Baumiller and Fordyce—New genus of feather star from Oligocene of New Zealand 1 2


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conditions is consistent with the interpretation of the Otekaike sediments as representing an upper to mid-shelf environment occasionally subjected to currents/storms capable of producing concentrations of aligned penatulaceans (Eagle, 2007). An unusual aspect of the pristinely preserved Waipati


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specimen of R. aotearoa n. comb. is its close association with fragments of calcitic bivalves and echinoid tests. Whereas the presence of both larger and smaller fragments entombed within the matrix between the arms indicates a lack of sorting, the long axes of these fragments are aligned parallel to the long axes of the crinoid’s arms, suggesting some process of preferential alignment. In addition, the shell fragments have sharp, angular edges, show no evidence of encrustation, and although most are ~1cm in their largest dimension, several are larger than 3 cm (Supplemental Data 3). The production of such angular fragments might generally be interpreted as the result of in situ compaction (Zuschin et al., 2003; Zatoń and Salamon, 2008), but that seems unlikely in this instance because: (1) most fossils show no structural deformation, and (2) judging from the shape, size, and surface detail of the angular fragments, it is evident that they represent multiple individuals with only parts of their skeletons present. It is plausible that biological agents may have been involved in producing these fragments (Oji et al., 2003; Cintra-Buenrostro, 2007; Stafford et al., 2012; Salamon et al., 2014).


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Figure 5. Brachials and cirrals of Rautangaroa aotearoa n. gen. n. comb. from the Otekaike Limestone, Oligocene, ‘Waipati,’ North Otago, New Zealand, (OU46680). Scale as indicated. (1) Straight muscular articulations on the distal facet of an axillary (IIBr2ax). (2) Synarthrial articulation on the proximal facet of an axillary in (1) (IIBr2ax). (3) Syzygial articulation on a proximal brachial. (4) Oblique muscular articulation on a proximal brachial. (5) Proximal cirral in lateral view. Proximal articular facet is to the right. (6) Medial cirral in lateral view. Proximal articular facet is to the right.


decay of soft tissues occurred after burial. It has been generally assumed that this type of preservation implies little transport, but experiments suggest that live crinoids or their fresh (nondecayed) carcasses can remain fully intact even when moved by turbulent, sediment-laden flows over substantial distances (Baumiller, 2003; Baumiller et al., 2008a). The Waipati specimen of R. aotearoa n. comb. is preserved with the long axes of the arms aligned parallel to the oral–aboral axis, in what has been referred to as a ‘shaving brush’ posture (Fig. 3, Supplemental Data 1, 2, 3). This may well represent feather stars’ response to trauma, as this posture has also been recognized in experiments with live specimens tumbled for


over one hour in sediment-laden water (Baumiller et al., 2008a, fig. 1.1). Counterintuitively, the intact R. aotearoa n. comb. specimen may have experienced transport prior to burial, whereas the highly disarticulated feather stars described by Eagle (2007, 2008) may have been buried in situ, though following a longer period of decay on the sediment–water interface. The existence of such a range of hydrodynamic


Ecological and evolutionary implications.—Several features of the Otekaike crinoids are worthy of note. First, the described fauna from a single locality, Ardlogie, consists of nine feather star species (Eagle 2007, 2008; this study). This is a slightly lower diversity than noted by Messing et al. (2006), who found 12 species of feather stars living on sandy substrates between 10 and 20m depth at Lizard Island, Great Barrier Reef, Australia. However, the latter are part of an extremely rich fauna of Lizard Island consisting of over 50 species (Hoggett and Vail cited in Messing et al., 2006) dominated by reef-dwelling feather stars, and five of the 12 Lizard Island species observed on soft sub- strates are also known to occur on reefs. Given that feather stars from Ardlogie likely lived in deeper water and not in vicinity of reefs, the diversity of this Oligocene locality must be considered strikingly similar to that at a comparable modern setting described by Messing et al. (2006). This suggests that alpha diversity in this type of an environment has not changed dramatically since the Oligocene. Admittedly, this is but a single comparison from one habitat, but it does shed some light on the history of feather stars, hinting that their past diversity may be greatly underrepresented by their known fossil record. A second noteworthy aspect of the Otekaike feather stars


relates to the presence of a regenerating arm in the Waipati specimen of R. aotearoa n. comb. (Fig. 4.2). The extraordinary ability to regenerate is a characteristic of all echinoderms, and in crinoids regenerating body parts are commonly encountered in extant specimens and have been reported in numerous fossil stalked crinoids (see Oji, 2001; Gahn and Baumiller, 2010 for reviews). However, regeneration has not previously been recorded in a fossil feather star. This may seem surprising given that observations of living populations reveal extremely high regeneration frequencies, sometimes with all individuals regen- erating one or more arms (Mladenov, 1983; Meyer, 1985;


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