Holocephali Bonaparte, 1841
publication ID |
https://doi.org/ 10.5281/zenodo.13741212 |
persistent identifier |
https://treatment.plazi.org/id/954A87EC-2C12-336B-FCDA-FD057AEE7F3D |
treatment provided by |
Felipe |
scientific name |
Holocephali Bonaparte, 1841 |
status |
|
Superorder Holocephali Bonaparte, 1841 View in CoL Order Helodontiformes Patterson, 1965 Family Helodontidae Patterson, 1965 Genus Diclitodus Davis, 1883
Diclitodus denshumani ( Newberry and Worthen, 1866) Fig. 7A View Fig .
1866 Helodus denshumani sp. nov.; Newberry and Worthen 1866: 76, pl. 4: 21.
Material.—One tooth.
Description.—The crown of Diclitodus denshumani is convex labially and concave lingually. Its lingual/lateral ends slope down at 45 ° and are gently crenulated. The biting edge is almost horizontal, with lateral corners only slightly higher than the median part. The base is strongly expanded lingually and excavated at the lingual end. The orolingual side of the base is perforated with numerous nutritive canals and grooves. Width of the tooth is 1.5 mm.
Remarks.—An almost identical tooth was described by Newberry and Worthen (1866: pl. 4: 21a–c) from the Viséan Keokuk Limestone of Illinois as Helodus denshumani ; although the illustrations are somewhat confusing, the description and diagrammatic sketch of the lateral view leave no doubt. However, as the tooth is much different from the specimens typically referred to as Helodus , and, on the other hand, resembles the type specimen of Diclitodus scitulus Davis, 1883 ( BMNH P.49629; Fig. 10A View Fig ) from the Carboniferous Limestone of Yorkshire, it should be included in Diclitodus . D. scitulus is much larger (7 mm wide) than D. denshumani and shows more prominent lateral corners of the crown, but the exposed labial part of the holotype (the rest is embedded in limestone) reveals a similar shape of the base.
Based on indirect reasoning, it was suggested (Woodward, unpublished notes, fide Stahl 1999: 54) that Diclitodus is a symphyseal tooth of a helodontiform. Such a position could explain the extreme rarity of such forms in comparison to other bradyodont teeth and tooth−plates. This being the case, it is quite possible that Diclitodus sp. is in fact a symphyseal tooth of the next described species, Helodus coniculus , and, consequently, represents the genus Helodus , as originally proposed.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
Kingdom |
|
Phylum |
|
Class |
Holocephali Bonaparte, 1841
Ginter, Michał & Sun, Yuanlin 2007 |
Helodus denshumani
Newberry, J. S. & Worthen, A. H. 1866: 76 |