A field guide to mesozoic birds and other winged dinosaurs

Holy Confucius Bird Confuciusornis sanctus
Time: 124.6-122 Ma ago Location: Liaoning, China Habitat: Yixian Formation Size: WS
63cm (2ft); BL 25cm (10in); TL 50cm (1.6ft) Features: Head round w/ long, sharply pointed
bill. Body black to dark grey, mottled w/ chestnut or reddish brown. Wings extremely
long & pointed in adults, slightly shorter in immature specimens. Wing claws very large,
strongly curved & unfeathered. Primaries white, secondaries & coverts grey to black. Legs
very short w/ small feet and medial hallux. Males ribbon-tailed w/ single pair of very long
rectrices. Females lack rectrices, tail consisting of tiny coverts (also present in males). Biology:
Young chicks have longer, bony tails which fuse & shorten as they mature. Males
develop rectrices at a young age at or near hatching; rectrices are proportionally longer in
smaller individuals. Growth slow during 1st year or two, & rapid from mid- to full-size.
Wing anatomy radically different from avians; breast small & undeveloped, breastbone
bears only a small, cartilaginous keel. Large opening in humerus indicates unique musculature
allowing some degree of flapping, but angle at which wings could be raised above
back limited by shoulder anatomy. Probably scaled trees using large wing claws, may have
been able to navigate canopy using medial hallux. May have glided between trees using
weak flapping, perhaps swooping in flocks over lakes where many have been preserved. By
far the most common bird species in the Yixian, they were possibly colonial, forming huge
flocks, some of which died en masse during volcanic eruptions & were buried simultaneously
on the lake bottoms. Young juveniles absent from large fossil assemblages, indicating
that birds below mid-size lived in isolation or in more inland environments before joining
flocks. Diet is unknown in this species.
Du’s Confucius Bird Confuciusornis dui
Time: 124.6 Ma ago Location: Liaoning, China Habitat: Yixian Formation Size: WS 52cm
(1.7ft); BL 17cm (7in); TL 40cm (1.3ft) Features: Very similar in overall anatomy to C.
sanctus. Differed in smaller adult size, an upturned bill tip, & a much smaller alular claw.
Biology: The differing bill shape is a strong indicator of a unique diet, though no stomach
contents are known. Later confuciusornithids are known to have fed on small fish, & this
seems like a good possibility for the bill function of C. dui.
Zheng’s Dawn Confucius Bird Eoconfuciusornis zhengi
Time: 131 Ma ago Location: Hebei, China Habitat: Sichakou Member, Huajiying Formation
Size: WS 38cm (1.2ft); BL 17cm (7in); TL 40cm (1.3ft) Features: Beak short & pointed,
head triangular. Wings pointed but broad & relatively stout, w/ long secondaries. Legs
short with partially reversed hallux. Ribbon-tail consisting of a single pair of very long
rectrices. Biology: Dark preservation of melanin in the only known specimen suggests a
very dark, possibly black uniform coloration. Similar in most respects to the Confuciusornis,
but much earlier chronologiacally. Also differed in small shoulder bones (coracoids) &
relatively solid vertebrae.
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