Abstract The Morrison Formation is a laterally extensive terrestrial deposit representingan ecologically diverse assemblage of paleoenvironments from the Late Jurassic ofwestern North America. Although the Morrison Formation has recently been interpretedas a semiarid lowland savannah on the basis of geological and paleobiologicalindicators, many microenvironments within this system are more consistent with newinterpretations of the Morrison as a ground-water dominated “wetland” deposit. Herewe report new fossils from a little-studied exposure of the Morrison Formation in andaround Temple Canyon Park near Cañon City, Colorado. The Temple Canyon sectionshows a relatively thin sequence of conglomerate, sandstone, siltstone, mudstone, andlimestone beds representing alluvial to fluvial and possibly lacustrine deposition. Thesection rests on Precambrian basement and is unconformably overlain by the LowerCretaceous Lytle Formation. The mudstone and limestone beds preserve an abundantfossil flora and fauna distinct from those previously described from the MorrisonFormation. The floral assemblage includes species of algae, bryophytes, ferns, ginkgophytes,horsetails, cycads, bennettites, and conifers; together these plants indicatea warm climate with abundant local water supply. The faunal assemblage containsostracodes, conchostracans, traces of aquatic insect larvae, a terrestrial insect bodyfossil, prosobranch and pulmonate gastropods, many species of fish, a possible frog,and rare turtle remains. The presence of prosobranch gastropods, fish, and aquaticinsect larvae suggests a perennial water body with high oxygen content, while thepresence of conchostracans and pulmonate gastropods may indicate some fluctuationin water quality. Keywords: Morrison Formation, Jurassic, Cañon City, Colorado, paleoecology.

Abstract The Upper Triassic Chinle Formation and the Upper Jurassic Morrison Formation preserve a record of lacustrine deposition along the western margin of tropical Pangaea and post-Pangaean North America. The lake deposits in these formations contain archives of sedimentary and geochemical paleoclimatic indicators, paleoeco-logical data, and characteristic stratal architecture that provide glimpses into the evolution of basins linked to global- and continental-scale tectonic events and processes, and the establishment of a mosaic of continental paleoecosystems. This field trip highlights the lacustrine and associated fluvial deposits of the Monitor Butte Member of the Chinle Formation and the Tidwell and Brushy Basin Members of the Morrison Formation in the southern part of the Colorado Plateau region, with emphases on: (1) sedimentary facies analysis and paleogeography of the paleolakes; (2) stratal architecture and high-frequency sequence stratigraphy; (3) recognition of lake basin-fill types; and (4) paleontology and ichnology of lake strata and their paleoecologic, paleohydrological, and paleoclimatic interpretation .

Abstract Non-crocodyliform crocodylomorphs, often called ‘sphenosuchians’, were the earliest-diverging lineages of Crocodylomorpha, and document the stepwise acquisition of many of the features that characterize extant crocodylians. The first crocodylomorph fossils are approximately 230 million years old (upper Carnian, Late Triassic), and at least one of these early lineages persisted until at least 150 million years ago (Late Jurassic). These taxa occupied a wide variety of terrestrial environments from equatorial regions to high-paleolatitudes during the early Mesozoic. Despite a quarter-century of quantitative phylogenetic work, the interrelationships of early crocodylomorphs remain in a state of flux, though recent studies suggest that these lineages are paraphyletic with respect to Crocodyliformes, rather than forming a monophyletic early offshoot of Crocodylomorpha as some previously hypothesized. Nearly all early crocodylomorphs were upright quadrupedal small-bodied taxa, but lumping them all together as small cursorial faunivores masks ecological and morphological disparity in diet and limb functional morphology. With the accelerated pace of recent discovery of new specimens and taxa, future consensus on early crocodylomorph phylogeny will provide a solid framework for understanding their change in diversity and disparity through time, potential biogeographic patterns, and the morphological transformation leading to Crocodyliformes.