Allaru Formation, Geological formation in Queensland, Australia.

The Allaru Formation is a geological sequence in the Eromanga Basin composed of mudstone, siltstone, sandstone, and limestone. These strata document an ancient marine period that once covered parts of Australia.

The formation took shape during the Early Cretaceous about 112 to 100 million years ago when seawater covered the Eromanga Basin. This marine phase ended as waters retreated and the landscape transformed.

The formation's name comes from Allaru, a locality in Queensland. Its mudstone layers yield possible indeterminate ankylosaur and ornithopod remains, plus reptile, fish and invertebrate fossils. Collecting and study of these specimens are carried out by palaeontologists rather than as a visitor activity.

Access to this geological formation typically occurs through scientific expeditions and fieldwork by geologists and researchers. Its location in Queensland requires planning and familiarity with the terrain.

The Allaru Formation is also called the Allaru Mudstone. Besides indeterminate ankylosaur and ornithopod dinosaur remains, it has yielded archosaur, reptile, fish and invertebrate fossils, all from Early Cretaceous strata in Queensland.