Ellisdale Fossil Site
Encyclopedia
The Ellisdale Fossil Site is located in the valley of the Crosswicks Creek
in Monmouth County, New Jersey
. The site has produced the largest and most diverse fauna of Late Cretaceous terrestrial animals from eastern North America, including the type specimens of the teiid lizard Prototeius stageri and the batrachosauroidid salamander Parrisia
neocesariensis. The site occurs within the basal portion of the Marshalltown Formation
, and dates from the Campanian
Stage of the Late Cretaceous
. The site is classified as a Konzentrat-Lagerstätten resulting from a prehistoric coastal storm.
. Parris encouraged the two collectors to continue monitoring the site, and within a few years hundreds of disarticulated bones of dinosaurs, crocodilians, turtles and fish had been donated to the New Jersey State Museum, which is the repository for the collection. The significance of the Ellisdale Site was recognized by the National Geographic Society
which sponsored research under Society grants in 1986 and 1987. To date over 20,000 specimens have been collected. The Ellisdale Site is currently owned by Monmouth County Park System and is under the management of the New Jersey State Museum. Fossil collecting by the general public is prohibited.
, of the Late Cretaceous
Matawan Group of New Jersey. The exposures of the Marshalltown Formation
at Ellisdale have basal flaser-bedded estuarine clays underlain by crossbedded coastal sands of the Englishtown Formation. The estuarine clays are overlain by well-sorted, crossbedded sand and offshore glauconites, respectively. The entire sequence is interpreted as preserving the landward migration of a barrier beach/backbay/estuarine/deltaic complex during the Marshalltown transgression. Vertebrate fossils are concentrated with rip-up clasts near the base of the estuarine clay sequence in a lag deposit consisting of siderite
pebbles, poorly graded sand, and lignite
. The fossil layer is considered a single-event storm deposit based on sedimentology and stratigraphy. The upper (marine) member of the Marshalltown was formerly considered latest Campanian
in age, due to the presence of the foraminifer Globotruncana calcarata; however the G. calcarata zone has since been redated as Middle Campanian in age (75-76 ma). A recent study of fossil pollen from the estaurine strata enclosing the fossil layer has determined an Early to Mid-Campanian age for the stratum (76 - 80 ma) and a fresh or brackish water tidal marsh environment of deposition..
Paleoecology
Remains of animals from at least four paleoenvironments are represented at the Ellisdale Site: marine, lagoonal/backbay, estuarine/freshwater, and terrestrial. Mixed faunal assemblages of this type are typically asssociated with transgressive lag deposits, and result from the slow accumulation of transported skeletal remains in tidal channels, backbays, and lagoons. Wave action and storms relocated the bones of marine animals to shallow water, while river currents and flooding events transported and deposited the remains of freshwater and upland terrestrial animals such as crocodilians and dinosaurs.
Megafossils of at least three different types of plants have been found at the site: Liriodendron
, Metasequoia
, and Picea. In addition, possible remains of Mangrove
roots have been found encased in siderite concretions. Amber has been found at the site occurring in small droplets, generally less than 5 millimeters in size.
Taphonomic analysis of the Ellisdale fauna has revealed two distinctly different types of preservation. Bones of both marine and upland terrestrial animals are typically broken, heavily worn, and missing the outermost layer of bone (periosteum
). Some bones show evidence of boring by the marine shipworm Teredo
. In contrast, the bones of microvertebrates such as amphibians, lizards and mammals are much more complete, with delicate processes and the periosteum intact.
The small animal fauna of the site probably represents a "proximal" assemblage that lived at or near the final point of deposition, while the heavily worn bones represent a "distal" fauna. It is thought that the proximal fauna may have lived within a freshwater deltaic estuary that was affected by a coastal storm surge
or a possible tsunami
. The presence of numerous well-preserved amphibian fossils support the idea that the environment was freshwater, as amphibians are salt-intolerant. The disarticulated bones which accumulated in the lagoonal backbays by river transport, and in the shallow marine environment offshore, would have been mixed with the skeletal remains of the animals that lived within the delta as the storm surge swept over the estuary. Return flooding from the overfilled lagoons and estuarine channels after the storm's passage would have subsequently filled with debris, resulting in the mixed assemblage of animal and plant remains that are found at the site today.
sp.
