Baumiller and Fordyce—New genus of feather star from Oligocene of New Zealand
information on the morphology of arms and cirri. As it repre- sents the first example of arm autotomy and regeneration in a fossil feather star, it offers evidence of the importance of predation to the evolutionary history of this group. The specimen is also critical for the reassessment of Cypelometra aotearoa Eagle, 2007, which is found to differ significantly from any presently established genus. As such, we propose a new genus, Rautangaroa, to accommodate this species.
Geologic setting
Localities and horizons for specimens discussed here are uniquely numbered in the New Zealand Fossil Record Electronic Database (see
www.fred.org.nz).Centrodorsals assigned by Eagle to Cypelometra aotearoa Eagle, 2007 were all collected at two localities in South Canterbury, South Island, New Zealand. For both localities, Eagle (2007) reported the age asWaitakian Stage, although age-diagnostic fossils were not cited. These localities are: (1) Ardlogie (or Pentland Hills) quarry (44.70277S, 170.78937E; Fossil Record numbers J40/f053A, J40/fl12, J40/f6636), and (2) the informally named Haughs’ (or Hurstlea, or Hakataramea) Quarry (44.6627S, 170.65021E; Fossil Record number I40/f324). The sequence at Ardlogie comprises lower Kokoamu
Greensand, grading up to Otekaike Limestone; these strata span the Duntroonian and Waitakian Stages so that surface-collected crinoids could represent either formation or stage. A sample from in situ transitional glauconitic limestone (J40/f0021) included the Waitakian Stage index species Globoquadrina dehiscens (Chapman, Parr, and Collins, 1934) (N. de B. Hornibrook, personal communication to Fordyce, 1978). At Haughs’ Quarry, the main upper fossil horizon
is a diffuse para-autochthonous shell bed with conspicuous Protula tubes. Fossils are readily surface collected. For this bed
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(I40/f0219B), Tanaka and Fordyce (2015) reported the planktic foraminiferan Globoturborotalita woodi (Jenkins, 1960), a zonal indicator for middle Waitakian Stage, equivalent to upper Chattian. Tanaka and Fordyce (2015) also cited a strontium (87Sr/86Sr) date, from just above the Protula bed, of 22.28± 0.13 Ma, or basal Aquitanian. The nearly complete crinoid, OU46680, described in this
study comes from a third locality: (3) Waipati (44.87833S, 170.65115E), west-southwest of the town of Duntroon, in North Otago, ~20km south of the two South Canterbury localities (Fig. 1). Specimen OU46680 (Fossil Record number I40/f0407) is from the Otekaike Limestone, probably high in the Duntroonian Stage, older than 25.2 Ma, roughly mid-Chattian. The crinoid matrix was not dated directly; rather, the age is from a nearby sample (I40/f0408) from the same horizon. ADuntroonian age is based on the presence of the foraminiferan Notorotalia spinosa (Chapman, 1926) and absence of Globoquadrina dehiscens from an otherwise diverse planktic assemblage. The geology of this region of Canterbury Basin has been
described in numerous publications, notably by Gage (1957), Forsyth (2001), Fordyce and Maxwell (2003), Eagle (2007), and Gottfried et al. (2012). During the late Oligocene, this part of New Zealand was experiencing an interval of relative tectonic quiescence between an earlier phase of submergence associated with the break-up of Gondwana and the subsequent emergence associated with plate-boundary tectonics of the early Miocene. Sediments deposited at this time include a thin, calcareous glauconitic sandstone (Kokoamu Greensand) overlain grada- tionally by a massive, low to moderately cemented, bioclastic limestone (Otekaike Limestone). The former represents a period of terrigenous-sediment starvation, distant shorelines, and/or low-lying landmasses, whereas the latter is interpreted as having
Figure 1. Map of New Zealand and the three localities (Haughs’, Ardlogie, Waipati) where specimens of Rautangaroa aotearoa n. gen. n. comb. were collected. Detailed coordinates of localities can be found in the text.
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