Hornerstown Formation

Last updated
Hornerstown Formation
Stratigraphic range: latest Maastrichtian-Danian [1]
66.5–62  Ma
O
S
D
C
P
T
J
K
Pg
N
Type Geological formation
Unit of Rancocas Group
Underlies Vincentown Formation
Overlies New Egypt Formation, Navesink Formation and Tinton Formation
Lithology
Primary Marl, greensand
Location
Region New Jersey
CountryUnited States
Type section
Named for Hornerstown, New Jersey

The Hornerstown Formation is a latest Cretaceous to early Paleocene-aged geologic formation in New Jersey. It preserves a variety of fossil remains, including those of dinosaurs, and contains direct evidence of the mass mortality that occurred at the Cretaceous-Paleogene boundary. [2] [3]

Contents

Outcrops of the Hornerstown Formation are known from sites such as Edelman Fossil Park. [4]

Age & significance

The age of the Hornerstown deposits have been controversial. While most fossils are of animal taxa known from the earliest Cenozoic era, several fossils of otherwise exclusively Cretaceous age have been found. These include remains of the shark Squalicorax , several types of non-avian dinosaurs, the teleost fish Enchodus , several species of ammonite, and marine lizards referred to the genus Mosasaurus . Some of these remains show signs of severe abrasion and erosion, however, implying that they may be re-worked from older deposits. Most of these fossils are restricted to the lowest point in the formation, one rich in fossils and known as the Main Fossiliferous Layer, or MFL. Other explanations for the out-of-place fossils in the MFL is that they represent a time-averaged assemblage that built up and remained unburied during a time of low sediment deposition, or that they were stirred up from deeper in the sediment and deposited together during a tsunami. [5] Biochemical analyses done on mosasaur bones from the Hornerstown Formation and the underlying, purely Cretaceous New Egypt Formation have found differing chemical signatures in the content of rare earth elements depending on whether the bones derive from the New Egypt or the Hornerstown Formation. This provides evidence against the idea that the presence of these remains in the Hornerstown is just the result of reworking, and supports the Hornerstown Formation including Cretaceous strata. [6]

To account for these Cretaceous fossils, the Hornerstown Formation is generally treated as including the last portion of the Maastrichtian shortly before the Cretaceous-Paleogene boundary, and is thus divided into three sections: the section below the MFL (entirely Maastrichtian), the MFL itself (at the K-Pg boundary), and the section above the MFL (entirely Danian). However, other studies continue to treat the Hornerstown Formation as a Paleocene formation that saw significant reworking of Cretaceous fossils into itself. [7] In addition, recent studies have found evidence of high iridium concentration and shocked quartz within the MFL, suggesting that the MFL represents a thanatocoenosis formed from an ecosystem collapse during the Cretaceous-Paleogene extinction event. This makes the Hornerstown Formation one of the few geological formations to contain direct evidence of the immediate impact of the extinction event. The Hornerstown Formation is important paleontologically, as it shows the impact of the K-Pg extinction on the coastal waters of eastern Appalachia, contains many of the last known records of taxa that went extinct at the K-Pg boundary, while also providing evidence of survivorship for the taxa that managed to survive the extinction event. [3]

Vertebrate paleofauna

Cartilaginous fishes

Based on Case (1996) and Boles et al (2024): [3] [8]

Chimaeras

Chimaeras of the Hornerstown Formation
GenusSpeciesLocationStratigraphic positionAbundanceMaterialNotesImages
Edaphodon E. agassizi Danian Tooth platesA callorhinchid chimaera. Edaphodon AMNH.jpg
E. mantelliDanian
E. mirificus Maastrichtian
E. stenobyrusMaastrichtian
Ischyodus I. bifurcatusMaastrichtian, potentially DanianTooth plates, jaw elementsA callorhinchid chimaera. Ischyodus quenstedti 45456 (cropped).jpg
I. thurmanniMaastrichtian
I. williamsaeDanian

