A new Lower Ordovician species of Calathium, and skeletal structure of western Utah calathids

Abstract

Conical and vase-shaped calathids are found in the Lower Ordovician Fillmore Formation of western Utah associated with intraformational conglomerates and small patch reefs. Calathium yersini n. sp. exhibits patterns of both the inner and outer walls of calathid two-wall construction. The broadly annulate walls are constructed from meroms with fused proximal merom feet forming the inner wall. The reticulate-patterned outer wall is formed by interlocking stellate ribs at the distal end of each merom. Latitudinal (horizontal) ribs interlock adjacent merom ribs side by side at the tips of ribs while meridional (vertical) ribs overlap merom shaft to merom shaft. Inner and outer walls are perforate. Pore-canal casts preserved in silicified molds suggest an exit and entrance current circulation for inner and outer wall pores. Upper ends of the calathids are not preserved, but an open cup is interpreted from infill material and encrustation of the interior cup wall by epibionts. Epibionts commonly encrust and thicken Calathium outer walls, with the cyanobacterium Girvanella as the dominant encrusting organism. Calathium yersini n. sp., among the earliest of receptaculitids, has a morphology suitable for water circulation consistent with that of filter-feeding organisms.

Early Ordovician sponge-Calathium-microbial reefs on the Yangtze Platform margin of the South China Block

“…Furthermore, Calathium, as the most import metazoan builder, has certain aspects in common with solitary archaeocyathans. Both Calathium and archaeocyathans have a porous doublewall, holdfasts at the base and an open upper end leading to the central cavity, which are suitable for water circulation (Church 1991). This suggests that the main metazoan reef builders were functionally similar in the early Cambrian and in the Early Ordovician.…”

The ecology of Lower Cambrian buildups from Zuune Arts, Mongolia: implications for early metazoan reef evolution

“…Soanitids and radiocyaths are morphologically similar, and may be related (Zhuravlev, 1986). According to Church (1991) soanitids have a morphology suitable for water circulation consistent with that of filter-feeding organisms. Lithistid sponges with their solitary and branching morphologies are similar to archaeocyaths, and both communities show some calcimicrobe development.…”

Untangling intricate microbial–sponge frameworks: The contributions of sponges to Early Ordovician reefs

“…3 cm in diameter and at least 4 cm in length, composed of perforated double walls (Church, 1991). Horizontal to vertical burrows mostly occur within micrites in the reefs, often dolomitized or filled with micrite and cement.…”