Tag: archosaur

Voay

Did you know some crocodiles have “horns”?

Formed from the corners of the squamosal bone at the back of their skulls, just above their ears, these structures are seen in living crocs like the Cuban crocodile and the Siamese crocodile, as well as some fossil species.

But perhaps the most impressively-horned croc was Voay robustus here.

Voay lived on the island of Madagascar during the Late Pleistocene and Holocene, between about 100,000 and 2,000 years ago. At about 5m long (16′5″) it was similar in size and build to a large male Nile crocodile – but despite this resemblance its closest living relative is actually the much smaller dwarf crocodile.

It had a fairly short and deep snout and chunky limbs, adaptations associated with a more terrestrial lifestyle that suggest it was specialized for hunting its prey on land rather than just at the water’s edge.

Much like modern horned crocodiles its particularly prominent horns were probably used for territorial displays, and may have been a sexually dimorphic feature with big mature males having the largest examples.

Voay’s disappearance just a couple of thousand years ago may have been the result of the arrival of human settlers on the island, either from being directly hunted or due to the large native species it preyed on also going extinct around the same time.

Glowing Dinosaurs

Many modern birds are capable of seeing into the ultraviolet regions of the electromagnetic spectrum, and some of their non-avian dinosaur ancestors might have had the same sort of vision. And much like their living relatives, that means various parts of their bodies and plumage may also have been UV-reflective and UV-fluorescent.

So here’s a Velociraptor with some speculative UV coloration – although this is just what it would look like to human eyes under a blacklight. What it would actually look like to a creature that can see extra colors is impossible to depict on a screen designed for trichromatic vision!

Conflicto

Conflicto antarcticus, a recently-named waterfowl bird from the earliest Palaeocene of Antarctica (~65-64 mya).

Standing around 50cm tall (1′8″), it had a slender body, long legs, a long neck, and a narrow goose-like beak. It also had an unusual pair of bony bumps on its skull which may have supported some sort of small crest superficially similar to the knob on the head of the modern magpie goose.

Temperatures in Antarctica at the time were much warmer than today, and the area where its fossils were found would have been a temperate estuary or river delta. It was probably an omnivorous wading bird, feeding on vegetation, small fish, and invertebrates in shallow freshwater.

Although it somewhat resembled a presbyornithid it was actually part of an even earlier branch of the waterfowl evolutionary tree – so its ancestors must have originated much further back in the Late Cretaceous – and their similar body shapes hint that the common ancestor of all waterfowl may also have been a rather leggy bird. Conflicto’s closest known relative might actually be the similarly-aged Anatalavis (which was previously though to be a primitive magpie-goose) from North America and Europe, suggesting that its lineage was quite widespread and already taking advantage of vacant niches in the immediate wake of the Cretaceous-Paleogene mass extinction.

Island Weirdness #29 – Leptoptilos robustus

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.

The island of Flores in the southeastern Lesser Sunda archipelago was formed fairly recently – sometime in the last 15 million years – and has been home to some highly unusual endemic species, including dwarf elephants, giant rats, Komodo dragons, and diminutive “hobbits”.

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. 

Island Weirdness #28 – The Rodrigues Solitaire

Located to the east of Mauritius, the small island of Rodrigues is the geologically youngest of the Mascarenes, formed only about 1.5-2 million years ago.

And it also had its own large flightless bird – the Rodrigues solitaire, Pezophaps solitaria.

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.

Island Weirdness #27 – The Réunion Ibis

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.

Island Weirdness #25 – The Broad-Billed Parrot

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.

Island Weirdness #24 – The Dodo

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.

Island Weirdness #22 – Aepyornis maximus

Along with a lot of unusual mammals, Madagascar was also home to some of the largest birds to ever exist: the giant elephant birds.

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.

Island Weirdness #17 – Tyto gigantea

The largest terrestrial predators on the Late Miocene Gargano-Scontrone island(s) were unusually big hedgehog-relatives, and likewise the local aerial predators also increased in size compared to most of their cousins on the mainland.

Tyto gigantea was a massive barn owl, estimated to have been at least as large as the modern eagle-owl – probably measuring somewhere around 80cm in length (2′7″). It likely grew so big thanks to the lack of competition and in order to keep up with the larger sizes of its prey, since the rodents and pikas of Gargano-Scontrone were also comparative giants.

Alongside the slightly smaller species Tyto robusta it would have been the dominant nocturnal predator on the island(s), while during the daytime the golden-eagle-sized buzzard Garganoaetus occupied the same large-carnivorous-bird niche.