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TABLE 1. Comparison of taphofacies recognized in the Morrison Formation, including A) a site example, lithology, paleontology, weathering of the bones (where available), transportability of the bones (where available), and B) the fauna represented (available in PDF only).

TABLE 2.Summary of taphofacies recognized in circum-lacustrine environments including 1) swampy environments with episodic fluvial influence, 2) fluvial environments which were periodically covered by lacustrine deposits (fluvio-deltaic), and 3) a swampy/lacustrine environment.

Taphofacies

Example

Sedimentology

Paleontology

Weathering

Transport Groups

Swampy environment with episodic fluvial influence Huelago-1 (Albderdi et al, 2001) Green and gray silts with charcoal intraclasts, cyanobacterial oncoids, root traces. Iron oxide preciptate horizons. Interbedded muddy sand-filled channel bodies with a basal mud pebble conglomeratic sand and silt and clay carbonate beds with incipient pedogenic features. Gastropods, fish, equilibrium between identified and unidentified bone remains, abundant isolated teeth, small animals most common, predator damage, algal crust, no articulated remains, some associated remains, trampling common, concentrations of bones, some orientation Advanced weathering stages 1-3 Appendages (2.5%), Teeth (28.87%), Group III (1.49%), Group II (7.13%), Group 1 (5.8%), Fragments (54.35%), Coprolites (0.64%)
Swampy / lacustrine environment Cullar de Baza-1 (Alberdi et al., 2001) Carbonates and marlstones interfingering with alluvial sediments Fish, reptiles, rodents, rabbits, carnivores, ungulates, some articulated remains Most are Stage 0, 12% in advanced stages Appendages (2.14%), Teeth (23.92%), Group III (5.71%), Gropu II (6.34%), Group I (4.76%), Fragments (56.44%), Coprolites (1.22%)
Delta plain Subenv. A (Mancuso and Marsicano, 2008) Medium- to coarse- grained sandstone interbedded with black mudstone and very fine grained sandstone. Sandstone beds are tabular to lenticular with basalt mudstone intraclasts. Logs, tetrapod footprints, invertebrate trace fossils, no bone orientation Most are Stage 0 Not directly reported, but skeletons were mostly articulated and showed no evidence of sorting
Deltaic front Huescar-1 (Alberdi et al., 2001) White calcareous silt beds devoid of organic matter and lamination. Detrital beds grade east into a 3 m thick bed which also contains bone remains. This bed is formed of stacked lens-like bodies of gravelly sands. Planar cross-stratification occurs occasionally . Fish, semi-aquatic birds and mammals, predominance of unidentified bone remains, abrasion and breakages common, rounding of bones, no carnivore evidence on bones (may have been abraded), densely concentrated and uniformally distributed, evident dip of the bone bed to the west, preferential orientation of bones Stages 2-3 (not including fragments) Appendages (0.23%), Teeth (19.76%), Group III (0.79%), Group II (2.54%), Group I (6.13%), Fragments (70.49%), Coprolites (0.07%)
Deltaic front Subenv. B (Mancuso and Marsicano, 2008) Upward caorsening sequence characterized by alternation of tabular-massive siltstone and claystone interbedded with parallel laminated, very fine grained sandstone. Sandstones with current-ripples to horizontal lamination and planar to trough cross-bedded in uppermost coarse grained material plant fragments, fish body fossils, tetrapod footprints, invertebrate trace fossils, no bone orientation, breaking common Stage 0-1 (not including fragments) Not directly reported, but skeletons were mostly articulated and only fish and trace fossils were reported, showed moderate evidence of sorting
Prodelta Subenv. C (Mancuso and Marsicano, 2008) Dark gray to black carbonaceous claystone Plant debris, conchostrans, bivalves, insects, scarse partially articulated fish remains, no bone orientation, breaking common Stage 0-1 (not including fragments) Not directly reported, but skeletons were partially articulated and only fish and trace fossils were reported, showed moderate evidence of sorting
Offshore lacustrine Subenv. D (Mancuso and Marsicano, 2008) Dark gray to black carbonaceous claystone plant debris, insects, conchostrans, fish, no bone orientation, breaking common Stage 0-1 (not including fragments) Not directly reported but skeletons were disarticulated and only fish fossils were reported, high evidence of sorting

TABLE 3. Voorhie’s groups for non-sauropod bones based on data from coyote skeletons (Voorhies, 1969) and Fluvial Transport Index Groups for sauropod bones based on elephant bones (Frison and Todd, 1986).

