Underwhelming Fossil Fish of the Month: June 2015
By Mark Carnall, on 30 June 2015
Now, this is the story all about how
My life got flipped-turned upside down
And I’d like to take a minute, just sit right there
I’ll tell you how I became an underwhelming fish fossil.
This might be how this month’s underwhelming fossil fish of the month would introduce itself, were it not a fossil fish and if fish could rap in the first place and if fish were keen fans of the Fresh Prince of Bel-Air and if the Fresh Prince of Bel-Air was aired in the Devonian. But unfortunately it is, they can’t, they’re not and it wasn’t. So it’s down to me to introduce yet another monthly underwhelming fossil fish in my mission to increase global fishteracy and to temporarily shine a spotlight on unloved museum specimens.
As you can tell from the flimsy preamble, there’s not much to say about this month’s specimen so back away from the edge of your seat and lower your expectations. We’re in for a uneventful ride.
Whilst searching the fossil drawers for this month’s candidate specimen, this one didn’t jump out at me at all which normally means it’s ripe for the blog treatment. I’d like you to take a minute to gaze upon the almost featureless pastel coloured mélange.
If you’re still with me then you have a very high threshold for underwhelment. This one’s not much to write home about at all. In fact I’ve had the displeasure of looking at this fossil what feels like weeks and there’s very little that jumps out and even less that I could confidently point to and identify. The bit on the left might be the head? There are some bobbly bits which are a key feature of the genus Coccosteus, which this has been identified as. Coccosteus is a Devonian genus of freshwater fishes which have been found throughout Europe and North America. This specimen was collected from Lethan Bar in what was Nairnshire in north east Scotland. Coccosteus is an arthrodiran placoderm fish, a group of armoured jawed fish that didn’t possess individual teeth but had a bony plate as a biting surface, sort of like, biting you with their skeleton which is cool and a bit weird from our toothed perspective.
Preservation I was all prepared to write a very short section here along the lines of ‘move along, nothing to see’ etc. However, when I checked our fossil vertebrate catalogue I found that this specimen is listed as a ‘very juvenile’ Coccosteus and that this specimen apparently ‘Shows “palatal” teeth better than any yet described’. Palatal teeth are teeth on the palate and warning may gross out people who have issues with teeth here’s what it might look like in humans. A number of reptile species have teeth on the roof of their mouth that help to grasp prey and stop it from slipping away and you may have spotted them inside the gob of the one-trick super gigantic mosasaur in Jurassic World. Coccosteus probably didn’t have palatal teeth but had an arrangement of ‘gnathal elements’ that may have functioned in the same way. In any case, I’ve scoured the surface of this specimen with a hand lense and even with the ever disappointing but temptingly cheap USB microscope I’m afraid I can’t confidently identify any teeth elements, let alone excellently preserved ones.
As an aside, I found one paper looking for illustrations of these teeth and there is mention of an excellent specimen of Coccosteus at UCL, a rare specimen showing the inside of the head (Heintz 1931). It’s described as a remarkable specimen from London University and one that frustratingly no longer seems to be here. So in short, move along, there’s literally nothing to see here.
Research Unlike other fossil fish which have been featured in this series, after a quick literature search, there are lots of mentions of Coccosteus and new species have relatively recently been described. In particular, as Coccosteus are fairly common and well described arthrodiran fish, they are often referenced when inferring the structure and function of armour in related fish. In many ways they are the ready-salted flavoured crisps of the arthrodirans in that they’re alright but you’d prefer to take cheese and onion, salt and vinegar or Worcester sauce if given the choice. Another feature of Coccosteus which gets a lot of mention is that the armour of the head was much more free and flexible than other armoured fishes so it is hypothesised that Coccosteus and close relatives could move their ‘upper and lower’ jaws to create a relatively wide gape. Sadly for Coccosteus, they are often mentioned at the same time as megastar, bigger, sexier relatives Dinichthys and Dunkleosteus, truly ununderwhelming fish that tend to steal the limelight because palaeontology works much in the same way as Hello! magazine does.
Popular Culture Here’s the rest of the intro because I know that’s what you’ve been waiting for.
In northeastern Scotland, born and raised
In freshwater environments I spent most of my days
Chillin’ out, maxin’, relaxin’ all cool
And all taking advantage of an articulated skull for a wider gape to feed on fairly large prey
When a geological event which was up to no good
Started burying everything and everyone in my neighborhood
I got in one little preserving environment and my mom got scared
And said, “You’re turning into a fibro-calcareous nodule and fossilising”
I waited for a palaentologist for 400 million years and when it came near
They commented on my excellently preserved gnathal elements
If anything I could say that this palaeontologist was rare
But I thought, nah forget it, yo home to a lifetime in a museum
I pulled up to the museum about seven or eight
And I yelled to the curator, nothing as my body had been turned to stone
Looked at my kingdom, I was finally there
To sit on my throne in fossil drawer 4
1931. Revision of the structure of Coccosteus decipiens Ag. Norsk geol. Tidsskr. 12: 291–313.
Mark Carnall is the Curator of the Grant Museum of Zoology