Westergaardodina

Chosonodina herfurthi, from Lehnert et al. (2005).

Belongs within: Conodonta.

Westergaardodina was a long-lived paraconodont genus found from the Middle or Late Cambrian to the Middle Ordovician. It had W- or U-shaped elements that Müller & Hinz-Schallreuter (1998) explained as growing through a combination of dorsal and/or lateral pressure being applied to points on a growing element. How the Westergaardodina elements were arranged in their original apparatus remains unknown.

Druce & Jones (1971) suggested a phylogenetic connection between Westergaardodina and the Ordovician genus Chosonodina with palmate elements bearing a higher number of denticles (up to seven). Chosonodina was in turn linked to Coleodus, a Middle Ordovician genus bearing blade-like elements with closely set denticles, and the aboral side grooved posterior to the pulp cavity and sharp-edged anteriorly (Hass 1962).

Characters (from Müller & Hinz-Schallreuter 1998): Bi- or tricuspidate elements; internal cavity may be divided between lateral cavities. Lateral projection(s) (one-sided only in bicuspidate forms) resulting from combination of upward growth from base and dorsal pressure alongside/on either side of median projection causing tearing of older lamellae; lamellae-free spaces became filled by a callus-like substance. Lateral projections of elements remain flexible; probably not heavily mineralised in life.

<==Westergaardodina Müller 1959 [Westergaardodinidae]DJ71
| i. s.: W. mosseburgensis Müller 1959DJ71
|--*W. bicuspidata Müller 1959DJ71
`--+--W. amplicava Müller 1959DJ71
`--Chosonodina Müller 1964DJ71
| i. s.: C. chirodina Zhang 1983AS93
| C. rigbyi Ethington & Clark 1982AS93
| C. tridentata Zhang 1983AS93
|--C. fisheri Druce & Jones 1971DJ71
`--+--*C. herfurthi Müller 1964DJ71
`--+--C. lunata Harris & Harris 1965DJ71
`--ColeodontidaeS88
| i. s.: Archaeognathus Cullison 1938S88
| Neocoleodus Branson & Mehl 1933S88
| |--*N. spicatus Branson & Mehl 1933H62
| `--N. breviconus Branson & Mehl 1933AS93
| Stereoconus Branson & Mehl 1933S88
| |--*S. gracilis Branson & Mehl 1933 [incl. S. robustus Branson & Mehl 1933]SS05
| |--S. crepidiformis Ethington et al. 1986LM05
| `--S. plenus Branson & Mehl 1933SS05
| Mixoconus Sweet 1955S88
| `--*M. primus Sweet 1955H62
|--HindeodellinaeH62
| |--Cervicornoides Stauffer 1938H62
| | `--*C. alternatus Staffer 1938H62
| |--Metaprioniodus Huddle 1934H62
| | `--*M. biangulatus Huddle 1934H62
| `--Hindeodella Bassler 1925H62
| |--*H. subtilis Ulrich & Bassler 1926H62
| `--H. qipanensisCB86
`--ColeodontinaeH62
|--Arcugnathus Cooper in Cooper & Sloss 1943H62
| `--*A. tenuis Cooper in Cooper & Sloss 1943H62
|--Branmehla Hass 1949H62
| `--*B. inornata (Branson & Mehl 1934) [=Spathodus inornatus]H62
|--Hindeodina Hass 1959H62
| `--*H. simplaria Hass 1959H62
|--Pravognathus Stauffer 1936 (see below for synonymy)H62
| `--*P. idonea (Stauffer 1935) [=*Heterognathus idonea]H62
`--Coleodus Branson & Mehl 1933DJ71, SS05
|--*C. simplex Branson & Mehl 1933H62, AS93
`--C. delicatus Branson & Mehl 1933AS93

Pravognathus Stauffer 1936 [=Heterognathus Stauffer 1935 nec Girard 1854 nec Schmarda 1859 nec King 1864 nec Rey 1888]H62

*Type species of generic name indicated

References

[AS93] Aldridge, R. J., & M. P. Smith. 1993. Conodonta. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 563–572. Chapman & Hall: London.

[CB86] Chen D.-Q. & Bao H. 1986. Lower Permian ostracodes from the Chihsia Formation of Jurong and Longtan, Jiangsu Province. Acta Micropalaeontologica Sinica 3 (2): 107–132.

[DJ71] Druce, E. C., & P. J. Jones. 1971. Cambro-Ordovician conodonts from the Burke River Structural Belt, Queensland. Commonwealth of Australia, Bureau of National Development, Bureau of Mineral Resources, Geology and Geophysics, Bulletin 110: 1–159.

[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.

[LM05] Lehnert, O., J. F. Miller, S. A. Leslie, J. E. Repetski & R. L. Ethington. 2005. Cambro-Ordovician sea-level fluctuations and sequence boundaries: the missing record and the evolution of new taxa. Special Papers in Palaeontology 73: 117–134.

Müller, K. J., & I. Hinz-Schallreuter. 1998. Internal structure of Cambrian conodonts. Journal of Paleontology 72 (1): 91–112.

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

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

 

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