Article: Janeia silurica, a link between nuculoids and solemyoids (Bivalvia)

Janeia silurica Liljedahl, 1984 from the Silurian of Gotland has unusual characters in common with the deposit-feeding nuculoids and the systematically controversial solemyoids, generally considered to have a life habit intermediate between deposit- and suspension-feeding but which in fact lives in symbiosis with chemoautotrophic bacteria. The extensive silicified material available is occasionally extremely well-preserved, reflecting soft-part anatomy of the muscles of the foot as well as of the mantle. J. silurica, which has conspicuous traces of the pallial muscles of the mantle (fused margins?), probably had an efficient system of cleaning the mantle cavity, a typically solemyoid feature. However, it was probably a more active burrower than the extant Solemya since it presumably had a larger foot and smaller gills. The gills were thus used for respiration only, as in nuculoids, while the inferred character of the mantle indicates an evolutionary trend towards the solemyoid life habit.