Zhang et al.—Cambrian Fortunian scalidophoran worms in South China
Chinese Academy of Sciences, and the depository numbers are prefixed with NIGP.
Systematic paleontology
Scalidophora Lemburg, 1995 total group Genus Eokinorhynchus Zhang et al., 2015
Type and only species.—Eokinorhynchus rarus Zhang et al., 2015.
Eokinorhynchus rarus Zhang et al., 2015 Figure 3
2015 Eokinorhynchus rarus Zhang et al., figs.1,2,3a–g, 5, supplementary figs. S2, S3, supplementary movies S1–S4.
Holotype.—Specimen NIGP160400 (Zhang et al., 2015, fig. 1), a completely preserved specimen with partly protruded pharyngeal teeth.
Diagnosis.—(Revised fromZhang et al., 2015) Worm-like animal composed of a frontal region, a neck region, and a trunk. Frontal region consists of a pharynx with octaradially arranged teeth and an introvert with pentaradially arranged hollow scalids. Neck region covered with five circlets of neck scalids. Trunk has at least 20 annuli, and each annulus is covered with a circlet of tightly sutured small plates and armored with spinose sclerites. Five pairs of large spinose sclerites are bilaterally arranged, and a single large spinose sclerite is midventrally located. Two pairs of caudal spines are located slightly ventral to the terminal anus.
17
Occurrence.—Xinli section, Nanjiang County, northern Sichuan Province, SouthChina (Yang et al., 1983; Zhang et al., 2015). Small shelly fossils, Anabarites trisulcatus–Protohertzina anabarica Assemblage Zone, Xinli Member, Dengying Formation, Cambrian Fortunian Stage (Steiner et al., 2007; Peng et al., 2012).
Materials.—One specimen, NIGP160436.
Measurements.—Specimen NIGP160436 is about 1.4mmlong, with the second large spinose sclerite about 180 μm long.
Remarks.—For a detailed description of Eokinorhynchus rarus, please refer to Zhang et al. (2015). Here, we revise the possible ontogenetic stages, with the originally proposed trunk part NIGP160414 (Zhang et al., 2015, fig. 3h) replaced by a new specimen NIGP160436 (Fig. 3). Specimens NIGP160400 (Zhang et al., 2015, fig. 1), NIGP160402 (Zhang et al., 2015, fig. 3a), NIGP160401 (Zhang et al., 2015, fig. 2), and NIGP160436 (Fig. 3) represent, most likely, progressively advanced ontoge- netic stages. With growth of the body length, the large spinose sclerites expand their bases, and the cuticular annuli becomemore differentiated. The rectangular plates on the annuli are not well differentiated inNIGP160400 andNIGP160402. InNIGP160436, the annular rectangular plates are not preserved; thus, the growth trend of the rectangular plates during ontogeny could not be detected. Orsten-type preserved animals may, as adults, be much longer than 2–3 mm; however, entire or fragmented specimens larger than 2mmin size are rare, indicative of a preservational bias (Maas et al., 2006; see also Müller and Hinz-Schallreuter, 1993, for their palaeoscolecid material; Duan et al., 2012). Specimen NIGP160436 is only part of the trunk but has a length of 1.4 mm. The original entire individual should presumably have a body length far exceeding 2 mm.
Form A Figure 4
Occurrence.—Xinli section, Nanjiang County, northern Sichuan Province, SouthChina (Yang et al., 1983; Zhang et al., 2015). Small shelly fossils, Anabarites trisulcatus–Protohertzina anabarica Assemblage Zone, Xinli Member, Dengying Formation, Cambrian Fortunian Stage (Steiner et al., 2007; Peng et al., 2012).
Figure 3. SEM images of Eokinorhynchus rarus Zhang et al., 2015 from the lower Cambrian Xinli section. (1) A specimen representing part of the trunk, NIGP160436, dorsal view; (2) ventral view of (1); (3) right lateral view of (1). 2ls–5ls = 2nd to 5th large spinose sclerite; ss = small spinose sclerite. Scale bar = 500 μm.
Description.—NIGP160437 represents the trunk part of a worm-like animal, and the overall morphology of this animal is currently unknown. It is cylindrical in shape and has a line of at least five large spinose sclerites on the dorsal side (ls-1, ls-2, ls-3, and two more sclerites caudally; Fig. 4.1, 4.3, 4.5, 4.6). Except the large spinose sclerites (Fig. 4.2), there are no other sclerites or spines on the trunk. The large spinose sclerites decrease in size from anterior to posterior (Fig. 4.1). The cuticle is ornamented with a large number of annuli (Fig. 4.4). The posterior end of the trunk might have a tuft of sclerites or spines, but they are embedded within secondary phosphate calcium and cannot be detected here (Fig. 4.6). The trunk is posteriorly nested within a tube, which has a smooth and multilayered wall (Fig. 4.5, 4.6).
Materials.—One specimen, NIGP160437.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124