Sharks

Sharks of the Hornerstown Formation
GenusSpeciesLocationStratigraphic positionAbundanceMaterialNotesImages
Araloselachus A. cuspidatusMaastrichtianTeethA sand shark. [9] FOS527C.jpg
Carcharias C. teretidens DanianA relative of the sand tiger shark. Carcharias taurus SI.jpg
Cretalamna C. appendiculataMaastrichtian & DanianA megatooth shark. Cretalamna reconstruction.png
Heptranchias H. howellii MaastrichtianA relative of the sharpnose sevengill shark. Heptranchias perlo (Sharpnose sevengill shark).gif
Hexanchus H. microdon DanianA sixgill shark. Hexanchus griseus (Bluntnose sixgill shark).gif
H. sp.Maastrichtian & Danian
Otodus O. obliquusDanianA megatooth shark. Otodus obliquus.jpg
Odontaspis O. sp.DanianA sand shark. Odontaspis ferox (Smalltooth sand tiger).gif
Palaeocarcharodon P. sp.DanianA megatooth shark. Palaeocarcharodon NT.png
Palaeogaleus P. vincentiMaastrichtian & DanianA houndshark. Palaeogaleus faujasi.jpg
Palaeohypotodus P. rutotiDanianA sand shark. Palaeohypotodus bronni.jpg
Pseudocorax P. affinisMaastrichtianA pseudocoracid shark. Psuedocorax granti.jpg
Scapanorhynchus S. texanusMaastrichtianA goblin shark. [10] Scapanorhynchus sp Sahel Alma Santonian.jpg
Scyliorhinus S. gilberti DanianA catshark. Scyliorhinus retifer.jpg
Sphenodus S. lundgreniMaastrichtianA orthacodontid shark. Sphenodus nitidus.jpg
Squalicorax S. pristodontusMaastrichtianA crow shark. Squalicorax2DB.jpg
Squalus S. minor Maastrichtian & DanianA spurdog. Squalus acanthias.jpg
S. sp
Squatina S. sp.MaastrichtianAn angelshark. Squatina tergocellata.jpg
Weltonia W. ancistrodonDanianA cow shark.
Xampylodon X. brotzeniMaastrichtianA cow shark. Notidanodon.jpg

Rays

Rays of the Hornerstown Formation
GenusSpeciesLocationStratigraphic positionAbundanceMaterialNotesImages
Aetomylaeus A. striatus MaastrichtianTeethAn eagle ray. [9] Aetomylaeus maculatus 01.jpg
Dasyatis D. crosswickense DanianA whiptail stingray. Type locality for species. Dasyatis bennettii by jordan and richardson.png
Hypolophites H. hutchinsiDanianA whiptail stingray. Type locality for species.
Hypolophodon H. sylvestrisDanianA whiptail stingray.
Ischyrhiza I. miraMaastrichtianA sclerorhynchid sawskate. [9] Onchosaurus (Ischyrhiza) marrocanus Arambourg 1935 - Dalpiazia stromeri Checcia-Rispoli, 1933 7100.5122.jpg
Rhinoptera R. sp.MaastrichtianA cownose ray. Rhinoptera bonasus (line art).jpg
Rhombodus R. laevisMaastrichtianA rhombodontid ray. Rhombodus NT small cropped.png
Viperecucullus V. kuehneiDanianA whiptail stingray, type locality for the species and genus.

