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FAD/MM, the ratio of the length of the first phalanx of the alular digit to that of the major metacarpal; MM/HL, the ration of the length of the major metacarpal to that of the manus; SMD/FMD, the ratio of the length of the second phalanx of the major digit to that of the first one; HL/H, the ratio of the length of the hand length to that of the humerus. Abbreviations: Arch, Archaeopteryx; Cath, Cathayornis; Conf, Confuciusornis; Eoen, Eoenantiornis; FAD, the first phalanx of the alular digit; FMD, the first phalanx of the major digit; H, humerus length, HL, hand length; Laru, Larus; MM, major metacarpal; Prot, Protopteryx; SMD, the second phalanx of the major digit.
II. Cladistic analysis of major groups of birds.
We have conducted a cladistic analysis (Hennig 86) of early birds based on 86 characters (characters 1 through 84 are modified from Sanz, Chiappe and Buscalioni, 1995; 85 and 86 are new characters) of 11 taxa, with Dromaeosaurids and Archaeopteryx as outgroups and Protopteryx, Cathayornis, Confuciusornis, Chaoyangia, Concornis, Enantiornis, Hesperornithiformes, Ichthyornithiformes, and modern birds as ingroups. We obtained one most parsimonious tree.
List of characters, the data matrix, and the most parsimonious cladogram are as follows:
List of characters and data matrix (0, primitive; 1, 2, derived; ?, missing or uncertain; N, not comparable) used in the parsimony analysis.
- Fusion of premaxillae in adults: absent (0), present (1).
- Maxillary process of premaxilla forming most of the facial margin: absent (0), present (1).
- Frontal process of premaxilla extends caudally to the level of lacrimals: absent (0), present (1).
- Premaxillary teeth absent: absent (0), present (1).
- Osseous external naris considerably larger than antorbital fenestra: absent (0), present (1).
- Loss of maxillary fenestrae: absent (0), present (1).
- Cranial jugal border very close to the caudal margin of the osseous external naris: absent (0), present (1).
- Ectopterygoid: present (0), absent (1).
- Orbital process of quadrate sharp and pointed: absent (0), present (1).
- Quadratojugal cotyle in lateral face of mandibular process ofquadrate: absent (0), present (1).
- Quadrate pneumaticity: absent (0), present (I).
- Articular pneumaticity: absent (0), present (1).
- Prominent ventral processes on cervicodorsal vertebrae: absent (0), present (1).
- Dorsal vertebral count more (0) or less (1) than 13-14 elements.
- Dorsal vertebral count more (0) or less (1) than 11 elements.
- Wide vertebral foramen in dorsal series, with ratio between the vertical diameter of the vertebral foramen and the articular cranial facet greater than 0,40: absent (0), present (1).
- Synsacrum with less (0) or more (1) than 8 vertebrae.
- Heterocoelous cervical vertebrae: absent (0), present (1).
- Pygostyle: absent (0), present (1).
- Caudal vertebral count more (0) or less (1) than 15 elements.
- Ossified uncinate processes: absent (0), present (1).
- Broad, firm articulation between the coracoid and scapula: present (I), absent (0).
- Procoracoid process: absent (0), present (1).
- Strutlike coracoid: absent (0), present (1).
- Scapulocoracoid articulation well below the shoulder end of coracoid: absent (0), present (1).
- Supracoracoid nerve foramen (incision) located in the medial margin of coracoid: absent (0), present (1).
- Coracoid forming a sharp angle with the scapula at the level of the glenoid cavity: absent (0), present (1).
- Scapula with sharp caudal end: absent (0), present (I).
- Sagittally curved scapular shaft: absent (0), present (1).
- Large, rectangular ossified shaped sternum: absent (0), present (I).
- Ossified keel of sternum: absent (0), present (1).
- V-shaped furcula, with long hypocleideum: absent (0), present (1).
- Proximal and distal ends of humerus expanded roughly in the same plane: absent (0), present (1).
- Humerus longer (0) or shorter than or nearly equivalent (1) to ulna.
- Craniocaudally convex, spherical head of humerus: absent (0), present (1).
