Lissodus sp.
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publication ID |
https://doi.org/ 10.5281/zenodo.13514789 |
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persistent identifier |
https://treatment.plazi.org/id/03DF87A9-A304-FF9A-4106-FD20B4FEFDFB |
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treatment provided by |
Felipe |
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scientific name |
Lissodus sp. |
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Lissodus sp. Morphotype 3
Figs. 4C, D View Fig , 5A View Fig .
Diagnosis.—Isolated microscopic hybodontoid teeth. Enameloid crown, overall triangular shaped, asymmetric in lingual or labial view with three to five non−differentiated cusps, broad median crest from lateral edge to lateral edge. Pronounced labial buttress, which continues into upper level of the base. Base triangular, central angle at labial buttress area, concave ventrally with raised margins, expanded pits and furrows occur on lingual surface with small pits on short labial surface of the base.
Material.—Three figured, isolated specimens, TCD.36767–69.
Description.—The length along the median crest ranges from 0.67 mm to 0.77 mm (crown only, 0.6 mm to 0.74 mm); the width of the crown labio−lingually (medially) ranges from 0.2 mm to 0.38 mm (base, 0.4 mm to 0.58 mm); height in lingual view is from 0.45 mm to 0.57 mm (crown only, 0.2 mm to 0.27 mm). Enameloid crown of three to five non−differentiated cusps with a median crest extending from lateral edge to lateral edge, asymmetric. Main cusp is off centre, higher than the remaining cusps and appears to have oblique ridges descending from the apex towards the crown−base interface on the lingual surface which is marked by a double horizontal ridge and groove structure; these non−differentiated cusps may be distinguished by slightly raised apices. Labially, a strong medio−labial buttress arises at upper crown level extending down and out to incorporate the upper level of the base. The base is triangular; lingually the base drops sharply from the crown−base interface and then fans out to the linguo−ventral margin; up to nine expanded pits and furrows occur on this surface. Labially the base is short with the medio−labial crown buttress extending into the upper level of the base; five to seven expanded pits occur on this surface. Ventrally the base is triangular with the central angle at the labial buttress where the surface is deeply concave; a number of furrows incise the ventral area.
Discussion.—In specimen TCD.36767 the base exceeds the length of the crown and only three non−differentiated cusps occur, in specimen TCD.36768 crown and base are equal and three non−differentiated cusps occur; in specimen TCD.36769 the base does not exceed the length of the crown and five non−differentiated cusps occur. Despite variations these teeth have been described together as their overall strongly triangular nature appear to separate them from the other Lissodus Morphotypes described.
Age, locality, and lithology.—Kilbride Limestone Formation, Polygnathus mehli conodont Biozone, Ivorian (probably Freyrian), late Tournaisian, Dinantian. Disused quarry, near Nobber, Co. Meath (N 845 848); crinoidal limestone.
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