Zygognathus pyramidalis, from Hass (1962).

Belongs within: Prioniodontida.

The Cyrtoniodontidae is a group of conodonts known from the Ordovician (Hass 1962).

Characters (from Hass 1962, for S elements only): Main cusp terminal; aboral side of posterior bar partly or wholly expanded into concavity; anticusp, if present, may be denticulated.

<==Cyrtoniodontidae [Cyrtoniodontinae]
    |--Cyrtoniodus Stauffer 1935 [incl. Barbarodina Stauffer 1935] H62
    |    `--*C. complicatus Stauffer 1935 H62
    |--Gothodus Lindström 1954 H62
    |    `--*G. costulatus Lindström 1954 H62
    |--Holodontus Rhodes 1953 H62
    |    `--*H. superbus Rhodes 1953 H62
    |--Keislognathus Rhodes 1955 H62
    |    `--*K. gracilis Rhodes 1955 H62
    |--Paracordylodus Lindström 1954 H62
    |    `--*P. gracilis Lindström 1954 H62
    |--Peridon Hadding 1913 H62
    |    `--*P. aculeatus Hadding 1913 H62
    |--Rhynchognathodus Ethington 1959 [=Rhynchognathus Ethington 1959 non Jaekel 1929] H62
    |    `--*R. typica (Ethington 1959) [=*Rhynchognathus typica] H62
    |--Phragmodus Branson & Mehl 1933 H62
    |    |--*P. primus Branson & Mehl 1933 H62
    |    `--P. undatus SS05
    `--Zygognathus Branson, Mehl & Branson 1951 [incl. Eoligonodina Branson, Mehl & Branson 1951] H62
         |--*Z. pyramidalis Branson, Mehl & Branson 1951 H62
         `--Z. robusta H62

*Type species of generic name indicated


[H62] Hass, W. H. 1962. Conodonts. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt W. Miscellanea: Conodonts, Conoidal Shells of Uncertain Affinities, Worms, Trace Fossils and Problematica pp. W3–W69. Geological Society of America, and University of Kansas Press.

[SS05] Sansom, I. J., & M. P. Smith. 2005. Late Ordovician vertebrates from the Bighorn Mountains of Wyoming, USA. Palaeontology 48 (1): 31–48.

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