Ray-finned fishes

Actinopterygii of the Hornerstown Formation
GenusSpeciesLocationStratigraphic positionAbundanceMaterialNotesImages
Acipenser A. cf. albertensis MaastrichtianA sturgeon. [3] Acipenser oxyrhynchus.jpg
Anomoeodus A. phaseolusMaastrichtian, potentially Danian8 teethA pycnodont. One tooth is known from the Danian section of the formation, which would be the latest record of this genus and prove its occurrence in the Cenozoic; however, it may have been reworked from lower layers. [3] Anomoeodus subclavatus.jpg
Atractosteus A. sp.Maastrichtian & Danian11 teethA gar. First record of gars from eastern North America during the Paleocene. [3] Alligator gar (Atractosteus spatula) I.jpg
cf. Bananogmius cf. B. sp.MaastrichtianA plethodid tselfatiiform. [3] [9] Pentanogmius Bananogmius1DB.jpg
Dercetidae indet.Maastrichtian & Danian27 flank scalesA dercetid aulopiform. The first evidence in eastern North America of the Dercetidae surviving the K-Pg extinction event. [3]
Enchodus E. feroxMaastrichtianAn enchodontid aulopiform. The E. gladiolus remains are the first record of the species in eastern North America. [3] Enchodus petrosus.png
E. gladiolus8 teeth
Iridopristis I. parrisi Sewell, New Jersey Danian3 partial articulated specimens, including a near-complete skull. [7] A stem-lineage member of Holocentridae. The earliest known definitive holocentrid. Type locality for genus and species. [7]
Paralbula P. marylandicaMaastrichtian & Danian23 teethA phyllodontid elopomorph. First evidence of P. marylandica existing during the Cretaceous, indicating that it survived the extinction event. [3]
Phyllodus P. paulkatoiMaastrichtian1 tooth plateA phyllodontid elopomorph. First known occurrence in eastern North America. [3]
Saurocephalus S. lanciformisDanian1 toothA saurodontid ichthyodectiform. First known occurrence in eastern North America and first known occurrence of ichthyodectiforms as a whole in the Paleocene and Cenozoic. [3] Saurocephalus lanciformis.JPG

Reptiles

Birds

A number of fossil birds are known from the greensands of the formation. The Hornerstown serves as the type locality for all these genera and species:

Birds of the Hornerstown Formation
GenusSpeciesLocationStratigraphic positionAbundanceNotes

Anatalavis

A. rex

MaastrichtianA waterfowl potentially related to the magpie-goose. [3] [11]

Graculavus

G. velox

A potential wader. [3] [11]

Laornis

L. edwardsianus

A laornithid wading bird. [3] [11]
Novacaesareala N. hungerfordiA potential tropicbird. [3] [11]

Palaeotringa

P. littoralis

A potential wader. [3] [11]

P. vagans

Telmatornis

T. priscus

A potential wader. [3] [11]

Tytthostonyx

T. glauconiticus

A potential seabird. [3] [11]

Non-avian dinosaurs

Dinosaurs of the Hornerstown Formation
GenusSpeciesLocationStratigraphic positionAbundanceNotes
Hadrosauridae indet.MaastrichtianA hadrosaurid ornithischian. [3]

The tyrannosauroid Dryptosaurus is sometimes referred to this formation, as its remains were found in the New Egypt Formation, which is sometimes considered a part of the Hornerstown. [12]

Crocodylomorphs

Crocodylomorphs of the Hornerstown Formation
GenusSpeciesLocationStratigraphic positionAbundanceMaterialNotesImages
Borealosuchus B. threeensisMaastrichtianLower jaw, postcranial remainsA eusuchian. Type locality of species. [3] [13] Borealosuchus wilsoni HMNS.jpg

Bottosaurus

B. harlani

Maastrichtian & DanianRemains including lower jaw of a juvenile individual [14] An early caiman. [3] [14]
B. tuberculatus [9] Maastrichtian
Hyposaurus H. rogersiiMaastrichtian & DanianA dyrosaurid. [3] [15]
cf. Procaimanoidea P. sp.MaastrichtianA caiman. [3] NMNH-USNM15996 1.jpg
Thoracosaurus T. neocesariensisMaastrichtian & DanianA gavialoid. [3] Dinosauria - Thoracosaurus 02.jpg

