Denver

A photograph of Coelophysis bauri taken at the Denver Museum of Nature and Science in 2007.

Terminocavus sealeyi holotype NMMNH P-27468 parietal. Dorsal (A) and ventral (B) views. Paired ep1 are deflected dorsally. em, median embayment of the posterior bar; ep, epiparietal loci numbered by hypothesized position (no epiossifications are fused to this specimen); f, parietal fenestra; lb, lateral bar; L-lr/R-lr, Left/Right lateral rami of the posterior bar; mb, median bar; te, tapering lateral edges of the median bar. Scalebar = 10 cm. Reconstruction adapted from Lehman (1998).

Navajoceratops sullivani holotype SMP VP-1500 parietal. Dorsal (A) and ventral (B) views. Cross section of median bar (mb) illustrated on dorsal view. Ep1 mostly removed during extraction or preparation (see Fig. S4 for original extent). em, median embayment of the posterior bar; ep, epiparietal loci numbered by hypothesized position (no epiossifications are fused to this specimen); f, parietal fenestra; L-lr/R-lr, Left/Right lateral rami of the posterior bar; te, tapering lateral edges of the median bar. Scalebar = 10 cm. Reconstruction adapted from Lehman (1998).

Fossil skeleton of Gargoyleosaurus parkpinorum taken in 2007 at the Denver Museum of Nature and Science.

Precious opal from Australia. (public display, Denver Museum of Nature & Science, Denver, Colorado, USA) A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 4900 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates. The silicates are the most abundant and chemically complex group of minerals. All silicates have silica as the basis for their chemistry. "Silica" refers to SiO2 chemistry. The fundamental molecular unit of silica is one small silicon atom surrounded by four large oxygen atoms in the shape of a triangular pyramid - this is the silica tetrahedron - SiO4. Each oxygen atom is shared by two silicon atoms, so only half of the four oxygens "belong" to each silicon. The resulting formula for silica is thus SiO2, not SiO4. Opal is hydrous silica (SiO2·nH2O). Technically, opal is not a mineral because it lacks a crystalline structure. Opal is supposed to be called a mineraloid. Opal is made up of extremely tiny spheres (colloids - <a href="https://www.uwgb.edu/dutchs/acstalks/acscolor/OPALSPHR.jpg" rel="nofollow">www.uwgb.edu/dutchs/acstalks/acscolor/OPALSPHR.jpg</a>) that can be seen with a scanning electron microscope (SEM). Gem-quality opal, or precious opal, has a wonderful rainbow play of colors (opalescence). This play of color is the result of light being diffracted by planes of voids between large areas of regularly packed, same-sized opal colloids. Different opalescent colors are produced by colloids of differing sizes. If individual colloids are larger than 140 x 10-6 mm in size, purple & blue & green colors are produced. Once colloids get as large as about 240 x 10-6 mm, red color is seen (Carr et al., 1979). Not all opals have the famous play of colors, however. Common opal has a wax-like luster & is often milky whitish with no visible color play at all. Opal is moderately hard (H = 5 to 6), has a white streak, and has conchoidal fracture. Several groups of organisms make skeletons of opaline silica, for example hexactinellid sponges, diatoms, radiolarians, silicoflagellates, and ebridians. Some organisms incorporate opal into their tissues, for example horsetails/scouring rushes and sawgrass. Sometimes, fossils are preserved in opal or precious opal. The precious opal shown above is surrounded by silicified claystone. The rock is from the Griman Creek Formation, a Cretaceous-aged succession of nonmarine, fine-grained and coarse-grained siliciclastic sedimentary rocks. Stratigraphy: Griman Creek Formation, Albian Stage, upper Lower Cretaceous Locality: Coocoran Opal Field, west-southwest of Coocoran Lake, northern New South Wales, eastern Australia Photo gallery of opal: <a href="http://www.mindat.org/gallery.php?min=3004" rel="nofollow">www.mindat.org/gallery.php?min=3004</a> References cited: Carr et al. (1979) - Andamooka opal fields: the geology of the precious stones field and the results of the subsidised mining program. Geological Survey of South Australia Department of Mines and Energy Report of Investigations 51. 68 pp.

