Iniasaurus and Nothocadborus

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Strange reptiles and other creatures inhabit the storm-protected estuaries to the west of the island. Found here can be Iniasaurus, Ryl Madol’s equivalent to a river dolphin. It is a phytosaur, an ancient group of crocodile-like archosauriform reptiles, that has adapted to a fully aquatic lifestyle. Its tail has become a proper fluke and the hindlegs are vestigial, only used during mating. Mostly unable to crawl on land, it gives live birth, not too dissimilar from other marine archosauromorphs that are now extinct, like Dinocephalosaurus or the metriorhynchids.

Calling Iniasaurus a marine reptile is however not entirely accurate, as from the estuary it may also advance into the island’s freshwater habitats. There it swims through the murky rainforest rivers and estuaries in search of fish, which it catches with its gharialous jaws. Instead of echolocation it perhaps uses electroreceptors at the snout-tip to detect its prey. The clawed flippers come in handy when clambering over sunken treelogs, while the ancestral dermal armour makes for good protection against the amphibious predators that lurk further inland.

Iniasaurus is often found in the same habitat as another strange creature. Nothocadborus is what appears to be a rainforest thalattosaur. Its bizarre-looking skull is actually quite archaic and still close to that of its clam-eating predecessors such as Nectosaurus or Clarazia. The derivation is instead observed in its body: Taking anguiliform swimming to a whole new level, Nothocadborus has lost its forelimbs and swims much more like a sea serpent. Similar to the Cretaceous pachyophiid marine snakes, the hindlimbs still remain and are used in steering or giving quick escape-bursts. The serpentine trunk greatly helps in navigating the cluttered river environment and probing deep into crevasses and burrows where the animal can pick up and crush freshwater brachiopods and arthropods.

Both Iniasaurus and Nothocadborus stand out among the island’s fauna, being part of only a handful of creatures whose ancestors were distinctively Triassic instead of Palaeozoic groups. However, as their exact phylogeny remains controversial, the possibility exists that both Phytosauria and Thalattosauria may have already had immediate ancestors in the Latest Permian.