PALEOENVIRONMENTAL ANALYSIS OF A MORRISON … · paleoenvironment and paleoecology of the site....
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PALEOENVIRONMENTAL ANALYSIS OF A MORRISON FORMATION DINOSAUR SITE, BIGHORN BASIN, WY: CONDUCTING AN INTERDISCIPLINARY FIELD STUDY THROUGH DISCIPLINARY TASKS DEMKO, Timothy M. 1 , BODENBENDER, Brian E. 2 , BAAR, Eric E. 3 , HOLBROOK, Cody W. 4 , KUBAREK, Sara J. 1 , MURPHY, Jennifer 5 , RAMIREZ, Elisa M. 6 ,SCOTT, Justin E. 7 , SWOR, Emily 1 , THOMASON, Carrie 2 , and YONOVITZ, Maureen 2 (1) Department of Geological Sciences, Univ of Minnesota Duluth, 217 Heller Hall, 1114 Kirby Drive, Duluth, MN 55812, [email protected] (2) Geological and Environmental Sciences, Hope College, 35 E. 12th St, Holland, MI 49423 (3) Grand Valley State Univ, Allendale, MI (4) Western Kentucky Univ, Bowling Green, KY (5) Lawrence Univ, Appleton, WI (6) Univ of Michigan, Ann Arbor, MI (7) Casper College, Casper, WY ABSTRACT A project investigating a dinosaur fossil site near Shell, WY provides a model for conducting interdisciplinary undergraduate field research. The project involves 10 students who undertake stratigraphic and paleontological subprojects that contribute to understanding the paleoenvironment and paleoecology of the site. These subprojects include: 1) construction of bedrock and surficial geologic maps of the dinosaur fossil site and surrounding area; 2) development of a composite stratigraphic column that includes the fossil-bearing intervals; 3) description and analysis of the sedimentary facies of the fossil-bearing and associated intervals, especially those that contain paleosols; 4) description and interpretation of sandstone body architecture, including paleocurrent analysis; 5) construction of detailed quarry maps that record bone positions, associations, and stratigraphy; 6) analyses of bone taphonomy and diagenesis, especially the incorporation of rare earth elements; 7) taphonomic analysis of plant material in the bone-bearing and associated strata; and 8) collection, preparation, and identification of dinosaur and other vertebrate fossils found at the site, including screen washing of rip-up clast conglomerates. Some subprojects require the temporary help of other students to complete successfully, leading to cross-disciplinary training between the project teams. Students working on the stratigraphic subprojects, which had a definitive end to field data collection, were able to join the work on dinosaur fossil excavation, which continues up to the last field day. This gives the students working on stratigraphy a taste of paleontological research, and allows mentoring opportunities for those working on paleontology. ACKNOWLEDGMENTS We thank J. Barwis (Holland, MI), E. Hansen, G. Peaslee, and P. Atkins (Hope College), and M. Uhen (Cranbrook Institute of Science) for assistance in classroom instruction. R. Simon (Dinosaur Safaris, Inc), G. Storrs (Cincinnati Museum of Natural History), and M. Uhen provided logistical support and field instruction, and J. Anderson facilitated field access. T. Vogel (Michigan State University) arranged for XRF and ICP-MS analyses, and I. Steele (University of Chicago) provided microprobe access. W. Simpson (Field Museum) generously provided access to comparative fossil collections. This material is based upon work supported by the National Science Foundation’s Research Experiences for Undergraduates program, grant number EAR-0353589. STRUCTURE OF THE PROGRAM The overall goal of research at the site is to understand the paleoenvironments in which the site’s fossils were preserved. Understanding the series of paleoenvironments represented at this one site is a necessary step toward building a regional picture of ancient faunas and environments in this portion of the Morrison Formation. A robust regional picture will in turn allow us to compare faunas and environments with other well-studied portions of the Morrison Formation. This program has been funded for three years, so our students’ research tasks are developed with that time-frame in mind. Ten students are supported to work in the program each year. This means that individual students or pairs of researchers can pursue independent investigations into varied