Plesiosaurs

Plesiosaurs of the Hornerstown Formation
GenusSpeciesLocationStratigraphic positionAbundanceMaterialNotesImages
" Plesiosaurus ""P." brevifemurMaastrichtianAn indeterminate plesiosaur known from a well-documented specimen, now lost. [16] [17]

Turtles

Testudines of the Hornerstown Formation
GenusSpeciesLocationStratigraphic positionAbundanceNotes Images
Adocus A. agilis [16] MaastrichtianAn adocid. [3] Adocus kirtlandius Gilmore, 1919.jpg
A. beatus
A. syntheticus [16]
Agomphus A. pectoralisMaastrichtianA kinosternoid related to Dermatemys . [3] [18] Agomphus.jpg
Bothremys B. sp.MaastrichtianA bothremydid side-necked turtle. [3]
Euclastes E. wielandiMaastrichtian & DanianA sea turtle. [3] Euclastes sp.jpg
Lytoloma L. jeanesiiMaastrichtianA sea turtle. [16]
Osteopygis O. emarginatusMaastrichtianA macrobaenid. [16]
Peritresius P. ornatusMaastrichtianA sea turtle.
Taphrosphys T. sulcatusMaastrichtianA bothremydid side-necked turtle. [3]
T. strenuus

Mosasaurs

Mosasaurs of the Hornerstown Formation
GenusSpeciesLocationStratigraphic positionAbundanceMaterialNotesImages
Halisaurus H. platyspondylusMaastrichtianA halisaurine. Type locality of the genus and species. Halisaurus arambourgi.jpg
Mosasaurus M. hoffmanni (=Nectoportheus validus) [16] MaastrichtianPterygoid, teeth, vertebrae [3] [6] A mosasaurine. This formation contains some of the last known remains, comprising individuals killed during the mass mortality event that formed the MFL. [3] A very large specimen is known. [6] Mosasaurus 21copy.jpg
Plioplatecarpus P. sp.MaastrichtianA plioplatecarpine. Plioplatecarpus primaevus life reconstruction.jpg

See also

Related Research Articles

<span class="mw-page-title-main">Late Cretaceous</span> Subdivision of Cretaceous Period

The Late Cretaceous is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after creta, the Latin word for the white limestone known as chalk. The chalk of northern France and the white cliffs of south-eastern England date from the Cretaceous Period.

<span class="mw-page-title-main">Scollard Formation</span> Upper Cretaceous to lower Palaeocene stratigraphic unit of the Western Canada Sedimentary Basin

The Scollard Formation is an Upper Cretaceous to lower Palaeocene stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta. Its deposition spanned the time interval from latest Cretaceous to early Paleocene, and it includes sediments that were deposited before, during, and after the Cretaceous-Paleogene (K-Pg) extinction event. It is significant for its fossil record, and it includes the economically important coal deposits of the Ardley coal zone.

<span class="mw-page-title-main">Laramie Formation</span> Geological formation in Colorado, US

The Laramie Formation is a geologic formation of the Late Cretaceous (Maastrichtian) age, named by Clarence King in 1876 for exposures in northeastern Colorado, in the United States. It was deposited on a coastal plain and in coastal swamps that flanked the Western Interior Seaway. It contains coal, clay and uranium deposits, as well as plant and animal fossils, including dinosaur remains. The formation contains some of the oldest records of Grass in western North America.

Congorhynchus is an enigmatic, likely polyphyletic genus of prehistoric marine ray-finned fish that was described by E. Darteville and E. Casier in 1949.

<i>Coriops</i> Extinct genus of fishes

Coriops is an extinct genus of freshwater osteoglossomorph fish, possibly a hiodontiform, with a single species known from the Late Cretaceous of western North America.

<span class="mw-page-title-main">Ichthyodectiformes</span> Extinct order of ray-finned fishes

Ichthyodectiformes is an extinct order of marine stem-teleost ray-finned fish. The order is named after the genus Ichthyodectes, established by Edward Drinker Cope in 1870. Ichthyodectiforms are usually considered to be some of the closest relatives of the teleost crown group.