- Ventral tubercie of humerus projecting distinctly caudally, separated from the humeral head by a deep capital incision: absent (0), present (1).
- Humerus with well-developed transverse ligamental groove: absent (0), present (I).
- Distal condyles of humerus located mainly on cranial aspect: absent (0), present (1).
- Dorsal condyle of ulna developed as a semilunar ridge: absent (0), present (1).
- Shaft of radius considerably thinner than that of ulna, ratio of diameter of radius to ulna smaller than 0.70: absent (0), present (1).
- Carpometacarpus: absent (0), present (1).
- Extensor process on carpometacarpus: absent (0), present (1).
- Fused pelvic elements: absent (0), present (1).
- Acetabulum small, ratio of acetabulum to ilium less than or equal to 0.11: absent (0), present (1).
- Ilium-ischium-pubis more or less parallel: absent (0), present (1).
- Pelvis with prominent antitrochanter: absent (0), present (1).
- Iliac brevis fossa: present (0), absent (1).
- Iliac fossa for M. cuppedicus (= M. iliofemoralis internus): present (0), absent (1).
- Ischiadic terminal processes not in contact: absent (0), present (1).
- Apices of pubis not in contact: absent (0), present (1).
- Shaft of pubis laterally compressed throughout its length: absent (0), present (1).
- Pubic foot: present (0), absent (1).
- Retroverted pubis, separated from the main synsacral axis by an angle smaller than 45~: absent (0), present (1).
- Femur with distinct fossa for capital ligament: absent (0), present (1).
- Trochanteric crest of femur: absent (0), present (1).
- Femur with deep patellar groove: absent (0), present (1).
- Popliteal fossa of femur bounded distally by a transverse ridge: absent (0), present (1).
- Tibiofibular crest in the lateral condyle of femur: absent (0), poorly developed (1), prominent (2).
- Posterior trochanter of femur: present (0), absent (I).
- Complete fusion of calcaneum, astragalus, and tibia: absent (0), present (1).
- Cranial cnemial crest of tibiotarsus: absent (0), present (1).
- Extensor canal on tibiotarsus: absent (0), present (1).
- Iliofibularis tubercle of fibula caudolaterally or caudally directed: absent (0), present (1).
- Fibula greatly reduced in length: absent (0), present (1).
- Free distal tarsals in adults: absent (0), present (1).
- Distal tarsals and metatarsals fused completely to form a tarsometatarsus: absent (0), present (1).
- Metatarsal fusion starting distally: absent (0), present (1).
- Metatarsal V: present (0), absent (1).
- Proximal end of metatarsal III plantarily displaced with respect to metatarsals II and IV: absent (0), present (1).
- Intercotylar eminence of tarsometatarsus well developed: absent (0), present (1).
- Distal vascular foramen of tarsometatarsus: absent (0), present (1).
- Prominent bicipital crest of humerus, cranioventrally projecting: absent (0), present (I).
- . Convex external cotyle of ulna, separated from the olecranon by a groove: absent (0), present (1).
- Convex lateral margin of coracoid: absent (0), present (1).
- Supracoracoid nerve foramen of coracoid opening into an elongate furrow medially and separated from the medial margin by a thick bony bar: absent (0), present (1).
- Strong lateral grooves on the bodies of dorsal vertebrae: absent (0), present (1).
- Costal fossae (parapophyses) located in the central part of the bodies of dorsal vertebrae: absent (0), present (1).
- Caudal projection of the lateral border of the distal end of femur: absent (0), present (1).
- Wide and bulbous medial condyle of tibiotarsus: absent (0), present (1).
- Metatarsal IV significantly smaller than metatarsals II and III: absent (0), present (1).
- Trochlea metatarsal II broader than the trochlea of metatarsals III and IV: absent (0), present (1).
- Round articular surface in the proximal end of tibiotarsus: absent (0), present (1).
- Lateral face of the humeral bicipital crest with a small fossa for muscular attachment: absent (0), present (1).
- Furcula laterally excavated: absent (0), present (1).
- Metacarpal III extends past metacarpal II distally: absent (0), present (1).
- Three wing claws: absent (0), present (1).
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