Sphenolithus furcatolithoides Locker (1967) subsp. labradorensis Firth (1989) - this is clearly the same taxonomic concept. Since "a name has no priority outside the rank in which it was published" (ICN Art 11.2) the name S. cuniculus is correct if the taxon is treated as a species [my opinion JRY 2016]
Taxonomic discussion: Similar to Sphenolithus furcatolithoides but lower quadrants shorter and upper quadrants broader: possibly a preservational variant.
Distinguishing features: forms with low basal quadrants (‘feet’) and ~90° bifurcations
Geological Range: Last occurrence (top): within NP16 zone (40.40-42.87Ma, top in Bartonian stage). Data source: [PRB rough estimate] First occurrence (base): within NP15 zone (42.87-46.29Ma, base in Lutetian stage). Data source: Bown 2005
Plot of occurrence data:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes