Kronosaurus

***Kronosaurus*** (meaning "lizard of Kronos") is an extinct genus of short-necked pliosaur. With an estimated length of 9 to 10.9 meters (30 to 36 ft), it was among the largest pliosaurs, and is named after the leader of the Greek Titans, Kronos. It lived in the Early Cretaceous period (Aptian to Late Albian). Fossil material has been recovered from the Toolebuc Formation (middle to late Albian) and Wallumbilla Formations (Aptian) of Queensland and New South Wales in Australia, and from the upper Paja Formation (late Aptian) in Boyacá, Colombia, and assigned to two species.

## Description

Like other pliosaurs, *Kronosaurus* was a marine reptile. It had an elongated head, a short neck, a stiff body propelled by four flippers, and a relatively short tail. The posterior flippers were larger than the anterior. *Kronosaurus* was carnivorous, and had many long, sharp, conical teeth. A feature of the genus *Kronosaurus* is that the first three maxillary teeth are enlarged to fangs. Current estimates put *Kronosaurus* at around 9 to 10.9 meters (30 to 36 ft) in length. In 2009, *K. queenslandicus* was estimated to weigh about 10.6 to 12.1 metric tons (11.7 to 13.3 short tons). The skull length of *Kronosaurus* was estimated to be 2.21–2.85 meters (7.3–9.4 ft).

All Sauropterygians had a modified pectoral girdle that supported a powerful swimming stroke. *Kronosaurus* and other plesiosaurs/pliosaurs had a similarly adapted pelvic girdle, allowing them to push hard against the water with all four flippers. Between its two limb girdles was a massive mesh of gastralia (belly ribs) that provided additional strength and support. The strength of the limb girdles, combined with evidence of large, powerful swimming muscles, indicates that *Kronosaurus* was likely a fast, active swimmer.

*Kronosaurus queenslandicus* has four pairs of premaxillary teeth. The first three pairs of its maxillary teeth are large caniniform teeth, and in its lower jaw there are also three pairs of large caniniform teeth which are located immediately in front of the three maxillary caniniforms when the mouth is closed. Two pairs of the lower jaw caniniforms occlude between the last pair of premaxillary teeth and first pair of maxillary teeth in a diastema (gap in the tooth row). The enlargement of these two pairs of lower jaw teeth in *K. queenslandicus* may be related to the absence of a fifth pair of premaxillary teeth, which are present in a number of other pliosaurs.

Oliver Hampe described *Kronosaurus boyacensis* as having five pairs of premaxillary teeth. Colin Richard McHenry has said that the premaxillary tooth count of *K. boyacensis* requires confirmation and that if its premaxillary tooth count is confirmed to be five, it may be appropriate to place *K. boyacensis* into a different genus to *K. queenslandicus*. In addition to apparently having a different premaxillary tooth count, *K. boyacensis* differs from *K. queenslandicus* in postcranial features and possibly tooth ornamentation.

### Teeth

*Kronosaurus* teeth exceed 7 centimeters (2.8 in) in length (the largest up to 30 centimeters (12 in) long with 12 centimeters (4.7 in) crowns). However, they lack carinae (cutting edges) and the distinct trihedral (three facets) of *Pliosaurus* and *Liopleurodon* teeth. The combination of large size, conical shape and lack of cutting edges allows for easy identification of *Kronosaurus* teeth in Cretaceous formations from Australia.

## *Kronosaurus* in The Amazing Dinosaur Adventure

Fantasy *Kronosaurus* from *The Missing Fast-Water Adventure*