The Severn Formation is a

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...

geologic

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondar ...

Maryland Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to ...

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

remains diagnostic to the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

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

Paleofauna

Dinosaurs

* '' "Coelosaurus" antiquus'' *

Ornithomimidae Ornithomimidae (meaning "bird-mimics") is a 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 of Lauras ...

indet. * Hadrosauridae indet.

Plesiosaurs The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared i ...

* '' Cimoliasaurus magnus''

Mosasaurs Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Greek ' meaning 'lizard') comprise a group of extinct, large marine reptiles from the Late Cretaceous. Their first fossil remains were discovered in a limestone quarry at Maastricht on th ...

* '' Halisaurus platyspondylus'' * ''

Prognathodon rapax ''Prognathodon'' is an extinct genus of marine lizard belonging to the mosasaur family. It is classified as part of the Mosasaurinae subfamily, alongside genera like ''Mosasaurus'' and ''Clidastes''. ''Prognathodon'' has been recovered from depo ...

'' * '' Mosasaurus hoffmanni'' * ''Mosasaurus sp''. * cf. ''

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

'' * Mosasauridae 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. During Mesozoic and early Cenozoic times, cr ...

* '' Deinosuchus rugosus'' * '' Thoracosaurus neocesariensis'' *

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.

Turtles Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked tur ...

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

Chondrichthyans Chondrichthyes (; ) is a class that contains the cartilaginous fishes that have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fishes'', which have skeletons primarily composed of bone tissue. C ...

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

Dasyatis ''Dasyatis'' (Greek δασύς ''dasýs'' meaning rough or dense and βατίς ''batís'' meaning skate) is a genus of stingray in the family Dasyatidae that is native to the Atlantic, including the Mediterranean. In a 2016 taxonomic revisi ...

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

Hybodus ''Hybodus'' (from el, ύβος , 'crooked' and el, ὀδούς 'tooth') is an extinct genus of hybodont, a group of shark-like elasmobranchs that lived from the Late Devonian to the end of the Cretaceous. Species closely related to the type sp ...

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

Myliobatis ''Myliobatis'' is a genus of eagle rays in the 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 broad and short, ...

sp.'' * '' Odontaspis aculeatus'' * '' Plicatoscyllium antiquum'' * '' Plicatoscyllium derameei'' * '' Pseudohypolophus mcnultyi'' * '' Ptychotrygon vermiculata'' * '' Raja farishi'' * ''

Rhinobatos ''Rhinobatos'' is a genus of fish in the Rhinobatidae family. Although previously used to encompass all guitarfishes, it was found to be polyphyletic, and recent authorities have transferred many species included in the genus to ''Acroteriobatu ...

sp.'' * '' Rhombodus binkhorsti'' * '' Serratolamna serrata'' * '' Squalicorax kaupi'' * '' Squalicorax pristodontus'' * '' Squatina hassei'' * ''

Ischyodus ''Ischyodus'' (from el, ισχύς , 'power' and el, ὀδούς '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 M ...

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 {{US-geologic-formation-stub