By Mark Carnall, on 30 January 2014
It’s the first underwhelming fossil fish of the month for 2014 and in order to usher in the new year I’ve picked a particularly unspecial fossil fish for your eyes only. If you want to be underwhelmed even more then all the UFFoTM posts can be found under this handy tag. First up though, what does this look like to you?
Wow. Well from your response I can tell you have some serious psychological issues that need dealing with. The above image isn’t actually a fossilised Rorschach inkblot (named after the comic book character with the same name in the Watchmen). The keen eyed amongst you will have spotted that it’s actually this month’s fossil fish of the ahem month albeit digitally tweaked. You know you’re in for a treat when the most interesting aspect of it is that it resembles an amorphous splodge and tenuously at that. Read on in the vain hope that it gets better than this.
This lovely fossil has a heft to it. It’s a big ‘un and note the wonderful straight edges. Three of the edges have a smooth texture like the underside of a Cadbury’s caramel bar, the fourth (lower edge in the picture below) is much rougher, the assumption is that this edge of the fossil was exposed and the fossil excavated and prepared from a mere splodge in cross section. According to the excellent not-at-all museum standard label handwritten on the front of the specimen in permanent ink this fossil fish is Cheiracanthus sp. There are three species of Cheiracanthus but I’m not confident enough to be able to identify this without a lot more research into the diagnostic features of each one. Cheirocanthus is a genus of freshwater acanthodian fish, an extinct group of fish confusingly referred to as spiny sharks although they are not sharks at all let alone true sharks (more on the idea of ‘true’ animals and the confusions they cause here). The distinctive scales of Cheiracanthus are found in rocks across the world but whole body fossils like this are known from Scotland. Sadly, we know we don’t have any further documentation about this specimen beyond it coming to the Grant Museum from Imperial College London in the 1980s.
Preservation Although it doesn’t look like much from a distance, considering that these fish didn’t have bony skeletons and are rarely found as whole body fossils, the detail of the skin is amazing. The three dimensional preservation looks and feels like the skin of a fish. It very much tastes like rock sadly. Not particularly tasty rock either. The fin spines give us some visual references and parts of the pectoral spines are preserved so I think our fish is preserved in this orientation (see below). There’s even a circular area of the skin without scales that’s tempting to attribute as the eye socket. Not too shabby for a fossil that’s probably 380 million years old.
Research As with most of the fossil fish we have here, former curator of the UCL zoology collection and legendary fish palaeontologist, D.M.S Watson has a number of papers on these animals including a wonderfully preserved individual that was here at UCL, presumably now at Cambridge. The specimen was so well preserved that the tissue detail, particularly the arrangement and position of myotomes, could be discerned and described (Watson 1959). From a quick search of the literature Cheiracanthus mostly features in dry lists of fossil fish and as a reference organism for more interesting relatives. Ho hum.
In Society Whilst
googling exhaustively researching this genus, I was pleasantly surprised to find that a number of the top results were about how to catch Cheiracanthus in a somewhat niche Nintendo Wii title Wii Fishing Resort. According to the Wii Fishing Resort Wikia, indeed the ancient fish can be caught alive and well. Fittingly it is found on the Scottish course. Important to note that in addition to players looking for this digital fish being ranked higher on Google than palaeontological resources the Wii Fishing Resort Wikia page is about the same length as the English language Wikipedia page. I leave why that might be up to you dear reader.
In Society 2
References Watson, D.M.S. The Myotomes of Acanthodians Proceedings of the Royal Society of London. Series B, Biological Sciences , Vol. 151, No. 942, pp. 23-25
Mark Carnall is the Curator of the Grant Museum of Zoology