounts, it was a fairly large bird measuring between 45 and 65cm in length (1′6″-2′1″). Unusually for a parrot it had a high degree of sexual dimorphism, with males being significantly bigger than females.
Many images depict it as entirely black or blue-grey, but this seems to be based on a misinterpretation. More recent translations of old Dutch descriptions suggest it was actually much more colorful, with a red beak, blue head, and reddish body.
It had a proportionally big head and a flattened skull, and seems to have had a highly specialized diet, using its its large strong beak to crack open hard seeds and nuts like modern hyacinth macaws.
It was near-flightless, capable of taking to the air only with difficulty, and was said to be “bad-tempered”. Attempts to keep individuals in captivity failed, the birds refusing to eat, and while the wild population had apparently learned to be wary of humans by the late 1660s by that point it was already too late. Much like the dodos they lived alongside, a combination of deforestation, hunting, and predation by invasive mammal species sent them into extinction by the 1680s.
Out of all the extinct island species we’ll be covering in this theme, there’s probably none more famous than the dodo (Raphus cucullatus) – a large flightless pigeon about 1m tall (3′3″).
The island of Mauritius was formed from a volcanic hotspot in the Indian Ocean about 10-7 million years ago, in a location roughly 1000km east of Madagascar (~620 miles). The dodo’s smaller flying ancestors must have arrived there sometime after that point via island-hopping from Southeast Asia – the area where its closest living relative the Nicobar pigeon is still found today – and finding themselves in an ecosystem completely lacking terrestrial mammals they quickly evolved to fill a large herbivore niche.
Although frequently depicted as blue-grey, the dodo’s actual life appearance is unknown for certain. No complete preserved specimens have survived into the present day, and contemporary accounts and drawings are somewhat inconsistent – but common elements among them suggest it was more of an earthy brown, with cream-colored primary feathers, yellow legs, a naked pale face, and a green-and-yellow streaked beak. The large white ostrich-like tail plumes shown in many images have also probably been highly exaggerated, since older images depict the dodo with only a tiny tufted tail at best.
Its appearance probably also varied based on the time of year, molting its feathers at the end of summer and being fattest during the breeding season in early spring.
And despite often being stereotyped as a slow dim-witted animal, the proportions of the dodo’s leg bones suggest it was actually quite fast and agile. Its brain-to-body size ratio was also typical compared to other pigeons – which are known to be highly intelligent birds – and it had a well-developed sense of smell.
Sadly this fascinating bird disappeared within only a century of being discovered by humans in the late 1500s. Its “island tameness” due to its lack of natural predators made it easy prey, its forest habitat was rapidly destroyed, and introduced mammal species (such as dogs, pigs, cats, rats, and macaques) competed for its food sources and ate its eggs and young – pressures that its population simply couldn’t hope to recover from all at one.
Its loss wasn’t even properly recognized until much later in the 1800s, but since then it has ironically become immortalized as a icon of human-caused extinction.
One of the most mysterious members of Madagascar’s pre-human ecosystem was a creature known as Plesiorycteropus, or the “bibymalagasy”.
It’s known only from fragmentary remains, including a few limb bones, vertebrae, partial skulls, and partial pelvises – with two different species identified, the larger Plesiorycteropus madagascariensis and the smaller Plesiorycteropus germainepetterae. For a long time it was it was unclear what type of mammal it even was and the best guess seemed to be “some sort of small aardvark-relative” based on anatomical similarities, but various studies disagreed and some even considered it to represent a completely unique order of mammals.
It was built for scratch-digging, using its strong forelimbs and claws to dig while bracing itself with its hindlimbs and long thick tail. Its snout had large nasal cavities, indicating a good sense of smell, and similarities to the skulls of armadillos suggest it had the same sort of diet of insects, grubs, worms, and other soft foods. It may also have fed on ants and termites.
Since it’s only known from fragments its full size is hard to determine, but rough estimates suggest Plesiorycteropus madagascariensis was “small dog-sized” – possibly having a head-and-body length of 60-80cm (2′-2′7), and a total length of over 1m (3′3″).
Unlike someotherextinct Malagasy animals there are no historical or folkloric accounts of anything resembling the bibymalagasy. One bone has been carbon dated to just over 2000 years ago, shortly after the arrival of human settlers, and it seems to have gone extinct very soon after that date.
Despite being located so close to mainland Africa, these enormous flightless ratites weren’t the closest relatives of ostriches as might be expected. Instead their closest living relatives are the kiwis of New Zealand, and they must have descended from flying ancestors that reached Madagascar across the Indian Ocean sometime during the early-to-mid Cenozoic.
Aepyornis maximus was one of the biggest of these big birds, standing around 3m tall (9′10″) and weighing over 500kg (1,100 lbs). Its eggs were equally massive, up to 34cm long (1’1″) and with a circumference of over 1m (3′3), making them the largest known eggs laid by any vertebrate.
Recent studies of the shape of its brain within its skull show that it had a good sense of smell but very poor eyesight – possibly being near-blind – suggesting that much like its kiwi relatives it was highly specialized for a nocturnal lifestyle.
There were several other species of elephant bird throughout Madagascar, and at least some of them appear to have successfully survived alongside humans for quite some time. Carbon dating of eggshells suggests they were still alive around 1000 years ago, and based on historical mentions they may have persisted as late as the 1600s before finally disappearing.