In search of the fabled Aussie brachiosaur
The possibility of a species of Brachiosaurus having lived in Australia has been suggested since the early 1980s. However, there has yet to be any official confirmation of a Brachiosaurus specimen having been discovered. Is there a conspiracy afoot? Or is it simply a case of mistaken identity? The following is an attempt to unravel the rumours surrounding the fabled "Aussie Brachiosaur".
The first specimen of Brachiosaurus was described in 1903. Brachiosaurus (meaning "arm reptile") was a very large sauropod that lived in North America during the Late Jurassic, around 145 MYA. It measured up to 30 metres long and perhaps 12 metres tall at the head. One of its most recognisable features are its long forelimbs, which give it a more upright stance than other sauropods like Diplodocus. Over the last hundred years more species of Brachiosaurus have been discovered in Africa and Europe, dating from the Late Jurassic to the Early Cretaceous. Given their wide geographic and temporal distribution, there was no reason why they shouldn't also turn up in other parts of the world.
Sauropod remains are few and far between in Australia, and mostly confined to Queensland (although footprints are known in Western Australia). The Australian sauropod Austrosaurus mckillopi was discovered in 1932, and is represented mostly by some dorsal vertebrae and rib fragments. It was found in the Allaru Mudstone Formation near Maxwelton in Queensland, dating to around 98-99 MYA. In 1959 the fragmentary remains of five more sauropods were discovered to the northwest of Maxwelton, from the slightly younger Winton Formation that dates to around 95-97 MYA. There was sufficient similarity in the vertebrae of these new finds to classify them as an unknown species of Austrosaurus, although not necessarily A.mckillopi. The forelimbs of these additional animals were quite long, with extremely elongated bones in the hand (metacarpals).
Elongated forelimbs are also a feature seen in brachiosaurs, although the radii (lower arm bones) of these Austrosaurus specimens are even more robust than those seen in Brachiosaurus. Other sauropod species have since been found in other parts of the world that also have elongated forelimbs. They tend to be titanosaurids, such as Paralititan stromeri and Titanosaurus colberti. Brachiosaurus is considered by some to be a basal relative of the titanosauriformes. In 1999 it was suggested that Austrosaurus itself may also be related to the titanosaurs, although how closely is a matter of debate. Perhaps Austrosaurus too was a basal titanosauriforme of some sort, although probably from a branch of the extended titanosaur family tree that was unique to Australia.
In 1982 news of a partial cervical (QM F6142) showing possible brachiosaur affinities was published. It was discovered in an unknown Early Cretaceous formation near Hughenden in Queensland. The specimen is a rear section of a single neck vertebra, and was said to be a close match in size and shape to that of Brachiosaurus. No cervicals are known for Austrosaurus, so this bone could be from the same type of animal (if not the same species), although the similarity between this cervical and that of Brachiosaurus was thought to be greater than the similiarity between other skeletal elements of both species. The presence of a large rib found in the opal fields of South Australia, similar to that of brachiosaurs, and two brachiosaur-like teeth from Lightning Ridge in New South Wales, was seen as further evidence of the animals in Australia.
In the late 1990s there were rumours of another Queensland "brachiosaurid" having been discovered. In a French paper published in 2000, a "pers.comm" (personal communication) from a prominent palaeontologist (then with the Queensland Museum) was sited by the authors. It mentioned "an incomplete sauropod forelimb attributed to Brachiosaurus sp" from Australia. The personal communication was dated to 1997.
In an article written in 1998, the same palaeontologist was quoted as having said that the partial Hughenden cervical was probably not that of Brachiosaurus, but that the genus may well have existed in Queensland, alluding to a then undisclosed find (probably the same as that mentioned in the French paper).
In a media release on the 10th of October, 2001, the Queensland museum announced the discovery of a large sauropod from an undisclosed area around Winton, Queensland. It was from the Winton Formation, the same as the five partial Austrosaurus specimens, and may represent a new species of Austrosaurus. At the time there were rumours that this was the fabled brachiosaur that had been mentioned years before. However there is a problem with this theory.
Known as "Elliot", the sauropod was discovered in 1999. The only forelimb elements known for Elliot so far come from the front foot, which was found in July 2002. Although this does qualify as a very incomplete forelimb, it was found five years too late to be the fabled brachiosaur mentioned in 1997. This suggests that there was another sauropod discovery that pre-dates that of Elliot by at least two years, one that has yet to be officially announced.
Is there evidence of an Australian Brachiosaurus? Or are the various brachiosaurids known from around the world simply a collection of basal titanosauriformes, of which Austrosaurus is a member? If the latter is correct, then all of the brachiosaur-like material from Australia may belong to a group of uniquely Australian basal titanosauriformes, that resemble brachiosaurs in just a few parts of the skeleton. If Elliot the sauropod turns out to be as complete as is expected, then perhaps some austrosaur neck vertebrae will turn up at last, proving one way or the other whether the Hughenden vertebra is actually from an Austrosaurus.
Given the slow rate of publication of major Australian finds (up to twenty years in some cases), we may be a long way from finding out for sure. Perhaps the evidence already exists, locked away in museum cabinets, kept from public knowledge by a conspiracy of silence. One way or the other, the truth is out there...
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