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Bryozoa
Puellina? catena (Wood, 1844)
Nomenclature
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Family: CribrilinidaeGenus: Puellina
- holotype: B.M.(N.H.) Palaeont. Dept. B1622
SUMMARY
Colonies are small, delicate, encrusting, uniserial, consisting of linear chains of zooids with occasional ramifications originating through the formation of one or two distolateral buds in addition to the distal bud that continues the original branch. New branches diverge from parent branches at variable angles of up to 90°. The ancestrula in the single known example is ovoidal, tatiform, with about a dozen spines surrounding the opesia covered by a closure plate. A distal, one distolateral and a proximal periancestrular bud are present in this example. Small oval pits are etched into calcareous substrates beneath each zooid; these correspond to the trace fossil Leptichnus dromeus Taylor, Wilson & Bromley, 1999.
Autozooids are small, about 0.3-0.4 mm long by 0.2 mm wide, and elongate ovoidal in outline shape without a cauda. The frontal shield is convex and formed by 7-10 costae (including the two costae forming the apertural bar) and a narrow marginal gymnocyst. Costae are sharply ridged, taper towards the midline of the zooid, adjacent costae being linked by 4-6 intercostal fusions with slit-like intercostal pores between. The orifice is roughly keyhole shaped, with a broad, shallow poster separated from the anter by a pair of condyles (teeth). Three blunt, non-articulated oral spines are present, reduced to two in ovicellate zooids. Ovicells are prominent, globular, apparently non-porous, the ectooecium bearing a few nodules and possessing an uncalcified proximal area. Branches often terminate after an ovicell.
Avicularia not observed, presumed to be absent.