A field guide to mesozoic birds and other winged dinosaurs

Martin’s Yan Bird Yanornis martini
Time: 120 Ma ago Location: Liaoning, China
Habitat: Jiufotang Formation Size: WS ~80cm (2.6ft); BL 32cm (1ft); TL unknown Features:
Head small & triangular, w/ small beak at jaw tips. Teeth located behind beak. Neck
long. Wings long (manus, ulna & humerus ~equal in length, ¾ the length of torso), broad,
and powerful. Alular digit clawed. Small claw on major digit. Minor digit fused to major.
Legs short, w/ femur & tibia equal in length, tarsus ¾ length of tibia. Toes equal to tarsus
length w/ robust but weakly curved claws. Hallux small. Biology: Evidence shows that
these fed on small fish, but also ingested large amounts of gizzard stones like herbivorous
birds, so were probably omnivorous generalists. May have employed seasonal diet switching.
Feet characteristic of ground foragers. Robust body, small head & long neck may have
given these an appearance similar to modern game birds like pheasants.
Grabou’s Yixian Bird Yixianornis graboui
Time: 120 Ma ago Location: Liaoning, China Habitat: Jiufotang Formation Size: WS
60cm (2ft); BL 27cm (11in); TL 35cm (1.1ft) Features: Head small & triangular, w/ small
beak at jaw tips. Teeth short & peg-like. Neck long. Wings short (humerus & ulna just
over half torso length, manus shorter than ulna) but broad (primary feather length up to
15cm). Alular & major digits w/ small weakly curved claws. Minor digit fused to major.
Legs long w/ long tibia but short tarsus (less than half tibia length). Toes very long & thin
(nearly twice the length of the tarsus). Toes w/ small & very weakly curved claws. Tail w/ at
least eight pennaceous rectrices up to 8cm long arranged into expandable fan, somewhat
rounded in shape when expanded. Biology: Similar to Y. martini, but w/ much longer legs,
longer, more slender toes, & somewhat shorter wings. Comparison of leg & wing proportions
to modern birds indicate these may have been semi-aquatic, foraging both from the
water surface & on the ground like modern ducks & geese. May have employed some degree
of foot-propelled diving (Bell & Chiappe 2010). While there is currently no evidence
of webbed feet, the long, slender toes & small, nearly straight claws would be consistent w/
this ecology.
Linghe Songling Bird Songlingornis linghensis
Time: 120 Ma ago Location: Liaoning, China Habitat: Jiufotang Formation Size: WS unknown;
BL 10cm (4in); TL unknown Features: Head slender w/ thin, pointed jaws & numerous,
close-packed teeth. Jaw tips beaked. Wings known from fragments, but indicate
well-developed shoulder girdle musculature. Biology: Similar in many respects to other
yanornithiformes, except for small size & better-developed wings. Probably omnivorous
shorebirds wading or swimming after fish & other forage.
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