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Skenidioides scoliodus
Taxonomy
Skenidioides scoliodus was named by Temple (1968). Its type specimen is SM A52188, a valve (brachial valve), and it is a 3D body fossil.
Sister species lacking formal opinion data
Synonymy list
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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.
†Skenidioides scoliodus Temple 1968
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| B. G. Baarli 1995 | Exterior. The shells are small with a maximum width of 3.5-7 mm, ventribiconvex, and subpentagonal in outline. The pedicle valve is relatively high, with a pronounced fold and flanks that flatten out laterally from the fold. The brachial valve is moderately convex and about % as long as wide. It bears a broad, well-developed sulcus. The hinge line is slightly curved and equal or near in length to the maximum width situated between the hinge line and midlength of the valve. The cardinal angles are obtusely rounded, while the margins are evenly rounded. The commissure is crenulated and broadly uniplicate. The ventral beak is erect, whereas the ventral interarea is very high, plane, apsacline, Y2 as high as wide, and much higher than the low, anacline dorsal interarea. The delthyrium and notothyrium are open, and the delthyrial angle is about 50-60°. The notothyrium is very wide and occupied medially by the cardinal process.
The radial ornament is costate with 1 5-2 1 costae along the margins of the valve. External impressions of the valve are not known, but internal impressions of ribbing indicates that the axial rib in the pedicle valve is accentuated and broader than the other ribs. The ribs seem to be rounded, with few secondary branches. In most valves the ribbing is only impressed around the margins. Internal of pedicle valve: The teeth are moderately small, attached to the anterior margin of the delthyrium, and unsupported basally. The lateral walls of the delthyrium are united medially across the delthyrial cavity to form a spondylium simplex. The spondylium is sessile posteriorly, but free and elevated slightly above the floor anteriorly. The length of the spondylium relative to the delthyrium walls is at least %, although the exact length is unknown. The spondylium is usually unsupported. The interior of the valve is partially impressed by ribs. Interior of brachial valve: The brachiophores are short, triangular in cross-section, and diverging at 1 20°. They are supported late rally by well developed fukral plates that merge with the hinge line and form bases for relatively shallow, unsupported sockets dipping just barely below the plane of the hinge line. The brachiophores are supported by ventrally concave brachiophore bases that converge anteromedially onto the base of the median septum to form a cruralium. The bases slope down and are without support anteriorly before they rise again to form a moderately high and thin cardinal process that extends along the length of the notothyrial cavity. The median septum is relatively thick and not so high as those of the two other species in the Solvik Formation. It occupies about % of total valve length and ascends just anterior of the muscle scars in most specimens. The muscle scars are moderately well impressed and consist of a quadripartite impression with the posterior pair being the smallest. They occupy 7/10 of the total length and Yr% of the total width. |