Warkalania is an extinct genus of Australian meiolaniid turtle from the Oligocene or early Miocene of Riversleigh, Queensland. While other meiolaniids are known for their elaborate headcrests or long horns, Warkalania only possesses very short horns that form a somewhat continuous ridge across the back of the head. The only known species of this genus, Warkalania carinaminor, is the oldest named meiolaniid turtle of Australia.
History and naming
Although the presence of meiolaniids in the Riversleigh fauna had been known on the basis of fragmentary remains since at least 1987, the first diagnostic remains were discovered by Neville Pledge in the form of a partial skull from strata dating to the late Oligocene to early Miocene. These remains were described by Eugene S. Gaffney, Michael Archer and Arthur White as a new genus of meiolaniid turtle they named Warkalania carinaminor. The holotype is specimen QMF 22649, a right squamosal bone including the tympanic cavity and various scales of that area, and was discovered at the Pancake Site in Queensland. Additional material has also been reported, such as QMF 22650, a left squamosal that may have belonged to the same individual as the type specimen. The other referred specimens include various skull bones including the parietals, a quadrate bone and the squamosal of at least one other turtle.
The genus name Warkalania combines the word "Warka" meaning "turtle", which Gaffney and colleagues attribute to a no closer specified Australian Aboriginal language of the Queensland region, and "lania". The suffix -lania is a common component in the names of meiolaniid turtles, also used in Meiolania, Gaffneylania and Niolamia. The meaning of the term is however interpreted differently by various authors, partly due to the lack of an etymology given in the description of Miolania. In the description of Warkalania, the word is translated as "butcher" from the Latin "lanius", but other researchers point to Owen's description of Megalania to argue that the suffix is actually derived from the Greek word for "to roam about". The species name of W. carinaminor on the other hand simply translates to "small ridge", a reference to the fact that this genus didn't possess the large horns of other meiolaniids.
Description
The skull of Warkalania is highly ankylosed, entirely obscuring the sutures between the individual skull bones. Consequently, Gaffney and colleagues describe the skull largely on the basis of the contacts between the overlying scutes, which are alphabetically labeled. The individual scale areas are separated by the presence of shallow grooves, similar to Ninjemys and Niolamia and different from the raised ridges of some individuals of Meiolania platyceps. One of the referred specimens preserves scale X, which is located in the central portion of the skull between the scales D and G, likely covering the back of the frontal bones and the front of the parietal bones. Scale X is of similar size to the same scale in Meiolania platyceps from Lord Howe Island and bears the same kind of conical protrusion on its surface, though smaller than in the later species. While only a single scale X is present, the scales D and G are paired and appear to meet their respective opposite along the midline of the skull. The actual contact between D and G might also be preserved, however it appears much weaker than any other scale contacts in this animal. Much like in Meiolania, scale D lies relatively flat against the skull rather than being notably convex as in Niolamia and Ninjemys.
The roof of the cranial cavity appears to be primarily composed of the parietal bones, with some contribution by the supraoccipital bones, and includes the region that would contain the remnants of the synotic tectum. This region however is not well enough preserved to show any differences to other turtles, which are typically rather uniform in the anatomy of this element.