Haenamichnus: giant pterosaur tracks from South Korea

Haenamichnus uhangriensis is a name for fossil footprints from the Late Cretaceous Uhangri Formation of South Korea. It is an ichnospecies – a trace fossil classified by the shape and arrangement of tracks – rather than a pterosaur body genus known from bones. The prints preserve both hand and foot impressions, including a reported 7.3-metre trackway with fourteen pairs. Their form is consistent with a large pterodactyloid, possibly an azhdarchid, but no track can identify an exact skeletal genus. The pterosaur catalogue includes it as evidence of movement rather than a complete animal skeleton.

Quick facts

How footprints received a name

Koo-Geun Hwang, Min Huh, Martin Lockley, David Unwin and Joanna Wright described the Uhangri pterosaur tracks in 2002. They named Haenamichnus uhangriensis from the region of Haenam and the Uhangri Formation, where the impressions occur in Late Cretaceous track-bearing beds. The name belongs to ichnology, the study of traces such as footprints, burrows and feeding marks. It does not mean that a corresponding bone-bearing genus called Haenamichnus has been found.

The track-bearing surfaces also preserve traces attributed to dinosaurs and web-footed birds. Their occurrence at the same stratigraphic level shows that different animals visited the broader setting represented by the beds. It does not prove that they crossed the surface at the same moment or interacted.

What the hands and feet preserve

The prints include narrow, three-toed impressions attributed to the hands and larger impressions attributed to the feet. The authors distinguished the Korean traces from previously named pterosaur ichnogenera using the combination of their proportions and the shape of the pes. In particular, the fifth pedal digit leaves little or no clear trace. That feature is consistent with a pterodactyloid pterosaur, whose foot anatomy differs from that of more basal long-tailed forms.

Reported pes impressions reach roughly 35 centimetres. Such measurements show that the trackmaker was large, but converting a footprint into a wingspan requires assumptions about limb proportions, gait and sediment deformation. The impressions were made in soft substrate, and depth or spreading can alter their apparent margins. A numerical body-size estimate is therefore less direct than the footprint itself.

The 7.3-metre trackway

At site P9, researchers mapped a sequence about 7.3 metres long with fourteen pairs of impressions. It was reported as the longest pterosaur trackway then known. The sequence provides evidence that a large pterosaur walked across the surface and allows the spacing and arrangement of its steps to be studied. It does not preserve a complete stride for every step: some impressions are eroded, absent or covered by another layer.

The alternating hand and foot traces support quadrupedal progression in this trackway. This is consistent with other well-preserved pterosaur trackways, in which the forelimbs and hindlimbs contact the ground. A walking trackway cannot by itself establish how the animal launched, landed, ran or moved its wings. Those questions require anatomy and biomechanical models as well as traces.

Who made Haenamichnus?

The large prints and lack of a distinct fifth-toe trace led the describers to infer a pterodactyloid trackmaker. They considered azhdarchids plausible because that group is represented in Late Cretaceous deposits and the print shape was compatible with their feet. This is a reasoned identification, not a direct association: the track surface contains no diagnostic pterosaur bone connected to the footprints.

It would therefore be too strong to label the maker Quetzalcoatlus, Hatzegopteryx or another named genus. Track morphology can distinguish broad patterns and support an ichnotaxon, while overlapping foot anatomy limits one-to-one identification. The trackmaker could belong to a group with no skeletal fossil yet discovered at the site.

Environment and limits of the record

The Uhangri Formation preserves sedimentary layers formed around a Cretaceous lake and coastal plain. Fine sediment could retain footprints before burial. The tracks record a brief episode of contact with a surface; they do not preserve the animal's feeding, nesting or flight. Even where prints and bones occur in the same formation, formation-level association alone does not show they belong to one species.

A reconstruction may show a large pterosaur walking with its hands and feet on the ground, but body outline, wingspan, colour, soft tissues and exact identity remain interpretive. The strongest statement is narrower and more useful: Uhangri preserves large pterosaur-like trackways, including one long sequence that documents terrestrial walking by a sizeable pterodactyloid-grade animal.