A couple of months ago I commissioned a painting of the shop logo shark, Akmonistion zangerli, from the palaeontological artist Bob Nicholls. He sent me this preliminary sketch (left) before starting work in the middle of May. He finished last week and sent me a picture of the completed work, which should arrive in a couple of days. You can see the picture below. The little fish are Acanthodes, a foot-long spiny shark abundant in the Early Carboniferous.Akmonistion was found in the early 80s by Stan Wood in the Manse Burn Formation, a 330 million year old series of rocks in Bearsden, Glasgow. The most complete specimen found is in the collection of Glasgow University's Hunterian Museum, who employed Stan as a fossil hunter for a time. There were some truly weird sharks (see Helicoprion) patrolling the
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seas of the Carboniferous and Akmonistion was certainly one of them. It was a stethacanthid shark, about the size of a big dogfish, and males had an anvil-shaped brush-like fin crested with little denticles covering the flat surface on top. These spiky, scaly bits were also in a patch on top of its head. A number of suggestions have been put forward for their purpose; display, as a weapon of sorts or even a way of hitching a lift by clamping on to a larger swimmer. Perhaps the most plausible is that they were used much like a stag's antlers, in a battle to prove dominance. Some pieces I have read on them say that only male stethacanthids have been found with the spiky anvil, and in fact only males have been found at all, suggesting that the females have been given another name entirely. It may be that Symmorium, a contemporary and similar shark of which apparently only females have been found, is the girl to the stethacanthid's boy - and consequently the reason behind the strange fin. I'm not sure about this, as I have also read articles about the Bearsden material that suggests both male and female sharks were found - some sexual dimorphism in the number of denticles (and presence of claspers) - but female stethacanthids. I'll need to ask...
Anyway - Bob's work is always great, so it's no surprise that the commission has turned out so well. I'm looking forward to getting it framed and up on the wall.
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7 comments:
Good to have pictures to bring stuff to life for dullards like me who lack imagination!! Top new site, really impressed!
{anyone reading this who hasn't seen Matt's site should a] go to it immediately and b] buy something as penance, hardly punishment given his quality}
www.mrwoodsfossils.co.uk
Thank you Christopher. The painting arrived this morning and is now at Greyfriars Gallery just around the corner getting framed.
Awesome! I'd love to get a piece with various Jurassic fish!
Look forwards to seeing next time I get to Edinburgh!
Emma
I wonder if they were not used as a tool, much like the sword of the swordfish? The big clue is the fact that there are large denticles, making it, in essence, a rasp.
Since this was a small shark, it likely fed on smaller prey, and one could easily imagine the animals using such a rasp to remove small animals or groups of shells from overhanging rock formations. Modern sharks are known to fall into a coma-like trance if turned upside-down. This is common to many species and is therefore likely a very ancient and common trait. Perhaps the shark could feed easily on such ground or reef dwelling crustaceans or cephalopods, bivalves or similar, provided the angle was not too steep. But if called upon to "graze" off overhanging structures, would be unable to do so. I could easily see an evolutionary path whereby the sharks started by merely rubbing with the rough skin of their backs, followed by a mutation which allowed the development of an ever more specialised tool-like structure for rasping off bivalves or similar from overhanging structures. Big advantage over those sharks who lacked this ability...
Sounds like a convincing argument to me. If the sexual dimorphism suggestion is wrong, then far more likely an explanation than display/dominance theory. Need to look into it more.
The shark's actual teeth will give an indication of its diet and they seem suited to fish. While this might rule out shell-crushing, it doesn't preclude soft bodied reef-clingers...
Agreed, I had thought that the dentition might give some clue, especially in context of modern species that eat a diverse range of smaller creatures or a perhaps analogous diet. Let's thrash this out, and if it looks reasonable after testing, we should write it up.
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