Marshalltown Formation

The Marshalltown Formation is a Late Cretaceous (Campanian)-aged geologic formation in New Jersey and Delaware, US. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation. It contains the most extensive Campanian-aged dinosaur fauna from New Jersey and Delaware.^[1][2]

Marshalltown Formation
Stratigraphic range: Middle to Late Campanian, 75–72 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Unit of	Monmouth Group
Underlies	Wenonah Formation
Overlies	Englishtown Formation
Lithology
Primary	Glauconite, sandstone
Other	Siderite
Location
Region	New Jersey, Delaware
Country	United States
Type section
Named for	Marshalltown, New Jersey

The famous Ellisdale Fossil Site, a konzentrat-lagerstätten which contains one of the most diverse Cretaceous vertebrate assemblages (likely rapidly buried in a massive flood event) known from eastern North America/former Appalachia, is an exposure of this formation.^[3]

The Marshalltown Formation stretches across southern New Jersey to northern Delaware, and is largely composed of marine sediments deposited off the eastern shore of Appalachia, although the Ellisdale site represents a fluvio-deltaic or tidal-estuarine environment reminiscent of the modern Albemarle Sound, and thus has more of a terrestrial influence.^[3][4]

Vertebrate paleobiota

Based on the Paleobiology Database:^[5][6]

Cartilaginous fish

Cartilaginous fish of the Marshalltown Formation
Genus	Species	Member	Location	Material	Notes	Images

Bony fish

Based on:^[5][6]

Bony fish of the Marshalltown Formation
Genus	Species	Member	Location	Material	Notes	Images
Acipenser	A. sp.		Ellisdale Site		A sturgeon.
Anomoeodus	A. phaseolus		Ellisdale Site, St. Georges		A pycnodont.
Atractosteus	A. sp.		Ellisdale Site		A gar.
Cyclurus	C. cf. fragosus		Ellisdale Site		An amiid related to bowfins.
cf. Cylindracanthus	C. sp.		St. George's		A fish of uncertain affinities.
Enchodus	E. ferox		Ellisdale Site, St. Georges		An enchodontid aulopiform.
	E. sp.		St. Georges
cf. Lepisosteus	L. sp.		St. Georges		A gar.
Paralbula	P. casei		Ellisdale Site, St. Georges		A phyllodontid elopomorph.
cf. "Platacodon"	P. sp.		Ellisdale Site		A sciaenid-like fish.
Stephanodus	S. sp.		St. Georges		A pycnodont.
Xiphactinus	X. audax		Ellisdale Site		An ichthyodectid.
	X. sp.		St. Georges

Amphibians

Amphibians of the Marshalltown Formation
Genus	Species	Member	Location	Material	Notes	Images
Albanerpetontidae indet.			Ellisdale Site		An albanerpetontid.
Alytidae indet.					An alytid frog.
cf. Habrosaurus	H. sp.				A sirenid salamander.
Parrisia	P. neocesariensis				A batrachosauroidid salamander. Type locality of genus and species.[7]
Pelobatidae indet.					A relative of European spadefoot toads.
cf. Proamphiuma	P. sp.				A sirenid salamander.
cf. Scotiophryne	S. sp.				A frog of uncertain affinities.
cf. Theatonius	T. sp.				A frog of uncertain affinities.

Reptiles

Dinosaurs

Based on Brownstein (2018):^[8][9]

Dinosaurs of the Marshalltown Formation
Genus	Species	Member	Location	Material	Notes	Images
"Coelosaurus"	C. antiquus				An ornithomimosaur.
Coelurosauria indet.			Ellisdale Site		A coelurosaur theropod of uncertain affinities.
Dromaeosauridae indet.					A dromaeosaurid theropod of uncertain affinities.
Dryptosaurus	D. sp.				A tyrannosauroid theropod. Specimens from this formation might belong to Appalachiosaurus instead.[10]
Hadrosauridae indet.					A hadrosaurid ornithopod.
?Hadrosauroidea indet.					A hadrosauroid ornithopod.
Hadrosaurus	H. foulkii				A hadrosaurid ornithopod.
	?H. sp.
Hypsibema	H. crassicauda				A hadrosauroid ornithopod.
Nodosauridae indet.					A nodosaurid ankyosaur.
Ornithopoda indet.					An ornithopod of uncertain affinities.

Crocodilians

Crocodilians of the Marshalltown Formation
Genus	Species	Member	Location	Material	Notes	Images
cf. "Allognathosuchus"	"A". sp.		Ellisdale Site		An alligatorid.
cf. Brachychampsa	B. sp.		Ellisdale Site		An alligatorid.
Deinosuchus	D. rugosus		Ellisdale Site		An alligatoroid, one of the largest known crocodilians. Remains of both juveniles and adults known.[11]
"Diplocynodon"	"D". sp.		Ellisdale Site		An alligatorid.
"Leidyosuchus"	"L". sp.		Cambridge Crossing Executive Park		An alligatorid.[12]

Turtles

Turtles of the Marshalltown Formation
Genus	Species	Member	Location	Material	Notes	Images
Adocus	A. beatus			Ellisdale Site	An adocid.
Chedighaii	C. barberi			Ellisdale Site	A bothremydid side-necked turtle.
Corsochelys	C. sp.			Ellisdale Site	A dermochelyid sea turtle.
Trionychidae indet.				Ellisdale Site, St. Georges	A softshell turtle of uncertain affinities.

Plesiosaurs

Plesiosaurs of the Marshalltown Formation
Genus	Species	Member	Location	Material	Notes	Images
"Elasmosaurus"	"E." orientalis		Swedesboro	Two back vertebrae	An elasmosaurid, species name is a nomen dubium due to fragmentary nature.[13]

Squamates

Squamates of the Marshalltown Formation
Genus	Species	Member	Location	Material	Notes	Images
Clidastes	C. iguanavus		Swedesboro		A mosasaurine mosasaur. Type locality of species.[13]
	cf. C. sp.		St. Georges
?Contogenys	C. sp.		Ellisdale Site		A globaurid lizard.
cf. Globidens	G. sp.		St. Georges		A globidensine mosasaur.
Glyptosaurinae indet.			Ellisdale Site		An anguid lizard.
cf. Halisaurus	H. sp.		Ellisdale Site		A halisaurine mosasaur.
Haptosphenus	H. sp.		Ellisdale Site		A chamopsid lizard.
cf. Odaxosaurus	O. sp.		Ellisdale Site		An anguid lizard.
cf. Machaerosaurus	M. sp.		Ellisdale Site		An anguid lizard.
Prototeius	P. stageri		Ellisdale Site		A chamopsid lizard. Type locality of genus and species.[14]

Choristodera

Choristoderes of the Marshalltown Formation
Genus	Species	Member	Location	Material	Notes	Images
Neochoristodera indet.			Ellisdale Site	1 vertebra	A neochoristodere, one of the very few records of this group from eastern North America.[15]

Mammals

Based on Grandstaff et al (1992):^[16]

Mammals of the Marshalltown Formation
Genus	Species	Member	Location	Material	Notes	Images
Cimolodontidae indet.			Ellisdale Site		A cimolodontid multituberculate.
Cimolomys	C. cf. clarki				A cimolomyid multiberculate.
cf. Didelphodon	D. sp.				A stagodontid metatherian.
Protalphadon	P. lulli				A metatherian.

See also

• Earth sciences portal
• Paleontology portal
• Dinosaurs portal

• List of dinosaur-bearing rock formations
  • List of stratigraphic units with few dinosaur genera