Bird Ichnology - Bird Ichnofossils - Footprints

Footprints

There exist documented tracks that appear avian since the Late Triassic, by some 55 million years predating the first proper evidence that very birdlike theropods were present. The Late Triassic and early-mid Jurassic tracks have been assigned to the ichnogenera Trisauropodiscus and Aquatilavipes. Few scientists would go as far though to consider these traces evidence that birds evolved much earlier than generally believed, and perhaps not from theropod dinosaurs as per today's mainstream opinion.

Footprints of at least Neornithes can be distinguished by several features:

• if a hallux is present, it is directed straight backwards or nearly so.
• the second to fourth (front) toes have a wide angle between them (generally 90-180° or so)
• due to Neornithes having a completely fused tarsometatarsus (the "lower leg", actually the ankle and midfoot bones) they have no heel pads (except large terrestrial birds)

It is notable that Heterodontosauridae are known from the localities and times when the first avian-looking footprints started to appear. These small ornithopod dinosaurs were entirely unbirdlike, except for their ornithischian pelvis and a tarsometatarsus strongly convergent to that of Enantiornithes. Though some details remain unresolved, it is far more plausible that Trisauropodiscus etc. were made by a Heterodontosaurus-like animal rather than some sort of bird.

• †Trisauropodiscus (Early Jurassic? of Stormberg, South Africa)

• †Archaeornithipus (Late Jurassic/Early Cretaceous of Soria, Spain)

• †Aquatilavipes (Early Cretaceous of Canada, E Asia ?and South Dakota, USA -? Anacleto Late Cretaceous of Sierra Barrosa, Argentina)

• †Fuscinapedis (Woodbine Early Cretaceous of Denton County, Texas)

• †Goseongornipes (Jindong Early? Cretaceous of Goseong County, South Korea) - Geongsangornipes is lapsus

• †Jindongornipes (Jindong Early? Cretaceous of Goseong County, South Korea)

• †Koreanaornis (Early Cretaceous of Korea)

• †Ichnogen. indet. (Jindong Early? Cretaceous of Goseong County, South Korea)

• †Magnoavipes (Early/Middle Cretaceous of Texas, ?and Israel -? Late Cretaceous of Korea)

• †Pullornipes (Early Cretaceous of China)

• †Shandongornipes (Tianjialou Early Cretaceous of Junan County, China)

• †Uhangrichnus (Haman Early - Uhrangi Late Cretaceous of SW Korea)

• †Barrosopus (Anacleto Late Cretaceous of Sierra Barrosa, Argentina)

• †Sarjeantopodus (Lance Late Cretaceous of Niobrara County, USA)

• †Saurexallopus (Late Cretaceous of WC USA)

• †Yacoraitichnus (Late Cretaceous of Quebrada del Tapón, Argentina) – Yacoriteichnus is lapsus

• †"Patagonichnornis" (Cretaceous of Ingeniero Jacobacci, Argentina) – nomen nudum

• †Iranipeda (Pliocene of Iran) - may be same as Gruipeda
• †Presbyorniformipes (Green River Early Eocene of Utah, USA)

• †Charadriipeda (Late Eocene of France, Spain and USA - Miocene or Romania) – including Ludicharadripodiscus

• †Leptoptilostipus (Liedena Sandstone Late Eocene of S Pyrenees, Spain)

• †Ornithoformipes (Puget Group Late Eocene of Kummer, USA)

• †Reyesichnus (Middle Miocene of Salar del Hombre Muerto, Argentina)

• †Avipeda (Copper Canyon Late Miocene of California, USA)

• †Roepichnus (Caños Late Miocene of Almería, Spain)

• †Anatipeda (Miocene of Romania)

• †Gruipeda

Ichnofamily Ignotornidae

• †Ignotornis (Haman Early Cretaceous of Korea - Dakota Sandstone Late Cretaceous of Colorado, USA, ?and Argentina)

• †Hwangsanipes (Uhangri Late Cretaceous of South Korea)