A field guide to mesozoic birds and other winged dinosaurs

Heilmann’s Climbing Wing Scansoriopteryx heilmanni
Time: 155 Ma ago Location: Inner Mongolia & Liaoning, China Habitat: Daohugou Formation
Size: (juvenile) WS >10cm (3.9in); BL 21cm (8.3in); TL 22cm (8.6in) Features:
Head round w/ short, rounded snout. Teeth forward-pointing. Wings large w/ extremely
long third finger. Legs short w/ four forward-pointing toes. Tail long w/ frond-like feathers
restricted to the tip of the tail. Biology: Known only from hatchling specimens. Had
an unusual suite of primitive & advanced features that initially led some scientists to conclude
that not only were these the ancestors of all birds, but were more primitive than
most other dinosaurs (mainly due to a hip lacking the characteristic perforated socket of
all dinosaurs, which may be explained by the juvenile nature of the specimens). Unlike
almost all other dinosaurs, the minor digit was longer than the major. Extending the third
finger & its claw past the primary feathers would have allowed greater use in climbing or
probing bark. Other features may also have been related to a climbing lifestyle. The hallux
was unreversed but level w/ other toes & forward-facing, and may have aided in climbing
tree trunks. These animals were probably insectivorous & more highly arboreal than their
relatives. Likely able to glide or parachute, remiges in the juvenile specimens display a
distinctive herringbone pattern indicative of vanes w/ barbules. The remiges appear to be
attached to the third digit in the fossil, suggesting that the second & third digits were fused
together with soft tissue in life.
Hu’s Display Feather Epidexipteryx hui
Time: 155 Ma ago Location: Inner Mongolia, China Habitat: Daohugou Formation (see
above) Size: WS n/a; BL 30cm (11.8in); TL >45cm (1.5ft) Features: Large, forward-pointing
teeth. Head tall & box-like. May have had a long third finger similar to Scansoriopteryx.
Tail short, bearing four long ribbon-like feathers. Because they lacked a true pygostyle, the
tail feathers were probably largely immobile relative to the tail & permanently fanned out.
Biology: Wings highly degenerate & lacking primaries, indicating loss of gliding ability.
Probably insectivorous. The short tail of E. hui was fused, a condition which probably
evolved independently of other birds and is related to tail shortening. This was used as support
for a dramatic set of four highly elongated tail feathers (ETFs). Unlike modern feathers
but similar to confuciusornithids & enantiornitheans, the central quill of these ETF was
broad, flat, and lacked a vane of barbs, forming a single ribbon-like sheet.
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