Group 1

Group 2

Group 3

Voorhies FTI Voorhies FTI Voorhies FTI
Sacrum Sacrum Scapula Scapula Mandible Mandible
Vertebrae Vertebrae (except Atlas) Humerus Humerus Skull Skull
Ribs   Tibia Tibia   Atlas
Sternum   Metapodials Metapodials   Pelvis
  Patella Femur     Radius-ulna
  Astragalus Pelvis     Femur
  Calcaneous Radius      
    Phalanges      
    Ulna      
      Ribs    

TABLE 4. Weathering and abrasion scale of bones.

0 No damage at all. Bone is in near perfect condition, smooth surface with no cracking or breaking.
0.5 Intermittent stage between 0 and 1.
1 Bone shows cracking, longitudinal and/or latitudinal congruent to structure.
1.5 Intermittent stage between 1 and 2.
2 Flaking on outer most layer, following and/or from cracks. Flakes are still attached to bones on one or more edges.
2.5 Heavier flaking, flakes easily removed from bone, or flakes fall off bone when the bone is moved.
3 Patches of rougher bone on surface, connecting patches In patches, and layers. External bone is missing. Patches of weathering are shallow.
3.5 Intermittent stage between 3 and 4.
4 First stage of advanced weathering. Large sections of flaking, pieces falling from the bone when touched or moved. Rough surface texture, rounding of cracked edges.
4.5 Intermittent stage between 4 and 5.
5 In Situ, the worst specimen to be examined. Virtually unrecognizable, splintered into pieces, breaks easily when moved. Perhaps undeterminable.

 

TABLE 5. Faunal list of organisms at the Aaron Scott Quarry.

 

Bivalvia Linnaeus, 1758                  
  Unionoida Rafinesque, 1820                
    Unionidae Rafinesque, 1820              
Reptilia Laurenti, 1768                  
  Testudines Batsch, 1788                
    Cryptodira Cope, 1868              
      Glyptopsidae Marsh, 1890            
        Glyptops Marsh, 1890          
          Glyptops cf. plicatulus        
    Sphenodontia Williston, 1925              
      Sphenodontidae Cope, 1869            
        Opisthias Marsh, 1890          
          Opisthias rarus Gilmore, 1905        
  Archosauria Cope, 1869                
    Crocodyliformes Benton and Clark, 1988              
      Goniopholididae Cope, 1875            
        Indet. cf. Eutretauranosuchus sp. Mook, 1967          
  Dinosauria Owen, 1842                
    Saurischia Seeley, 1888              
      Theropoda Marsh 1881            
        Carnosauria Heune, 1920          
          Allosauridae Marsh, 1879        
            Allosaurus Marsh, 1877      
              Allosaurus cf. fragilis Marsh, 1877    
        Coelurusauria Huene, 1914          
          Coeluridae Marsh, 1881        
            Coelurus sp. Marsh, 1879      
      Sauropoda Marsh, 1878            
        Diplodocidae Marsh, 1884          
          Barosaurus Marsh, 1890        
          Apatosaurus March, 1877        
        Camarasauridae Cope, 1877          
          Camarosaurus Cope, 1877        
    Ornithischia Seeley, 1888              
      Ornithopoda Marsh, 1881            
        Dryosauridae Milner & Norman, 1985          
          Dryosaurus sp. Marsh, 1894        
      Stegosauria Marsh, 1877            
        Stegosauridae Marsh, 1880          
          Stegosaurus sp. Marsh, 1877        
Mammalia Linnaeus, 1758                  
    Triconodonta Osborn, 1888              
                   

 

 

TABLE 6. Comparison of the Aaron Scott Quarry to the Huescar-1 locality, interpreted to be a fluvio-deltaic depositional setting. Red text indicates areas where the different examples match.

