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3D modeling of footprint formation
Sub-surface foot movements of a bird walking through sediment, used to simulate footprint
formation, may assist in the interpretation of fossilized dinosaur tracks, according to a study.
Complex deformation of sediment at various depths during footprint formation complicates
fossilized track interpretation. To understand track formation, Peter L. Falkingham and
Stephen M. Gatesy collected bi-planar X-ray video of guineafowl walking across both a solid
surface and a bed of poppy seeds. The videos allowed the authors to reconstruct the 3D
motions of the birds’ feet even when the feet were hidden from sight below the sediment
surface. The authors incorporated the motions into a discrete element simulation that
modeled the movement of more than 2 million individual poppy seed grains in reaction to a
foot, creating a virtual footprint. The simulation also displayed the development of the track
through time and throughout the sediment volume, a dynamic development called track
ontogeny. Peeling apart the layers of the virtual track, the authors directly compared the
simulated footprint with a 200-million-year old dinosaur track. Previously enigmatic features
of the dinosaur track may be linked to specific motions of the guineafowl foot, the authors
note, highlighting features formed during both the entry and exit of the foot. The results may
lead to improved interpretation of fossil footprints and the locomotion of the animals that
created the footprints, according to the authors.
Article #14-16252: “The birth of a dinosaur footprint: Subsurface 3D motion reconstruction
and discrete element simulation reveal track ontogeny,” by Peter Lewis Falkingham and
Stephen M. Gatesy.
MEDIA CONTACT: Peter Lewis Falkingham, Comparative Biomedical Sciences, Royal
Veterinary College, Hatfield, UNITED KINGDOM; tel: 447474838049; e-mail:
<pfalkingham@rvc.ac.uk>
AFTER THIS ARTICLE PUBLISHES, it will be available at
http://www.pnas.org/cgi/doi/10.1073/pnas.1416252111