<i>Euclastes</i> Extinct genus of turtles

Euclastes is an extinct genus of sea turtles that survived the Cretaceous–Paleogene mass extinction. The genus was first named by Edward Drinker Cope in 1867, and contains three species. E. hutchisoni, was named in 2003 but has since been reassigned to the genus Pacifichelys, while E. coahuilaensis named in 2009 was reassigned as Mexichelys coahuilaensis in 2010.

<span class="mw-page-title-main">Maastricht Formation</span> Geological formation in the Netherlands and Belgium

The Maastricht Formation, named after the city of Maastricht in the Netherlands, is a geological formation in the Netherlands and Belgium whose strata date back to the Late Cretaceous, within 500,000 years of the Cretaceous–Paleogene boundary, now dated at 66 million years ago. The formation is part of the Chalk Group and is between 30 and 90 metres thick. It crops out in southern parts of Dutch and Belgian Limburg and adjacent areas in Germany. It can be found in the subsurface of northern Belgium and southeastern Netherlands, especially in the Campine Basin and Roer Valley Graben. Dinosaur remains are among the fossils that have been recovered from the formation.

The Lopez de Bertodano Formation is a geological formation in the James Ross archipelago of the Antarctic Peninsula. The strata date from the end of the Late Cretaceous to the Danian stage of the lower Paleocene, from about 70 to 65.5 million years ago, straddling the Cretaceous-Paleogene boundary.

Bottosaurus is an extinct genus of alligatorid from the Late Cretaceous-Early Paleocene of New Jersey, Texas, and possibly North Carolina and South Carolina. Two species are currently accepted, with a third requiring re-evaluation.

Ampheristus is an extinct genus of prehistoric marine ray-finned fish. It was a basal or stem member of the family Ophidiidae, which contains modern cusk-eels. Fossils are known from worldwide from the Late Cretaceous to the late Paleogene, making it a rather successful survivor of the Cretaceous-Paleogene extinction event.

<i>Anomoeodus</i> Extinct genus of fishes

Anomoeodus is an extinct genus of prehistoric marine ray-finned fish belonging to the family Pycnodontidae. This genus primarily lived during the mid-to-late Cretaceous period, ranging from the Albian to the very end of the Maastrichtian age, and possibly into the Danian. The first fossils of Anomoeodus were described by Louis Agassiz in 1833, although they were described under Pycnodus. Some studies have recovered it as a wastebasket taxon.

<i>Saurocephalus</i> Extinct genus of fishes

Saurocephalus is an extinct genus of ray-finned fishes within the family Saurodontidae. The genus was first described in 1824 and contains six or seven species, including the type species S. lanciformis. Saurocephalus first appeared during the early Valanginian and continued on to the Maastrichtian, where it nearly went extinct. However, the recent discovery of S. lanciformis remains from the earliest Paleocene indicates that it just barely survived into the Cenozoic. This would make it the last surviving ichthyodectiform.

The Intertrappean Beds are a Late Cretaceous and Early Paleocene geologic formation in India. The beds are found as interbeds between Deccan Traps layers, including the slightly older Lameta Formation. The formation spans the Cretaceous–Paleogene boundary, with a stratigraphic range of only a few hundred thousand years before and after the boundary, and a significant debate exists about whether specific sites belong to the Cretaceous or the Paleocene.

<span class="mw-page-title-main">Ojo Alamo Formation</span> Geologic formation in New Mexico

The Ojo Alamo Formation is a geologic formation in New Mexico spanning the Mesozoic/Cenozoic boundary. Non-avian dinosaur fossils have controversially been identified in beds of this formation dating from after the Cretaceous–Paleogene extinction event, but these have been explained as either misidentification of the beds in question or as reworked fossils, fossils eroded from older beds and redeposited in the younger beds.

