By Mark Carnall, on 19 June 2013
According to the age old adage, all fossil fish are born equal. This isn’t true. Some fossil fish are born, then die, then get fossilised to wow and impress. Suffice to say that not all fossil fish can be superstars, opening shopping centres, turning on Christmas lights and the like. Some fossil fish are born, then die, then get fossilised, to underwhelm. To de-inspire. To turn people away. If had a dime for every bank manager, accountant, dentist and cashier I’ve met who turned down a lucrative career in palaeontology because of an underwhelming fossil fish, then after the Bureau de Change took a cut I’d be out of pocket, I can tell you.
It’s June already meaning that including this one we’re only four more of these away from having enough monthly underwhelming fossil fish to produce a very uninspiring calendar. This month, in order to spice up the normally dry description of a particularly uninteresting fossil fish, see if you can guess what this month’s fossil is from the underside of the box. CLUE: it isn’t Sarcoprion edax.
Yes! As some of you may have correctly guessed this box holds this wonderful fin spine from Gyracanthus sp. Here it is in all its glory.
What is a fin spine I hear you say? Well in palaeontological circles at some field localities a fin spine is anything that is long and thin that doesn’t look like anything else. More scientifically, fin spines are large bony spines that support the fins in a group of fish called Acanthodii, AKA ‘spiny sharks’ even though they aren’t sharks. Acanthodii is an extinct class of fish that thrived for 200 million years appearing at least as early as the Silurian Period and eventually going extinct in the Permian. It’s easy to think of fish being one big group of swimmy, finny animals but there are at least six fundamentally different ways of being ‘a fish’ with each class being more distinct from each other than say every single mammal (from humans to shrews to whales to bats to armadillos) which is but one puny class.
Gyracanthus, a genus found in the Devonian and Carboniferous is a bit of an enigma as fossils in this genus are only known from isolated fin spines like this one and a few other isolated bones. Better preserved and complete individuals of fish presumed to be in the same family as this one have been found shedding some light on what these fish may have looked like. The function of the spines is still debated but it’s thought that these rigid spines held the fins in place and may have functioned much like the wings of an airplane, earlier interpretations of these were that they were used in defense.
Preservation The detail on this fin spine is amazing but don’t take my word for it. have a look yourself.
Gyracanthus fins spines are covered in ridges and tubercules. The ornamentation along this spine are symmetrical around the spine and as the spine itself is relatively straight so this spine is probably one of the paired dorsal spines along the back of the fish. Written on the specimen is Smeaton and the label records this specimen from Coal Measures. One interpretation of this information is that this specimen is from Smeaton Colliery in East Lothian, Scotland. This is consistent with other specimens which have been recorded from Scottish coal measures making this specimen approximately 300 million years old. We’re most familiar with coal being the shapeless lumps associated with misbehaved children, however, some of the most important and best preserved fossils are excellently preserved in coaliliferous sediments including plants, some of the earliest vertebrates on land and this spine.
Research As ever, former curator of the Grant Museum and renowned palaeontologist D.M.S Watson has something to say about Gyracanthus. In his 1937 tome, The Acanthodian Fishes, Watson briefly mentions Gyracanthus, then thought to be the remains of shark. He only mentions them to say that they probably aren’t. More often than not Gyracanthus gets a cursory reference and is recorded as ‘also found’ amongst descriptions of far more interesting animals. However, for underwhelming fossil fish there was a recent (over a decade ago) boom in interest in Gyracanthus from one paper in particular. In 1999, Sullivan, Lucas and Randall published a never before described scapulocoracoid complex (shoulder) of Gyracanthus resulting in a reinterpretation of what Gyracanthus and its relatives may have looked like. But of course, I needn’t remind you of this. I remember exactly where I was when this paper came out and I’m sure you do too.
In Society Says it all really.
In Society 0
Watson, D. M. S. 1937. The Acanthodan Fishes. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences , Vol. 228, No. 549, pp. 49-146.
Mark Carnall is the Curator of the Grant Museum of Zoology
UPDATE: The typotron-3000 filter seems to have failed this month. Updated a number of typos and grammatical errors.