Australia's Own Sea Serpent

David Cook — 29 July 2021
Sea monsters are the stuff of legend, but some forms of them existed on Australia millennia ago

In the early 1950s, prominent American businessman and philanthropist Godfrey Cabot found himself in a discussion with well-known biologist Alfred Romer at the Harvard Museum of Comparative Zoology. Cabot suggested that he was interested in funding research into the subject of sea serpents. Cabot, who was then in his nineties, had a strong family interest in the subject as a result of a childhood experience with his family when they witnessed what was known as the Cape Horn Sea Serpent, a seasonal phenomena along the New England coast of the USA, first reported in 1641, until the late 19th Century when sightings suddenly stopped.

Romer didn’t exactly poo-poo the idea of sea serpents, as there was no research being conducted by a reputable institution into these mythical beasts, but, thinking fast, he mentioned he had a large ‘sea serpent-like’ fossil in the basement that needed preparation and would be a great addition to the museum’s display. Cabot asked how much that might cost and Romer, off the top of his head, suggested $10,000.

Thus Australia’s (and one of the world’s) largest sea-going reptiles from the dinosaur age found its way in front of the public.

The fossil consisted of a number of large chunks of limestone, weighing up to 6 tons apiece, containing a near complete specimen of a creature that had been named Kronosaurus queenslandicus by Australian researcher, Heber Longman. The initial specimen — a scrap of bone with six conical teeth — had been found in 1891, and a number of partial specimens came to light through the next three decades.

In 1931, the Harvard Museum sent an expedition to Australia to collect marsupial specimens and included a young palaeontologist, William Schevill, in the team. When the rest of the expedition returned to the USA, Schevill remained and was told by a station owner near Richmond, Qld, of some unusual bones protruding from the ground on his property. Schevill recognised them as parts of a large animal, but they were encased in tough limestone.

Schevill hired an English migrant, nicknamed ‘The Maniac’ because it was rumoured he’d killed someone, to break up the layer of limestone with dynamite. The blocks were then shipped to Harvard. This process — the removal of a unique and valuable specimen from its country of origin — has attracted much criticism but it must be pointed out that the Queensland Museum was offered a place on the expedition and turned it down, citing a lack of funds, and turned down the possibility to extracting the bones from the rock on the same basis.

The skull of the Kronosaurus was the first component to be prepared after two years of hard work, and it was certainly spectacular — close to 2.8m long and lined with a formidable array of conical teeth the size of bananas. The rest of the skeleton remained in the rock for the next two decades, until Cabot came along.

Kronosaurs are a type of creature broadly belonging to a group of marine reptiles called pliosaurs. These short-necked beasts typically had large heads with huge jaws, a short tail and four large paddles to propel them through the Cretaceous seas which flooded central Australia, though they are found around the world

When Cabot signed his cheque and work began removing the limestone, it was discovered the specimen was missing some bones. The smaller front paddles and some of the backbone had been lost to erosion before Schevill and The Maniac arrived on the scene. This is not unusual in fossils of large vertebrates. Many are known from only partial remains and complete reconstructions are often the result of several individuals, or extrapolations from other similar organisms. The famous dinosaur Iguanodon, first described from a horn-like specimen discovered in a quarry in Britain, was initially reconstructed as a creature looking much like a rhinoceros, with the horn mounted on the nose. More recent finds of complete specimens reveal the creature more closely resembled a Tyrannosaurus, with the horn being one of a pair on the forelimbs, where we would have our thumbs.

Romer’s team was faced with a jigsaw puzzle when it came to reconstructing Kronosaurus and replacing the missing bones to create a complete mounted specimen for public display. What they came up with was a creature 12.8m long, but more recent finds of other pliosaur specimens have begun to paint a slightly different picture and it now appears that the overall length of the specimen might be more accurately placed at 10.9m, and for the skull to be flatter, more like that of a crocodile. So much reconstruction was employed in the Harvard specimen that it has become somewhat disparagingly labelled Plasterosaurus.

Nonetheless this was a significant top predator in those ancient seas. It was not an animal to mess with and it would have weighed around 12 metric tonnes. The structure of its skeleton implies a powerful set of muscles and a capacity to swim very fast. Fossilised remains of meals found within or associated with Queensland specimens of Kronosaurus indicate that it fed on turtles and plesiosaurs (long necked and generally smaller versions of pliosaurs) and likely on squid-like creatures that also inhabited those seas. Its round teeth indicate an animal that fed by simply crushing its prey, with a bite possibly upwards of four times that of a Tyrannosaurus.

There is now some doubt about the real identity of the Kronosaurus whose reconstruction is such a feature of the centre of Richmond in north-west Queensland. Under scientific policies, the first named specimen of any creature becomes the ‘type’ specimen, and it is on this that all future examples, even if more complete, are based. There are some doubts about the original specimen from 1894, as described and named by Longman in 1923. While only fragmentary, it features some differences to the Harvard specimen, and either or both of these are different to some of the other fragmentary remains found since then — so maybe we actually have several different creatures here.

Cabot’s generous gesture at restoring a sea serpent has brought to life a scientific monster of sorts, but there’s plenty more of these out there under the north Queensland soil, so if you’re ever up that way, keep your eyes peeled. 


Regulars Beneath the Surface Column Australian history Sea-going reptile Kronosaurus Fossils