Lonchidion sp.
cf. Paranomotodon angustidens
Pseudocorax granti
Squalicorax
kaupi
Cretolamna appendiculata lata
Cretodus arcuata
Cretodus borodini
Scapanorhynchus
texanus
Odontaspis
samhammeri
Synodontaspis holmdelensis
Squatina hassei
Batoidea
Ischyrhiza
mira
cf. Sclerorhynchus
sp.
Ptychotrygon vermiculata
Ptychotrygon hooveri
Borodinopristis sp.
Rhombodus
levis
Brachyrhizodus wichitaensis
Pseudohypolophus sp.
Protoplatyrhina sp.
Osteichthyes
Acipenser
sp.
Amia
cf. fragosa
Atractosteus
occidentalis
Anomoeodus
sp.
Pycnodontidae indet.
Paralbula
casei
Albula
sp.
Xiphactinus
vetus
Enchodus
petrosus
cf. Platacodon sp.
cf. Cimolichthyes sp.
neocesariensis
Sirenidae indet.
cf. Habrosaurus
sp.
cf. Eopelobates
sp.
cf. Discoglossus
sp.
Apalone
sp.
Bothremys
barberi
Baenidae indet.
Corsochelys
sp.
stageri
cf. Haptosphenus
sp.
Iguanidae
indet.
Xenosauridae
indet.
[[Helodermatidae]] indet.
Anguinae indet.
Necrosauridae indet.
cf. Halisaurus
sp.
Crocodilia
Borealosuchus
threensis
cf. Brachychampsa sp.
cf. Allognathosuchus sp.
Deinosuchus
sp.
Saurischia
Dryptosaurus
sp.
cf. Dromaeosauridae
indet.
Theropoda
indet.
Multituberculata
Cimolomyidae indet.
cf. Mesodma
sp.
cf. Cimolodon
sp.
Cimolodontidae indet.
times, the North American Continent was divided by an inland sea into two subcontinents: a western continent now known as "Laramidia
", and an eastern continent named "Appalachia
". Although a rich and diverse assemblage of taxa has been found from Laramidia
, little is known of the contemporaneous terrestrial fauna of the Appalachian subcontinent. The Ellisdale Site has provided the first detailed look at the terrestrial fauna of Appalachia, including the rare fossil remains of frogs, salamanders, lizards and mammals.
It has been suggested that land animals may have migrated between Laramidia and Appalachia, and possibly even the European Archipelago, throughout the Late Cretaceous; however the presence of an endemic "Ellisdalean" land fauna does not support this hypothesis. The Ellisdale fauna together with geological data suggest that eastern North America was an isolated continent from the Turonian
Stage of the Late Cretaceous onward, and thus may have become a refugium for relatively underived Early Cretaceous taxa that underwent vicariant speciation. If dispersal to the European archipelago did take place via a North Atlantic route, it could not have happened until near the close of the Cretaceous Period, based on paleogeographic and paleontologic studies.
Crosswicks Creek
Crosswicks Creek is a tributary of the Delaware River in Burlington County, in western New Jersey in the United States.Crosswicks Creek watershed encompasses parts of Burlington, Mercer, Monmouth and Ocean Counties...
in Monmouth County, New Jersey
Monmouth County, New Jersey
Monmouth County is a county located in the U.S. state of New Jersey, within the New York metropolitan area. As of the 2010 Census, the population was 630,380, up from 615,301 at the 2000 census. Its county seat is Freehold Borough. The most populous municipality is Middletown Township with...
. The site has produced the largest and most diverse fauna of Late Cretaceous terrestrial animals from eastern North America, including the type specimens of the teiid lizard Prototeius stageri and the batrachosauroidid salamander Parrisia
Parrisia
Parrisia is an extinct genus of legless batrachosauroidid salamander from Campanian-age rocks in the Marshalltown Formation, Monmouth County, New Jersey...
neocesariensis. The site occurs within the basal portion of the Marshalltown Formation
Marshalltown Formation
The Marshalltown Formation is a Mesozoic geologic formation. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation.-See also:* List of dinosaur-bearing rock formations...
