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  • Underwhelming Fossil Fish of the Month: April 2016

    By Mark Carnall, on 29 April 2016

    Since the last Underwhelming Fossil Fish, we’ve been betrayed comrades. Last month, one of our own, a hitherto underwhelming fossil fish got interesting, as hacks reported. Of course, nobody remembers this news now but the underwhelming fossil fish of the month community was rocked so hard by this betrayal, et tu Tully Monster?, that there wasn’t an underwhelming fossil fish of the month for March 2016, the first ever break in the series. In a touching act of solidarity, appropriately for the series, nobody even seemed to notice. This month, there haven’t been any more turncoats so we can get back to the business of this blog series, that is to celebrate the unremarkable fossil fish in museum collections precisely for their distinctive uninterestingness.

    This month, widely heralded on the Twitter as #TheReturnOfFossilFish, I’ve got a specimen that’s appropriately uncommemorating in any way, unless slightly resembling a bald person’s head whilst they are frowning, is at all commemorative.

    Image of LDUCZ-V1244 Ptychodus sp. tooth from the Grant Museum of Zoology

    LDUCZ-V1244 Ptychodus sp. tooth . Photography continues to slip in that this month we do have the correct background but sadly no scale bar. It’s almost enough to want to go back to the good old days of the unreliable but affordable USB miscroscope. ALMOST ENOUGH.

    This wonderful fossil, resembling a topographical map of a mushroom is, according to the label, in fact a tooth from a fish in the genus Ptychodus. Ptychodus and related fish are hybodont sharks, an extinct group of cartilaginous fish closely related to today’s modern sharks and rays. Ptychodus lived from the end of the Cretaceous period through to the Palaeocene epoch from 95 to 60 million years ago, surviving the mass extinction that did in for the ammonites, belemnites, plesiosaurs and some other obscure group of reptiles whose name escapes me. Ptychodus is a well known genus of fossil shark as the hard teeth, like this specimen, are more readily preserved than soft tissue and cartilage and each individual shark would have had numerous sets of these flat teeth throughout life and up to 550 teeth in the jaws at any one time. Similar in function to modern ray teeth, hundreds of these broad teeth arranged in a battery would probably have been used for crushing shells of marine molluscs and crustaceans (a durophagous diet). Unfortunately, we don’t know where this fossil was collected but one of the numbers written on the underside, indicates it was once part of the UCL Geology collections. Hybodont shark experts out there may be able to identify which species this tooth is from from the pattern of the raised bars on the tooth, if so, drop a comment down below!

    Preservation All we’ve got here is the tooth so in terms of the whole animal the preservation isn’t fantastic however, what is preserved is what palaeontologists call ‘nice’. As this slightly zoomed in image of the surface of the tooth shows:

    Image of LDUCZ-V1244 Ptychodus sp. tooth from the Grant Museum of Zoology

    LDUCZ-V1244 Nice. Close up of the surface of the tooth of Ptychodus sp.

    There’s even a little not so hidden angry face which is always a treat and quite distinctive as these ridges on the teeth.

    Image of LDUCZ-V1244 Ptychodus sp. tooth from the Grant Museum of Zoology

    Hidden angry face in LDUCZ-V1244 not at all an attempt to engage with the young people, 80% of which enjoy emoticons according to our  marketing department

     

    Research Due to being quite common and readily identified as teeth, Ptychodus fossils have a long history when it comes to scientific research and there are some palaeontological luminaries who have pondered the fossils, albeit not for very long. Ptychodus was first described by legendary geologist Louis Agassiz in 1833. In 1868, palaeontologist American palaeontologist Joseph Leidy, better known for describing Hadrosaurus and the extinct dire wolf, commented on American fossil species of Ptychodus, distinguishable from European species by their “generic peculiarity” which is high praise in the world of underwhelming fossil fish (Leidy 1868). Although isolated teeth are fairly common it wasn’t until the discovery of an articulated set of teeth in 1976 that the structure of the teeth was described, each tooth possessing structures to interlock with adjacent teeth, giving the tooth battery strength for engaging in the business of crushing shelly animals (Macleod 1982). A more recent paper is a notable contribution to the history of Ptychodus, the first known example of a Ptychodus-bearing coprolite, that is fossilised faeces with a tooth in it. The discussion section in particular is of interest, the serious scientific examination of whether or not this was a tooth swallowed by a Ptychodus or that of a predator (Shimada 1997). Although there are hundreds of references mentioning Ptychodus, most merely mention that teeth were found during the more interesting business of describing extinct crocodyliform reptiles, crocodiles, lizards, mammals and even, for shame, other more interesting fossil hybodont sharks.

    In Society Until recently, it was thought that Ptychodus and 16th Century Danish astronomer and astrologer Tycho Brahe may have been related because their names sound the same. Recent analysis has determined that Tycho Brahe, who lost his nose in a duel over a mathematical theory, owned one percent of the wealth of Denmark in 1580 and discovery of librations in the inclination of the lunar orbit plane was in fact nothing to do with the Cretaceous shark at all beyond the similar beginning part of the name.

    Ptychodus sp.
    Preservation 7 (+1 angry face bonus)
    Research 5
    In Society 0.5
    Underwhelmingness 8

    References

    Leidy, J.. (1868). Notice of American Species of Ptychodus. Proceedings of the Academy of Natural Sciences of Philadelphia, 20, 205–208. Retrieved from http://www.jstor.org/stable/4059893

    MacLeod, N.. (1982). The First North American Occurrence of the Late Cretaceous Elasmobranch Ptychodus rugosus Dixon with Comments on the Functional Morphology of the Dentition and Dermal Denticles. Journal of Paleontology, 56(2), 403–409. Retrieved from http://www.jstor.org/stable/1304466

    Shimada, K.. (1997). Shark-Tooth-Bearing Coprolite from the Carlile Shale (Upper Cretaceous), Ellis County, Kansas. Transactions of the Kansas Academy of Science (1903-), 100(3/4), 133–138. http://doi.org/10.2307/3628001

    Mark Carnall is the Collections Manager (Life Collections) at the Oxford University Museum of Natural History, and former Curator of the Grant Museum

    3 Responses to “Underwhelming Fossil Fish of the Month: April 2016”

    • 1
      Whewell’s Gazette: Year 2, Vol: #38 | Whewell's Ghost wrote on 4 May 2016:

      […] UCL: Underwhelming Fossil Fish of the Month April 2016 […]

    • 2
      Helen Chavez wrote on 8 May 2016:

      Sorry, but this is a Whelming Fossil. I even recognised what it was. “That’s a tooth!” I exclaimed to myself. I have to admit I didn’t see the angry face until you pointed it out, but hey – nobody’s perfect.

      But sadly, I think the foray into fame has gone to one’s head and you’re subliminally looking for even more cheap excitement. A palaeo-Kardashian. Sorry if that comparison hurts, but this is Tough Love. I need more lumps of rock. More badly-written (and incorrect) labels. More of the old days of the unreliable but affordable USB microscope.

      On the plus side, though, that is one heck of a lovely and very interesting tooth. Interlocking structure, eh? That, I’m also sorry to say, is AWESOME.

    • 3
      Underwhelming Fossil Fish of the Month: August 2016 | UCL Museums & Collections Blog wrote on 31 August 2016:

      […] (durophagous) and possibly even nipped on coral as modern reef fish do. However, unlike Ptychodus, they do not have angry little faces on their teeth. This is how you can tell them apart in the field. This and the fact they they look completely […]

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