TAANELLA YUKONENSIS N. GEN. N. SP., A UNIQUELY PERFORATE AGGLUTINATED FORAMINIFER FROM THE UPPER TRIASSIC OF PANTHALASSA (LIME PEAK, YUKON, CANADA)

This paper describes the new calc-cemented, agglutinated Panthalassan species Taanella yukonensis n. gen. n. sp. from the upper Norian of Lime Peak, Yukon, Canada. The species, morphologically close to a Triassic "trochamminid", possesses unusually coarse wall perforations. This attribute is unknown from coeval agglutinated forms, which typically display imperforate or poorly perforate walls (i.e., loose agglutinated tests with gaps between particles). In the Late Triassic, remarkably large pores started to develop in a variety of foraminifers, including porcelaneous forms. This evolutionary tendency might indicate a heightened need to promote gas-exchange with the exterior. In T. yukonensis, this evolution is complemented with the development of externally globular chambers, separated by deep sutural slits, maximizing the surface ratio to the exterior.