, and dates from the Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
Stage of the Late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
. The site is classified as a Konzentrat-Lagerstätten resulting from a prehistoric coastal storm.
History of the Discovery
The Ellisdale site was discovered in 1980 by two avocational paleontologists, Robert K. Denton Jr. and Robert C. O'Neill, who brought it to the attention of David C. Parris, the Director of the Bureau of Natural History at the New Jersey State MuseumNew Jersey State Museum
The New Jersey State Museum is located at 205 West State Street in Trenton, New Jersey, United States, overlooking the Delaware River. The Museum is operated as part of the New Jersey Department of State. General admission is free....
. Parris encouraged the two collectors to continue monitoring the site, and within a few years hundreds of disarticulated bones of dinosaurs, crocodilians, turtles and fish had been donated to the New Jersey State Museum, which is the repository for the collection. The significance of the Ellisdale Site was recognized by the National Geographic Society
National Geographic Society
The National Geographic Society , headquartered in Washington, D.C. in the United States, is one of the largest non-profit scientific and educational institutions in the world. Its interests include geography, archaeology and natural science, the promotion of environmental and historical...
which sponsored research under Society grants in 1986 and 1987. To date over 20,000 specimens have been collected. The Ellisdale Site is currently owned by Monmouth County Park System and is under the management of the New Jersey State Museum. Fossil collecting by the general public is prohibited.
Geological Setting
The Ellisdale site occurs within the basal portion of the Marshalltown FormationMarshalltown Formation
The Marshalltown Formation is a Mesozoic geologic formation. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation.-See also:* List of dinosaur-bearing rock formations...
, of the Late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
Matawan Group of New Jersey. The exposures of the Marshalltown Formation
Marshalltown Formation
The Marshalltown Formation is a Mesozoic geologic formation. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation.-See also:* List of dinosaur-bearing rock formations...
at Ellisdale have basal flaser-bedded estuarine clays underlain by crossbedded coastal sands of the Englishtown Formation. The estuarine clays are overlain by well-sorted, crossbedded sand and offshore glauconites, respectively. The entire sequence is interpreted as preserving the landward migration of a barrier beach/backbay/estuarine/deltaic complex during the Marshalltown transgression. Vertebrate fossils are concentrated with rip-up clasts near the base of the estuarine clay sequence in a lag deposit consisting of siderite
Siderite
Siderite is a mineral composed of iron carbonate FeCO3. It takes its name from the Greek word σίδηρος sideros, “iron”. It is a valuable iron mineral, since it is 48% iron and contains no sulfur or phosphorus...
pebbles, poorly graded sand, and lignite
Lignite
Lignite, often referred to as brown coal, or Rosebud coal by Northern Pacific Railroad,is a soft brown fuel with characteristics that put it somewhere between coal and peat...
. The fossil layer is considered a single-event storm deposit based on sedimentology and stratigraphy. The upper (marine) member of the Marshalltown was formerly considered latest Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
in age, due to the presence of the foraminifer Globotruncana calcarata; however the G. calcarata zone has since been redated as Middle Campanian in age (75-76 ma). A recent study of fossil pollen from the estaurine strata enclosing the fossil layer has determined an Early to Mid-Campanian age for the stratum (76 - 80 ma) and a fresh or brackish water tidal marsh environment of deposition..
PaleoecologyPaleoecologyPaleoecology uses data from fossils and subfossils to reconstruct the ecosystems of the past. It involves the study of fossil organisms and their associated remains, including their life cycle, living interactions, natural environment, and manner of death and burial to reconstruct the...
and TaphonomyTaphonomyTaphonomy is the study of decaying organisms over time and how they become fossilized . The term taphonomy was introduced to paleontology in 1940 by Russian scientist Ivan Efremov to describe the study of the transition of remains, parts, or products of organisms, from the biosphere, to the...
