Underwhelming Fossil Fish of the Month: February 2016
By Mark Carnall, on 26 February 2016
February 2016 won’t be remembered as the beginning of the end because nobody will be here to remember it. The plankton are a-shuffling, the seabirds are a-vanishing, the seas, they are arising and the Arctic is a-heating. Was it this bad growing up? It is getting worse and worse. Did we pass the point of no return already? Are we already in the Age of Stupid? Did our children volunteer for this? Can you honestly kiss them goodnight knowing that they’ll grow up with the same liberties and freedoms we enjoyed or will it be a fight for basic survival like so many already endure today?
[Note to editor. If the intro is ‘too real’ I could change it to something about croissants being straightened but that’s a harder segue.]
I tell you who won’t be fighting for survival anymore and that’s underwhelming fossil fish, the ‘stars’ of this monthly series, where we take a break from the harsh realities of life to focus on the uncelebratable fishy fragments of the Grant Museum fossil drawers. Why, you ask? Well. It passes the time if nothing else, the most precious resource you have. But who are you kidding? You got this far, you clearly don’t have much pressing on.
This month’s fossil fish is technically naked so I’d advise having a spreadsheet open in another window that you could Alt+Tab to, to save the blushes of passing colleagues.
Blushes, hopefully spared, this beautiful nu.. what do you mean where is it? It’s clearly this innocuous smudge in the bottom left, not the deceptive hammer marks on the right that look a helluva lot more interesting. The very faint line above it might be either the trace of the outline of this fish or a conveniently ridge in the rock. Zooming in any closer, borders on the pornographic so we’ll keep a respectable distance.
Blushes, hopefully spared, this beautiful nude is an example of Lasanius problematicus, a name that I’m finding very difficult not to write as Lasianus. Lasanius problematicus is a basal (thought to be a very early kind of) anaspid fish – a class of jawless fish distinct from the other early jawless fish which had bony armour. Lasanius problematicus is described as naked, lacking bony plates or scales. As the name implies, this species is a bit of an enigma which we’ll come on to. Lasanius problematicus is closely related to Birkenia which have also been featured here, which puts the anaspids in contention for the most underwhelming class of fish of all time based on this highly subjective small sample set. Lasianus Lasanius problematicus is only known from 420 million year old Silurian rock deposits in Scotland. Scotland, the Pompeii of fossil fish albeit without the volcanic ash, or people, or 2014 film glorifying the ancient tragedy with John Snow in it. According to the unusually good label on this specimen, this was collected by F.R.Parrington from Slot Burn in Scotland in 1949 which is VERY EXCITING for reasons we’ll come on to.
Preservation Archaeologically speaking, this fossil is a complete perfect example of Lasianus Lasanius problematicus, meaning that it’s incomplete and missing bits. By bits, I mean most of the animal. What we do have here though, appears to be the, bear with me, lateral spine and post-cephalic rods, a particular feature of Lasianus Lasanius problematicus that caused generations of fish palaeontologists to puzzle over this species. Even though it may not look much, one could argue, this is absolutely the most interesting bit of this fish, or at least in the top three most interesting bits. Which isn’t a stiff competition given that aside from the head and some spikes along the back there’s not actually much more to these fish that readily preserves.
Research Normally, there’s never much to go in this section. Most of the fossil fish we feature here have, at best, a noteworthless career appearing in dry geographical lists of fish species found. With Lasanius (yes!) problematicus, there’s a twisty-turny tale of mild intrigue, momentary chin scratching and poor line drawings. Which for a Silurian fossil fish is as good as it gets. Lasanius problematicus was first described by Ramsay Heatley Traquair, a Scottish palaeontologist of some repute. Traquair originally figured and described Lasanius upside down but didn’t make much attempt to interpret the weird lateral rods and spines we have here. Later scientists, recognising the age and taxonomic position of these fish, posited that these rods and spines could be beginnings of the visceral skeleton and branchial arches, which in later fish became jaws so Lasanius could be the earliest or very early ancestors of far more interesting later fishes and the first animals to evolve the skeletons we know and love today. The problem with interpreting Lasanius caused palaeontologists some consternation, especially whether the lateral rods were internal support or external projections (Stetson 1927) and even legendary palaeontologist George Gaylord Simpson was hesitant to speculate if Lasanius truly represented a naked ancestral vertebrate (Simpson 1925). It wasn’t until 1958 that Francis Rex Parrington, the collector of this fossil and later Director of Cambridge University Museum of Zoology, that these lateral spines were interpreted not as gill arches but as supports for a primitive fin (Parrington 1958). Interestingly, this paper was published in 1958 in a special volume, Studies on Fossil Vertebrates, which was presented to our old friend D.M.S Watson who collected many of the specimens featured in this series. Given that Watson
stole would borrow specimens from Cambridge University Museum of Zoology for extended periods of times and Parrington collected this specimen and wrote the paper revising this odd structure, could this specimen have been figured or mentioned? Frustratingly, I’ve not been able to get hold of this paper in time for this to go out to check.
Unfortunately for Lasanius, better candidates for the earliest vertebrates have been discovered, including living hagfish and lampreys. Now Lasanius and the other anaspids are considered a derived group of jawless fish, and not the direct ancestors of vertebrates.
In Society Nothing says societal impact like this sad flickr photo of a Lasanius plaster model fallen off of its stand at the National Museums of Scotland. The symbolism of its fallen status as a potentially interesting fish is strong.
Preservation 2 (10 if you’re archaeologically inclined)
In Society 0
Parrington, F.R. (1958) On the nature of the anaspida. In Studies on Fossil Vertebrates (ed. T.S. Westoll), Athlone Press, London, pp. 108–28.
Simpson, G.G. (1926) New reconstruction of Lasanius. Bulletin of the Geological Society of America, 37, 397–402.
Stetson, H. C. (1927) Lasanius and the Problem of Vertebrate Origin. The Journal of Geology 35 (3). University of Chicago Press: 247–63.
UPDATE 26/02/2016 Updated a few typos that managed to sneak through the editing machine.