Character (1) is derived within Apodiformes and only found in Jungornithidae (sensu Karhu 1999) and Apodidae. Character (3), presumably, is also derived and shared by Jungornithidae and Troch- ilidae. Characters (2), (4) and (5) are probably plesiomorphic but distinguish Jungornithidae from Apodidae and Trochilidae. Owing to preservation, other diagnostic characters of the Jungornithidae which were listed by Karhu (1999) are not clearly visible in the new specimen. Although the Jungorni- thidae (sensu Karhu 1999) exhibit a very characteristic morphology, monophyly of Argornis and Jungornis has not been established with unique derived characters so far; for this reason the classification of the new taxon from Messel is tentative (see Discussion).
Parargornis, gen. nov.
Parargornis gen. nov. includes very small birds which are characterized by: humerus similar in proportions to that of Argornis, with weakly developed and distally situated processus supracondylaris dorsalis; carpometacarpus slightly shorter than humerus; phalanx proximalis digiti majoris not fenestrated; legs long; tarsometatarsus with large and medially protruding trochlea metatarsi II; claw of hallux straight and longer than those of three anterior toes; wings very short and rounded; tail long with nearly symmetrical rectrices.
DIFFERENTIAL DIAGNOSIS Parargornis gen. nov. differs from
Argornis Karhu 1999 in: carpometacarpus rela-
tively shorter; phalanx proximalis digiti majoris not fenestrated.
Cypselavus Gaillard 1908 in: humerus slightly
more abbreviated and stouter, without ventrally protruding tuberculum supracondylare ventrale; crista deltopectoralis situated somewhat further proximally.
Jungornis Karhu 1988 in: humerus less abbrevi-
ated; caput humeri without distal enlargement; no ventrally protruding tuberculum musculi pronator superficialis (terminology after Karhu 1988).
Eocypselus Harrison 1984 in: humerus much
more abbreviated; crista deltopectoralis larger and more tapering; olecranon (ulna) narrower and more pronounced.
© 2003 British Ornithologists’ Union, Ibis, 145, 382–391
Aegialornis Lydekker 1891 in: humerus much more
abbreviated; crista deltopectoralis situated further proximally; processus supracondylaris dorsalis smaller.
Primapus Harrison & Walker 1975 in: processus
supracondylaris dorsalis smaller and situated further distally; crista bicipitalis less developed; crista delto- pectoralis larger.
Scaniacypselus Harrison 1984 in: humerus less
abbreviated; processus supracondylaris dorsalis much smaller; manus relatively shorter (only known from
szarskii); legs relatively longer (only known from
szarskii); wings shorter and broader, and tail much
longer (only known from S. szarskii).
Para (Gr.): near, the generic name refers to the great morphological similarity between the new taxon and Argornis. It is masculine in gender.
Parargornis messelensis, sp. nov.
HLMD Be 163 + 193 (complete, articulated skeleton on two slabs; Figs 1–9).
DIAGNOSIS As for genus.
TYPE LOCALITY AND HORIZON Messel (Hessen, Germany), Lower Middle Eocene.
DIMENSIONS OF HOLOTYPE
(Dimensions of Argornis caucasicus in square brackets, after Karhu 1999): Coracoid, 9.6 (r) [10.0]; humerus, ∼10.3 (r) [∼10.4]; ulna, 16.2 (r) [∼16.0]; carpometacarpus, 9.6 (l), 9.7 (r) [∼11.6]; femur, 12.1 (r); tibiotarsus, ∼20.1 (l), 20.3 (r); tarsometatarsus, ∼9.3 (l), 9.3 (r). Pedal phalanges: dI p1, ∼4.5; dI p2, 3.0; dII p1, 2.4; dII p3, ∼2.0; dIII p1, 2.5; dIII p2, 2.5; dIII p3, 3.1; dIII p4, 2.8; dIV p1, 1.6; dIV p2, 1.6; dIV p3, 1.9; dIV p4, 2.2; dIV p5, 2.4.
ETYMOLOGY The specific name refers to the type locality.