Remains of animals from at least four paleoenvironments are represented at the Ellisdale Site: marine, lagoonal/backbay, estuarine/freshwater, and terrestrial. Mixed faunal assemblages of this type are typically asssociated with transgressive lag deposits, and result from the slow accumulation of transported skeletal remains in tidal channels, backbays, and lagoons. Wave action and storms relocated the bones of marine animals to shallow water, while river currents and flooding events transported and deposited the remains of freshwater and upland terrestrial animals such as crocodilians and dinosaurs.Megafossils of at least three different types of plants have been found at the site: Liriodendron
Liriodendron
Liriodendron is a genus of two species of characteristically large deciduous trees in the magnolia family .These trees are widely known by the common name tulip tree or tuliptree for their large flowers superficially resembling tulips, but are closely related to magnolias rather than lilies, the...
, Metasequoia
Metasequoia
Metasequoia is a fast-growing, deciduous tree, and the sole living species, Metasequoia glyptostroboides, is one of three species of conifers known as redwoods. It is native to the Sichuan-Hubei region of China. Although the least tall of the redwoods, it grows to at least 200 feet in height...
, and Picea. In addition, possible remains of Mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
roots have been found encased in siderite concretions. Amber has been found at the site occurring in small droplets, generally less than 5 millimeters in size.
Taphonomic analysis of the Ellisdale fauna has revealed two distinctly different types of preservation. Bones of both marine and upland terrestrial animals are typically broken, heavily worn, and missing the outermost layer of bone (periosteum
Periosteum
Periosteum is a membrane that lines the outer surface of all bones, except at the joints of long bones. Endosteum lines the inner surface of all bones....
). Some bones show evidence of boring by the marine shipworm Teredo
Teredo
Teredo may refer to:* Teredo , a genus of shipworm that bores holes in the wood of ships** Teredo portoricensis, a species of shipworm in the Teredo genus* Teredo wood, a form of fossilized wood showing marks of shipworm damage...
. In contrast, the bones of microvertebrates such as amphibians, lizards and mammals are much more complete, with delicate processes and the periosteum intact.
The small animal fauna of the site probably represents a "proximal" assemblage that lived at or near the final point of deposition, while the heavily worn bones represent a "distal" fauna. It is thought that the proximal fauna may have lived within a freshwater deltaic estuary that was affected by a coastal storm surge
Storm surge
A storm surge is an offshore rise of water associated with a low pressure weather system, typically tropical cyclones and strong extratropical cyclones. Storm surges are caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea...
or a possible tsunami
Tsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...
. The presence of numerous well-preserved amphibian fossils support the idea that the environment was freshwater, as amphibians are salt-intolerant. The disarticulated bones which accumulated in the lagoonal backbays by river transport, and in the shallow marine environment offshore, would have been mixed with the skeletal remains of the animals that lived within the delta as the storm surge swept over the estuary. Return flooding from the overfilled lagoons and estuarine channels after the storm's passage would have subsequently filled with debris, resulting in the mixed assemblage of animal and plant remains that are found at the site today.
Selachimorpha
HybodusHybodus
Hybodus is an extinct genus of once-common, widespread and long lived sharks, first appearing towards the end of the Permian period, and disappearing at the beginning of the Cretaceous. During the Triassic, Jurassic, and Cretaceous periods the hybodonts were especially successful and could be...
sp.
Lonchidion sp.
cf. Paranomotodon angustidens
Pseudocorax granti
Squalicorax
Squalicorax
Squalicorax is a genus of extinct lamniform shark known to have lived during the Cretaceous period. A fully articulated 1.9 m long fossil skeleton of Squalicorax has been found in Kansas, evidence of its presence in the Western Interior Seaway...
kaupi
Cretolamna appendiculata lata
Cretodus arcuata
Cretodus borodini
Scapanorhynchus
Scapanorhynchus
Scapanorhynchus is an extinct genus of shark from the Cretaceous era. Their extreme similarities to the living goblin shark, Mitsukurina owstoni, lead some experts to consider reclassifying it as Scapanorhynchus owstoni...
texanus
Odontaspis
Odontaspis
Odontaspis is one of two genera in the sand shark family, Odontaspididae. They are large-bodied sharks with long, conical snouts, broad-based dorsal and anal fins, and an asymmetrical caudal fin with a strong lower lobe. Their teeth are large, with prominent narrow cusps...
samhammeri
Synodontaspis holmdelensis
Squatina hassei
BatoideaBatoideaBatoidea is a superorder of cartilaginous fish commonly known as rays and skates, containing more than 500 described species in thirteen families...
