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Journal of Paleontology 92(1):99–113 which allows identification to the species level, and a large,
isolated flap (Fig. 4.6, 4.7) are also discussed here for the first time. In addition, appendages previously interpreted as Peytoia nathorsti Walcott, 1911 (Conway Morris and Robison, 1988) are here reinterpreted as belonging to a Sidneyia-like taxon. KUMIP 314145a/b (Fig. 2.1) is a small, single incomplete
Hurdia appendage with seven visible podomeres with well- defined boundaries of around 1mm in thickness. Podomeres at the proximal end of the appendage where the ventral spines attach are not preserved. KUMIP 314178 (Fig. 2.2) is a mostly complete small, single Hurdia appendage with 10 podomeres separated by clear podomere boundaries of around 1mm thickness. KUMIP 314040a/b (Fig. 2.3, 2.4) is a small Hurdia appendage with nine podomeres. Five large ventral spines, attached to podomeres 2–6, are tightly packed and appear curved forward, beyond the distal end of the appendage. Auxiliary spines are only visible on the distal-most ventral spine. KUMIP 314042 (Fig. 2.5) is a larger Hurdia appendage with 10 podomeres with clear podomere boundaries of around 1mm thickness. The five large, straight ventral spines have slightly curved distal ends. Briggs et al. (2008) identified KUMIP 312405a/b (Fig. 3)
as a pair of radiodontan appendages with mouthparts. The two appendages are preserved with one (‘app. 1’ in Fig. 3.3) on a higher level of rock than the other (‘app. 2’ in Fig. 3.3). App. 1 is well preserved and made up of 10 podomeres. Large ventral spines are present on podomeres 2–6, and a small ventral spine is visible on podomere 9 (‘vs’ in Fig. 3.3). A terminal spine is visible on podomere 10 (‘ts’ in Fig. 3.3). App. 2 is not as clearly visible. The distal-most podomeres are visible. Three large ventral spines are preserved together, with the distal one angled forward, similar to the overlying appendage. The mouthparts are made up of four large plates (‘lp’ in Fig. 3.3) arranged at 90° to each other around a rectangular opening. The total number of smaller plates is not clear, as the outer edge of the oral cone is not well preserved, but where it can be counted there are seven smaller plates between the large plates, which extrapolates to a total of 32 plates, four large and 28 small, characteristic of Hurdia and Peytoia. By contrast, Anomalocaris mouthparts have three large plates at 120° (Daley and Bergström, 2012). Peytoia mouthparts can be differentiated from Hurdia as Hurdia has numerous tooth rows in the central opening, whereas in Peytoia the central opening lacks tooth rows (Daley and Bergström, 2012). In the central opening of this specimen, additional tooth rows are visible (‘tr’ in Fig. 3.3), indicating this specimen is a Hurdia. The appendages associated with the mouthparts are consistent with this interpretation and are likely from the same animal. KUMIP 314175a/b (Fig. 2.6) is a small, oval oral cone of Hurdia. It is unusual in that it has small raised nodes (radius 1mm) visible on one of the large plates and several small plates. KUMIP 314265a/b (Fig. 2.7) is another small Hurdia oral cone. The outer margins of the plates are not
Figure 3. Assemblage of two Hurdia appendages with an oral cone. (1) KUMIP 312405a; (2) KUMIP 312405b, counterpart to 1;(3) interpretative drawing of 2. app. 1 = appendage 1; app. 2 = appendage 2; as = auxiliary spine; lp = large plate; p1 = podomere 1; p6 = podomere 6; tr = tooth row; ts = terminal spine; vs = ventral spine. Scale bars = 10mm.
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