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Gogosardina — Aussie ceratosaur
Published: 2012-05-07 08:35:42 +0000 UTC; Views: 10131; Favourites: 189; Downloads: 201
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Description
2012, acrylics, digital & photographyca. 125,000,000 years ago, Early Cretaceous (early Aptian), San Remo, (87 km southeast of Melbourne), Victoria, Australia.
Under the 24-hour sunlight of the south polar summer, a 2.5 metre long ceratosaurian theropod hisses at a potential threat as she slinks back to her lair after a hunting foray. Grasped in her foreclaws is a dromaeosaurid chick.
This is a largely hypothetical reconstruction, based on an isolated astragalocalcaneum (NMV P221202) from the Early Cretaceous Wonthaggi Formation at San Remo, Victoria. Although only 6 cm wide, this fragment provides sufficient anatomical data to provide the first unambiguous evidence for an Australian ceratosaur.
In addition to the astragalocalcaneum, I've also incorporated a few other bits and pieces of fragmentary Victorian theropod - including some Masiakasaurus-like teeth from Flat Rocks. The end result is a sort of generalised "proto-Masiakasaur". The presence of dromaeosaurs in EK Victoria is based on isolated teeth.
REFERENCE
Fitzgerald EM, Carrano MT, Holland T, Wagstaff BE, Pickering D, Rich TH, Vickers-Rich P. (2012) First ceratosaurian dinosaur from Australia. Naturwissenschaften. 2012 May 3. [Epub ahead of print]
copyright 2012, Brian Choo
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Comments: 41
this is beautifull work!I write paleo/sci-fi so I see all kinds and this is outstanding work!please contact me?
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Thanks - with so few Australian theropods, they need all the publicity they can get!
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Excuse me, but one isolated bone does not provide sufficient anatomical data for an Australian ceratosaur - or any dinosaur for that matter. There's been many examples of dinosaurs classified by a few or only one bone, only to turn out wrong or to remain nomen dubium. There's been a lot of such claims from single bones found in Australia, especially by the Richs. While their claims are not impossible, a simpler explanation is convergant evolution. Some dinosaur group (or groups) native to Gondwana gave rise to dinos adapted to lifestyles similar to the more familiar Laurasian ones. Why not? Australia is famous for the same thing with marsupials. Why not with dinosaurs in a pretty much isolated Australia, even back then? Until a more complete skeleton is found, I'm sticking with that idea, instead of trashing current ideas of dinosaur emigration.
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Primitive ceratosaurs, dromeosaurs, ceratopsians, "hypsilophodontids", ornithomimids, oviraptorosaurs, all were present when Laurasia was still connected to Gondwana in the early-mid jurassic, hence they must have gone for the ride when the 2 superconitinents separated. That is obviously why they are present in Australia, because they got there early, and only changed marginally by the early cretaceous.
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Errr, your data is in error.
Firstly, although the Riches are tacked on as last authors, primary research and writing for the manuscript was conducted by Matt Carrano (curator of dinosaurs at the Smithsonian Institution and theropod expert) and Erich Fitzgerald. The Riches oversaw the field collecting and preparation, but had nothing to do with the taxonomic determination of this specimen.
Secondly, it is widely recognised that astragali *are* diagnostic in different groups of theropods. The only theropods that have an intimately fused astragalocalcaneum are ceratosaurians and paravians. But, no paravian has a tall plate-like ascending astragalar process - but all ceratosaurs do. When I first saw the specimen I was struck by its similarity to that Masiakasaurus and Xenotarsosaurus.
Thirdly, how is identifying a specimen as a ceratosaur indicative of "familiar Laurasian" chauvanism? Cretaceous Gondwana is FULL of ceratosaurians (in South America, India, Africa and Madgascar) so we'd expect them in Australia, while there are hardly any ceratosaurs in Laurasia (just a few European abelisaurs). The paper alludes to similarities between the Victorian specimen and Elaphrosaurus plus Deltadromeus, both African (ie. Gondwanan) ceratosaurs.
Fourthly - since when was Mesozoic Australia isolated? It simply a lump of eastern Antarctica that did not acheive full separation until the Eocene - thus the Australian biota did not start "going its own way" until after the Cretaceous.
