Marshalltown Formation

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	USA
Type section
Named for	Marshalltown, New Jersey

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]

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

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

Footnotes

1. Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607.
2. "Geolex — Marshalltown publications". ngmdb.usgs.gov. Retrieved 2024-11-12.
3. "PBDB Collection". paleobiodb.org. Retrieved 2024-11-12.
4. Denton, Robert (2022-04-07). "ALBEMARLE SOUND NC - A MODERN ANALOG FOR THE ELLISDALE FOSSIL SITE (LATE CRETACEOUS, CAMPANIAN, NJ)". Geological Society of America Abstracts with Programs. 54 (4). GSA.
5. "PBDB Collection". paleobiodb.org. Retrieved 2025-01-18.
6. "PBDB Collection". paleobiodb.org. Retrieved 2025-01-18.
7. Denton Jr., Robert K.; O'Neill, Robert C. (1998-09-15). "Parrisia neocesariensis, a new batrachosauroidid salamander and other amphibians from the Campanian of eastern North America". Journal of Vertebrate Paleontology. 18 (3). doi:10.1080/02724634.1998.10011076. ISSN 0272-4634.
8. Brownstein, Chase D. (2018-02-08). "The biogeography and ecology of the Cretaceous non-avian dinosaurs of Appalachia". Palaeontologia Electronica. 21 (1): 1–56. doi:10.26879/801. ISSN 1094-8074.
9. Brownstein, Chase D. (2018). "The distinctive theropod assemblage of the Ellisdale site of New Jersey and its implications for North American dinosaur ecology and evolution during the Cretaceous". Journal of Paleontology. 92 (6): 1115–1129. doi:10.1017/jpa.2018.42. ISSN 0022-3360.
10. Mortimer, Mickey (2024). "Tyrannosauroidea". The Theropod Database. Retrieved Jan 28, 2025.
11. Brownstein, Chase Doran (2019-04-01). "First Record of a Small Juvenile Giant Crocodyliform and its Ontogenetic and Biogeographic Implications". Bulletin of the Peabody Museum of Natural History. 60 (1): 81. doi:10.3374/014.060.0104. ISSN 0079-032X.
12. "PBDB Collection". paleobiodb.org. Retrieved 2025-01-18.
13. "PBDB Collection". paleobiodb.org. Retrieved 2025-01-18.
14. Denton Jr., Robert K.; O'Neill, Robert C. (1995-06-13). "Prototeius stageri, Gen. et sp. Nov., a New Teiid Lizard from the Upper Cretaceous Marshalltown Formation of New Jersey, with a Preliminary Phylogenetic Revision of the Teiidae". Journal of Vertebrate Paleontology. 15 (2). doi:10.1080/02724634.1995.10011227. ISSN 0272-4634.
15. Dudgeon, Thomas W.; Landry, Zoe; Callahan, Wayne R.; Mehling, Carl M.; Ballwanz, Steven (2021). "An Appalachian population of neochoristoderes (Diapsida, Choristodera) elucidated using fossil evidence and ecological niche modelling". Palaeontology. 64 (5): 629–643. doi:10.1111/pala.12545. ISSN 1475-4983.
16. Grandstaff, Barbara S.; Parris, David C.; Robert K. Denton, Jr.; Gallagher, William B. (1992). "Alphadon (Marsupialia) and Multituberculata (Allotheria) in the Cretaceous of Eastern North America". Journal of Vertebrate Paleontology. 12 (2): 217–222. ISSN 0272-4634.

References

• Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. ISBN 0-520-24209-2.