TABLE 1. Select measurements from STM7-156. Measurements in millimeters. Asterix indicates estimates.
| Skull length | 30.7 |
| Rostral length | 18.2 |
| Synsacrum | 15.5 |
| Pygostyle | 13.1 |
| Coracoid length | 12.3 |
| Coracoid, sternal width | 5.6 |
| Furcula, ramus length | 8.8 |
| Furcula, hypocleideum length | 5.8 |
| Interclavicular angle | 55.5˚ |
| Sternum, length | 16.2 |
| Sternum, width (distal expansions, lateral trabeculae) |
20 |
| Humerus, length | 20.9 |
| Humerus, deltopectoral crest | 6.3 |
| Ulna | 23.7 |
| Radius | 22.1 |
| Carpometacarpus | 9.9 |
| Alular metacarpal | 1.8 |
| Alular metacarpal, phalanx 1 | 3.2 |
| Alular metacarpal, phalanx 2 | 1.7 |
| Major metacarpal | 8.3 |
| Major metacarpal, phalanx 1 | 4.3 |
| Major metacarpal, phalanx 2 | 2.8 |
| Major metacarpal, phalanx 3 | 1.8 |
| Minor metacarpal | 9.3 |
| Minor metacarpal, phalanx 1 | 2.7 |
| Ilium | 10.5* |
| Pubis | 15.3 |
| Femur | 17.7 |
| Tibiotarsus | 21.3 |
| Tarsometatarsus | 13.1 |
TABLE 2. Comparative measurements of longipterygid taxa. Body mass was calculated from humeral length based on the formula presented by Liu et al.(Liu et al., 2012).
| Taxon | Collection No. | Skull | Rostrum | Rostrum: Skull |
Humerus | Skull: Humerus |
Femur | Tibiotarsus | Inter-membral index |
Body mass |
| Chromeornis | STM7-156 | 30.7 | 18.2 | 0.59 | 20.9 | 1.47 | 17.7 | 21.3 | 1.14 | 33.5 |
| Longipteryx | IVPP V12325 | 55 | ~35.5 | 0.61 | 42 | 1.31 | 28.3 | 30 | 1.51 | 119.3 |
| Longipteryx | IVPP V12552 | 48.6 | 29.7 | 0.61 | 39.4 | 1.23 | 27 | 28.3 | 1.44 | 100.6 |
| Longipteryx | DNHM D2889 | 67.7 | 48.5 | 0.72 | 50.6 | 1.34 | 30 | 39.6 | 1.47 | 155.5 |
| Longirostravis | IVPP V13309 | 32.9 | 24.6 | 0.75 | 23.5 | 1.40 | 20 | 25 | 1.07 | 42.6 |
| Shanweiniao | DNHM D1878 | 32.4 | 19.6 | 0.60 | 22.4 | 1.45 | 17.6 | 22.5 | 1.23 | 37.9 |
| Rapaxavis | DMNH D2522 | 30.4 | 17.8 | 0.59 | 23.6 | 1.29 | 19.1 | 24 | 1.09 | 44.1 |
TABLE 3. Comparison of the size of individual gastroliths and total gastrolith mass in Chromeornis STM7-156 with Jehol ornithuromorphs, Archaeorhynchus and Iteravis. Volumes are in mm3. Asterix indicates estimates. Ranges for Archaeorhynchus and Iteravis taken from Liu et al. (2023). < indicates greater than that number of gastroliths (too many small low density objects to get a precise count).
| Taxon | Collection No. |
Body mass |
Gastrolith No. |
Average stone volume |
Gastrolith volume range |
Total gastrolith volume |
Reference |
| Chromeornis | STM7-156 | 33.5 | >800 | 1.09 | <0.1-9.36 | 2454.6 | current paper |
| Archaeorhynchus | IVPP V14287 | 261.83 | 47 | 2.14 | <1-<8 | 100.76 | Liu et al., 2023 |
| Archaeorhynchus | IVPP V17091 | 250.93 | 94 | 2.59 | <1-<7 | 243.36 | Liu et al., 2023 |
| Archaeorhynchus | IVPP V17075 | 201.65 | 321 | 0.67 | <1-<3 | 214.65 | Liu et al., 2023 |
| Archaeorhynchus | IVPP V20312 | 486.83 | 75 | 1.92 | <1-<10 | 144.03 | Liu et al., 2023 |
| Iteravis | IVPP V23346 | 349.21 | 12 | 29.42 | <1-<90 | 353.01 | Liu et al., 2023 |
| Iteravis | IVPP V18958 | 208.2 | 15 | 16.33 | <1-<60 | 244.93 | Liu et al., 2023 |
| Iteravis | IVPP V20133 | 297.68 | 17 | 11.06 | <1-<40 | 188.05 | Liu et al., 2023 |
| Iteravis | IVPP V20134 | 233.79 | 45 | 10.8 | <1-30 | 485.83 | Liu et al., 2023 |
