The Severn Formation is a

Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...

geologic formation in

Maryland Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. It borders the states of Virginia to its south, West Virginia to its west, Pennsylvania to its north, and Delaware to its east ...

Dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

remains diagnostic to the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

level are among the

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s that have been recovered from the formation.Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607.

Paleofauna

Dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...
s

* '' "Coelosaurus" antiquus'' *

Ornithomimidae Ornithomimidae (meaning "bird-mimics") is an extinct family of theropod dinosaurs which bore a superficial resemblance to modern ostriches. Ornithomimids were fast, omnivorous or herbivorous dinosaurs known mainly from the Late Cretaceous Period ...

indet. *

Hadrosauridae Hadrosaurids (), also hadrosaurs or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod fam ...

indet.

Plesiosaur The Plesiosauria or plesiosaurs are an Order (biology), order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared in the latest Triassic Period (geology), Period, possibly in the Rhaetian st ...
s

* '' Cimoliasaurus magnus''

Mosasaur Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Ancient Greek, Greek ' meaning 'lizard') are an extinct group of large aquatic reptiles within the family Mosasauridae that lived during the Late Cretaceous. Their first fossil remains wer ...
s

* '' Halisaurus platyspondylus'' * '' Prognathodon rapax'' * '' Mosasaurus hoffmanni'' * ''Mosasaurus sp''. * cf. ''

Mosasaurus conodon ''Mosasaurus'' (; "lizard of the Meuse (river), Meuse River") is the type genus (defining example) of the mosasaurs, an extinct group of aquatic Squamata, squamate reptiles. It lived from about 82 to 66 million years ago during the Campanian an ...

'' *

Mosasauridae Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Greek ' meaning 'lizard') are an extinct group of large aquatic reptiles within the family Mosasauridae that lived during the Late Cretaceous. Their first fossil remains were discovered in ...

indet.

Crocodylomorphs Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. Extinct crocodylomorphs were considerably more ...

* '' Deinosuchus rugosus'' * ''

Thoracosaurus neocesariensis ''Thoracosaurus'' (chest lizard) is an extinct genus of long-snouted eusuchian which existed during the Late Cretaceous and Early Paleocene in North America and Europe. Taxonomy ''Thoracosaurus'' had traditionally been thought to be related to ...

'' *

Alligatorinae Alligatorinae is a subfamily within the family Alligatoridae that contains the alligators and their closest extinct relatives, and is the sister taxon to Caimaninae (the caimans). Many genera in Alligatorinae are described, but only the genus ' ...

indet.

Turtle Turtles are reptiles of the order (biology), order Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Crypt ...
s

* ''Peritresius ornatus'' * '' Osteopygis emarginatus'' * '' Trionyx priscus'' * Toxochelyidae indet.

Chondrichthyans Chondrichthyes (; ) is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fish'', which have skeletons ...

* '' Carcharias holmdelensis'' * '' Carcharias samhammeri'' * '' Chiloscyllium greeni'' * '' Cretalamana appendiculata'' * ''

Dasyatis ''Dasyatis'' (Greek alphabet, Greek δασύς ''dasýs'' meaning wikt:rough, rough or Density, dense and βατίς ''batís'' meaning Skate (fish), skate) is a genus of stingray in the family (biology), family Dasyatidae that is native to the ...

sp.'' * '' Tomewingia problematica'' * '' Galeorhinus garadoti'' * '' Ginglymostoma sp.'' * '' Heterodontus sp.'' * ''

Hybodus ''Hybodus'' (from , 'crooked' and 'tooth') is an extinct genus of Hybodontiformes, hybodont. Species closely related to the type species ''Hybodus reticulatus'' lived during the Early Jurassic epoch. Numerous species have been assigned to ''Hyb ...

sp.'' * '' Ischyrhiza cf. avonicola'' * ''

Ischyrhiza mira ''Ischyrhiza'' is an extinct genus of sclerorhynchoid ray from the Late Cretaceous (Cenomanian-Maastrichtian). It had a large, toothed rostrum closely resembling that of a modern-day sawfish. Despite formerly being classified within a family ...

'' * ''

Myliobatis ''Myliobatis'' is a genus of eagle rays in the family (biology), family Myliobatidae. Description ''Myliobatis'' species can reach a width up to about . Their bodies consist of a rhomboidal disc, wider than long, with one dorsal fin. The head is ...

sp.'' * '' Odontaspis aculeatus'' * '' Plicatoscyllium antiquum'' * '' Plicatoscyllium derameei'' * '' Pseudohypolophus mcnultyi'' * '' Ptychotrygon vermiculata'' * '' Raja farishi'' * '' Rhinobatos sp.'' * '' Rhombodus binkhorsti'' * '' Serratolamna serrata'' * '' Squalicorax kaupi'' * '' Squalicorax pristodontus'' * '' Squatina hassei'' * ''

Ischyodus ''Ischyodus'' (from , 'power' and 'tooth') is an extinct genus of chimaera. It is the most diverse and long-lived chimaera genus, with over 39 species found worldwide spanning over 140 million years from the Middle Jurassic to the Miocene. Alm ...

sp.''

Osteichthyans

* Albuidae indet. * '' Anomoedus cf. haseolus'' * '' Cylinadracanthus sp.'' * '' Egertonia sp.'' * '' Enchodus ferox'' * '' Hadrodus sp.'' * '' Lepidosteus sp.'' * '' Paralbula casei''

Footnotes

References

* Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. . Maastrichtian Stage of North America Cretaceous Maryland Geologic formations of Maryland {{US-geologic-formation-stub

Paleofauna

Dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...s

Plesiosaur The Plesiosauria or plesiosaurs are an Order (biology), order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared in the latest Triassic Period (geology), Period, possibly in the Rhaetian st ...s

Mosasaur Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Ancient Greek, Greek ' meaning 'lizard') are an extinct group of large aquatic reptiles within the family Mosasauridae that lived during the Late Cretaceous. Their first fossil remains wer ...s

Crocodylomorphs Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. Extinct crocodylomorphs were considerably more ...

Turtle Turtles are reptiles of the order (biology), order Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Crypt ...s

Chondrichthyans Chondrichthyes (; ) is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fish'', which have skeletons ...

Osteichthyans

See also

Footnotes

References

Dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...
s

Plesiosaur The Plesiosauria or plesiosaurs are an Order (biology), order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared in the latest Triassic Period (geology), Period, possibly in the Rhaetian st ...
s

Mosasaur Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Ancient Greek, Greek ' meaning 'lizard') are an extinct group of large aquatic reptiles within the family Mosasauridae that lived during the Late Cretaceous. Their first fossil remains wer ...
s

Turtle Turtles are reptiles of the order (biology), order Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Crypt ...
s