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The Crystal Geyser Dinosaur Quarry, near Green River, Utah, is located at the base of the Lower Cretaceous (Barremian) Yellow Cat Member of the Cedar Mountain Formation. The quarry preserves a nearly monospecific accumulation of a new basal therizinosauroid, Falcarius utahensis. We used field descriptions and petrographic analysis to determine the depositional environment and development of the quarry strata. Results of these analyses suggest that the quarry represents multiple episodes of bone accumulation buried by spring and overbank flood deposits. Evidence for these previously undescribed spring deposits includes calcite macroscopic structures within the quarry strata—such as pisolites and travertine fragments—and...
Categories: Publication; Types: Citation, Journal Citation; Tags: PALAIOS
The Eocene Green River Formation (GRF) (United States) is one of the best-known and most extensively studied Konservat Lagerst�tte in the world. As most studies have focused on the fossil fish and plants, few studies have examined the invertebrates, particularly the ostracodes of the renowned GRF fauna. Six species of ostracodes were recovered from 18 intervals within a 154 m section of the Laney Member (LM) in the Washakie Basin (WB). Ostracode species recovered occupied a variety of biological niches, including plant and mud dwellers as well as nektonic lifestyles. Ecological tolerances of these ostracodes were used to reconstruct environmental conditions of the lake through this portion of its history. The taphonomic...
Here we document the occurrence of locally common oncoids in the Cedar Mountain Formation of Utah in the Woodside Anticline area of the San Rafael Swell and use them to understand changes in the Early Cretaceous landscape and their effects on the dinosaur fauna. Detailed facies analysis is required to understand the context of these changes within the broader patterns of Mesozoic tectonics and the fossil record. Oncolite crops out in the Cedar Mountain Formation, directly overlying the Buckhorn Conglomerate. Oncolite is not widely distributed outside of the Woodside Anticline area. The oncoids are found in a bimodal population with the majority in the 2–5-cm-diameter range and a smaller population >25 cm in diameter....
Principal components analysis and subsequent discriminant function analysis helped interpret environments of some fish deposits in the Eocene Green River Formation of Utah and Wyoming. The analysis related 61 environ- mental variables to differing qualities of fish preservation in 45 fish deposits. It greatly facilitated a Waltherian or "guilt by association" type of facies analysis and it also served to counteract observational biases and preconceptions. Analysis indicates that completely preserved fishes are especially associated with 1) environments that can also preserve fish coprolites, 2) environments, probably deep, that exclude scavengers and physical disturbances, and 3) abiotic mudfiats with episodic inundations...
The Crystal Geyser Dinosaur Quarry contains a large monospecific accumulation of bones from a basal therizinosaur, Falcarius utahensis. The quarry is located approximately 16 km south of Green River, Utah, at the base of the early Cretaceous (Barremian) Yellow Cat Member of the Cedar Mountain Formation. Fossil bones in the quarry occur in three units that have distinct taphonomic, lithologic, and geochemical characteristics. Rare earth element compositions of fossils suggest that bones from each unit were drawn from different reservoirs or sources having distinctly different compositions, and fossils were not reworked between units. Compositions of bones differ greatly within Units 1 and 2, even within the same...
Categories: Publication; Types: Citation, Journal Citation; Tags: PALAIOS
Exposures of the upper Eocene to middle Oligocene White River Formation in northeastern Colorado contain ichnofossil-rich paleosols in a meandering alluvial system. The paleoenvironmental, paleoecological, and paleoclimatic significance of these paleosols and ichnofossils record the effects on soil ecosystems of the initial stages of global cooling in the late Eocene and early Oligocene. Previous studies of Eocene-Oligocene paleosols in Wyoming and South Dakota suggest a transition from woodland to grassland ecosystems in response to global cooling and drying. We describe four paleosol types from the study area. Type I paleosols include compound Entisols characterized by shallow networks of fine rhizoliths and ichnofaunal...
A polycotylid plesiosaur (Dolichorhynchops sp.), recently discovered in the Upper Cretaceous (Cenomanian-Turonian) Tropic Shale in Glen Canyon National Recreation Area, southern Utah, is associated with 289 gastroliths. This specimen is significant due to the general lack of gastroliths associated with most short-necked plesiosaur skeletons. The skeleton (MNA V10046) was excavated from a stratigraphic interval of marine shale that does not contain coarser-grained material. The stones were generally concentrated in one area of the skeleton, with the majority situated near the back of the skull. The stones are mainly composed of dark grey chert, are smooth and well rounded, and have varying degrees of polish. The...