{{Short description|Geological Formation in Maryland}} {{Infobox rockunit | name = Severn Formation | image = | caption = | type = Geological formation | period = Maastrichtian | age = | prilithology = | otherlithology = | namedfor = | namedby = | region = | country = | coordinates = | unitof = | subunits = | underlies = | overlies = | thickness = | extent = | area = | map = | map_caption = }}

The '''Severn Formation''' is a Mesozoic geologic formation in Maryland. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation.<ref name="dinosaurdistribution">Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607.</ref>

==Paleofauna==

=== Dinosaurs === * ''"Coelosaurus" antiquus''<ref name=":0">{{Cite journal |last=Baird |first=Donald |date=1986 |title=Upper Cretaceous Reptiles from the Severn Formation of Maryland |url=https://archive.org/details/baird-1986-severn-formation/ |journal=The Mosasaur |volume=3 |pages=63–85}}</ref> * Ornithomimidae indet.<ref name=":1">{{Cite journal |last=Hartstien |first=Eugene F |last2=Decina |first2=Lawrence E |last3=Keil |first3=Ronald F |date=1999 |title=A Late Cretaceous (Severn Formation) Vertebrate Assemblage from Bowie, Maryland |url=https://archive.org/details/hartstein-et-al-1999-severn-fm |journal=The Mosasaur |volume=6 |pages=17–23}}</ref> *Hadrosauridae indet.<ref name=":0" /><ref name=":1" />

=== Plesiosaurs === * ''Cimoliasaurus magnus''<ref name=":0" /><ref name=":1" />

=== Mosasaurs === * ''Halisaurus platyspondylus''<ref>{{cite journal|last1=Holmes|first1=Robert B.|last2=Sues|first2=Hans-Dieter|title=A Partial Skeleton of the Basal Mosasaur Halisaurus platyspondylus from the Severn Formation (Upper Cretaceous: Maastrichtian) of Maryland|journal=Journal of Paleontology|date=2000|volume=74|issue=2|pages=309–316|jstor=1306908}}</ref><ref name=":0" /> * ''Prognathodon rapax''<ref name=":0" /> * ''Mosasaurus hoffmanni''<ref name=":0" /> * ''Mosasaurus sp''.<ref name=":1" /> * cf. ''Mosasaurus conodon''<ref name=":0" /> * Mosasauridae indet.<ref name=":0" />

=== Crocodylomorphs === * ''Deinosuchus rugosus''<ref name=":1" /> * ''Thoracosaurus neocesariensis''<ref name=":0" /> * Alligatorinae indet.<ref name=":1" />

=== Turtles === * ''Peritresius ornatus''<ref name=":0" /><ref name=":1" /> * ''Osteopygis emarginatus''<ref name=":0" /> * ''Trionyx priscus''<ref name=":0" /><ref name=":1" /> * Toxochelyidae indet.<ref name=":0" />

=== Chondrichthyans ===

* ''Carcharias holmdelensis''<ref name=":1" /> * ''Carcharias samhammeri''<ref name=":1" /> * ''Chiloscyllium greeni''<ref name=":1" /> * ''Cretalamana appendiculata''<ref name=":1" /> * ''Dasyatis sp.''<ref name=":1" /> * ''Tomewingia problematica''<ref name=":1" /> * ''Galeorhinus garadoti''<ref name=":1" /> * ''Ginglymostoma sp.''<ref name=":1" /> * ''Heterodontus sp.''<ref name=":1" /> * ''Hybodus sp.''<ref name=":1" /> * ''Ischyrhiza cf. avonicola''<ref name=":1" /> * ''Ischyrhiza mira''<ref name=":1" /> * ''Myliobatis sp.''<ref name=":1" /> * ''Odontaspis aculeatus''<ref name=":1" /> * ''Plicatoscyllium antiquum''<ref name=":1" /> * ''Plicatoscyllium derameei''<ref name=":1" /> * ''Pseudohypolophus mcnultyi''<ref name=":1" /> * ''Ptychotrygon vermiculata''<ref name=":1" /> * ''Raja farishi''<ref name=":1" /> * ''Rhinobatos sp.''<ref name=":1" /> * ''Rhombodus binkhorsti''<ref name=":1" /> * ''Serratolamna serrata''<ref name=":1" /> * ''Squalicorax kaupi''<ref name=":1" /> * ''Squalicorax pristodontus''<ref name=":1" /> * ''Squatina hassei''<ref name=":1" /> * ''Ischyodus sp.''<ref name=":1" />

=== Osteichthyans ===

* Albuidae indet.<ref name=":1" /> * ''Anomoedus cf. haseolus''<ref name=":1" /> * ''Cylinadracanthus sp.''<ref name=":1" /> * ''Egertonia sp.''<ref name=":1" /> * ''Enchodus ferox''<ref name=":1" /> * ''Hadrodus sp.''<ref name=":1" /> * ''Lepidosteus sp.''<ref name=":1" /> * ''Paralbula casei''<ref name=":1" />

==See also== {{Portal|Earth sciences|Paleontology|Dinosaurs||}} * List of dinosaur-bearing rock formations ** List of stratigraphic units with few dinosaur genera

==Footnotes== {{Reflist}}

==References== * Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp.&nbsp;{{ISBN|0-520-24209-2}}.

Category:Maastrichtian Stage of North America Category:Cretaceous Maryland Category:Geologic formations of Maryland

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