Academic literature on the topic 'Kronosaurus'

A new fossil MP111209-1 found in the Barremian beds of Sáchica, a town near Villa de Leiva representing the more complete skeleton found in the region is described here. After a detailed study of its morphological characteristics, it is evident that the new specimen represents a new genus and species of brachauchenine pliosaurid from Central Colombia that we named Sachicasaurus vitae gen. et sp. nov. Sachicasaurus is a large brachauchenine (almost 10 m in length) characterized by the following combination of characters: skull exceeding two meters in length, transverse constriction in the rostrum, caniniform teeth present, pineal foramen in a very advanced position, palatines separated in the midline by the pterygoids, very short mandibular symphysis (bearing four teeth positions), reduced number of mandibular teeth (less than 20), slender hyoid bones, 12 cervical vertebrae, cervical centra showing ventral foramina, single rib facet in all cervical centra, at least 40 pre-caudal vertebrae, and ilium with a long posterior projection. Although it is difficult to clearly establish the phylogenetic position of Sachicasaurus viate within Brachaucheninae due to its combination of primitive and derived features, the morphological comparisons and the cladistic analysis show an evident phylogenetic proximity of Sachicasaurus to the Aptian-Albian genus Kronosaurus.

Research Doctorate - Doctor of Philosophy (PhD)
The large pliosaur Kronosaurus queenslandicus is known from numerous specimens from the Early Cretaceous marine sediments of the Australian Great Artesian Basin. The preservation of these specimens in nodular limestone generally lacks pronounced taphonomic distortion, allowing the three-dimensional shape of the osteology, in particular the skull, to be inferred with confidence. Three-dimensional geometry is critical data for the functional analyses that can form the basis for reconstruction of palaeoecology, in particular, approaches based in computational biomechanics that make use of high resolution Finite Element Modelling. These techniques have been used successfully to infer diet and feeding behaviour in various species of extinct carnivore, and are here applied to a species of large pliosaur for the first time. The cranial anatomy of Kronosaurus queenslandicus is here summarised for the first time, and outstanding questions concerning the taxonomy of the relevant material are addressed as fully as possible given available data. Overall body proportions and size are estimated in the context of other known material from specimens of large pliosaurs. The material examined supports the hypothesis that there is one species of large pliosaur in the Late Albian the Great Artesian Basin, and this material is referred to Kronosaurus queenslandicus Longman 1924. Material from the Late Aptian of the Great Artesian Basin is also Kronosaurus, and is presently referred to Kronosaurus queenslandicus Longman 1924: however questions about the anatomy of Kronosaurus boyacensis Hampe 1992 mean that further examination of material to hand, or recovery of new specimens from the Late Aptian, may require the taxonomic status of the Late Aptian material to be reviewed. Kronosaurus is a member of the Brachaucheniidae Williston 1925. Maximum size is 10.5 metres total length and approximately ~11,000 kg body mass. Biomechanical analysis of the skull of Kronosaurus shows that it had a high bite force, comparable to that predicted for a hypothetical similar sized saltwater crocodile Crocodylus porosus. The magnitude of its maximum bite force, around 30,000 Newtons, was likely exceeded by Tyrannosaurus rex and Carcharocles megalodon. Finite element modelling of the skull, compared with the skull of a 3.1 metre Crocodylus porosus, suggests that the skull of Kronosaurus carried more strain under loads simulating feeding on large prey. Accordingly, maximum prey size, relative to predator body size, is interpreted as lower in Kronosaurus than for a 3.1 metre C. porosus, although the magnitude of this limit is unknown due to incomplete data on the feeding ecology of C. porosus. Other evidence, from functional morphology, taphonomy, and comparison with extant aquatic carnivores suggests that Kronosaurus was the apex predator of the Australian Early Cretaceous inland seas. Relatively small prey were likely to be an important component of the diet of Kronosaurus, although certain morphological features of the skull appear to have permitted predation upon larger prey when available. Several of these morphological features may constitute evolutionary adaptations to the conflicting mechanical demands of feeding on small and large prey.