The unreliability of the first and last observed instances of these objects is explained through the Signor–Lipps effect. Ichnologists (“ick-NOL-uh-jists”) study so-called “trace” examples of these objects, which (10[1])provide the primary evidence for the substrate revolution. The relative ordering of these objects are considered when invoking the law of faunal succession. Stratigraphic (10[1]-5[1])correlation (10[1])may be performed using easily identifiable examples of these objects (10[1]-5[1])with short (10[1])temporal range and wide (10[1])geographic distribution. Lagerstätten of these objects (10[1])include the Burgess Shale and La Brea (-5[1])Tar Pits. For 10 points, graptolites (10[1])and brachiopods are examples of the “index” type of what preserved remains of past organisms? ■END■ (10[5])