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Virgiana barrandei
Taxonomy
Pentamerus barrandi was named by Billings (1857) [Pentamerus Barrandi]. It is the type species of Virgiana.
It was recombined as Virgiana barrandei by Twenhofel (1914), Jin and Copper (2000).
It was recombined as Virgiana barrandei by Twenhofel (1914), Jin and Copper (2000).
Synonymy list
| Year | Name and author |
|---|---|
| 1857 | Pentamerus barrandi Billings p. 296 |
| 1914 | Virgiana barrandei Twenhofel |
| 2000 | Virgiana barrandei Jin and Copper pp. 30 - 31 figs. Pl. 5, figs. 1-19; Pl. 6, figs. 1-18; Pl. 7, figs, 1-4; Text-figs. 14, 15 |
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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.
†Virgiana barrandei Billings 1857
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| J. Jin and P. Copper 2000 | Shell medium to large in size, elongate, strongly and smoothly ventribiconvex, with ventral valve twice as deep as dorsal valve; average length 31.3 mm, width 23.7 mm, and thickness 20.2 mm (Text-fig. 14), with largest specimen in collection attaining 47 mm long, 40 mm wide, and 30 mm thick; greatest convexity located in central portion of shell. Hingeline short, curved, attaining about half of shell width. Anterior commissure weakly sulcate.
Ventral umbo strongly convex, massive, high, extending 6-1 0 mm above hingeline, with strongly incurved beak appressed onto dorsal umbo; apex flattened in some specimens; sulcus narrow, relatively shallow, present in posterior I /3 of valve, containing I median costa, changing into weak fold anteriorly; interarea absent; delthyrium obscured by strongly arched umbo and beak. Dorsal umbo weakly to moderately convex, with small beak buried in delthyrial cavity; dorsal fold generally weak, restricted to posterior I /4-1/3 of valve, bifurcating at about I /4 valve length from dorsal beak to form shallow, usually faint, median sulcus, which extends to anterior margin. Both valves covered by weak, rounded costae increasing anteriorly through bifurcation and intercalation; costae commonly better developed in medial and anterior than in lateral portions of shell; very faint or obscure in some specimens to make shells appear smooth; growth lines fine (4-6 per I mm), well preserved in some shells, interrupted by irregularly spaced growth lamellae (Pl. 5, figs. 3, 4; Pl. 6, figs. 1-3). Shell thick in umbonal portion (2-3 mm), becoming thinner anteriorly (0.5-0.2 mm). Prismatic layer well developed in posterior part of ventral valve, virtually absent in dorsal valve. Spondylium shallow, relatively long, extending for about 1/3-1/2 of shell length, with comb structure developed at anterior 2-3 mm of spondylium (Text-fig. 15); ventral median septum about twice as high, but half as long, as spondylium. Outer plates in dorsal valve parallel to each other, short, extending for about 1/5-114 of valve length, with microstructure continuous with that of shell wall; inner plates slightly longer than outer plates, divergent from each other at about 80-100°; brachial processes strong, rod-like; dorsal muscle field located in posterior part of umbonal fold, poorly delimited. |
Measurements
No measurements are available
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| Source: g = genus, o = order, c = class, p = phylum, uc = unranked clade | |||||
| References: Hendy 2009, Nesnidal et al. 2013, Aberhan et al. 2004 | |||||
Age range: Rhuddanian or 443.10000 to 440.50000 Ma
Collections (7 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Rhuddanian | Canada (Quebec) | Virgiana barrandei (113165 158508 163500 163501 163502 163503 163504) |