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I really like the flow of this one! The background is so pretty, it's almost like the ceratosaur is bringing the prey to high tea or something.
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Yeah, shes going to a "bring-your-own-dromaeosaur chick" party.
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"I'm here for the potluck" As LOLcats once said.
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Sounds like great fun!
"I caught this dromaeosaur chick myself, you know. That's why I didn't have time to get cleaned up for our tea!"
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Great work! 
So what type of ceratosaur do the paleonotologists think this would be? Noasaurid? Or maybe a relative of Elaphrosaurus or Deltadromaeus?
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My hunch is that it is a noasaur, or at least a basal abelisauroid. The analyses in the paper give it a possible kinship to Elaphrosaurus or Deltadromeus (which are resolved as nesting withing Abelisauroidea) although, being based on a lone foot-bone, I'd take this with a grain of salt.
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Yes, a noasaur does indeed sound most likely to me. Maybe it is a primitive Masiakasaurus relative...
By the way, were there any dromaeosaurs found in Australia?
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>primitive Masiakasaurus relative...
Thats what I was aiming for when conceptualising this critter.
>By the way, were there any dromaeosaurs found in Australia?
Numerous dromaeosaurid teeth have been recovered from Flat Rocks. Some workers have tentatively proposed that Timimus is an unenlagiine dromaeosaur but, after a conversation with Paul Barrett, I've convinced its something else.
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I see... Thanks for the information!
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Yeah... it was refreshing to do an "old school" theropod without all those annoying feathers.
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Many thanks - there are so few Australian dinosaurs, much less predatory ones, so I decided to give him the full treatment!
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I don't believe this is the first Australian ceratosaur; Ozraptor was probably one.
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The Victorian specimen is the first *definative* Aussie ceratosaur based on hard anatomical data. At present there is nothing else it could be.
The Ozraptor tibia hardly provides the same degree of diagnostic information and subsequent researchers have failed to find strong support for Rauhut's abelisauroid classification. Its effectively an indeterminate neotheropod.
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excuse me, but didn't ceratosaurs have a horn on the nose ?
Also I had a notion they were extinct by Creatceous, but it's not as if I kept up with the latest developments. I'm pretty sure about the horn though; so basically what other difference was there that would alow to differentitae between a ceratosaurian and an allosaurian or other theropod ?
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Clade Ceratosauria = Ceratosaurus, Limusaurus Elaphrosaurus, Deltadromeus & abelisauroids (Carnotaurus, Skorpiovenator, Rugops, Majungasaurus, Masiakasaurus etc) The only ceratosaur with a nasal horn is Ceratosaurus itself.
While listing all the diagnostic characters of the Ceratosauria would take up too much space, NMV P221202 (an isolated astragalocalcaneum) is considered a ceratosaur primarily due to the shape of the ascending process of the astragalus (tall and plate-like with a parallel-side base) and the fact that the astragalus and calcaneum are intimately fused to one another (the only other theropods that do this are deinonychosaurs and birds, and the rest of the astragalocalcaneum doesn't look like one of those)
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nothing like talking with an expert. Thnks.
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I was at the dig where they found this... must have found it after I had left. Bugger.
Anyway, excellent work.
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Never done any other of the Strzelecki digs - been on a few of the Otway sessions though, notably "Eric the Crayfish" (Eric the Red West) where they found that articulated ornithopod + spinosaur cervical.
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Megaraptoran allosaurs (the "polar-Allosaurus astragalus is from the same unit), various small ornithopods, lungfish and Koolasuchus.
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Do you think relatives of Deltadromaeus could turn up in Australia? And what kind of dinosaur would be Australia's most likely cretaceous apex predator? Big megaraptorids, or something more like Giganotosaurus?
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According to the Fitzgerald et. al paper, one analysis has NMV P221202 as the sister taxon to Deltadromeus within Abelisauroidea.
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Oh great, another good skeletal ref would be Delta' then
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Great that this thing is finally published.
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That's even more aweosme!
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A Victorian noasaur sounds quite interesting.
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Megaraptoran allosaurs (the "polar-Allosaurus astragalus is from the same unit), various small ornithopods, lungfish and Koolasuchus.
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