IschyrhizaIschyrhiza
Ischyrhiza is an extinct genus of cartilaginous fish from the Cretaceous and Paleogene belonging to the primitive Batoidea family Sclerorhynchidae.-Sources:* Fossils by David Ward * accessed on 8/21/09...
mira
cf. Sclerorhynchus
Sclerorhynchus
Sclerorhynchus is an extinct genus of primitive batoidean that lived in the Cretaceous. The namesake of the Mesozoic suborder Sclerorhynchoidea, it is not quite clear whether they were closer to the Rajiformes or to the Pristiformes . Its fossils have been found mainly around the Mediterranean...
sp.
Ptychotrygon vermiculata
Ptychotrygon hooveri
Borodinopristis sp.
Rhombodus
Rhombodus
Rhombodus is a prehistoric genus of ray whose fossils are found in rocks dating from the Maastrichtian stage. It is found in Africa, Europe, Asia and the Americas. Most prominent are the teeth which are all that usually fossilises-See also:...
levis
Brachyrhizodus wichitaensis
Pseudohypolophus sp.
Protoplatyrhina sp.
OsteichthyesOsteichthyesOsteichthyes , also called bony fish, are a taxonomic group of fish that have bony, as opposed to cartilaginous, skeletons. The vast majority of fish are osteichthyes, which is an extremely diverse and abundant group consisting of over 29,000 species...
AcipenserAcipenser
Acipenser is genus of sturgeons. With about 19 species, many of which are threatened, it is the largest genus in the order Acipenseriformes.-Species:*Acipenser baerii J. F. Brandt, 1869**Acipenser baerii baerii J. F...
sp.
Amia
Bowfin
The Bowfin, Amia calva, is the last surviving member of the order Amiiformes , and of the family Amiidae...
cf. fragosa
Atractosteus
Atractosteus
Atractosteus is a genus of gars in the family Lepisosteidae.There are three species:* Atractosteus spatula * Atractosteus tristoechus...
occidentalis
Anomoeodus
Anomoeodus
Anomoeodus is an extinct genus of prehistoric bony fish.-See also:* Prehistoric fish* List of prehistoric bony fish...
sp.
Pycnodontidae indet.
Paralbula
Paralbula
Paralbula is an extinct genus of prehistoric bony fish.-See also:* Prehistoric fish* List of prehistoric bony fish...
casei
Albula
Albula
The term albula can refer to:*Albula Range, a mountain range in Switzerland*Albula , in Switzerland*Albula , a district in canton Graubünden, Switzerland*Albula Pass*Albula Railway, which forms part of the Rhaetian Railway...
sp.
Xiphactinus
Xiphactinus
Xiphactinus was a large, 4.5 to 6 m long predatory bony fish that lived in the Western Interior Sea, over what is now the middle of North America, during the Late Cretaceous. When alive, the fish would have resembled a gargantuan, fanged tarpon...
vetus
Enchodus
Enchodus
Enchodus is an extinct genus of bony fish. It flourished during the Upper Cretaceous and was small to medium in size. One of the genus' most notable attributes are the large "fangs" at the front of the upper and lower jaws and on the palatine bones, leading to its misleading nickname among fossil...
petrosus
cf. Platacodon sp.
cf. Cimolichthyes sp.
