Revisiting the identification of Syllipsimopodi bideni
“Recently, on the basis of a single specimen (ROMIP 64897) from the Royal Ontario Museum (Canada), Whalen and Landman described the new coleoid taxon with a fairly completely preserved frontal part as Syllipsimopodi bideni. The specimen, recovered from the Bear Gulch Limestone, Heath Formation in Fergus County, Montana, USA, is of Serpukhovian age Based on the suggested presence of a gladius, ten arms, and fins, as well as the supposed absence of a phragmocone, the authors interpreted the “remarkably well-preserved” specimen as “the oldest definitive vampyropod and crown coleoid”. We herein test if the fidelity of preserved characters in S. bideni affects the interpretation of this organism—particularly by comparing these characters to other soft bodied cephalopod fossils from Bear Gulch. We provide evidence for the likely synonymy of S. bideni and Gordoniconus beargulchensis. Our interpretation casts doubt on the phylogeny proposed by Whalen and Landman, who suggested S. bideni as the oldest vamyropod. Vampyropoda ( = Octobrachia or Octopodiformes) is considered to be the sister group of all ten-armed cephalopods (Decabrachia), which is also supported by recent molecular analyses.” Read more