|University of Bristol|
Can tracks tell us anything about the ancient ecosystem?
Tracks can provide a limited census of the sorts of creatures (as identified by footprints) that inhabited an area in space and time. Often these tracks and traces will form a typical group or assemblage. Assemblages can be monotypic, reflecting the activity of a single species or polytypic for a number of species. The type of assemblage can indicate the type of environment, although this depends greatly on our knowledge of the possible tracemakers, and the environments we assume they prefered.
Tracks of a herd or group can be used to estimate some aspects of population dynamics. We can examine and record the number of large and small prints and hypothesise about age structures and size frequencies within populations. In addition polytypic assemblages may supply evidence of predator-prey relationships ratios, so that we may hypothesise about their interactions.
Strangely, we find that there is a "domination of theropod footprints over plant-eaters" (Thulborn, 1990). This may be a result of:
"Tracks of swimming or wading dinosaurs may give fairly precise indications to the depth of water covering ancient sedimentary environments" (Perkins, 1974 in Thulborn, 1990). Deflections in footprints can also give clues to the directions of current at time of burial.
Regular changes of track assemblages found in a single locality may indicate seasonal changes, or migrations. The overall coverage of a type of assmeblage may indicate the geographical ranges of dinosaur species. "The discovery of dinosaur tracks in Spitzbergen is often quoted as convincing evidence for dinosaur endothermy" (Lockley, 1986), since this region was within the arctic circle at the time.
The track record sometimes preserves prints of limping animals, perhaps wounded or deformed (Jenny & Jossen, 1982; Tucker & Burchette, 1977 in Lockley, 1986).
Finally, tracks can be used to identify stratigraphic zones, especially when the rock record fails to preserve body fossils (Lockley, 1986).
Jenny, J., Jossen, J.A. (1982) Decouverte d'emprientes de pas de dinosauriens dans le Jurassique inferieur (Pleinsbachien) du Haut-Atlas central Maroc. C.R. Acad. Sci. Paris, V.294, pp.223-226.
Lockley, M.G. (1986) The Paleobiological and Paleoenvironmental Importance of Dinosaur Footprints. Palaios. 1, pp.37-47.
Perkins, B.F. (1974) Paleoecology of a rudist reef complex in the Comanche Cretaceous Glen Rose Limestone of central Texas. Geoscience and man. Vol.8, pp.131-173.
Thulborn, R.A. (1990) Dinosaur Traces. Chapman & Hall, London.
Tucker, M.E., Burchette, T.P. (1977) Triassic dinosaur footprints from south Wales: their context and preservation. Palaeogeog. Palaeoclim. Palaeoecol., V.22, pp.195-208.
Identify the Trackmaker