Diplocraterion, a U-shaped burrow attributed to infaunal invertebrates, is normally a shallow-marine trace fossil and not part of a continental vertebrate ichnoassemblage. Hence, the Glen Rose Formation (Aptian–Albian) of Texas (USA) presents an opportunity to study Diplocraterion associated with a world-class dinosaur tracksite. Most Diplocraterion are in a bioclastic wackestone–packstone bed just above the Taylor Tracklayer, a significant dinosaur track horizon. Diplocraterion are consistently sized, but with variable depths; most have protrusive spreiten and northeast–southwest trends. Smaller Arenicolites co-occur with Diplocraterion, and other trace fossils include Rhizocorallium and a large theropod trackway. Based on our analysis, a sea-level rise buried the Taylor Tracklayer, with a shallow-marine carbonate mud colonised by Diplocraterion and Arenicolites tracemakers. Protrusive Diplocraterion, eroded burrow tops, Rhizocorallium, and other criteria point towards firming and net erosion of the bed caused by a stillstand. The depositional environment of the Diplocraterion bed was possibly a subtidal lagoon that covered shoreward sediments impacted by large theropods. Burrow orientations suggest bidirectional currents consistent with trends of theropod trackways, implying each were controlled by a shoreline. The results of our study demonstrate how marine invertebrate and continental vertebrate trace fossils can be used together to define fine-scale changes in former carbonate shorelines.
ichnology, trace fossils, dinosaur tracks, burrows, Cretaceous, sea level
Earth Sciences | Geology | Paleobiology | Paleontology | Sedimentology
Anthony J. Martin, Michael Blair, Benjamin F. Dattilo, Sadye C. Howald, and James O. Farlow (2015).
The Ups and Downs of Diplocraterion in the Glen Rose Formation (Lower Cretaceous), Dinosaur Valley State Park, Texas (USA). Geodinamica Acta.