Interpreting behavior with fossil tracks

Footprint on the moon
Photograph (A) and labeled line drawing (B) of Ignotornis mcconnelli paratype (UCM 98122). Trackway 13 is interpreted as being made by a "shuffling" bird. Photo courtesy of the University of Colorado Museum of Natural History; line drawing from Lockley et al. 2009.

In Golden, Colorado, USA, multiple trackways were found of Ignotornis mcconnelli, the track of a Cretaceous bird. Two of the trackways (including trackway 13 in the image above) have very small step and stride lengths compared to other Ignotornis trackways found at the site, making it look like the bird sometimes "shuffled." This track pattern can be evaluated by considering the documented behaviors of modern herons, which make tracks similar to Ignotornis. Herons, and other wading birds sometimes engage in a feeding behavior called "foot-stirring," where they shuffle their feet in order to flush out prey in the shallow waters. "Foot-stirring" may be a plausible interpretation of the two "shuffling" Ignotornis trackways at this particular site, and may provide evidence for shallow water at that location.

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