 

Aaron Scott Quarry

Huescar-1

Los Rastras Formation Subenvironment C

Figures

Sedimentology Basal siltstone with rip-up clasts; calcareous siltstone; beds dipping to the west; shale layer on top White calcareous silt beds, detrital beds dipping to the west Upward caorsening sequence characterized by alternation of tabular-massive siltstone and claystone interbedded with parallel laminated, very fine grained sandstone. Sandstones with current-ripples to horizontal lamination and planar to trough cross-bedded in uppermost coarse grained material Fig. 4
Orientation Slight preferential orientation Slight preferential orientation No bone orientation Fig. 8, 10
Taxonomy Abraded unidentified bones common, semi-aquatic animals, large herbivores common, carnivore teeth, disarticulated remains Abraded unidentified bones common, semi-aquatic animals, large herbivores common, disarticulated remains Abraded unidentified bones common, articulated fish remains, plant debris, conchostrans, bivalves, insects Table 3, Fig. 9
Distribution Bones are densely concentrated and uniformly distributed Bones are densely concentrated and uniformly distributed Bones are densely concentrated Fig. 4
Weathering Average stage 2 Average stage 2 Stage 0-1 Fig. 11
Transport Groups Groups 1 and 2 dominant (excluding teeth) Groups 1 and 2 dominant (excluding teeth) Groups 1 and 2 dominant Fig. 6, 9

 

 

FIGURE 1. General location of the Aaron Scott Site in Emery County, Utah (modified from the US Census Bureau, 2000)

figure 1 3

FIGURE 2. General stratigraphy of the Morrison Formation in the vicinity of the Aaron Scott Site.

figure 2 3

FIGURE 3. Sequence stratigraphy of the Aaron Scott Site, showing the position of the dinosaur bones and overlying Unio clams. Beds coarsen upward and measured sections tend to coarsen upward and westward as well. Erosional truncational surfaces are bold correlation lines while truncated and onlapping bedding are finer correlation lines.

figure 3 3

FIGURE 4. Reconstruction of a circum-lacustrine environment combined from Alberdi et al. (2001) and Mancuso and Marsicano (2008) showing the position of the six taphofacies: A) swampy environment with periodic fluvial influence; B) swampy/lacustrine environment; C) delta plain; D) delta front; E) prodelta; and F) offshore lacustrine. The Aaron Scott Quarry is at position D. (Adapted from Mancuso and Marsicano, 2008).

figure 4 3

FIGURE 5. Stratigraphic view of the Aaron Scott Site showing the vertical distribution of the bones in the quarry. The diplodocid bones tend to be slightly higher stratigraphically than other bones in the quarry.

figure 5

FIGURE 6. Quarry map of the Barosaurus associated skeleton of the Aaron Scott Site showing distribution of the bones collected 2005-2012 in map view.

figure6

FIGURE 7. A distribution of the bones of the diplodocid based on FTI groups (Frison and Todd, 1986).

figure 7 3

FIGURE 8. Rose diagram showing the orientation of the sauropod bones. A poor bimodal distribution is indicated, with one set of bones oriented to the west and a second set oriented northwest-southeast.

figure8

FIGURE 9. Ternary diagram showing the expected bones of a complete sauropod skeleton and the path of enrichment that bones would take if they were transported from their source compared to if they were enriched at the source. Bones of the sauropod indicate an enrichment in group 1 bones, suggesting a terminal transport deposition of the bones.

figure 9 3

FIGURE 10. A distribution of the non-sauropod bones on Voorhie’s groups. The bones were plotted with and without the Allosaurus teeth because the abundance of Allosaurus teeth suggest that the Allosaurus was feeding on the sauropod and that the teeth were not transported into the area. Excluding the Allosaurus teeth, the bones show an enrichment of group 1 bones, suggesting a terminal transport deposition of these bones.

figure 10 3

FIGURE 11. Rose diagram showing the orientation of the non-sauropod bones. The distribution of these bones shows very weak orientation, but does indicate a bimodal distribution with one set oriented to the west and a second set oriented northwest-southeast.