aspects of the paleoenvironment, working in parallel with other researchers during the field season and in series with researchers who hand off some of the projects from one season to the next. We divided the students into those pursuing fossil-based projects and those pursuing geology-focused projects, and assigned faculty to advise each group. One consideration in choosing student participants is to provide a balance between the two kinds of projects and therefore more consistent project advising for all students. Another consideration is the inclusion of students from two-year colleges in the program. This has focused student selection on those relatively early in their undergraduate careers so as to provide a cohort of researchers with somewhat similar backgrounds and levels of experience. The focus on early-career undergraduates has the advantage of providing the opportunity for the research experience to inform students’ subsequent coursework and career goals, and also allows some students to continue their projects through independent study at their home institution. Quarry Fill m s vf f m c g 103/9˚S 108/7˚S 84/12˚S 95/12˚S 80/10˚S 75/10˚S 76/10˚S 0/6˚W South North 0 meters “Scorpion Sandstone” 5 m 10 m 15 m 20 m 25 m 30 m 35 m 40 m 45 m 50 m 55 m 60 m 65 m 70 m 75 m 80 m 85 m 90 m 95 m 100 m 105 m tan calcareous sandstone shell bed Starting from a shell ridge: top of the Sundance thin clay curtains and fractures in the general direction of dip dark gray silty mudstone, finely laminated, iron staining in thin beds (<3cm) silty sandstone reddish siltstone well-consolidated calc-sandstone orange and gray siltstone gray siltstone brown siltstone w/ interbedded fine, gray siltstone (3cm) well-consolidated, tan sandstone gray siltstone orange siltstone alternating beds of orange and yellow-gray/tan siltstones gray siltstone alternating with orange and more-consolidated beds limestone, calc-siltstone with limestone nodules, interbedded sandstone has orange top and gypsum, then more limestone N calc-siltstone tan calc-sandstone w/ interbedded gray mudstones that pinch out iron concretions calcareous gray-tan siltstone interbedded pale-tan sandstones and dinosaur tracks in a couple of beds reddish-brown calc-siltstone gray-brown, gray siltstone tan sandstone w/ channel 7.1m thick gray and orange silty calc-mudstones w/ interbedded sandstones and crevasse splays crevasse splays pinching out towards the west tan sandstone gray-green (LOG) siltstone tan sandstone normal fault Starting at top of redbed gray siltstone tan, fine sand with a distinct bed of concretions gray, silty sandstone gray mudstone with the consistency of chocolate tan sandstone with channel thickness of 2.15m gray sandy siltstone graduating to LOG siltstone LOG to yellowish-gray siltstone with a few, more-consolidated, thin beds LOG siltstone more-consolidated bed LOG calc-siltstone yellowish gray calc-(silty)sandstone with chert nodules/barite? subrounded-rounded silty mud w/ dusky yellow green & dark reddish brown interbedded graduates into LOG dark reddish brown paleosol? near surface pinches out to the West. dips oppositely and steeply. pale olive and olive gray TOP OF THE MORRISON FORMATION dark yellowish orange (very intense) w/ some alternating LOG beds beds of dark gray chert cobbles, subrounded-rounded yellowish gray sand, unconsolidated non-calcareous LOG siltstone tuff/clay drape? near top of siltstone poorly-consolidated, light tan, calc-sand with a more-consolidated bed toward the bottom, which is more prominent and/or consolidated to the south non-calcareous, yellowish gray, muddy sands (tuffaceous?) with interbedded orange LOG siltstone with some moderate brown and dark yellowish orange calcite pseudomorphs after selenite (~1cm) moderate brown maybe modern soil? calc-siltstone with evaporites, maybe starting to have silicified calcrete nodules calc-siltstones, orange & brown & white white and LOG calc-siltstones (tuffaceous?) calcareous, grayish red, tuffaceous?, fine siltstone with silicified calcrete nodules on top graduates into moderate brown with more nodules (up to 2 ft. across) graduates into LOG siltstone with less-silicified calcrete nodules Tertiary mud? then brown, soil-looking, calc-siltstone