ENIGMATIC PHOSPHATIC TUBULAR FOSSILS FROM THE EARLY-MIDDLE PALEOZOIC BOUVETTE FORMATION, YUKON, CANADA

Phosphatization is an important taphonomic window into the early history of metazoan life in the Phanerozoic. However, this window is limited as it closes in the Middle to Late Cambrian. In addition, phosphatization only occurs in specimens that are relatively small, resistant to decay, and/or enriched with calcium phosphate.

Enigmatic phosphatic tubular fossils of Cambrian-Devonian age were found in the Bouvette Formation of Nadaleen Mountain in Yukon, Canada. The fossils were determined to be phosphatic through the use of Energy-dispersive X-ray spectroscopy (EDS). Many of these phosphatic macrofossils are morphologically simple and cylindrically shaped with an average length of 2.23 mm and diameter of .27 mm; there are also small, circular fossils of similar complexity and composition that appear throughout the samples with an average diameter of .16 mm. We interpret the tubes as body fossils as opposed to trace fossils since they display sharp breaks likely to be present only in body fossils, narrowing sections that contrast the widening sections of trace fossils, and a lack of crosscutting or evidence of bioturbation. Despite their poor age constraints, these body fossils might reflect phosphatization occurring past the Late Cambrian, similar to phosphatized tubes found in Iowa, Kentucky, Missouri, and Ohio. Further work on these tube-shaped fossils including additional microscopic, microchemical, and morphometric analyses can assist in determining their taphonomy and phylogeny and potentially shed light on the true extent of the phosphatization window in the early Paleozoic.