Precious opal from Australia. (public display, Denver Museum of Nature & Science, Denver, Colorado, USA) A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 4900 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates. The silicates are the most abundant and chemically complex group of minerals. All silicates have silica as the basis for their chemistry. "Silica" refers to SiO2 chemistry. The fundamental molecular unit of silica is one small silicon atom surrounded by four large oxygen atoms in the shape of a triangular pyramid - this is the silica tetrahedron - SiO4. Each oxygen atom is shared by two silicon atoms, so only half of the four oxygens "belong" to each silicon. The resulting formula for silica is thus SiO2, not SiO4. Opal is hydrous silica (SiO2·nH2O). Technically, opal is not a mineral because it lacks a crystalline structure. Opal is supposed to be called a mineraloid. Opal is made up of extremely tiny spheres (colloids - <a href="https://www.uwgb.edu/dutchs/acstalks/acscolor/OPALSPHR.jpg" rel="nofollow">www.uwgb.edu/dutchs/acstalks/acscolor/OPALSPHR.jpg</a>) that can be seen with a scanning electron microscope (SEM). Gem-quality opal, or precious opal, has a wonderful rainbow play of colors (opalescence). This play of color is the result of light being diffracted by planes of voids between large areas of regularly packed, same-sized opal colloids. Different opalescent colors are produced by colloids of differing sizes. If individual colloids are larger than 140 x 10-6 mm in size, purple & blue & green colors are produced. Once colloids get as large as about 240 x 10-6 mm, red color is seen (Carr et al., 1979). Not all opals have the famous play of colors, however. Common opal has a wax-like luster & is often milky whitish with no visible color play at all. Opal is moderately hard (H = 5 to 6), has a white streak, and has conchoidal fracture. Several groups of organisms make skeletons of opaline silica, for example hexactinellid sponges, diatoms, radiolarians, silicoflagellates, and ebridians. Some organisms incorporate opal into their tissues, for example horsetails/scouring rushes and sawgrass. Sometimes, fossils are preserved in opal or precious opal. The precious opal shown above is surrounded by silicified claystone. The rock is from the Griman Creek Formation, a Cretaceous-aged succession of nonmarine, fine-grained and coarse-grained siliciclastic sedimentary rocks. Stratigraphy: Griman Creek Formation, Albian Stage, upper Lower Cretaceous Locality: Coocoran Opal Field, west-southwest of Coocoran Lake, northern New South Wales, eastern Australia Photo gallery of opal: <a href="http://www.mindat.org/gallery.php?min=3004" rel="nofollow">www.mindat.org/gallery.php?min=3004</a> References cited: Carr et al. (1979) - Andamooka opal fields: the geology of the precious stones field and the results of the subsidised mining program. Geological Survey of South Australia Department of Mines and Energy Report of Investigations 51. 68 pp.

Aquifers in the Denver Basin (USGS)

The nodosaurid dinosaur, Glyptodontopelta is mostly known from isolated osteoderms ("armor plates"). The specimen SMP VP-1580 (State Museum of Pennysylvania) is however, the most complete known specimen, comprising parts of the skull, hundreds of osteoderms and fragments. This specimen was discovered in 2003 by Warwick Fowler, in the Naashoibito Member of the Ojo Alamo Formation (Maatrichtian, Late Cretaceous) of the San Juan Basin, New Mexico, during an expedition led by Dr. Robert Sullivan.

Magnoavipes sp. - dinosaur track from the Cretaceous of Colorado, USA. (replica; public display, Red Rocks Amphitheater visitor center, west of Denver, Colorado, USA) Dinosaur Ridge, Colorado has numerous dinosaur fossils, including bones and tracks. The most common track type at the site is Caririchnium leonardii, which was made by an iguanodontid dinosaur. A less common track is this - a slender, three-toed print called Magnoavipes, which was made by a theropod dinosaur. Stratigraphy: Dakota Sandstone, upper Lower Cretaceous Provenance: eastern side of Dinosaur Ridge, Dakota Hogback, west of Denver, north-central Colorado, USA

Caririchnium leonardii - dinosaur track from the Cretaceous of Colorado, USA. (replica; public display, Red Rocks Amphitheater visitor center, west of Denver, Colorado, USA) Dinosaur Ridge, Colorado has numerous dinosaur fossils, including bones and tracks. The most common track type at the site is Caririchnium leonardii, which was made by an iguanodontid dinosaur. The large, wide, three-toed print was produced by a hindfoot. Stratigraphy: Dakota Sandstone, upper Lower Cretaceous Provenance: eastern side of Dinosaur Ridge, Dakota Hogback, west of Denver, north-central Colorado, USA