Although Not Actually Fossils,

as in bones or say teeth,

  photograph Stephen Rowland/Grand National Park, after a land slip, a boulder with fossilized tracks was revealed, park officials said in a news release last Thursday, the fossil footprints are about 313 million years old, according to researchers, “These are by far the oldest vertebrate tracks in Grand Canyon, which is known for its abundant fossil tracks” Stephen Rowland, a paleontologist at the University of Nevada, Las Vegas, said in the news release. “More significantly, they are among the oldest tracks on Earth of shelled-egg-laying animals, such as reptiles, and the earliest evidence of vertebrate animals walking in sand dunes.” apparently the footprints are the oldest recorded tracks of their kind, the tracks were in plain view for many hikers, but weren’t discovered until Allan Krill, a Norwegian geology professor, was hiking with students and saw a boulder containing “conspicuous fossil footprints,” park officials said, researchers said the footprints show two separate animals passing on the slope of a sand dune, which is significant because of the “distinct arrangement of footprints.” 

above trackway-bearing blocks. (A) Main trackway block adjacent to Bright Angel Trail, with tracks in concave epirelief (impressions). Scale is calibrated in decimeters. (B) Sketch of main trackway surface. Note occurrence of Trackway 2 (alignments of small black spots) above Trackway 1. (C) Jumble of rocks adjacent to Bright Angel Trail, including at least two rocks with amniote tracks. (D) Counterpart block with tracks in convex hyporelief (natural casts). Scale is calibrated in decimeters, from PLOS ONE, from this document, “The researchers’ reconstruction of this animal’s footfall sequence reveals a distinctive gait called a lateral-sequence walk, in which the legs on one side of the animal move in succession, the rear leg followed by the foreleg, alternating with the movement of the two legs on the opposite side,” Grand Canyon officials said, they “previously had no information about that,” Rowland said. The fossil also shows the earliest-known use of sand dunes by vertebrate animals, park officials said, amazing!