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Sphyrna gracile
Taxonomy
Sphyrna gracile was named by Cicimurri et al. (2025). Its type specimen is SC2013.28.158, a tooth, and it is a 3D body fossil. Its type locality is Jones Branch, which is in a Chattian marine sandstone in the Catahoula Formation of Mississippi.
Sister species lacking formal opinion data
Synonymy list
| Year | Name and author |
|---|---|
| 2025 | Sphyrna gracile Cicimurri et al. p. 38 figs. Fig. 10 |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
†Sphyrna gracile Cicimurri et al. 2025
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| D. J. Cicimurri et al. 2025 | Mesio-distally wide teeth consisting of a large main cusp and a distal heel. The main cusp is broadly triangular and distally inclined to varying degrees. The mesial cutting edge is straight to weakly convex on the main cusp, but it extends to the end of the mesial root lobe generally through a sloping transition at the base of the cusp. The distal cutting edge is shorter and straight to weakly convex. The distal heel is elongated, low, straight to weakly convex, and differentiated from the distal cutting edge by a shallow notch. All cutting edges are smooth. The root is bilobate with short, sub-rectangular lobes that are highly diverging. The basal margin is straight to weakly concave. The lingual root face is thick, and there is a distinctive medially located nutritive groove. These teeth differ from fossil species reported in the
literature, like those of the Miocene Sphyrna arambourgi Cappetta, 1970, by having a wider main cusp and weakly sinuous (as opposed to straight) mesial cutting edge. Additionally, “S.” gracile sp. nov. teeth can be separated from those of both S. arambourgi and S. integra (Probst, 1878) by having an elongated and straight to weakly convex distal heel (as opposed to being rather short and occasionally cuspidate in the latter taxa). Furthermore, the lower teeth of the former taxon have an angular mesial cutting edge, whereas this edge is curved in the latter taxa. “Sphyrna” gracile teeth differ from those of the Miocene S. laevissima (Cope, 1867) by being less robust and by being smaller in mesio-distal width (up to 6 mm for “S.” gracile vs 1 cm for S. laevissima). |
Measurements
No measurements are available
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| Source: o = order, subp = subphylum | |||||
| References: Hendy et al. 2009, Carroll 1988, Wagner 2023 | |||||