light brown calcareous alluvium with pebbles/cobbles of limestone and silicate sandstones non-calcareous sand weathered/stained dark yellowish orange with a well-consolidated, yellowish gray bed non-calcareous sandstone outcrop some stained moderate reddish brown and grayish yellow. bottom half not exposed well and seems poorly-consolidated N N Q Q Q Fe Fe Fe Fe Q silicious cobbles N nodules Fe iron concretions ripple cross-laminations trough cross-laminations crystalline evaporites planar bedded planar cross-bedded bone fossils plant remains fossilized wood rip-up clasts shell fossils sandstone silty sandstone trough cross- bedded sandstone dinosaur tracks 6 7 8 9 10 11 12 13 14 15 Fe c p g c m f vf s m Fe Fe c p g c m f vf s m Fe Fe c p g c m f v f s m Fe Fe Fe Fe Fe c p g c m f vf s m Fe c p g c m f vf s m c p g c m f vf s m Fe Fe Fe =Fe= =Fe= =Fe= Fe Fe Fe Fe c p g c m f vf s m c p g c m f vf s m Fe c p g c m f vf s m c p g c m f vf s m Fe Sandstone Siltstone Rip-up clast conglomerant Trough cross bedding Rip-up clasts Plant bits Fe Iron concretion Petrified wood Fossilized bone Comminuted organic drape Possible dinoturbation Major bounding surfaces Minor surfaces Inferred/Covered Stratal Architecture of the Scorpion Sandstone N n=34 Sector angle = 10° Scale: tick interval = 5% [1.7 data] Maximum = 29.4% [10 data] Mean Resultant dir'n = 139 [95% Confidence interval = ±5°] 5m 5m 5m Mud Silt Sand N W C S V 5 YR 10 YR 5 Y 6m 5m 4m 3m 2m 1m 0617041-06170426 Mud Silt Sand N W C S V 10 YR 2.5 Y 5 Y 7m 8m 9m Key Calcareous Nodules Horizontal Lamination Concretions Silt Sized Grains Gypsum Crystals N = Noncalcareous Calcareousness W = Weakly Calcareous C = Calcareous S = Strongly Calcareous V = Very Strongly Calcareous I. Sedimentologic Data: Petrified Logs lateral extent <1mm 10m 100m >1km thickness 1mm 1m 10m >100m form tabular bar/channel irregular continuity continuous persistent patchy lithology ms slt ss congl order, arrangement of plant parts random mixed oriented ___________________________________________________________________ Taphonomic Data # identifiable parts 1 10 100 >1000 spatial density ( parts/m 2 ) 1 10 100 >1000 size of remains (cm) 1 10 100 >1000 organ dominance (stem/leaf ) 1 10 100 >1000 diversity (# organ types) 1 2 3 4 5 6 >7 transport autoch parautoch alloch preservational mode (ranked, most common=1) permin coalified unmodified 3 1 2 H. Sedimentologic Data: Scorpion Sandstone System lateral extent <1mm 10m 100m >1km thickness 1mm 1m 10m >100m form tabular bar/channel irregular continuity continuous persistent patchy lithology ms slt ss congl order, arrangement of plant parts random mixed oriented ___________________________________________________________________ Taphonomic Data # identifiable parts 1 10 100 >1000 spatial density ( parts/m 2 ) 1 10 100 >1000 size of remains (cm) 1 10 100 >1000 organ dominance (stem/leaf ) 1 10 100 >1000 diversity (# organ types) 1 2 3 4 5 6 >7 transport autoch parautoch alloch preservational mode (ranked, most common=1) permin coalified unmodified 1 Taphonomy of Fossil Plants Paleopedology Stratigraphy Vertebrate Paleontology Surficial and Bedrock Geologic Maps Photomicrographs of: A. permineralized Xenoxylon, longitudinal section; B. permineralized Xenoxylon, transverse section; C. permineralized Mesembrioxylon, longitudinal section; D. permineralized Mesembrioxylon, transverse section; E. compression/impression Coniopteris? frond; F. original cuticle and Jensenispermum fragments. A B C D E F G. Sampling localities for dispersed cuticle within the Scorpion Sandstone overbank mudstones; H and I. Taphograms based on Demko (1995) ms, mudstone; slt, siltstone; ss, sandstone; congl, conglomerate; autoch, autochtonous; parautoch, parautochthonous; alloch, allochthonous; permin, permineralized. Paleosol descriptions from palustrine facies in the Lower Morrison; hue and coloration, 10YR, 2.5Y, 5YR. Rip-up clasts Ripple cross lamination Extrabasinal pebbles Microprobe images of dinosaur bones; left are from lower quarry, right are from upper quarry Relative percentage of SO 3 in dinosaur bones Map of bones in upper quarry. G 4 mm
Transcript of PALEOENVIRONMENTAL ANALYSIS OF A MORRISON … · paleoenvironment and paleoecology of the site....
