Table 1 Average dimensions and ratios of ventral and dorsal valves of Eohadrotreta zhenbaensis from the Cambrian (Series 2) Shuijingtuo Formation of the Three Gorges area, South China
Ventral valve | Lpr | Wpr | Lms | Wms | Lf | Wf | Lpr/Wpr | Lms/Wms | Lpr/Lms | Wpr/Wms |
N | 23 | 23 | 61 | 67 | 23 | 24 | 23 | 59 | 21 | 23 |
Mean | 47 | 71 | 173 | 206 | 53 | 65 | 66.94% | 84.76% | 25.95% | 32.27% |
Min | 40 | 58 | 125 | 146 | 25 | 52 | 53.25% | 68.15% | 20.48% | 25.88% |
Max | 55 | 79 | 213 | 282 | 77 | 83 | 77.59% | 97.52% | 34.87% | 42.53% |
Median | 48 | 70 | 173 | 203 | 52 | 65 | 66.23% | 85.71% | 25.81% | 32.46% |
SD | 4 | 5 | 24 | 29 | 14 | 8 | 7.13% | 6.80% | 3.52% | 3.61% |
Dorsal valve | Lpr | Wpr | Lms | Wms | Lpr/Wpr | Lms/Wms | Lpr/Lms | Wpr/Wms | ||
N | 19 | 7 | 32 | 34 | 6 | 31 | 17 | 6 | ||
Mean | 53 | 71 | 166 | 220 | 74.25% | 74.96% | 29.57% | 33.77% | ||
Min | 40 | 60 | 114 | 186 | 60.00% | 55.38% | 21.14% | 27.76% | ||
Max | 65 | 78 | 246 | 274 | 82.35% | 93.90% | 38.56% | 41.94% | ||
Median | 53 | 74 | 159 | 214 | 74.55% | 77.25% | 28.82% | 33.17% | ||
SD | 7 | 6 | 32 | 25 | 8.15% | 10.89% | 4.28% | 5.24% | ||