SALVAGE SURVEY OF AN EARLY CRETACEOUS DINOSAUR TRACKWAY SITE IN ARKANSAS

A new dinosaur trackway site with the first reported occurrence of theropod trackways in southwest Arkansas was exposed on private property. The trackways were exposed over an area of approximately 6000 m² on a thin (ca. 0.5 – 0.7 m thick) limestone layer within the De Queen Limestone member of the Trinity Group (early Cretaceous) and displaying numerous tracks of theropod and sauropod dinosaurs. A salvage survey of the site acquired high resolution (0.006 m resolution) LiDAR of the entire exposed trackway limestone, very high resolution LiDAR (0.001 m resolution) of selected theropod tracks, a photo mosaic of ca. 1700 m² (1-m² photo grid) of the limestone surface exposing the greatest concentration of tracks, 36 plaster casts of individual theropod tracks (possibly representing two different theropod types), several thousand oblique photos of tracks and trackways, high-definition professional video, rock samples of sedimentary strata above, below, and within the trackway limestone for isotopic and paleoenvironmental analysis. The largest theropod tracks (apparent foot length ca. 0.7 m long and apparent foot width ca. 0.6 m wide) occur in two 30-m long trackways that are parallel but opposing directions. Individual tracks along each trackway show significant inward rotation with left and right pes impressions nearly in-line. Several other theropod trackways in excess of 100 m are also present. Individual tracks within these longer trackways are somewhat smaller (approximately half the size of the largest theropod tracks), show less inward rotation, and display greater interpedal distance with distinct claw, digit and foot pad impressions. These tracks may represent a different theropod species than the largest tracks. The trackways and exposure surface have important implications for early Cretaceous paleogeography and paleoclimate, theropod biomechanics and biogeography.