figure11

FIGURE 12. Histogram of bone weathering and abrasion for non-sauropod bones (sauropod bones had weathering of zero and are not included on this diagram). Weathering rank of 2 indicates flaking and cracking of the outer layer of the bone and is the most common in non-fragmented bones. Fragmented bones are ranked as a 5, indicating that the bones have broken apart and may have been rounded

figure 12 3

FIGURE 13. Examples of weathering stages of bones at the Aaron Scott Quarry. 13.1) Dryosaurus vertebra (VP 8612) with weathering stage 2. Note that the neural arch was broken prior to burial. Scale bar equals 5 cm.

figure13

FIGURE 14. Fragments of bones (VP 8958) with weathering stage 5. Scale bar equals 5 cm.

figure14

FIGURE 15. Allosaurus metatarsal (VP 8628) with weathering stage 0. Scale bar equals 5cm.

figure15

FIGURE 16. Barosaurus caudal vertebra (A. S. S. 772) with weathering stage 0. Scale bar equals 5 cm. 

figure16

 

 

bertogJanet Bertog
Department of Physics and Geology
Northern Kentucky University
Highland Heights, Kentucky 41099
USA
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Janet Bertog began working at the South Dakota School of Mines Museum of Geology in Rapid City, South Dakota in 1990. She graduated with a bachelor of science in geology in 1995 and her master of science in paleontology in 1997 at the South Dakota School of Mines. She completed her PhD in geology at the University of Cincinnati in 2002. She has worked at Northern Kentucky University since 2003, where she has been working on the paleontology and taphonomy of the Aaron Scott Quarry.

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jeffereyDavid L. Jeffery
Department of Petroleum Engineering and Geology
Marietta College
Marietta, Ohio 45750
USA
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Dave Jeffery is currently an Associate Professor of Geology in the department of Petroleum Engineering and Geology at Marietta College in southeastern Ohio where he has been for the last ten years. His current interests include the stratigraphic and paleoecological aspects of Jurassic dinosaur deposits in Utah and Permian tetrapod trackways in Ohio. Before coming to Marietta, Dave worked for seven years as a petroleum geologist for ARCO/Vastar and then BP in Houston. He worked in both exploration and development, primarily in basins throught the US western states from North Dakota and down to west Texas. Dave earned his PhD from Texas A&M University working on paleoecological trends in Mississippian carbonate ramp and mudmound reef strata in the Sacramento Mountains of New Mexico. Prior to that, he completed his MS at Bowling Green State University working on taxonomy of Mississippian gastropods. During his graduate studies he worked summer jobs for national parks including Badlands in South Dakota and the Guadalupe mountains in West Texas.

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coodeKatherine Coode
Department of Physics and Geology
Northern Kentucky University
Highland Heights, Kentucky 41099
USA
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Katherine Coode was an undergraduate student at Northern Kentucky University, graduating in 2010 with a double major in geology and geography and minors in physics and honors. She is currently working on her master of science degree in geospatial technology and groundwater hydrology at Bowling Green State University in Ohio.

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hesterWilliam B. Hester
Department of Physics and Geology
Northern Kentucky University
Highland Heights, Kentucky 41099
USA
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William Hester was an undergraduate student at Northern Kentucky University, graduating in 2009 with a major in anthropology. He is currently working on his Master of Arts in history.

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robinsonRath R. Robinson
Department of Physics and Geology
Northern Kentucky University
Highland Heights, Kentucky 41099
USA
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Rath Robinson was an undergraduate student at Northern Kentucky University, graduating in 2009. He completed a double major in geology and anthropology.

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bishopJohn Bishop
Department of Petroleum Engineering and Geology
Marietta College
Marietta, Ohio 45750
USA
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John Bishop has worked in the late Jurassic for the past 28 years mostly in the San Raphael swell in southern Utah. His specialty is in the taphonomy and taxonomy of the Morrison Formation.

 
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Taphonomic patterns of a dinosaur accumulation in a lacustrine delta system in the Jurassic Morrison Formation, San Rafael Swell, Utah, USA

Janet Bertog, David L. Jeffery, Katherine Coode, William B. Hester, Rath R. Robinson, and John Bishopp

Plain Language Abstract

The Aaron Scott Quarry was deposited along the margin of a large lake. Remains of several dinosaurs and other animals accumulated on this delta over a period of time as a result of a prolonged drought. Animals congregated near the lake as other watering holes dried up.       

