ABSTRACT: Colorado's Dinosaur Freeway--A Cretaceous Megatracksite in the Dakota Group: Implications for Sequence Stratigraphy
Martin G. Lockley, R. Farley Fleming
Recent studies of regionally extensive dinosaur track-bearing strata reveal that all known occurrences are associated with coastal plain lithosomes. These can be associated with clastic facies assemblages, as in the case of the Dakota Group of Colorado (Cretaceous, Albian-Cenomanian), or with carbonate platform environments, as in the case of the Glen Rose Formation of Texas (Cretaceous, Albian).
Preliminary work on the Dakota megatracksite reveals a package of track-bearing beds in the upper part of the economically productive Muddy (or J) Sandstone of the Colorado Front Range. The track-bearing layers appear to be confined to a single valley fill sequence and are therefore closely associated with relative sea-level changes that have recently been documented.
Despite the lack of vertebrate and invertebrate fossils in the Dakota Group, there are considerable prospects for detailed stratigraphic correlation using palynology and trace fossils. This appears to be generally true for many clastic coastal plain facies. Although invertebrate trace fossils have been used effectively in depositional environment interpretation and modeling, the integration of vertebrate track and palynological data in sequence stratigraphy and studies of relative sea level is unprecedented.
AAPG Search and Discovery Article #91002©1990 AAPG Rocky Mountain Section Meeting, Denver, Colorado, September 16-19, 1990