You may assume all vital dinosaur “discoveries” are made as quickly as fossils are collected within the area – that palaeontologists immediately know the importance of what they’ve discovered.
That is usually true. However typically, and possibly extra usually than you’d assume, fossils will likely be saved in museum collections for years earlier than the proper researchers come alongside to “rediscover” them. This was the case for one Australian ankylosaur cranium, which we’ve printed about immediately within the journal Frontiers in Earth Sciences.
Initially found in 2005 close to the regional Queensland city of Boulia, the specimen remained on the South Australian Museum till we enquired in regards to the museum’s dinosaur assortment.
Ankylosaurs, the so-called “armoured” dinosaurs, are a bunch of dinosaurs that lived from the Early Jurassic to the Late Cretaceous – roughly 196 to 66 million years in the past.
In comparison with different dinosaurs, such because the long-necked sauropods and smaller herbivorous ornithopods, ankylosaur stays are not often present in Australia and the broader southern hemisphere. So you’ll be able to think about our pleasure after we “rediscovered” Australia’s second ankylosaur cranium.
An evaluation of the cranium bones and enamel suggests it belongs to the genus Kunbarrasaurus, which additionally incorporates the primary Australian ankylosaur cranium.
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What had been ankylosaurs like?
Ankylosaurs had been medium-to-giant herbivorous dinosaurs (anyplace between 200-5,000kg) that walked on 4 legs and had been coated in armoured plates or spikes. Some are recognisable by tail golf equipment, such because the five-tonne Ankylosaurus magniventris from North America.
Of the 75 recognised ankylosaur species, solely 5 are from the southern hemisphere. A number of small and incomplete fossils are spattered throughout the traditional Gondwana supercontinent – which is now dispersed and damaged up into Australia, India (which again then was within the southern hemisphere), Africa, Antarctica and South America.
These fossils provide tantalising hints of what was as soon as a widespread ankylosaur presence in these areas. The 5 Gondwanan ankylosaur species are Kunbarrasaurus ieversi and Minmi paravertebra from Australia, Antarctopelta oliveroi from Antarctica, Spicomellus afer from Africa, and Stegorous elengassen from Chile.
A dinosaur from Boulia
The bones of the ankylosaur from Boulia had been discovered encased in a big, onerous rock referred to as a concretion. Concretions usually kind round natural matter, and sure helped the preliminary preservation of the fossil. When it was found, all that was seen was a sequence of rock chunks that would have simply been neglected.
Benjamin Kear (Uppsala College)
The collected fossils embody limbs, vertebrae, many armoured plates and, excitingly, a partial cranium. Together with a number of cranium bones, the cranium additionally consists of the impressions of many enamel from the higher jaw.
Your complete cranium block was scanned on the Australian Synchrotron in Melbourne. The synchrotron shoots x-rays on the specimen, producing a sequence of photographs that may be processed to disclose the bones in 3D (as seen under).
This system is usually used for fossils that will in any other case get broken or lose vital info if bodily faraway from the rock.
We analysed the scans and found the bones are these of the roof of the mouth (or the palate). We additionally discovered a number of enamel “floating” inside the block.
Putting southern ankylosaurs within the household tree
Figuring out this new ankylosaur as Kunbarrasaurus suggests this specific dinosaur was probably extra widespread in Queensland than beforehand thought, and should have existed for greater than 5 million years. However what do ankylosaurs from Australia, and Gondwana extra typically, inform us in regards to the group’s evolution as an entire?
Because it stands, the overwhelming majority of ankylosaurs are from both North America, Europe, or Asia. And most are from the late Cretaceous (100 to 66 million years in the past). Nevertheless our examine suggests a separate and presumably earlier variety of ankylosaurs within the south, a idea which is supported by current discoveries from South America and Africa.
The southern radiation of ankylosaurs consists of the species from Australia, Chile and Antarctica, all of which collectively kind the group referred to as Parankylosauria.
The significance of the Boulia ankylosaur
As a result of the fossil block was scanned with x-rays and reconstructed in 3D, we had been in a position to discover points of the ankylosaur’s airways, or “choanae”. These weren’t properly preserved within the first and solely different identified Kunbarrasaurus cranium.
Usually ankylosaur choanae are lengthy, situated near the entrance of the snout and may have a number of openings inside the palate. Coupled with advanced nasal passages, these options level to the group typically having a eager sense of scent.
Nevertheless, within the Boulia ankylosaur there is just one opening on all sides, and they’re situated in direction of the again of the palate. This means Kunbarrasaurus didn’t have the advanced nasal system seen in ankylosaurs reminiscent of Pawpawsaurus campbelli and Euplocephalus tutus. As such, it could have had a lowered sense of scent in comparison with most of its northern counterparts.
There’s nonetheless loads we don’t learn about ankylosaur evolution, particularly the Gondwanan species. Maybe extra of those discoveries await us in museum troves.
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