A field guide to mesozoic birds and other winged dinosaurs

Cooper’s Fan-tail Bird Shanweiniao cooperorum
Time: 122 Ma ago Location: Liaoning, China Habitat: Upper Yixian Formation (see
above) Size: WS 32cm (1ft); BL 14cm (5in); TL >20cm (8in) Features: Head long w/ long,
narrow snout, & teeth restricted to the jaw tips. Wings relatively long (distal primary
8.2cm), but hand bones reduced, & all digits lacked claws. Legs long w/ short tarsus &
long toes w/ very large, gently curved claws. Up to six ribbon-like feathers formed the tail
& overlapped each other at the base. Biology: The lack of wing claws indicates that these
would have exclusively alighted on branches by grasping w/ the feet, rather than hooking
foliage or tree trunks w/ the wing claws, as in some other enantiornitheans. The large
number of tail feathers, which overlapped each other, may have evolved in parallel w/ the
retractable fan-like tails of euornitheans. These would have granted higher maneuverability
when flying among dense foliage & allowed more precise landings.
Pan’s Grasping Bird Rapaxavis pani
Time: 120 Ma ago Location: Liaoning, China Habitat: Jiufotang Formation (see above)
Size: WS ~25 cm (10in); BL 17cm (7in); TL 30cm (11.8in) Features: Snout long, thin, &
slightly down-curved, w/ small, slender teeth restricted to jaw tips. Wings short w/ short
alular digit & lacking any claws. Legs relatively long, w/ long, forward-directed hallux.
Foot claws extremely long, nearly the same length as the toes. Possible specimen has pair
of rectrices w/ partly unbarbed vanes (O’Connor & al. 2012). Biology: Lack of a J-shaped
1st metatarsal may indicate a pamprodactyl foot (all four toes facing forward) as seen in
modern swifts & mousebirds. This, combined w/ very large foot claws, long hallux, & lack
of wing claws suggests arboreal perchers, alighting on branches from the air, rather than
landing & climbing w/ assistance from the forelimbs. The toes would have been able to
grasp twigs or even flat surfaces like tree trunks or rock faces in a pincer-like arrangement
rather than the opposed grasping arrangement of normal reversed halluces. Long, thin
snout w/ slender-toothed tip indicates a probing lifestyle, either foraging on the ground on
in tree bark for invertebrates.
Yang’s Shenyang Bird Shengjingornis yangi
Time: 122 Ma ago Location: Liaoning, China Habitat: Jiufotang Formation (see above)
Size: WS >22cm (8.6in); BL 20cm (7.8in); TL unknown Features: Snout relatively long
& down-curved. Teeth large & conical, restricted to jaw tips. Upper wing bones equal in
length, hands short & clawed. Leg slightly longer than skeletal wing. Biology: The combination
of decurved snout & wing claws suggests an intermediate position between longirostrisavisines
and other longipterygids. Feathers not preserved.
Han’s Long-snout Bird Longirostravis hani
Time: 122 Ma ago Location: Liaoning, China Habitat: Upper Yixian Formation (see
above) Size: WS 32cm (1ft); BL 17cm (7in); TL >21cm (8in) Features: Head large w/ long,
very thin & delicate snout. Teeth relatively long & peg-like, restricted to jaw tips. Wings
long (primaries ~8cm) but broad & rounded (secondaries ~8cm, extending beyond bony
tail). All digits lack claws. Legs & feet very small. Single pair of ribbon-like rectrices. Biology:
Long thin snout resembles sandpipers, though anatomy of the feet shows that these
were specialized perchers. May therefore have been arboreal insectivores &/or bark probers.
130