Meiolania was first described as a species of lizard related to Megalania by Richard Owen towards the end of the 19th century, before the continued discovery of additional fossils solidified its placement as a kind of turtle.

M. damelipi from Holocene Vanuatu, which may represent a non-meiolaniid turtle, and the Wyandotte species, an unnamed form from Pleistocene Australia tentatively identified as M. cf.

The discovery of fossil nests and certain adaptations against sand entering its nasal cavity indicate that they spent at least some time in arid regions or on the beaches of the islands they inhabited.

Several hypotheses have been proposed ranging from it spreading across the now submerged continent of Zealandia to it swimming between islands (the latter of which is now considered unlikely based on its heavy build and lack of aquatic adaptations).

The extinction of this turtle was most likely a multi-facetted process with ties to climate change, reduction of its native territory by rising sea levels, predation from invasive livestock and possibly hunting by humans.

Multiple researchers appear to have been actively collecting turtle fossils at the time, including FitzGerald and Wilkinson who were seemingly unaware of each other's efforts despite working for the same institution.

[2][3] BMNH R675, an incomplete and damaged skull embedded in hardened calcarenite, was chosen to serve as the holotype for the genus and although its precise age and location is not known, Eugene S. Gaffney suggests it may have come from the 100,000 to 120,000 year old rocks of Ned's Beach.

Meanwhile, upon receiving some additional fossil remains collected by Wilkinson (including a fully preserved skull), Owen came to believe that Meiolania was related to both lizards and turtles and thus placed the animal in a group he called Ceratosauria (a name already occupied by a clade of dinosaurs).

Gaffney published three papers on the subject: the first, dealing with the history of Meiolania's discovery and its skull,[1] the second on the vertebrae and tail club,[11] and the final publication covering the shell and limbs while also reviewing Meiolaniidae as a whole.

These advances in our understanding of Meiolania lead Gaffney to re-examine the material of M. oweni, finding that it was sufficiently distinct from all other species to warrant being placed in its own genus, Ninjemys.

[12][5] While this removed one species from the genus, another was added that same year when Dirk Megirian described Meiolania brevicollis based on Miocene remains from the Camfield Beds (Northern Territory) of mainland Australia.

The A scale area, which overlays the rear-most surface of the skull, forms only relatively small horns differing greatly from the massive, shield-like structure seen in Ninjemys and Niolamia.

The area where ischium and pubis meet is massive and forms a large plate of bone that has thyroid fenestrae, something typically considered to be a basal condition for turtles that was lost and redeveloped across the clade.

The second type correlates to more traditional protective osteoderms and can be found in the form of disc and cone-shaped bones that likely covered the limbs in a manner similar to the dermal ossicles of modern tortoises.

Rhodin notes that the largest complete M. platyceps carapace measures 63.5 cm (25.0 in), and that the size of larger specimens was estimated based on the proportions of this individual.

[16] The Wyandotte species stands out as the largest member of Meiolania, with the horn cores indicating an animal similar in size to Ninjemys[12] and a carapace length of perhaps up to 2 m (6 ft 7 in). ?M.

Finally, the recovered cow-like horns and absence of a continuous shelf of scales at the back of the skull separates Meiolania from its closest relative, Warkalania.

Throughout this family tree, one can also observe a gradual decrease in the size of the A scales, which begin as a large shield-like structure in basal taxa like Niolamia and Ninjemys and are comparably reduced in Meiolania.

It is hypothetically possible to find clades within the genus based on the width of the B horns, however as Gaffney notes this is not a consistent feature and varies greatly once one is met with a greater sample size.

A commonly proposed but somewhat controversial hypothesis for the appearance of Meiolania is direct dispersal across water, which may range from drifting, floating, walking, and wading to active swimming.

Finally, studies have shown that adult tortoises introduced to new areas are very likely to disperse soon after release if not contained, an inconvenience if the turtle was meant to serve as a foodsource.

However, they too make for a poorly sustainable source of meat due to the long time tortoises take to grow and reproduce, again causing issues with establishing a stable population.

Allan Riverstone McCulloch for instance believed that the fossils on Lord Howe Island were preserved when turtles came ashore to lay their eggs, only to die in the process.

Besides the questionable nature of their ratio-based approach, the two authors point out that Lichtig and Lucas based their conclusion on a single juvenile specimen which was a composite reconstruction, thus not only providing an extremely poor sample size but also not reflecting the real proportions of the animal, much less those of an adult.

This matches the fact that some researchers have suggested that Meiolania platyceps was a beachgoing animal, spending at least parts of its life in sandy areas, even if only to lay eggs.

Generally, aquatic turtles possess the smallest nasal cavities in living testudines, while those of terrestrial tortoises are notably larger and allow for a better sense of smell.

The inner ear anatomy of tortoises and meiolaniids is generally associated with stabilizing the head while walking, while aquatic turtles are built to deal with rolling during swimming.

[16][15] Various aspects of its general morphology also draw closer comparison to terrestrial tortoises than aquatic ones, such as the robustness of the limbs, the rounded head of the femur and the shape of the shoulder girdle.

Combat between Meiolania specimens could further involve the use of armored limbs, the spiked tails covered in bony rings and the large horns situated atop the animal's head.

[14] Due to the great range of Meiolania, which covered many ecosystems entirely independent from each other, the genus' extinction is thought to have been a multifaceted process caused by various factors not directly tied to one another.