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Leptaena (Septomena) alaskensis
Taxonomy
Leptaena (Septomena) alaskensis was named by Rasmussen et al. (2012). Its type specimen is MGUH 29456 and is a 3D body fossil. Its type locality is Locality A-1230 Blocks 4-6, which is in an Ashbyan deep subtidal ramp limestone/siltstone in the Telsitna Formation of Alaska.
Sister species lacking formal opinion data
Synonymy list
Year | Name and author |
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2012 | Leptaena (Septomena) alaskensis Rasmussen et al. pp. 15 - 16 figs. Plate 1, figures 20–23 |
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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.
†Leptaena (Septomena) alaskensis Rasmussen et al. 2012
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Diagnosis
Reference | Diagnosis | |
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C. M. O. Rasmussen et al. 2012 | Shell medium to large, plano-convex, subquardrate to slightly bilobate in outline; shell sharply geniculate dorsally. Maximum width at mid-valve. Anterior commissure uniplicate, sharply geniculate dorsally. Ventral interarea wide and high. Ornament of closely spaced parvicostellate intersected by larger costellae and concentric rugae. Dorsal interior with brachiophores flat and wide. Cardinal process bifid and undercut. Median septum weak with two pairs of transmuscle ridges. Inner pair subparallel, outer pair divergent, shorter, but more pronounced. |
Measurements
No measurements are available
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Source: f = family, o = order, c = class, p = phylum, uc = unranked clade | |||||
References: Aberhan et al. 2004, Nesnidal et al. 2013, Hendy 2009 |