PBDB Collection

Dragon's Grave bonebed, Hanson Ranch (Cretaceous of the United States)

Also known as Edmontosaurus bonebed, Dragons' Grave, Roxson, HR

Where: Niobrara County, Wyoming (43.5° N, 104.5° W)

• Paleocoordinates: 54.0° N, 65.6° W (Wright 2013)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Lance Formation, Late/Upper Maastrichtian (72.2 - 66.0 Ma)

• bed-level stratigraphic resolution

Environment/lithology: "floodplain"; poorly lithified, gray claystone and lithified, fine-grained, quartzose sandstone

• "The bonebed in the main quarry area is overlain by a bed of tan, poorly cemented, fine- grained, immature quartz sandstone in conformable contact with the underlying mudstone. The sediment containing the bones is a 1–2 m thick, light to medium gray (sometimes almost black in fresh exposures), claystone to siltstone, which is also poorly to moderately indurated. Weathered surfaces, when wet, quickly revert to mud. The bones are found within the claystone, generally in the lower part, in a normally graded bed. The largest bones may rest on the bottom of the bed, or where the bed is thicker, bones appear to be entirely suspended within the mudstone. The underlying bed is often a layer of greenish, moderately well-cemented quartz, fine-grained quartz sandstone with secondary chlorite cement. This layer, generally only a few centimeters thick, may rest on an orange-weathering, fine-grained well-cemented quartz sandstone with carbonate cement."

Size classes: macrofossils, mesofossils

• "In the HR Bonebed, skeletal elements are completely disarticulated with three exceptions. In North quarry, three complete Edmontosaurus caudal vertebrae were found articulated as were a femur, tibia, fibula, calcaneum and astragalus. The only other associated bones were two Edmontosaurus tibiae found adjacent to each other in South quarry that appeared to be a paired set. Thus <0.1% of the bones found show actual or possible articulation."

Collected by K. Derstler; SWAU in 1991–1992; 1997–2017

Collection methods: quarrying, surface (in situ), mechanical,

• Eggshells and teeth from Troodon. Bivalves are "freshwater". Originally found by K. Derstler then taken over by crews from Southwestern Adventist University (SWAU).

Primary reference: D. A. Ein. 1992. A dinosaur by any other name. Lapidary Journal 46(8):24-28 [M. Carrano/M. Carrano]more details

Purpose of describing collection: taphonomic analysis

PaleoDB collection 26760: authorized by Matthew Carrano, entered by Matthew Carrano on 29.10.2002

Creative Commons license: CC0 (CC0)

Taxonomic list

• created date somehow set to null, hand-set to an estimated value by JA 30.10.06

Show authors, comments, and common names

unclassified
-	Plantae indet.¹ Plantae indet.¹ Haeckel 1866
Osteichthyes
Actinopterygii -	Actinopterygii indet.² Actinopterygii indet.² Cope 1887 ray-finned fish
Actinopteri
Lepisosteiformes - Lepisosteidae	Lepisosteus sp.² Lepisosteus sp.² Agassiz 1843 gar
Teleostei -	Teleostei indet.² Teleostei indet.² Müller 1846
Mammalia
Mammalia -	Mammalia indet.² Mammalia indet.² mammal
Reptilia
-	Reptilia indet.² Reptilia indet.² Laurenti 1768 reptile
Squamata -	Squamata indet.² Squamata indet.² Oppel 1811 squamates
Ornithischia - Hadrosauridae	Edmontosaurus annectens Edmontosaurus annectens Marsh 1892 hadrosaurine 12503+ specimens
Ornithischia -	Thescelosaurus sp.², Pachycephalosaurus sp.² Thescelosaurus sp.² Gilmore 1913 ornithopod Pachycephalosaurus sp.² Brown and Schlaikjer 1943 ornithischian
Ornithischia - Ceratopsidae	Triceratops sp.² Triceratops sp.² Marsh 1889 ceratopsid
Ornithischia - Nodosauridae	Nodosaurus sp.² Nodosaurus sp.² Marsh 1889 ankylosaur
Theropoda -	Theropoda indet.² Theropoda indet.² Marsh 1881 theropod
Theropoda - Ornithomimidae	Struthiomimus sp.² Struthiomimus sp.² Osborn 1916 ornithomimid
Theropoda - Dromaeosauridae	Dromaeosaurus sp.², Acheroraptor sp.², Richardoestesia sp.¹ Dromaeosaurus sp.² Matthew and Brown 1922 maniraptoran Acheroraptor sp.² Evans et al. 2013 maniraptoran Richardoestesia sp.¹ Currie et al. 1990 maniraptoran
Theropoda - Troodontidae	Troodon sp.² Troodon sp.² Leidy 1856 maniraptoran
Aves
Aves -	Aves indet.² Aves indet.² bird
Reptilia
Theropoda - Tyrannosauridae	"Nanotyrannus sp." = Tyrannosaurus², Tyrannosaurus rex¹, cf. Aublysodon sp.² "Nanotyrannus sp." = Tyrannosaurus² Osborn 1905 tyrant lizard Tyrannosaurus rex¹ Osborn 1905 tyrant lizard king cf. Aublysodon sp.² Leidy 1868 tyrannosaurid "Aublysodon-like forms"
Crocodylia -	Crocodylia indet.², Leidyosuchus sp.² Crocodylia indet.² Owen 1842 crocodilian Leidyosuchus sp.² Lambe 1907 crocodilian
Crocodylia - Alligatoridae	Brachychampsa sp.² Brachychampsa sp.² Gilmore 1911 crocodilian
Testudines -	"Chelonia indet." = Testudines¹ "Chelonia indet." = Testudines¹ Batsch 1788 turtle
Chondrichthyes
Rajiformes - Rajidae	Rajidae indet.² Rajidae indet.² Blainville 1816 skate
Bivalvia
-	Bivalvia indet.¹ Bivalvia indet.¹ Linnaeus 1758 clam

¹Derstler 1995; ²Snyder et al. 2020