PALEOENVIRONMENTAL ANALYSIS OF A MORRISON FORMATION DINOSAUR SITE, BIGHORN BASIN, WY:CONDUCTING AN INTERDISCIPLINARY FIELD STUDY THROUGH DISCIPLINARY TASKSDEMKO, Timothy M.1, BODENBENDER, Brian E.2, BAAR, Eric E.3, HOLBROOK, Cody W.4, KUBAREK, Sara J.1, MURPHY, Jennifer5,RAMIREZ, Elisa M.6,SCOTT, Justin E.7, SWOR, Emily1, THOMASON, Carrie2, and YONOVITZ, Maureen2
(1) Department of Geological Sciences, Univ of Minnesota Duluth, 217 Heller Hall, 1114 Kirby Drive, Duluth, MN 55812, [email protected](2) Geological and Environmental Sciences, Hope College, 35 E. 12th St, Holland, MI 49423(3) Grand Valley State Univ, Allendale, MI(4) Western Kentucky Univ, Bowling Green, KY(5) Lawrence Univ, Appleton, WI(6) Univ of Michigan, Ann Arbor, MI(7) Casper College, Casper, WY
ABSTRACTA project investigating a dinosaur fossil site near Shell, WY provides a model for conducting interdisciplinary undergraduate field research. The project involves 10 students who undertake stratigraphic and paleontological subprojects that contribute to understanding the paleoenvironment and paleoecology of the site. These subprojects include: 1) construction of bedrock and surficial geologic maps of the dinosaur fossil site and surrounding area; 2) development of a composite stratigraphic column that includes the fossil-bearing intervals; 3) description and analysis of the sedimentary facies of the fossil-bearing and associated intervals, especially those that contain paleosols; 4) description and interpretation of sandstone body architecture, including paleocurrent analysis; 5) construction of detailed quarry maps that record bone positions, associations, and stratigraphy; 6) analyses of bone taphonomy and diagenesis, especially the incorporation of rare earth elements; 7) taphonomic analysis of plant material in the bone-bearing and associated strata; and 8) collection, preparation, and identification of dinosaur and other vertebrate fossils found at the site, including screen washing of rip-up clast conglomerates. Some subprojects require the temporary help of other students to complete successfully, leading to cross-disciplinary training between the project teams. Students working on the stratigraphic subprojects, which had a definitive end to field data collection, were able to join the work on dinosaur fossil excavation, which continues up to the last field day. This gives the students working on stratigraphy a taste of paleontological research, and allows mentoring opportunities for those working on paleontology.
ACKNOWLEDGMENTSWe thank J. Barwis (Holland, MI), E. Hansen, G. Peaslee, and P. Atkins (Hope College), and M. Uhen (Cranbrook Institute of Science) for assistance in classroom instruction. R. Simon (Dinosaur Safaris, Inc), G. Storrs (Cincinnati Museum of Natural History), and M. Uhen provided logistical support and field instruction, and J. Anderson facilitated field access. T. Vogel (Michigan State University) arranged for XRF and ICP-MS analyses, and I. Steele (University of Chicago) provided microprobe access. W. Simpson (Field Museum) generously provided access to comparative fossil collections. This material is based upon work supported by the National Science Foundation’s Research Experiences for Undergraduates program, grant number EAR-0353589.
STRUCTURE OF THE PROGRAMThe overall goal of research at the site is to understand the paleoenvironments in which the site’s fossils were preserved. Understanding the series of paleoenvironments represented at this one site is a necessary step toward building a regional picture of ancient faunas and environments in this portion of the Morrison Formation. A robust regional picture will in turn allow us to compare faunas and environments with other well-studied portions of the Morrison Formation.
This program has been funded for three years, so our students’ research tasks are developed with that time-frame in mind. Ten students are supported to work in the program each year. This means that individual students or pairs of researchers can pursue independent investigations into varied aspects of the paleoenvironment, working in parallel with other researchers during the field season and in series with researchers who hand off some of the projects from one season to the next. We divided the students into those pursuing fossil-based projects and those pursuing geology-focused projects, and assigned faculty to advise each group. One consideration in choosing student participants is to provide a balance between the two kinds of projects and therefore more consistent project advising for all students. Another consideration is the inclusion of students from two-year colleges in the program. This has focused student selection on those relatively early in their undergraduate careers so as to provide a cohort of researchers with somewhat similar backgrounds and levels of experience. The focus on early-career undergraduates has the advantage of providing the opportunity for the research experience to inform students’ subsequent coursework and career goals, and also allows some students to continue their projects through independent study at their home institution.