Caudata
ParrisiaParrisia
Parrisia is an extinct genus of legless batrachosauroidid salamander from Campanian-age rocks in the Marshalltown Formation, Monmouth County, New Jersey...
neocesariensis
Sirenidae indet.
cf. Habrosaurus
Habrosaurus
Habrosaurus is an extinct genus of prehistoric salamander, and the oldest known member of the family Sirenidae. Two species are known, Habrosaurus prodilatus from the Campanian of Alberta, and Habrosaurus dilatus from the late Maastrichtian and Paleocene of western North America...
sp.
Anura
Hylidae indet.cf. Eopelobates
Eopelobates
Eopelobates is an extinct genus of frog.-Reference:*Spinar, Z.V. & Rocek, Z. 1984. . Amphibia-Reptilia 5: 87-95....
sp.
cf. Discoglossus
Discoglossus
Discoglossus is a genus of frogs in the Discoglossidae family found in southern Europe, northwestern Africa, Israel, and perhaps Syria.-Species:...
sp.
Chelonia
Adocus beatusApalone
Apalone
Apalone is a North American genus in the Trionychidae family of turtles, a family whose members are commonly referred to as softshell turtles. Apalone species are native primarily to the United States, though they are also found in parts of southern Canada and northern Mexico...
sp.
Bothremys
Pleurodira
The Pleurodira are one of the two living suborders of turtles, the other being the Cryptodira. In many cases in the nomenclature of animals, ranks such as suborder are considered of little importance apart from nomenclatural or taxonomic reasons. However, this is not the case with the suborders of...
barberi
Baenidae indet.
Corsochelys
Corsochelys
Corsochelys is an extinct genus of sea turtle that lived in the Late Cretaceous . Zangerl named the type species , based upon remains found in Alabama within the Mooreville Chalk Formation .-Description:Corsochelys is a basal dermochelyid...
sp.
Lacertilia
PrototeiusTeiidae
Teiidae is a family of lizards native to the Americas, generally known as whiptails. The group includes the parthenogenic genera Cnemidophorus and Aspidoscelis, and the non-parthenogenic Tupinambis. It has over 230 member species in ten genera...
stageri
cf. Haptosphenus
Teiidae
Teiidae is a family of lizards native to the Americas, generally known as whiptails. The group includes the parthenogenic genera Cnemidophorus and Aspidoscelis, and the non-parthenogenic Tupinambis. It has over 230 member species in ten genera...
sp.
Iguanidae
Iguanidae
Iguanidae is a family of lizards, composed of iguanas and related species.-Classification of Iguanidae:Two different classification schemes have been used to define the structure of this family. These are the "traditional" classification and the classification presented by Frost et al. .Frost et...
indet.
Xenosauridae
Xenosauridae
The Xenosauridae is a family of lizards native to Central America and China. Also known as knob-scaled lizards, they have rounded, bumpy scales and osteoderms. Most species prefer moist or semi-aquatic habitats, although they are widespread within their native regions, with some even inhabiting...
indet.
[[Helodermatidae]] indet.
Anguinae indet.
Necrosauridae indet.
Varanoidea
Varanoidea is a superfamily of lizards, including the well-known family Varanidae . Also included in the Varanoidea are such extinct marine and semi-aquatic forms as mosasaurs and dolichosaurs, the venomous helodermatids , the Lanthanotidae , and the extinct Necrosauridae.Throughout their long...
cf. Halisaurus
Halisaurus
Halisaurus is an extinct genus of marine lizard belonging to the mosasaur family. With a length of 3–4 m , it was small compared to most other mosasaurs. It was named by Othniel Charles Marsh in 1869, but renamed Baptosaurus by Marsh in 1870, who thought the name was already in use by a fish...
sp.
CrocodiliaCrocodiliaCrocodilia is an order of large reptiles that appeared about 84 million years ago in the late Cretaceous Period . They are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria...
BorealosuchusBorealosuchus
Borealosuchus is an extinct genus of crocodilian that lived from the Late Cretaceous to the Eocene in North America. It was named by Chris Brochu in 1997 for several species that had been assigned to Leidyosuchus. The species assigned to it are:B...
threensis
cf. Brachychampsa sp.
cf. Allognathosuchus sp.
