Fossils in Wellington Caves, NSW

Where are Wellington Caves?

The area surrounding Wellington Caves has long been inhabited by the Wiradjuri people. Wellington Caves in NSW is roughly 350 km Northwest of Sydney or 60 km Southeast of Dubbo.

Why are Wellington Caves important?

Wellington Caves is a complex cave system that provides a unique and awe-inspiring insight into natural history. The caves are famous for the Cathedral and Garden Caves lined with beautiful stalagmites and stalactites formed by droplets of water redepositing limestone in the same spot over millions of years. Particular sections of the system are also incredibly rich in vertebrate bones. Fossils from the region are recognizable due to the vibrant red iron-stained sediments which entomb them. Following European occupation fossil material begun to be collected from the caves, the first published descriptions of which emerged in 1830. While the caves were mined for phosphate briefly in the early 1900s the importance of keeping the site intact has since been recognized and eventually the Wellington Caves region gained protection under a national heritage listing.

The vertebrate fossil material of Wellington Caves is now known to demonstrate an impressively diverse cross section of Australian fauna. This ranges from now extinct megafauna through to long-lived modern species. Ongoing analysis of fossil material found in the caves provides important data regarding long-term changes in the diversity and ecology of the region.

Fossil time period: Wellington Caves

The caves themselves are carved out of fossiliferous Early Devonian (419.2 to 393.3 million year old) limestone which is rich in invertebrate fossils. The more recent vertebrate fossils in the cave sediments are more challenging to date as the rock that surrounds the fossils has in some places been dissolved and redeposited multiple times, confounding the timing of the original deposition. For this reason, most of the vertebrate material is dated by linking it to material found in more reliably dated fossil contexts elsewhere. Accordingly, the earliest dates associated with these more recent vertebrate fossils is the early Pliocene. These latest dates for the vertebrate fossils appear to be slightly later in the Pleistocene, around the time of the most recent ice age.

Devils and thylacines from the mainland

While commonly associated with Tasmania, devils and thylacines were also once present on the Australian mainland. Both groups are represented amongst fossil material found at the Wellington Caves. Recent analysis suggests that these two groups may have gone extinct on the mainland around the same time, just over 3000 years ago. Devils and thylacines would have represented the dominant carnivores of this region over the last 50,000 years, being replaced by canids (dogs) at the time of their mainland extinction.

_{Sarcophilus sp. partial jaw. View fullscreen on Pedestal3D}

The jaw of a devil (Sarcophilus sp.), on which you can see the markings of a palaeontologist’s tools from when the specimens was prepared.

_{Sarcophilus sp cranium. View fullscreen on Pedestal3D.}

The partial skull of a devil (Sarcophilus sp.), with a large amount of the Wellington Caves signature red sediment still attached.

_{Thylacinus sp.View fullscreen on Pedestal3D}

An almost complete skull of a large Thylacine (Thylacinus sp.) sticking out of a slab filled with the bones of other animals.

Extinct Macropods

Living species of the family Macropodidae include kangaroos and wallabies, however there are numerous extinct marcopods known only from the fossil record. Two of these are Sthenurus and Procoptodon, genera of the extinct subfamily Sthenurinae also known as the short-faced kangaroos. Sthenurinaes are strangely thought to have been bipedal ‘walkers’, rather than ‘hoppers’ like modern kanagroos.

_{Procoptodon rapha jaw. View fullscreen on Pedestal3D}

This jaw of a young Procoptodon rapha showing how unusually robust these animals were compared to modern kangaroos. The preparation of this particular juvenile specimen shows an unerupted premolar, which is important for helping palaeontologists identify the fossil.

_{Sthenurus atlas partial cranium. View fullscreen on Pedestal3D}

The semi-complete skull of the large Sthenurus atlas which demonstrates how similar their teeth were to those of modern kangaroos. The body mass of the largest specimen of Sthenurus has been estimated at 240 kg (530 lb), nearly three times the weight of the largest red kangaroo.

Palorchestes

Palorchestes were a genus of large marsupial herbivores that lived from the Late Oligocene to the Late Pleistocene throughout Eastern Australia including Tasmania. The anatomy of this group is extremely unusual compared to modern marsupials, for instance they are thought to have had a tapir-like snout. It is for this reason they aredifficult to place taxonomically, although they are thought to belong to the Order Diprotodontia and possibly the Suborder Vombatiformes. This would make their closest relatives wombats and koalas. Palaeontologists have recently proposed that palorchestid species had a specialised foraging style, raising themselves on their hindlimbs and using their forelimbs to graze vegetation. Based on recent studies, some palorchestid species are thought to have weighed around a tonne.

_{Palorchestes azael jaws. View in fullscreen on Pedestal3D}

The upper and lower jaws of this large Palorchestes azael have been compressed from the sides during the fossilisation process.

_{Palorchestes azael teeth. View fullscreen on Pedestal3D.}

As you can see from this Palorchestes azael specimen, palorchestid species exhibit a classic ‘bilophodont’ herbivorous tooth type with enamel ridges forming rings across a flat axis, used for grinding up plant material.