Quarry Fill
msvffmcg
103/9˚S
108/7˚S
84/12˚S
95/12˚S
80/10˚S
75/10˚S
76/10˚S
0/6˚W
SouthNorth
0 meters
“Scorpion Sandstone”
5 m
10 m
15 m
20 m
25 m
30 m
35 m
40 m
45 m
50 m
55 m
60 m
65 m
70 m
75 m
80 m
85 m
90 m
95 m
100 m
105 m
tan calcareous sandstone
shell bed
Starting from a shell ridge: top of the Sundance
thin clay curtains and fractures in the general direction of dip
dark gray silty mudstone, finely laminated,iron staining in thin beds (<3cm)
silty sandstone
reddish siltstone
well-consolidated calc-sandstoneorange and gray siltstone
gray siltstone
brown siltstone w/ interbedded fine, gray siltstone (3cm)
well-consolidated, tan sandstone
gray siltstone
orange siltstonealternating beds of orange and yellow-gray/tan siltstones
gray siltstone alternating with orange and more-consolidated beds
limestone, calc-siltstone with limestone nodules, interbedded sandstone has orange top and gypsum, then more limestone
N
calc-siltstone
tan calc-sandstone w/ interbedded gray mudstones that pinch outiron concretions
calcareous gray-tan siltstone
interbedded pale-tan sandstones and dinosaur tracks in a couple of beds
reddish-brown calc-siltstone
gray-brown, gray siltstone
tan sandstone w/ channel 7.1m thick
gray and orange silty calc-mudstones w/ interbedded sandstones and crevasse splays
crevasse splays pinching out towards the west
tan sandstone
gray-green (LOG) siltstone
tan sandstone
normal faultStarting at top of redbed
gray siltstone
tan, fine sand with a distinct bed of concretions
gray, silty sandstone
gray mudstone with the consistency of chocolate
tan sandstone with channel thickness of 2.15m
gray sandy siltstone graduating to LOG siltstone
LOG to yellowish-gray siltstone with a few, more-consolidated, thin beds
LOG siltstone
more-consolidated bed
LOG calc-siltstone
yellowish gray calc-(silty)sandstone with chert nodules/barite? subrounded-rounded
silty mud w/ dusky yellow green & dark reddish brown interbedded
graduates into LOG
dark reddish brown paleosol? near surface pinches out to the West. dips oppositely and steeply.
pale olive and olive gray
TOP OF THE MORRISON FORMATION
dark yellowish orange (very intense) w/ some alternating LOG beds
beds of dark gray chert cobbles, subrounded-rounded
yellowish gray sand, unconsolidated
non-calcareous LOG siltstone
tuff/clay drape? near top of siltstone
poorly-consolidated, light tan, calc-sand with a more-consolidated bed toward the bottom, which is more prominent and/or consolidated to the south
non-calcareous, yellowish gray, muddy sands (tuffaceous?) with interbedded orange
LOG siltstone with some moderate brown and dark yellowish orange
calcite pseudomorphs after selenite (~1cm)
moderate brown maybe modern soil?
calc-siltstone with evaporites, maybe starting to have silicified calcrete nodules
calc-siltstones, orange & brown & white
white and LOG calc-siltstones (tuffaceous?)
