The first tracks were found atW3 Bird site in the summer of 1998 during the large-scale mapping of the W3 Main tracksite. A faint bipedal trackway of a large theropod (Irenesauripus mclearni) marches across an intensely rippled substrate. There are also very distinct claw impressions scattered throughout the same surface, but these are most likely crocodilian swim traces.
In another area there are the footprints and trackways of small, short-legged birds which are currently being described, and also a few tracks of large, long-legged birds (Aquatilavipes curriei). The Grande Cache tracksites are among the richest in the world for bird footprints.
A single bird footprint (scale in centimetres).