Oneotodus simplex, from Ethington & Brand (1981).

Belongs within: Conodonta.
Contains: Scolopodus.

Oneotodus is a genus of very early conodonts from the Lower Ordovician. The original life apparatus of Oneotodus has not been fully established, but would have been composed of an undetermined number of simple single-pointed elements differing in curvature and cross-section. Druce & Jones (1971) derived a number of other early conodont genera from Oneotodus; however, most of the species they assigned to Oneotodus were excluded by Ethington & Brand (1981).

Characteristics (from Ethington & Brand 1981): Simple cone elements with stout cusps whose cross-sections are subcircular, or ellipsoidal, may be flattened to recessed posteriorly. Elements moderately to strongly curved proximally in the region of the basal cavity, straight distally. Entire cusp albid; region enclosing basal cavity hyaline. Basal outline circular to ovoid. Base not flared laterally but may be expanded posteriorly. Basal cavity with low, asymmetrically triangular profile in lateral view; anterior outline of cavity close to anterior surface of cusp, posterior outline subtends an acute angle with basal margin. Cavity terminates upward as a slender, orally-directed conical tip. Anterior surface of cusp broadly rounded, usually smooth; remainder of cusp bears microscopic longitudinal striae and may display numerous costae as well. Apparatus consists of generally similar elements that vary among themselves in the cross-sections of their cusps, in the curvature that they display, and in the development of their costae.

<==Oneotodus Lindström 1954 DJ71
    |  i. s.: *O. simplex (Furnish 1938) [=Distacodus simplex] DJ71
    |         O. circularis Mound 1968 WSQ86
    |         O. tenuis Müller 1959 DJ71
    |--O. gallatini Müller 1959 DJ71
    |--O. terashimai Nogami 1967 DJ71
    `--+--O. nakamurai Nogami 1967 DJ71
       `--+--O. erectus Druce & Jones 1971 DJ71
          |--O. gracilis (Furnish 1938) [=Distacodus gracilis] DJ71
          |--O. variabilis Lindström 1954 DJ71
          |--Scolopodus DJ71
          `--+--O. bicuspidatus Druce & Jones 1971 DJ71
             |--O. datsonensis Druce & Jones 1971 DJ71
             `--Strigaconus Druce & Jones 1971 DJ71
                  `--*S. simplex Druce & Jones 1971 [incl. Hirsutodontus hirsutus] DJ71

*Type species of generic name indicated


[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.

Ethington, R. L., & U. Brand. 1981. Oneotodus simplex (Furnish) and the genus Oneotodus (Conodonta). Journal of Paleontology 55 (1): 239-247.

[WSQ86] Wang C.-Y., Shi C.-G. & Qu G.-S. 1986. Conodonts and ostracodes from the Devonian "Heitai Formation" of Mishan County, Heilongjiang Province. Acta Micropalaeontologica Sinica 3 (2): 205-214.

No comments:

Post a Comment

Markup Key:
- <b>bold</b> = bold
- <i>italic</i> = italic
- <a href="">FoS</a> = FoS