A Forgotten Collection of Vertebrate and Invertebrate Ichnofossils from the Nugget Sandstone (?Late Triassic-?Early Jurassic), Near Heber, Wasatch County, Utah
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181 Lockley, M.G. & Lucas, S.G., eds., 2014, Fossil footprints of western North America: NMMNHS Bulletin 62 A FORGOTTEN COLLECTION OF VERTEBRATE AND INVERTEBRATE ICHNOFOSSILS FROM THE NUGGET SANDSTONE (?LATE TRIASSIC-?EARLY JURASSIC), NEAR HEBER, WASATCH COUNTY, UTAH DANIEL J. CHURE1, THOMAS ROGER GOOD2 AND GEORGE F. ENGELMANN3 1Dinosaur National Monument, Box 128, Jensen UT 84035 U.S.A. [email protected]; 2Department of Geology and Geophysics, Frederick Albert Sutton Build- ing, University of Utah, 115 S 1460 East, Salt Lake City, UT 84112 U.S.A. [email protected]; 3Department of Geography and Geology, University of Nebraska, Omaha, NE 68182 U.S.A. [email protected]; Abstract—In the University of Utah Ichnology Collection we have located a small collection of ichnofossils from the Nugget Sandstone that was part of an unpublished Master’s thesis by Sheryl Albers. This historically significant collection, which was made from an active stone quarry, includes invertebrate and vertebrate traces, both as latex molds of specimens and actual fossils. These specimens allow a description of all the ichnofossils from the Heber quarry, based on both museum specimens and field photos of uncollected fossils. The ichnofauna is typical of late Paleozoic and Mesozoic eolian dune slipface paleoenvironrnents. Most of the vertebrate traces are referable to Brasilichnium, with the exception of three rare lacertoid trackways, one of which preserves excellent detail. Invertebrate trackways are referable to both Paleohelcura and Octopodichnus. A few Entradichnus burrows are present. The abundance of trace fossils and closely spaced invertebrate and vertebrate traces with parallel orientation and the same direction of travel on the same bedding surface is unusual in the Nugget Sandstone and suggests that further examination of the Nugget exposures in the Heber area might prove fruitful. INTRODUCTION GEOLOGICAL SETTING The first scientific description of ichnofossils from the Nug- During the Late Triassic through Early Jurassic a vast eo- get Sandstone is in a Master’s thesis (Albers, 1975). Although lian sand sea covered much of what is now the western United that work remains unpublished, it has been cited and discussed States, the largest erg in the history of North America. This erg in the peer-reviewed scientific literature (Stokes, 1978; Lockley, covered more than 2.2 million km2 of Idaho, Wyoming, Utah, 2011; Lockley et al., 2011 for example). Albers made 19 latex Colorado, New Mexico, Arizona, Nevada, and California (Mil- molds of ichnofossils in the field during her study, but neither ligan, 2012; Kocurek and Dott, 1983). The deposits of this erg illustrated nor described most of them. We made hydrostone include the Wingate and Navajo sandstones of the Glen Canyon casts from those molds and deposited them in the University of Group and the Aztec Sandstone to the south, and the Nugget Utah Ichnology Collection. All field photos of ichnofossils in Sandstone in the north (Sprinkel et al., 2011). The erg deposits her thesis are of fossils that were not collected. are extensively exposed and studied in the central and southern These Heber Nugget ichnofossils occurred in an active parts of the Colorado Plateau, but exposures on the northern part stone quarry where new surfaces were continually being ex- of the plateau along the north and south limbs of the Uintah posed and destroyed. Other than seven small slabs bearing Mountains, as in the Heber area, are less extensive, and have vertebrate and invertebrate traces, which were collected but not received less study. described, all specimens Albers observed in the field were These Triassic-Jurassic erg deposits are mostly unfossilifer- destroyed through either human agency or erosion. In one field ous, with only a handful of localities with vertebrate body fossil photo the trace-bearing slab has a large white number or letter material reported from the central and southern Colorado Pla- painted on it (see Octopodichnus below), which may have been teau (Brady, 1935, 1936; Camp, 1936; Irmis, 2005; Sertich and related to the quarrying operations. Loewen, 2010), and until recently (Britt et al., 2011), none from Here we document the complex history of the Heber quarry the Nugget Sandstone to the north. In contrast, both vertebrate collection, provide an inventory of the existing specimens, pro- and invertebrate trace fossils are much more common than body vide an inventory of figured fossils that were neither collected fossils in these erg deposits and can be locally abundant (Lucas et nor molded and, thus, no longer exist, illustrate all the material al., 2006; Engelmann and Chure, 2011; Engelmann et al., 2010). in the collection, provide a description and some assessment of These eolian