The American Heritage® Dictionary of the English Language, 4th Edition
n. The branch of paleontology dealing with the study of fossilized footprints, tracks, burrows, or other traces as evidence of the activities of the organisms that produced them.
n. A branch of paleontology concerned with the study of trace fossils. It can be divided into paleoichnology and neoichnology.
the GNU version of the Collaborative International Dictionary of English
n. The branch of science which treats of fossil footprints.
The Century Dictionary and Cyclopedia
n. That branch of paleontology which treats of fossil footprints; the science of fossil footprints; the study of those animals which are known only by their footprints.
Word Usage
"The study of trace fossils - called ichnology - is very useful for reconstructing ancient environments."