Making the most of fragments: a method for estimating shell length from fragmentary mussels (Mytilus californianus and Mytilus trossulus) on the Pacific Coast of North America

Measuring Mytilus californianus: an Addendum to Campbell and Braje (2015) and Singh and McKechnie (2015) including commentary and an integration of data

“…2, referred to as umbo length in Campbell and Braje). We note that the San Diego data presented in Campbell and Braje (2015) is adjacent to the Southern California samples presented in Singh and McKechnie (2015).DOIs of original article: http://dx. …”

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This JAS issue includes two articles that address the same methodological topic: estimating California mussel (Mytilus californianus) shell sizes from umbo fragments (Campbell and Braje, 2015;Singh and McKechnie, 2015). The coincidental submission and acceptance of these articles in the same journal, featuring a very similar methodological approach specific to the Pacific Coast of North America, was a surprise unbeknownst to the authors.

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“…2). Interested researchers can access these data in the supplemental online materials associated with Singh and McKechnie (2015) and for Campbell and Braje (2015) in the file associated with this addendum (see supplementary data).…”

Proxy Measurements of California Mussel Valve Length

“…) measurements obtained from valve fragments, and we propose several new metrical proxies that have the potential of utilizing a large proportion of valve fragments occurring in mussel shell assemblages. Our efforts build on those of Singh and McKechnie (2015) and Campbell and Braje (2015), who recently gave extensive attention to this topic (see also McKechnie et al 2015). We also evaluate a visual technique developed by White (1989:132-133) and utilized by a number of archaeologists working in California.…”

“…For valve fragments of black mussel (Choromytilus meridionalis) from South Africa's west coast, Buchanan (1985) proposed using the breadth of the distinct blue band of the prismatic shell material visible on the valve's interior surface, measured from the ventral margin of the valve (this band is not distinct on California mussel valves). Hamilton (1992) proposed using the measurement from the umbo tip to the internal septum, i.e., interior apex, (umbonal length or umbo thickness) of zebra mussels (Dreissena polymorpha), a measurement also proposed by Campbell and Braje (2015) and Singh and McKechnie (2015) for California mussel shells. Campbell and Braje (2015) and Singh and McKechnie (2015) also suggested other measurements: umbo width where the hinge plate is widest, umbo height 5 mm from its tip, length from umbo tip to the anterior end of the ligament shelf, length from umbo tip to the posterior end of the ligament shelf, and length of the ligament shelf.…”