calcareous, grayish red, tuffaceous?, fine siltstone with silicified calcrete nodules on top
graduates into moderate brown with more nodules (up to 2 ft. across)
graduates into LOG siltstone with less-silicified calcrete nodules
Tertiary mud? then brown, soil-looking, calc-siltstone
light brown calcareous alluvium with pebbles/cobbles of limestone and silicate sandstones
non-calcareous sand weathered/stained dark yellowish orange with a well-consolidated, yellowish gray bed
non-calcareous sandstone outcrop some stained moderate reddish brown and grayish yellow.bottom half not exposed well and seems poorly-consolidated
N
N
Q
Q
Q
Fe
Fe
Fe
Fe
Q silicious cobbles
N nodules
Fe iron concretions
ripple cross-laminationstrough cross-laminationscrystalline evaporites planar beddedplanar cross-bedded
bone fossils
plant remains
fossilized wood
rip-up clasts
shell fossils
sandstone
silty sandstone
trough cross-bedded sandstone
dinosaur tracks
6 7 8 9 10 11 12 13 14 15
Fe
c p g c m f vf s m
Fe
Fe
c p g c m f vf s m
Fe
Fe
c p g c m f v f s m
FeFe
Fe
Fe
Fe
c p g c m f vf s m
Fe
c p g c m f vf s m c p g c m f vf s m
Fe
Fe
Fe
=Fe=
=Fe=
=Fe=
Fe
Fe
Fe
Fe
c p g c m f vf s m
c p g c m f vf s m
Fe
c p g c m f vf s m
c p g c m f vf s m
Fe
Sandstone
Siltstone
Rip-up clast conglomerant
Trough cross bedding
Rip-up clasts
Plant bits
Fe Iron concretion
Petrified wood
Fossilized bone
Comminuted organic drape
Possible dinoturbation
Major bounding surfaces
Minor surfaces
Inferred/Covered
Stratal Architecture of the Scorpion Sandstone
N
n=34
Sector angle = 10°Scale: tick interval = 5% [1.7 data]Maximum = 29.4% [10 data]Mean Resultant dir'n = 139[95% Confidence interval = ±5°]
5m
5m
5m
Mud Silt Sand N W C S V 5 YR 10 YR 5 Y
6m
5m
4m
3m
2m
1m
0617041-06170426
Mud Silt Sand N W C S V 10 YR 2.5 Y 5 Y
7m
8m
9m
Key
Calcareous Nodules
Horizontal Lamination
Concretions
Silt Sized Grains
Gypsum Crystals
N = Noncalcareous
Calcareousness
W = Weakly Calcareous
C = Calcareous
S = Strongly Calcareous
V = Very Strongly Calcareous
I. Sedimentologic Data: Petrified Logslateral extent <1mm 10m 100m >1kmthickness 1mm 1m 10m >100mform tabular bar/channel irregularcontinuity continuous persistent patchylithology ms slt ss conglorder, arrangementof plant parts random mixed oriented___________________________________________________________________Taphonomic Data# identifiable parts 1 10 100 >1000spatial density( parts/m2) 1 10 100 >1000size of remains (cm) 1 10 100 >1000organ dominance(stem/leaf ) 1 10 100 >1000diversity(# organ types) 1 2 3 4 5 6 >7transport autoch parautoch allochpreservational mode(ranked, most common=1) permin coalified unmodified
3 1 2
H. Sedimentologic Data: Scorpion Sandstone Systemlateral extent <1mm 10m 100m >1kmthickness 1mm 1m 10m >100mform tabular bar/channel irregularcontinuity continuous persistent patchylithology ms slt ss conglorder, arrangementof plant parts random mixed oriented___________________________________________________________________Taphonomic Data# identifiable parts 1 10 100 >1000spatial density( parts/m2) 1 10 100 >1000size of remains (cm) 1 10 100 >1000organ dominance(stem/leaf ) 1 10 100 >1000diversity(# organ types) 1 2 3 4 5 6 >7transport autoch parautoch allochpreservational mode(ranked, most common=1) permin coalified unmodified
1
Taphonomy of Fossil Plants Paleopedology
Stratigraphy
Vertebrate Paleontology
Surficial and Bedrock Geologic Maps
Photomicrographs of: A. permineralized Xenoxylon, longitudinal section; B. permineralized Xenoxylon, transverse section; C. permineralized Mesembrioxylon, longitudinal section; D. permineralized Mesembrioxylon, transverse section; E. compression/impression Coniopteris? frond; F. original cuticle and Jensenispermum fragments.
A B C D
E
F
G. Sampling localities for dispersed cuticle within the Scorpion Sandstone overbank mudstones; H and I. Taphograms based on Demko (1995) ms, mudstone; slt, siltstone; ss, sandstone; congl, conglomerate; autoch, autochtonous; parautoch, parautochthonous; alloch, allochthonous; permin, permineralized.
Paleosol descriptions from palustrine facies in the Lower Morrison; hue and coloration, 10YR, 2.5Y, 5YR.
Rip-up clasts
Ripple cross lamination
Extrabasinal pebbles
Microprobe images of dinosaur bones;left are from lower quarry, right are from upper quarry
Relative percentage of SO3 in dinosaur bones
Map of bones in upper quarry.
G
4 mm
