Spathognathodus

Spathognathodus sp., from Louisville Fossils.

Belongs within: Spathognathodontidae.

Spathognathodus has been recognised as a genus of conodonts dating from the Lower Silurian to the Middle Triassic (Hass 1962); in the form-taxon sense it corresponds to the Pa elements of more complete apparatus. Bardashev et al. (2002) suggested that S. postexcelsus probably represented the ancestor of the Lower Devonian genus Pseudogondwania, which possesses a narrow platform that may or may not reach the posterior end, ornamented by two lateral rows of nodes, and a free anterior blade bearing five to seven high denticles in an arched row.

Characters (from Hass 1962, for P₁ element only): Essentially straight in oral view; denticles along midline closely set, may be flanked laterally by one or more denticles; oral surface of lips or lateral expansions of pulp cavity may support denticles.

Spathognathodus Branson & Mehl 1941 H62 (see below for synonymy)
    |--S. frankenwaldensis BWZ02
    `--+--S. optimus Moskalenko 1966 [=Pandorinellina optima] BWZ02
       `--+--S. postexcelsus (Wang & Ziegler 1983) BWZ02
          `--Pseudogondwania Bardashev, Weddige & Ziegler 2002 BWZ02
               |--P. klapperi Bardashev, Weddige & Ziegler 2002 BWZ02
               `--+--+--*P. kindlei (Lane & Ormiston 1979) [=Eognathodus sulcatus kindlei] BWZ02
                  |  `--P. ethingtoni Bardashev, Weddige & Ziegler 2002 BWZ02
                  `--+--P. clarki Bardashev, Weddige & Ziegler 2002 BWZ02
                     `--P. murphyi Bardashev, Weddige & Ziegler 2002 BWZ02

Spathognathodus incertae sedis:
  *S. primus (Branson & Mehl 1933) [=*Spathodus primus] H62
  S. anteposicornis N79
  S. bidentatus N79
  S. coloradoensis T85
  S. costatus N79
  S. ellisoni Merrill 1973 L73
  S. johnsoni N79
  S. jugosus H62
  S. minutus (Ellison 1941) L73
  S. murchisoni (Pander 1856) H62, M62 [=*Ctenognathus murchisoni M62, *Ctenognathodus murchisoni M62]
  ‘Ctenognathus’ pseudofissilis S88
  S. stabilis BWZ02
  S. steinhornensis N79

Spathognathodus Branson & Mehl 1941 H62 [=Spathodus Brandon & Mehl 1933 non Boulenger 1900 H62; incl. Ctenognathodus Fay 1959 M62, Ctenognathus Pander 1856 non Fairmaire 1843 M62]

*Type species of generic name indicated

REFERENCES

[BWZ02] Bardashev, I. A., K. Weddige & W. Ziegler. 2002. The phylomorphogenesis of some Early Devonian platform conodonts. Senckenbergiana Lethaea 82: 375–451.

[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.

[L73] Lane, H. R. 1973. Lectotype or neotype: a problem for ICZN clarification. Systematic Zoology 22 (3): 324–325.

[M62] Müller, K. J. 1962. Supplement to systematics of 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. W246–W249. Geological Society of America, and University of Kansas Press.

[N79] Norris, A. W. 1979. Devonian in the Western Hemisphere. In: Robison, R. A., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt A. Introduction. Fossilisation (Taphonomy), Biogeography and Biostratigraphy pp. A218–A253. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

[S88] Sweet, W. C. 1988. The Conodonta: Morphology, taxonomy, paleoecology, and evolutionary history of a long extinct animal phylum. Clarendon Press: Oxford.

[T85] Thayer, D. W. 1985. New Pennsylvanian lepospondyl amphibians from the Swisshelm Mountains, Arizona. Journal of Paleontology 59 (3): 684–700.