First Neogene Record of an Articulated Polyplacophoran

Deep molluscan phylogeny: synthesis of palaeontological and neontological data

“…Fossil polyplacophorans are typically represented by isolated valves. Articulated fossils, while relatively rare (Dell'Angelo et al 2003), are more informative, and thus more significant for phylogenetic studies. All polyplacophoran-like articulated Palaeozoic fossils were included in our study after an exhaustive review of the literature, with the exception of two genera that, although represented by articulated material, are too poorly preserved for meaningful characterization.…”

Late Pleistocene and Holocene chitons (Mollusca, Polyplacophora) from Uruguay: Palaeobiogeography and palaeoenvironmental reconstruction in mid latitudes of the southwestern Atlantic

“…The fossil record of chitons remains poorly known as their occurrence as fossils is sporadic and occasional, especially when compared with the more diverse molluscan classes Bivalvia and Gastropoda. The oldest remains of this group extend back to the Upper Cambrian (Smith, 1960) and with the exception of some infrequent preservational conditions (e.g., Dell'Angelo et al, 2003;Pojeta et al, 2003;Vendrasco et al, 2004), most palaeontological records are based on disarticulated and isolated plates. The fossil record of chitons is also a poorly investigated topic and it has not been adequately assessed with respect to geographic areas or geologic time (Puchalski et al, 2008).…”

An Eocene Articulated Polyplacophora (Mollusca) from the La Meseta Formation, Antarctica and the Stratigraphy of the Fossil-Bearing Strata

“…Otherwise, postmortem transportation and long exposure on the sea floor would result in the decay of the muscular girdle and subsequent loss of valve articulation. Preservation or disintegration of the girdle may still be possible in anoxic or dysoxic settings (Dell'Angelo et al, 2003), but in that case the postmortem contraction of the muscular fibers would cause a curled preservation of the shell. As the shell of Leptochiton sp.…”

“…Modern Polyplacophora have a worldwide distribution from the Arctic to the Antarctic; fossil Polyplacophora are known since the Cambrian-Ordovician and have also a wide geographic distribution with records in all modern continents (Sirenko, 2006a;Puchalski et al, 2008) except for Antarctica, but most of the fossil record of Polyplacophora consists of disarticulate valves. To the authors' knowledge, four examples of fully articulate specimens are known in the Cenozoic fossil record and the preservation of these extraordinary examples are related to exceptional conditions of fossilization (Itoigawa, et al, 1977;Ivany et al, 1990;Squires and Goedert, 1995;Dell'Angelo et al, 2003).…”