Dinosaur Footprints from the Lower Jurassic East Berlin Formation, Dinosaur State Park, Rocky Hill, Connecticut

In 1966 and 1967 three-toed footprints made by bipedal dinosaurs were discovered in the Lower Jurassic East Berlin Formation at Rocky Hill, Connecticut [now Dinosaur State Park (DSP)]. The tracks occur in a larger East Tracksite and an adjacent smaller West Tracksite. We present a thorough description of the dinosaur tracks of the West Tracksite, and as complete a description of the East Tracksite as is presently possible. Footprints mainly occur in two beds; tracks in the lowermost of these beds are mostly or entirely transmitted undertracks. Most DSP trackways were made by dinosaurs walking normally. Quality of morphological preservation is variable. Prints show features consistent with those of tracks attributed to theropod dinosaurs, being longer than broad, with acuminate toetips, sometimes with a slight sigmoid curvature to the digit III impression. Two discrete digital pads are sometimes seen in the digit II impression. Most of the footprints fall in the length range of 30–40 cm, but some prints in the East Tracksite were made by considerably smaller dinosaurs. The more common larger prints are consistent with the ichnotaxa Eubrontes and possibly Kayentapus, and the smaller prints with Anchisauripus (or Grallator). Trackways are mostly linear, with relative stride lengths comparable to those of other trackways attributed to theropods; footprints generally angle outward with respect to the trackmaker's direction of travel. Some trackways, however, show more erratic movements, and one trackway preserves touchdowns of the manus. Although some trackways parallel others, for the site as a whole there is no clearly defined direction of trackmaker travel. Some unusual trackways show features that in other ichnofaunas are interpreted as showing swimming or punting behavior on the part of their makers, but making the same inference for the odd DSP trackways is complicated by the possibility that the putative “swimmer” footprints are undertracks.