environments are dominated by dune deposits, but the diversity (based on both the UUIC collection and the uncol- desert lake sediments (both sandstone and carbonate) of very lected specimens), and describe the few specimens in other limited lateral extent are present. Some of these bodies of water collections that came from the Heber quarry. must have persisted at least for decades and supported diverse oasis communities (Eisenberg, 2003; Parrish and Falcon-Long, INSTITUTIONAL ABBREVIATIONS 2007; Wilkens, 2008; Britt et al., 2011). Abundant invertebrate trace fossils in some dune beds indicate long pluvial intervals BYU Museum of Paleontology, Brigham Young (Loope and Rowe, 2003; Loope et al., 2004; Ekdale et al., 2007). University, Provo, UT. In the study area, only the upper part of the Nugget Sand- UUIC University of Utah Ichnology Collection, stone is exposed, but its thickness has been estimated at 385 m Department of Geology and Geophysics, Salt Lake City, UT. from well data (Biek et al., 2003). The deposits are dominated 182 by cross-bedded, eolian sandstone beds with both siliceous and abandoned….” (Buss, 1921, p. 159). If the quarry had a name Buss calcareous cement (Biek et al., 2003). did not give it. The Buss locality description is very similar to Albers’ description of her study area “Most of the field data for this LOCALITY thesis were gathered from quarries in T4S, R6E, Sec. 6 and 7 on Lake Creek about four miles east of Heber” (Albers, 1975, p. 5). In The Nugget Sandstone in the Heber area is well indurated, a review of Navajo and Nugget Sandstone fossil tracks, Stokes parts well along bedding planes, and has long been commercially (1978) identified a series of track-producing quarries in the Nugget quarried for building stone. Albers (1975) wrote that her fossils Sandstone about 4 miles east of Heber. He wrote that these were came from either currently or recently active quarries with fresh the quarries that were studied by both Buss and Albers and that he working faces. personally saw many tracks in that area. She described her study area as follows “Most of the field data Today East Center Street proceeds east out of Heber, becom- for this thesis were gathered from quarries and outcrops in T4S, ing Lake Creek Road and then East Lake Creek Road. This is road R6E, Sec. 6 and 7 on Lake Creek about four miles east of Heber” 169 mentioned by Albers (Fig. 1). At the intersection of 6400 East (Albers, 1975, p. 3) and “The best exposures can be seen north of and East Lake Road, at the mouth of Lake Creek Canyon, the still Utah state route 169 which leads east out of Heber, Utah, and active American Stone Quarry produces flagstone and building follows Lake Creek” (Albers, 1975, p. 5). The map of the forma- stone from the Nugget Sandstone. That quarry is marked on the tions, outcrops, and the stone quarry in Albers’ thesis is reproduced Center Creek Geologic Map (Biek et al., 2003) and within 0.7 km in part here as Figure 1. However, her text provides limited and east of it on East Lake Road an additional 10 quarries in the somewhat unclear information as to which fossil trackways she Nugget Sandstone are noted. In contrast, the older Center Creek molded. Although Albers mentioned studying outcrops in “quar- topographic map (Anonymous, 1993) shows only four quarries in ries,” she recounted that the 19 molds of trackways were all made addition to the American Stone Quarry. Vertebrate tracks can still from a single quarry that she identified as “the Heber Quarry.” Fig- be seen in the area of the American Stone Quarry (TRG pers. obs.) ure 1, reproduced here from her thesis, marks the quarry location. and our observations are consistent with our conclusion that it is Previously, Buss (1921) had reported similar fossil trackways the locality where Buss’ specimens came from and where Albers from a quarry in the Heber area. Although he did not identify the molded trackways and collected specimens. formation from which they were collected, he referred to it as Tri- The catalog cards for the molds suggest that they were made at assic or Jurassic in age. Buss’ description of the locality for these several different sites; Tuckett Home (3 molds), Upper Quarry specimens is “Four miles east of Heber City, Utah, at the mouth of (1 mold), Lower Quarry Road (3 molds), and a series numbered 1 Lake Creek Canyon, is a quarry of red sandstone, now practically through 13 (Table 1). However, Eugene Tuckett granted Albers TABLE 1. Data on the existing ichnological collection from the Susan Albers’ study. Albers’ identifications are those given on the current UUIC catalog cards. UUIC catalog number for each mold is written on the back of each mold in fine tipped magic marker. Locality data is given as written on back of molds. Tuckett Home, Upper Quarry, and Lower Quarry Road are written on back of molds in wider tipped magic marker. Numbers (with no locality name) are written on back of molds in fine tip magic marker or pencil.