Arundel Formation | |
---|---|
Stratigraphic range: | |
Type | Geological Formation |
Unit of | Potomac Group |
Underlies | Patapsco Formation (Unconformity) |
Overlies | Patuxent Formation |
Thickness | up to 125 feet (40 m) [1] |
Lithology | |
Primary | Clay |
Other | Siderite nodules |
Location | |
Region | Maryland, Washington D. C. |
Country | United States |
Type section | |
Named for | Anne Arundel County, Maryland |
Named by | W. B. Clark, 1897 [1] |
The Arundel Formation, also known as the Arundel Clay, is a clay-rich sedimentary rock formation, within the Potomac Group, found in Maryland [2] of the United States of America. It is of Aptian age (Lower Cretaceous). This rock unit had been economically important as a source of iron ore, but is now more notable for its dinosaur fossils. It consists of clay lenses within depressions in the upper part of the Patuxent Formation that may represent oxbow swamp facies. [3] It is named for Anne Arundel County, Maryland. [4]
Dinosaurs present include cf. Acrocanthosaurus , [5] [6] the possible ornithischian Magulodon , [5] the poorly known theropods "Allosaurus" medius, "Creosaurus" potens , and "Coelurus" gracilis, the ornithomimosaurian "Dryosaurus" grandis, [7] as well as another indeterminate ornithomimosaurian (though it most likely is Nedcolbertia ), [8] the sauropod Astrodon , the nodosaurid Priconodon , [9] a possible basal ceratopsian, [10] and potentially the ornithopod Tenontosaurus . [3] Other vertebrates are not as well known from the formation, but include a freshwater shark, a lungfish, [11] at least three genera of turtles, and at least one crocodilian. [3]
Color key
| Notes Uncertain or tentative taxa are in small text; |
Dinosaurs reported from the Arundel Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Acrocanthosaurus [5] [12] | A. cf. atokensis [12] |
| "Teeth", [5] "incomplete skeleton" [12] | A large carcharodontosaurid theropod. Presence long suspected but uncertain, but confirmed in 2024 following the discovery of more complete remains. [12] | ||
| "A." medius [13] |
| "Tooth." [14] | An indeterminate theropod tooth. | ||
A. johnstoni [15] | "Tooth." [17] | |||||
"C." potens |
| "Vertebra." [14] | A neotheropod possibly synonymous with Acrocanthosaurus. [19] | |||
| "C." gracilis | "Manual ungual and teeth." [14] | A dromaeosaurid synonymous with Deinonychus. [19] | |||
| "C." potens [13] | Reclassified as "Capitalsaurus" potens | ||||
cf. Deinonychus [13] | Indeterminate [13] |
| A dromaeosaurid | |||
| "D." grandis |
| "Limb elements." [20] | An indeterminate member of Ornithomimosauria. | ||
M. muirkirkensis [21] |
| "Tooth" [21] | Likely an ornithischian, this genus is a nomen nudum that has not been formally published. | |||
Neoceratopsia indet. [10] | Indeterminate [10] |
| "Teeth" [10] | An indeterminate member of Neoceratopsia. Initially believed to have belonged to an indeterminate member of Dryosauridae or the genus Tenontosaurus . | ||
| "O." affinis | Junior synonym of "Dryosaurus" grandis | ||||
P. altus [13] |
| "Tibia [and] fibula." [22] | Possibly synonymous with Astrodon. | |||
P. nanus [13] |
| Possibly synonymous with Astrodon. | ||||
P. crassus [13] |
| "Teeth, tibia." [23] | A large nodosaurid. | |||
cf. Tenontosaurus [24] | Indeterminate [24] |
| ||||
Unassigned pteradactyloid tracks. [25]
Color key
| Notes Uncertain or tentative taxa are in small text; |
Pterosaurs of the Arundel Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Abundance | Notes | Images |
William Bullock Clark (1897) described lignitized trunks of trees often found in upright positions with their roots still intact. [1]
G. J. Brenner (1963) described spores and pollen within the formation. [26]
Acrocanthosaurus is a genus of carcharodontosaurid dinosaur that existed in what is now North America during the Aptian and early Albian stages of the Early Cretaceous, from 113 to 110 million years ago. Like most dinosaur genera, Acrocanthosaurus contains only a single species, A. atokensis. It had a continent-wide range, with fossil remains known from the U.S. states of Oklahoma, Texas, and Wyoming in the west, and Maryland in the east.
Tenontosaurus is a genus of iguanodontian ornithopod dinosaur. It had an unusually long, broad tail, which like its back was stiffened with a network of bony tendons.
Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous period in what is now North America, South America, Europe, and Asia.
Astrodon is a genus of large herbivorous sauropod dinosaur, measuring 20 m (66 ft) in length, 9 m (30 ft) in height and 20 metric tons in body mass. It lived in what is now the eastern United States during the Early Cretaceous period, and fossils have been found in the Arundel Formation, which has been dated through palynomorphs to the Albian about 112 to 110 million years ago.
Priconodon is an extinct genus of dinosaur, known from its large teeth. Its remains have been found in the Aptian-Albian age Lower Cretaceous Arundel Formation of Muirkirk, Prince George's County, Maryland, USA and the Potomac Group, also located in Maryland.
Nedcolbertia is a genus of theropod dinosaur from the Early Cretaceous Period of North America.
The Wealden Group, occasionally also referred to as the Wealden Supergroup, is a group in the lithostratigraphy of southern England. The Wealden group consists of paralic to continental (freshwater) facies sedimentary rocks of Berriasian to Aptian age and thus forms part of the English Lower Cretaceous. It is composed of alternating sands and clays. The sandy units were deposited in a flood plain of braided rivers, the clays mostly in a lagoonal coastal plain.
The Cedar Mountain Formation is the name given to a distinctive sedimentary geologic formation in eastern Utah, spanning most of the early and mid-Cretaceous. The formation was named for Cedar Mountain in northern Emery County, Utah, where William Lee Stokes first studied the exposures in 1944.
The Cloverly Formation is a geological formation of Early and Late Cretaceous age that is present in parts of Montana, Wyoming, Colorado and Utah in the western United States. It was named for a post office on the eastern side of the Bighorn Basin in Wyoming by N.H. Darton in 1904. The sedimentary rocks of formation were deposited in floodplain environments and contain vertebrate fossils, including a diverse assemblage of dinosaur remains. In 1973, the Cloverly Formation Site was designated as a National Natural Landmark by the National Park Service.
The Lameta Formation, also known as the Infratrappean Beds, is a sedimentary geological formation found in Madhya Pradesh, Gujarat, Maharashtra, Telangana, and Andhra Pradesh, India, associated with the Deccan Traps. It is of the Maastrichtian age, and is notable for its dinosaur fossils
The Twin Mountains Formation, also known as the Twin Mak Formation, is a sedimentary rock formation, within the Trinity Group, found in Texas of the United States of America. It is a terrestrial formation of Aptian age, and is notable for its dinosaur fossils. Dinosaurs from this formation include the large theropod Acrocanthosaurus, the sauropod Sauroposeidon, as well as the ornithopods Tenontosaurus and Convolosaurus. It is the lowermost unit of the lower Cretaceous, lying unconformably on Carboniferous strata. It is overlain by the Glen Rose Formation. It is the lateral equivalent of the lower part of the Antlers Formation.
Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1998.
The Vectis Formation is a geological formation on the Isle of Wight and Swanage, England whose strata were formed in the lowermost Aptian, approximately 125 million years ago. The environment of deposition was that of a freshwater coastal lagoon with occasional marine influence after the early Aptian marine transgression, transitioning from the floodplain environment of the underlying Wessex Formation. The primary lithology is of laminated grey mudstones. The Vectis Formation is composed of three geological members: the Shepherds Chine member, the Barnes High Sandstone member, and the Cowleaze Chine member. It is overlain by the fully marine Atherfield Clay Formation, part of the Lower Greensand Group. Dinosaur remains are among the fossils that have been recovered from the formation.
The El Castellar Formation is a geological formation in La Rioja and Teruel, Spain whose strata date back to the possibly the Valanginian to the Barremian stages of the Early Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.
The Ulansuhai Formation is a geological formation in Inner Mongolia, north China. Dinosaur remains are among the fossils that have been recovered from the formation.
The Koum Formation is a geological formation in the North Province of Cameroon, western Africa.
The Eumeralla Formation is a geological formation in Victoria, Australia whose strata date back to the Early Cretaceous. It is Aptian to Albian in age. Dinosaur remains are among the fossils that have been recovered from the formation, particularly from the Dinosaur Cove locality.
The Elrhaz Formation is a geological formation in Niger, West Africa.
The Xinlong Formation is an Early Cretaceous geologic formation in Guangxi, southern China.
The Xiguayuan Formation is an Early Cretaceous (Barremian) geologic formation in Hebei Province of China. Fossil ornithopod tracks have been reported from the formation. It was deposited in a shallow lacustrine setting and is noted for its hyperpycnite facies.