Dinosaurs - Muttaburrasaurus langdoni

Introduction

Muttaburrasaurus was a large, plant-eating ornithopod from the Early Cretaceous of eastern Australia. It is one of the most complete dinosaurs from Australia and the first to be cast and mounted for display. Muttaburrasaurus had an unusual skull with a long, rounded snout.

Identification

Muttaburrasaurus was a large ornithopod that had an unusual, rounded bony snout.

Muttaburrasaurus had many other features seen in other basal ornithopods, including reduced forelimbs and a long, stiffened tail. Based on the length and strength of its limbs, Muttaburrasaurus may have been able to move on either its two back legs or on all four legs.

Habitat

Muttaburrasaurus would have lived in araucarian conifer forests near the edge of the inland Eromanga Sea that covered vast areas of Australia between 125-100 million years ago. The forest understorey would have included ferns and cycads, possibly part of the diet of Muttaburrasaurus. In the more southerly part of its range (Lightning Ridge), there would have been extremes of daylight during winter and summer months, although the climate was much milder then than it is today.

Distribution

Muttaburrasaurus is Australia's most widely distributed dinosaur, known from both Queensland and New South Wales. It was discovered near the town of Muttaburra in central Queensland (on the Thomson River in the coastal Mackunda Formation). Other Queensland Muttaburrasaurus material comes from Dunluce Station near Hughenden in the north-central part of the state, and from Iona Station southeast of Hughenden. A possible second species of Muttaburrasaurus has been found at Lightning Ridge in north central New South Wales.

Feeding and diet

There is no direct fossil evidence for the diet of Muttaburrasaurus although it probably included ferns, cycads, club-mosses and podocarps, all of which are known from the region. Although it was mainly (if not fully) a plant-eater, some scientists have suggested that, based on the shape of its teeth, Muttaburrasaurus may have occasionally eaten some meat.

Fossils description

The holotype of Muttaburrasaurus is a partial skeleton found near the town of Muttaburra in central Queensland. This skeleton (about 60% complete) was washed up on a coastline, based on the environment preserved in the Mackunda Formation. Other Queensland Muttaburrasaurus material includes a second skull from Hughenden in the north-central part of the state (older and more primitive than the original Muttaburra skull specimen) and isolated teeth and bones collected from Iona Station southeast of Hughenden. Opalised teeth and a scapula (shoulder blade) of what may be a different species of Muttaburrasaurus have been found at Lightning Ridge in north central New South Wales (held by the Australian Museum). There are, therefore, at least two (and possibly three) species of Muttaburrasaurus although this this needs to be confirmed by more research.

Evolutionary relationships

The evolutionary relaltionships of Muttaburrasaurus are uncertain. It may be closely related to the Tenontosauridae, a group of basal ornithopods with few specializations that evolved from an early ornithopod group in the latter part of the Jurassic. Tenontosauridae includes Tenontosaurus, a large ornithopod similar to Muttaburrasaurus in shape and form (except for the distinctive snout of Muttaburrasaurus). It also resembles the small Australian ornithopod Atlascopcosaurus from Victoria, whose relationships are currently under study.

References

• Bartholomai, A. and Molnar, R. E., 1981. Muttaburrasaurus, a new iguanodontid (Ornithischia: Ornithopoda) dinosaur from the Lower Cretaceous of Queensland. Memoirs of the Queensland Museum 20: 319-349.
• Molnar, R. E., 1996. Observations on the Australian ornithopod dinosaur, Muttaburrasaurus. Memoirs of the Queensland Museum 39, 639-652.

Further reading

• Long, J. A. et al. 2002. Dinosaurs of Australia and New Zealand and Other Animals of the Mesozoic Era. New South Wales University Press, Sydney.
• Cannon, L., 2006. The Muttaburra Lizard. Australian Age of Dinosaurs 4, 16-31.