During the mid-Pleistocene, between about 900,000 and 500,000 years ago, the Mediterranean islands of Malta and Sicily were connected and shared a unique ecosystem made of up a mix of weird endemic species. While the tiny elephants and giant swans are probably the most famous, there were also several other unusual animals such as dwarf hippos, huge owls, large cranes, giant tortoises, and big lizards.
And also massive rodents.
Leithia melitensis, the Maltese giant dormouse, was descended from garden dormice, but thanks to the lack of large land predators on Siculo-Malta it was able to evolve a much much larger body size – about 60-70cm long (2′-2’4″), almost the size of a cat.
Recent reconstructions of its skull have shown it was also proportioned differently compared to its tiny modern relatives, more chunkily built with a shorter and wider snout, bigger teeth, and thicker cheekbones that must have anchored some incredibly powerful muscles for chewing. It may have been eating a much more herbivorous diet than other dormice, processing a lot of tough fibrous vegetation.
The island of Sicily was isolated about 5.3 million years ago when the Mediterranean rapidly refilled. During the next few million years changes in sea level and tectonic uplift allowed repeated colonizations by mainlaind species via the sea strait separating Sicily from Italy, and opened up occasional connections with nearby Malta, resulting in a series of different ecosystems over time.
During the mid-Pleistocene, between about 900,000 and 500,000 years ago, a lack of large land predators on Sicily and Malta allowed a weird mix of endemic species to evolve. Most famous are the tiniest elephants (Palaeoloxodon falconeri), but there were also a couple of giant owls, a small long-legged owl, a giant crane, a big lizard, a giant tortoise, an otter, and giant dormice.
And then there were the swans.
Cygnus falconeri was enormous, at least a third larger than the biggest living swans, at least 1.5m tall (4’11”) — taller than the native elephants, although not nearly as heavy. Its wings were large, with a span of around 3m (9’10”), but at such a hefty size it would have been either a very poor and reluctant flier or functionally flightless.
Its legs were better adapted for walking around on land than for swimming, with shorter toes and possibly reduced webbing. It would have been one of the biggest terrestrial herbivores on Siculo-Malta, probably mainly a grazer but also capable of reaching much higher vegetation than the elephants or tortoises.
It lived alongside another unique swan species, the goose-like dwarf swan Cygnus equitum. Both the giant and dwarf swans probably evolved from the same whooper swan-like ancestor species, but each resulted from separate colonization events — otherwise interbreeding would have probably prevented them from developing such a huge difference in size.
Or an alternative scale comparison to highlight the utter ridiculousness of this island:
Between 500,000 and 200,000 years ago multiple sea level fluctuations allowed new species to colonize Siculo-Malta from the mainland, including various large mammalian herbivores and carnivores. With new competition and predators, Cygnus falconeri probably disappeared around the same time as the tiny elephants and most of the other mid-Pleistocene endemic animals.
The dwarf swan, smaller and still a strong flier, may have survived the altered ecosystem for a bit longer, but would have gone extinct during the rapid climate changes at the start of the last glacial period 115,000 years ago.
Mammuthus lamarmorai lived on the island of Sardinia during the middle and late Pleistocene, between about 450,000 and 40,000 years ago. Standing around 1.4m tall at the shoulder (4’7″), it was a dwarf form roughly one-third the size of its ancestor, the huge Eurasian steppe mammoth.
Its remains are known only from the west and south of the island. Strangely it appears to be have been absent from the nearby island of Corsica, despite the two being joined as a single landmass a few times during lower sea level periods in the Pleistocene.
It’s not clear why this mini-mammoth disappeared. The date of the earliest human settlement of Sardinia is controversial (ranging from 250,000 to 20,000 years ago), so Mammuthus lamarmorai might never have actually encountered them. Instead it may have struggled to cope with climate changes during the last glacial period towards the end of the Pleistocene, which rapidly turned Sardinia colder and drier.
Over on Sicily and Malta (which were also occasionally a single island when sea levels were lower), there were several different species of miniature elephant during the mid-to-late Pleistocene, each with a different body size and occupying its own ecological niche. They were all descendants of the massive straight-tusked elephant (Palaeoloxodon antiquus) but each resulted from independent colonization waves swimming over to the island(s).
Around 200,000 years ago a sea level drop allowed new colonization from the Italian mainland. If Palaeoloxodon falconeri was still around at that time it likely didn’t survive long with new competition from large herbivores like bison and deer, and being preyed on by newly-arriving large carnivores like wolves, lions, and hyenas.
Another small elephant soon evolved to take its place, although due to the presence of predators it was never able to get nearly so tiny.
Palaeoloxodon mnaidriensis was in fact one of the largest dwarf elephants in the Mediterranean, standing about 1.8-2m tall (5’11”-6’6″), but despite its larger size its limbs still show signs of adaptation for more fast and agile movement. Its tusks also show a lot of variation in shape, with some much more curved and twisted than others.
This elephant had disappeared by about 13,000 years ago, probably due to the climate significantly warming towards the end of the last ice age. Much like Sardinia, the earliest arrival of humans on Sicily and Malta is controversial, and it’s unclear whether they ever encountered Palaeoloxodon mnaidriensis — the earliest definite date for Sicily is about 16,000 years ago, so a human-induced extinction can’t be ruled out entirely.
The subfossil remains of the Siculo-Maltese elephants may have also ended up inspiring legends of the cyclops, as their skulls would have resembled large human ones with the nasal cavity forming a single big “eye socket”.