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Machairaspis - A Jawless Fish of the Devonian

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  • Neal Robbins
          This link has a piece of artwork that portrays Machairaspis and other fishes. Machairaspis is the one with red and orange coloration.
    Message 1 of 1 , Apr 30, 2013
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          This link has a piece of artwork that portrays Machairaspis and other fishes. Machairaspis is the one with red and orange coloration.
          Machairaspis was a genus of jawless fish that lived during the Devonian. The systematic paleontology of Machairaspis is:
      Agnatha Cope Cope 1889
      Osteostraci Lankester 1868
      Zenaspidida Stensio 1958
      Zenaspididae Stensio 1958
      Machairaspis Janvier 1985
      Machairaspis battaili Janvier 1985
      Machairaspis corystis Janvier 1985=Cephalaspis corystis Wangsjo 1952
      Machairaspis isachseni Janvier 1985=Cephalaspis isachseni Wangsjo 1952
      M. ibex Janvier 1990
      M. hastata Janvier 1990
      M. serrata Wilson 2013
          Fossil remains of a new species called Machairaspis serrata were found in Canada. They date to the Lochkovian age (416 - 411 million years ago) of the Devonian. Mark V.H. Wilson wrote an article titled A new species of osteostracan from the Lochkovian (Early Devonian) of the Mackenzie Mountains, with comments on body size, growth, and geographic distribution in the genus Machairaspis. It was published in 2013 in the Canadian Journal of Earth Sciences. This quote from the abstract says:
          Machairaspis, a genus of the Osteostraci, an extinct clade of jawless vertebrates, has been reported from localities in Spitsbergen, Norway, Podolia (Ukraine), and Prince of Wales Island (Nunavut, Canada). A new species of Machairaspis, described from the Delorme Formation at the MOTH locality, extends the geographic range of this genus to the Mackenzie Mountains. Machairaspis serrata sp. nov. is known from a very small headshield and a fragment of an even smaller individual. The two specimens share distinctive, dorsally pointed serrations on the posterior margin of the exceptionally tall dorsal spine of the headshield. The new species can also be differentiated from other species of Machairaspis by characteristic rows of denticles along the headshield and is represented by much smaller individuals than are known for previously described species in the genus. Differences in the proportions of the cephalic spine illustrate allometric increase in relative spine height during growth, as previoulsy documented for the related genus Superciliaspis. Machairaspis is here included with Scolenaspis in the subfamily Scolenaspidinae, sister to the subfamily Zenaspididae. The presence of Machairaspis at MOTH is an additional similarity with Early Devonian fauna of Spitsbergen and is consistent with Lochkovian (Early Devonian) age that has been previously for the Moth locality and with the suggestion that Spitsbergen represents part of the Laurentia terrane.
          Neal Robbins
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