Dissidocerida

Extinct order of molluscs

Dissidocerida
Temporal range: Lower Ordovician - Lower Silurian
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: †Orthoceratoidea
Order: †Dissidocerida
Zhuravleva (1994)
Families

See text

Dissidocerida is an order of Early Ordovician to the Early Silurian orthoceratoid cephalopods in which the siphuncle has a continuous lining or a longitudinal rod-like structure within.

The order Dissidocerida was proposed by Zhuravleva (1994) for Dissidoceras undosum Zhuravleva, 1964, a Silurian orthoconic genus with a wide, nearly central, tubular siphuncle, suborthochoanitic septal necks, and endosiphuncular rod; in many aspects similar to rod-bearing orthocones of the Ordovician. It is thought by some that Ordovician-Silurian orthocones with continuous longitudinal endosiphuncular laminar deposits constitute a single phylogenetic stock.

The Dissidocerida as understood includes the Polymeridae, Rangeroceratidae, Troedssonellidae, and Dissidocertidae. The Polymeridae and Rangeroceratidae were proposed by Evans in 2005 for Polymeres Murchison 1839 and Rangeroceras Hook and Flower 1977, respectively. Troedssonellidae was established by Kobayashi in 1935 and is based on the genus Troedssonella. The Dissidoceratidae was established by Zhuravleva for Dissidoceras undosum

References

  • A. A. Shevyrev 2004, The Cephalopod Macrosystem: A Historical Review, the Present State of Knowledge, and Unsolved Problems: 2. Classification of Nautiloid Cephalopods.
  • Bjorn Kroger, 2008. A new genus of middle Tremadocian orthoceratoids and the Early Ordovician origin of orthoceratoid cephalopods. Brief Report Acta Palaeontologica Polonica 53 (4): 745–749
  • Paleobiology -Dissidocerida
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Notable fossil cephalopods (listed by first occurrence)
Cenozoic
  • The belemnite-cuttlefish-like Belosaepia
Evolution of
cephalopods
Mesozoic
Advanced nautiloids
Nautilaceae
True ammonites
Ceratitid ammonoids
late Nautilida
Advanced belemnoids
Diplobelids: Diplobelus
Belemnites:
Belemnites
Belemnopsis
Belemnotheutis
Palaeozoic
First appearance of long-lasting lineages
Goniatite and ceratite ammonoids
Probable coleoid ancestor Bactritida
Early coleoids: Jeletzkya?, Gordoniconus, Syllipsimopodi
Earliest belemnoids: Aulacocerids
Phragmoteuthids
Early forms
the earliest cephalopod group Ellesmerocerida
Orthocones: Endocerida, Orthocerida, Actinocerida
Brevicones: Ascocerida, Oncocerida
Earliest coiled cephalopods: Tarphycerida
Spirulid?: Shimanskya
Misidentified
Taxon identifiers
Dissidocerida