Kunbarrasaurus ieversi (formerly Minmi sp.)

Kunbarrasaurus ieversi represents the most complete dinosaurian fossil from eastern Gondwana (Australia, New Zealand, India and Antarctica), and the most complete ankylosaurian fossil from Gondwana. It is also one of the world’s most complete ankylosaurians. Moreover, it includes one of the few ankylosaurian skulls in which most of the sutures have not fused or been obliterated by dermal ossifications or remodelling of bone.

ETYMOLOGY: Levers' shield-lizard 
GEOLOGY: Marathon Station near Richmond, north-western Queensland
AGE: Earliest Late Cretaceous (Aptian) 110 million years ago

DISCOVERY

In November 1989, local grazier Ian Ievers while mustering cattle at his Marathon Station property near Richmond, Queensland discovered the skeleton of an ankylosaurian. In January 1990 it was secured by a team led by Ralph Molnar. In 1996, in a provisional description, Molnar concluded that it could be referred to the genus Minmi as a Minmi sp. Subsequently, the specimen was further prepared by an acid bath and investigated by a CAT scan. The new information led to the conclusion that the species could be named in a separate genus of ankylosaur.

SKELETAL REMAINS

The assignment of a new genus and species name K. ieversi to QM F18101 (formerly known as Minmi sp.) is based on a significant number of features that distinguish it from other ankylosaurians. Many of the cranial sutures of K. ieversi have not fused, nor are they obscured by dermal ossifications. The closure of the antorbital and supratemporal fenestrae of K. ieversi is most likely due to the expansion of cranial bones, and not the result of overgrowth of dermal ossifications. The ornamentation of the skull of K. ieversi is the result of both epidermal ossification (osteoderms) and periosteal osteogenesis. Some aspects of the nasal cavity remain obscure, but there is enough evidence to suggest that K. ieversi had a more complicated airway than in non-ankylosaurian outgroups. It is presently unclear whether K. ieversi had a convoluted, looping nasal passage to the extent seen in more advanced ankylosaurians. Some aspects of the braincase are potentially unique among known species, such as the unusual inner ear, which is not only extremely large but also has a divergent morphology due to lack of ossification medially and ventrally. The skeleton of Kunbarrasaurus ieversi is currently on display at the Queensland Museum (Southbank). A replica articulated display can be seen at Kronosaurus Korner, Richmond.

Left: Kunbarrasaurus ieversi skeleton. Right Kunbarrasaurus ieversi cranium (dorsal and ventral views).

 

FOR MORE INFORMATION WE RECOMMEND READING... 

Scientific papers, Kunbarrasaurus ieversi. 

WikipediaKunbarrasaurus ieversi.

For more information read an excerpt from "Minmi, Armoured car of the Cretaceous" (1.87mb) by Natalie Schroeder found in AAOD Journal, Issue 8

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