Deinosuchus
Deinosuchus
Deinosuchus is an extinct genus related to the alligator that lived 73 to 80 Ma , during the late Cretaceous period. The name translates as "terrible crocodile" and is derived from the Greek deinos , "terrible", and soukhos , "crocodile"...
sp.
SaurischiaSaurischiaSaurischia meaning 'lizard' and ischion meaning 'hip joint') is one of the two orders, or basic divisions, of dinosaurs. In 1888, Harry Seeley classified dinosaurs into two orders, based on their hip structure...
DryptosaurusDryptosaurus
Dryptosaurus was a genus of primitive tyrannosaur that lived in Eastern North America during the middle Maastrichtian stage of the Late Cretaceous period. Although largely unknown now outside of academic circles, a famous painting of the genus by Charles R...
sp.
cf. Dromaeosauridae
Dromaeosauridae
Dromaeosauridae is a family of bird-like theropod dinosaurs. They were small- to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek dromeus meaning 'runner' and sauros meaning 'lizard'...
indet.
Theropoda
Theropoda
Theropoda is both a suborder of bipedal saurischian dinosaurs, and a clade consisting of that suborder and its descendants . Dinosaurs belonging to the suborder theropoda were primarily carnivorous, although a number of theropod groups evolved herbivory, omnivory, and insectivory...
indet.
MultituberculataMultituberculataThe Multituberculata were a group of rodent-like mammals that existed for approximately one hundred and twenty million years—the longest fossil history of any mammal lineage—but were eventually outcompeted by rodents, becoming extinct during the early Oligocene. At least 200 species are...
Cimolomyidae indet.cf. Mesodma
Mesodma
Mesodma is an extinct genus of mammal, a member of the extinct order Multituberculata within the suborder Cimolodonta, family Neoplagiaulacidae. It lived during the upper Cretaceous and Paleocene Periods of what is now North America...
sp.
cf. Cimolodon
Cimolodon
Cimolodon is a genus of mammal from the Upper Cretaceous of North America. It was a member of the extinct order of Multituberculata within the suborder Cimolodonta and possibly the family Cimolodontidae....
sp.
Cimolodontidae indet.
Significance
During Late CretaceousCretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
times, the North American Continent was divided by an inland sea into two subcontinents: a western continent now known as "Laramidia
Laramidia
Laramidia is a name coined by J. David Archibald in 1996 to describe an island continent that existed during the Late Cretaceous period, when the Western Interior Seaway split the continent of North America in two. Two landmasses existed: the eastern one is called Appalachia; Laramidia is the name...
", and an eastern continent named "Appalachia
Appalachia (Mesozoic)
In the Mesozoic Era, Appalachia was a land area which is now an eastern part of the USA and Canada, separated from Laramidia by the Western Interior Seaway, which shrank, divided across the Dakotas, retreated south towards the Gulf of Mexico and finally dried up.-Fauna:From the Turonian age of the...
". Although a rich and diverse assemblage of taxa has been found from Laramidia
Laramidia
Laramidia is a name coined by J. David Archibald in 1996 to describe an island continent that existed during the Late Cretaceous period, when the Western Interior Seaway split the continent of North America in two. Two landmasses existed: the eastern one is called Appalachia; Laramidia is the name...
, little is known of the contemporaneous terrestrial fauna of the Appalachian subcontinent. The Ellisdale Site has provided the first detailed look at the terrestrial fauna of Appalachia, including the rare fossil remains of frogs, salamanders, lizards and mammals.
It has been suggested that land animals may have migrated between Laramidia and Appalachia, and possibly even the European Archipelago, throughout the Late Cretaceous; however the presence of an endemic "Ellisdalean" land fauna does not support this hypothesis. The Ellisdale fauna together with geological data suggest that eastern North America was an isolated continent from the Turonian
Turonian
The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...
Stage of the Late Cretaceous onward, and thus may have become a refugium for relatively underived Early Cretaceous taxa that underwent vicariant speciation. If dispersal to the European archipelago did take place via a North Atlantic route, it could not have happened until near the close of the Cretaceous Period, based on paleogeographic and paleontologic studies.