By Mark Carnall, on 31 March 2017
It’s the end of March which means only one thing. Well it means many things but in the specific context of this monthly series that explores the underwhelmingest of fossil fish, which to be honest is most fossil fish, from the collection at the Grant Museum of Zoology it means its time for a new one.
But don’t confuse this perfunctory progress of the seconds, minutes, hours, days and months as an excuse for any kind of celebration. That’s not what we’re here for. Instead we are here to review a not-very-interesting fossil fish, unloved by all but the most…. no, just unloved by all. Why might we do this? Well as the French say, “C’est la fin des haricots”.
So without further ado, as the Germans say, “Wer weiß, warum die Gänse barfuß gehen”.
Here’s this month’s fossil fish.
Someone has helpfully varnished around the fossil, which makes spotting it on this giant chunk of rock that little bit easier. According to the label for this specimen and indeed the label written directly onto the surface of the specimen, this is a fossil of Rhamphodopsis threiplandi from Edderton in Scotland and this fossil is individual plates of the dermal armour. If you squint from a distance you can convince yourself you can see what they are in this image.
Rhamphodopsis threiplandi is one of two species in the genus Rhamphodopsis which are ptyctodont placoderm fish. Placoderm fish are an extinct group of armoured fishes and ptyctodonts (pronounced p-t-y-c-t-o-d-o-n-t*) were an unusual group that bear an extremely suspicious similarity to chimaeras, the cartilaginous fish not the goat/lion/snake monsters from mythology. You may remember Rhamphodopsis from April 2014’s underwhelming fossil fish of the month and I think you’ll agree this specimen is almost exactly as uninteresting. How very underwhelming or as the Italians say, “Trattare a pesci in faccia”.
Preservation This month we’ve got a fossil that has stirred the old fieldwork memories so it’s time for the first ever TALES FROM THE FIELD…
This specimen of Rhamphodopsis threiplandi looks like it has been varnished possibly to keep the sections together or from falling apart. From the large size of this specimen, it’s one that hasn’t been prepared from when it was collected in the field and could do with some cutting down of the excess matrix to take up less space in museum drawers. When collecting fossils in the field it’s always a difficult decision to decide when to draw the line in chipping down larger fossil bearing rocks to be more portable versus the risk in smashing the fossil altogether. A seasoned collector will be able to trim a fossil down to size, so it’s less to lug around in the field, with a well aimed whack or two. For those who are less adept, they’ll keep hammering away or make a misjudged tap that will split the fossil into many pieces, breaking it in a way that is near impossible to unite again. Even after onlookers suggest that they might want to think about holding off trying to split the fossil until there was a better plan, or at least a referendum that made sense or at the very least some kind of mandate some people just wanna break it up. Even if it ruins lives or appears to be inherently stupid or even embarrassing to be lugging around a big ol’ lumpy fossil sometimes. But do you want a slightly lumpy fossil that exists or do you break it up and have nothing? Ahh, there’s nothing quite like fieldwork, or as the Belgians say “Waarheid als een koe”.
Scientific Research The two species of Rhamphodopsis have caused an amount of head-scratching amongst palaeontologists for the similarity with chimaeras or rabbit fish the lesser known relatives of sharks, skates, rays and sawfish still represented by living species today. In addition to a similar bizarre body shape, large head and eyes, unusually for fossil fish Rhamphodopsis are also thought to show sexual dimorphism. Rhamphodopsis specimens with large pelvic claspers preserved are presumed to be males and the same feature is seen in chimaeras. The superficial resemblences are curious but finer details including differences in the teeth, skin, armoured plates and scales indicate that these two groups aren’t closely related, similarities may be due to convergent evolution or as the famous Greek saying goes “Έχω χάσει τα αυγά και το καλάθι μου”.
In Society Unlike most other fossil fish featured here, Rhamphodopsis threiplandi, is extremely famous and well known across all sectors of society for what the Danish call “Det blæser en halv pelican”. And I think you’d all agree too right?
In Society 0.2
*That’s PTYCT O DONT. PARLEZ VOUS FOSSIL FISHEZ?
Mark Carnall is the Collections Manager (Life Collections) at the Oxford University Museum of Natural History, and former Curator of the Grant Museum