The size of digits is important in describing tracks. The largest digit is often digit III and is described as the principle digit . The shape of the feet, particularly the morphology of the nodes and any oddly shaped digit, may be vital clues in detecting the type of trackmaker. Isolated or shallow node traces may indicate that the dinosaur was walking lightly. Equally it might suggest that the substrate it walked upon was only just pliable enough for footprints to leave their mark.
Many dinosaur tracks have a nearly symmetrical pattern.
Such measurements must be treated with a degree of scepticism though, since there are a number of reasons, other than phylogenetic ones, that might explain changes in interdigital angles. Photographs contributed by Phil Manning Ichnotaxonomy is a system of scientific classification used to identify tracks and traces of ancient animals. Ichnites include vertebrate footprints, invertebrate burrows, fossil eggs and various other traces resulting from biological activity. Ichnotaxonomy should not be confused with normal Linnean taxonomy which is used in reconstructing evolutionary family trees, or phylogenies . Evidence from trace fossils can be used to influence the reconstruction of phylogenetic trees, or to suggest a more likely tree from a choice of several.