Resumen en Español

text

Traducción: Enrique Peñalver

Résumé en Français

Motifs taphonomiques d'une accumulation de dinosaure dans un système de delta lacustre dans la Formation de Morrison du jurassique, San Rafael Swell, Utah, États-Unis

Le membre du bassin de Brushy de la Formation de Morrison du Jurassique supérieur est largement reconnue comme ayant accumulé dans un écosystème semi-aride de fleuves sinueux/ plaines inondables. Toutefois, dans le centre de l'Utah, la partie inférieure du membre du bassin de Brushy est interprété comme un lac d'eau douce, intérieur et fermé avec un delta formant sa marge est. La faune de la Carrière de Aaron Scott comprend de nombreux dinosaures ainsi que des taxons semi-aquatiques typiques comme des tortues et des crocodiles et offre une occasion unique d'étudier la taphonomie d'un cadre lacustre fluvio-deltaïque au Jurassique. Nous interprétons que pendant une période de sécheresse, de nombreux animaux se sont rassemblés sur le delta, pendant que d'autres points d'eau locaux se sont taris. Au fil du temps, leurs carcasses se sont accumulées, ont été brisées, abrasées et retravaillés par une variété d'agents biologiques et physiques avant le recouvrement final. L'alignement préférentiel des os fossiles suggère deux sens d'écoulement: le canal distributeur coule au large du delta et un courant induit par les vagues à 90 degrés du canal. Les os sont répartis en une couche d'environ 1 m d'épaisseur. Les os à la base sont très fragmentés et abrasés tandis que ceux plus élevés dans le lit appartiennent à un seul individu d'un sauropode diplodocidé. De nombreuses dents d'Allosaurus sont associées aux os du diplodocidé et peuvent avoir été perdu au cours de charognage répété par plusieurs Allosaurus.

Mots-clés: delta; lac; sauropode; dinosaure; taphonomie

Translator: Kenny J. Travouillon

Deutsche Zusammenfassung

Taphonomische Muster einer Dinosaurieransammlung im lakustrinen Deltasystem der jurassischen Morrison Formation, San Rafael Swell, Utah, USA

Es ist weithin anerkannt, dass das oberjurassische Brushy Basin Member der Morrison Formation in einem semi-ariden mäandrierenden Fluss/Flussauenökosystem entstand. Jedoch geht in Zentral-Utah die Interpretation dahin, dass das untere Brushy Basin Member ein umschlossener Frischwassersee im Inland mit einem Flussdelta an seinem östlichen Rand war. Die Aaron Scott Quarry Fauna beinhaltet viele Dinosaurier aber auch typische semi-aquatische Taxa wie Schildkröten und Krokodile und stellt eine einzigartige Gelegenheit dar, die Taphonomie eines fluvio-deltaischen Milieus im Jura zu untersuchen. Wir interpretieren, dass sich während einer Dürreperiode zahlreiche Tiere im Delta versammelten, während andere lokale Wasserlöcher austrockneten. Mit der Zeit sammelten sich die Körper an, zerbrachen, wurden erodiert und durch verschiedene Arten von biologischen und physikalischen Mitteln aufgearbeitet bevor sie endgültig begraben wurden. Die bevorzugte Ausrichtung der Knochen weist auf zwei Fließrichtungen hin: der Hauptarm der vom Delta abfließt und die welleninduzierte Strömung mit 90 Grad zum Kanal. Die Knochen sind in einer 1 Meter mächtigen Schicht verteilt. Die Knochen an der Basis sind in hohem Maße fragmentiert und erodiert, während die weiter oben liegenden zu einem Einzelindividuum eines diplodociden Sauropoden gehören. Mit den diplodociden Knochen sind zahlreiche Allosaurus-Zähne assoziiert, die durch wiederholtes Aasfressen mehrerer Allosaurus verloren wurden.

Schlüsselwörter: Delta; See; Sauropode; Dinosaurier; Taphonomie

Translator: Eva Gebauer

Arabic

372 arab

Translator: Ashraf M.T. Elewa