Table 2.
Tests for the effects of factors hypothesized to influence occurrence of bivalve taxa in the fossil record, using log-likelihood ratio (G) test, with Williams' correction (47)
| Category | Number missing | Proportion missing | Number fossil | Adjusted G |
|---|---|---|---|---|
| Shell composition | ||||
| Entirely aragonite | 275 | 0.25 | 831 | 8.56** |
| Calcitic or bimineralic | 25 | 0.15 | 142 | |
| High-organic | 27 | 0.28 | 70 | 1.31 |
| Moderate and low-organic | 264 | 0.23 | 903 | |
| High SAV | 40 | 0.51 | 38 | 41.13*** |
| Moderate and low SAV | 170 | 0.17 | 802 | |
| Depth | ||||
| Shelf | 266 | 0.22 | 965 | 57.80*** |
| Deep-sea | 42 | 0.69 | 19 | |
| Life habit | ||||
| Epifauna | 40 | 0.15 | 235 | 18.20*** |
| Infauna | 269 | 0.26 | 749 | |
| Suspension feeder | 226 | 0.23 | 769 | |
| Deposit feeder† | 41 | 0.25 | 125 | 0.31 |
| Chemosymbiotic† | 12 | 0.15 | 66 | 2.41 |
| Carnivore† | 29 | 0.55 | 24 | 23.47*** |
| Commensal | 64 | 0.57 | 62 | 61.78*** |
| Free-living | 244 | 0.21 | 922 | |
| Geographic range‡ | ||||
| Confined to one province | 128 | 0.50 | 72 | 118.87*** |
| More than one province | 127 | 0.50 | 468 | |
| Date of description | ||||
| Pre-Treatise | 220 | 0.19 | 921 | 95.91*** |
| Post-Treatise | 88 | 0.58 | 63 |
Taxa living partially exposed above the sediment–water interface (“semi-infaunal”) grouped with epifaunal taxa. Numbers in category groupings do not sum consistently because of missing data.
**, P < 0.01;
***, P < 0.001 (after sequential Bonferroni correction).
†Compared with suspension feeders.
‡For the 540 genera in Flessa and Jablonski's (31) database having a fossil record.