Table 1. Overview of flight-related pectoral girdle features in pennaraptorans and the inferred flight capacities.
Features similar to condition of Ornithuromorpha are highlighted in bold. GFO, glenoid fossa orientation (0: caudoventral; 1: lateral; 2: dorsolateral); CSJ, coracoscapular joint (0: long synchondrosis fused in adult; 1: localized articular surface fused in adult; 2: localized articular surface unfused but tightly articulated; 3: localized articular surface fused during early ontogeny; 4: localized articular surface of flexible joint); PAR, acromion process of the scapula (0: caudal to coracoscapular articular surface; 1: dorsally at the same level as the coracoscapular articular surface; 2: cranially over the coracoscapular articular surface); SCJ, scapuloclavicular joint (0: along the dorsal edge of the scapula; 1: at the cranial tip of the acromion process of the scapula); PAC, acrocoracoid process (0: ventral to the coracoid foramen; 1: same level as the coracoid foramen; 2: close to the glenoid fossa; 3: same level as the glenoid fossa; 4 dorsally over the glenoid fossa); ACJ, acrocoracoid process of the coracoid articulate with the furcula form the acrocoracoclavicular joint (0: no; 1: yes); PPC, coracoid with procoracoid process (0: no; 1: yes); SCA, scapula-coracoid angle (0: <110°; 1: 90–100°; 2: <90°); CRS, coracoid shape (0: trapezoidal; 1: mediolaterally narrow forming a distinct neck near the scapular articular surface; 2: strut-like); CBO, coracoid body orientation (0: mediolateral; 1: dorsoventral); IFC, inferred flight capacity (0: terrestrial; 1: potential volant and gliding flight; 2: weak powered flight; 3: intermittent powered flight, 4 continuous powered flight).
| GFO | CSJ | PAR | SCJ | PAC | ACJ | PPC | SCA | CRS | CBO | IFC | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Early pennaraptorans | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Troodontidae | 0 | 0 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 1 | 0 |
| Buitreraptor | 1 | 1 | 2 | 1 | 2 | 0 | 0 | 1 | 0 | 1 | 1 |
| Rahonavis | 1 | 2 | 2 | 1 | ? | ? | ? | ? | ? | ? | 2 |
| Microraptorinae | 1 | 1 | 2 | 1 | 2 | 0 | 0 | 1 | 1 | 1 | 1 |
| Bambiraptor | 1 | 1 | 2 | 1 | 2 | 0 | 0 | 1 | 1 | 1 | 1 |
| Velociraptorinae | 0 | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Anchiornithidae | 1 | 1 | 0 | 1 | 2 | 0 | 0 | 2 | 0 | 1 | 1 |
| Archaeopteryx | 1 | 1 | 2 | 1 | 2 | 0 | 0 | 1 | 0 | 1 | 2 |
| Jeholornis | 1 | 2 | 2 | 1 | 3 | 0 | 1 | 2 | 2 | 1 | 2 |
| Sapeornis | 1 | 2 | 2 | 1 | 3 | 0 | 0 | 2 | 0 | 1 | 2 |
| Confuciusornis | 1 | 3 | 2 | 1 | 3 | 0 | 0 | 2 | 2 | 1 | 2 |
| Enantiornithes | 2 | 4 | 2 | 1 | 4 | 0 | 0 | 2 | 2 | 1 | 3 |
| Ornithuromorpha | 2 | 4 | 2 | 1 | 4 | 1 | 1 | 2 | 2 | 1 | 4 |