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Moerella quasimacoma
Taxonomy
Moerella quasimacoma was named by Hickman (2015). Its type specimen is UCMP 110702 and is a 3D body fossil. Its type locality is Columbia (USGS 25031) - Hickman (1980), which is in a Priabonian deep-water siltstone/mudstone in the Keasey Formation of Oregon.
Sister species lacking formal opinion data
Synonymy list
| Year | Name and author |
|---|---|
| 2015 | Moerella quasimacoma Hickman p. 26 figs. Fig. 12A–J |
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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.
†Moerella quasimacoma Hickman 2015
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| C. S. Hickman 2015 | Shell thin (thickness 0.2 mm), compressed, subovate-elongate, and strongly inequivalve, with more inflated left valve and posterior flexure to right of both valves; umbones low, beaks prosogyrate and small but
sharply pointed, right beak slightly higher than left; almost equilateral, with slightly concave anterior and posterior dorsal margins nearly equal length; exterior surface glossy and smooth with numerous faint growth lines and growth checks; pallial sinus faint but deep, broadly U-shaped, almost touching anterior adductor, with ventral limb confluent with pallial line to varying degree; sunken external ligament prominently developed, escutcheonal region broad but not clearly demarcated; lunule absent; hinge plate with thin, elongate posterior and anterior lateral teeth and two cardinal teeth in each valves. Description—The anterior end of the shell is broadly rounded, and the posterior end is more sharply rounded. In the right valve the anterior cardinal is simple and rela- tively heavy, and the posterior cardinal is broadly triangular, strongly developed and deeply bifid (Fig. 12I). In the left valve the posterior cardinal is also simple but thinner than the equivalent right anterior cardinal, and the left anterior cardinal is narrower and less deeply bifid than the posterior right cardinal (Fig. 12J). The thin, elongate lateral teeth in the left valve are at the valve margins and fit into sockets on the left valve dorsal to the submarginal laterals (Fig. 12G–H). The average umbonal angle measured on 50 specimens is 126o. The adductor muscle scars are relatively large, shal- lowly impressed, and situated closer to the dorsal margins. The posterior scar is smaller and sub-rounded in outline than the larger, more elongate anterior scar. There is a broad but very shallow groove and ridge along the posterior dorsal valve margins where growth lines change direction more abruptly than on the more evenly rounded anterior dorsal margin (Fig. 12A, B, D, E). |
Measurements
No measurements are available
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| Source: g = genus, f = family, c = class | |||||
| References: Sanchez Roig 1926, Kiessling 2004, Aberhan et al. 2004 | |||||
Age range: Priabonian or 38.00000 to 33.90000 Ma
Collections (19 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Priabonian | USA (Oregon) | Moerella quasimacoma (39943 39946 39947 39948 39951 39952 40182 40183 40184 40185 40186 40189 40191 type locality: 40192 40195 40197 40199 126108 233549) |