<span class="mw-page-title-main">Appalachia (landmass)</span> Mesozoic land mass separated from Laramidia to the west by the Western Interior Seaway

During most of the Late Cretaceous the eastern half of North America formed Appalachia, an island land mass separated from Laramidia to the west by the Western Interior Seaway. This seaway had split North America into two massive landmasses due to a multitude of factors such as tectonism and sea-level fluctuations for nearly 40 million years. The seaway eventually expanded, divided across the Dakotas, and by the end of the Cretaceous, it retreated towards the Gulf of Mexico and the Hudson Bay.

<span class="mw-page-title-main">Lefipán Formation</span> Geologic formation in Argentina

The Lefipán Formation is a Maastrichtian to Danian, straddling the Cretaceous-Paleogene boundary, geologic formation of the Cañadón Asfalto Basin in Chubut Province, Patagonia, Argentina. The up to 380 metres (1,250 ft) thick stratigraphic unit comprises mudstones, sandstones, siltstones and conglomerates, sourced from the North Patagonian Massif and deposited in a deltaic to shallow marine environment with a strong tidal influence. The basin that in those times was connected to the widening South Atlantic Ocean with a seaway connection to the Austral Basin and possibly with the Pacific Ocean.

<span class="mw-page-title-main">Paleocene ammonites</span> Possible survival of ammonites into the early Paleocene epoch

The term Paleocene ammonites describes families or genera of Ammonoidea that may have survived the Cretaceous–Paleogene extinction event, which occurred 66.043 million years ago. Although almost all evidence indicated that ammonites did not survive past the K–Pg boundary, there is some scattered evidence that some ammonites lived for a short period of time during the Paleocene epoch, although none survived the Danian ; they were likely extinct within 500,000 years of the K-Pg extinction event, which correlates to roughly 65.5 Ma. The evidence for Paleocene ammonoids is rare and remains controversial.

<i>Cyclurus</i> Extinct genus of fishes

Cyclurus is an extinct genus of freshwater amiid ray-finned fish known from the Late Cretaceous to the Early Oligocene across much of the Northern Hemisphere. It is thought to be the closest relative of the extant bowfins in the genus Amia, although species of Cyclurus were significantly smaller in size compared to Amia.

References

  1. Gentry, A.D.; Kiernan, C.R.; Parham, J.F. (2022). "A large non-marine turtle from the Upper Cretaceous of Alabama and a review of North American "Macrobaenids"". The Anatomical Record. 306 (6): 1411–1430. doi:10.1002/ar.25054. PMID   37158131.
  2. Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Boles, Zachary; Ullmann, Paul; Putnam, Ian; Ford, Mariele; Deckhut, Joseph (2024-04-12). "New vertebrate microfossils expand the diversity of the chondrichthyan and actinopterygian fauna of the Maastrichtian–Danian Hornerstown Formation in New Jersey". Acta Palaeontologica Polonica. doi: 10.4202/app.01117.2023 .
  4. Voegele, Kristyn K.; Ullmann, Paul V.; Lonsdorf, Tara; Christman, Zachary; Heierbacher, Michael; Kibelstis, Brian J.; Putnam, Ian; Boles, Zachary M.; Walsh, Shane; Lacovara, Kenneth J. (2021-11-01). "Microstratigraphic Analysis of Fossil Distribution in the Lower Hornerstown and Upper Navesink Formations at the Edelman Fossil Park, NJ". Frontiers in Earth Science. 9: 1033. Bibcode:2021FrEaS...9.1033V. doi: 10.3389/feart.2021.756655 . ISSN   2296-6463.
  5. Gallagher, W.B. (2005). "Recent mosasaur discoveries from New Jersey and Delaware, USA: stratigraphy, taphonomy and implications for mosasaur extinction." Netherlands Journal of Geosciences — Geologie en Mijnbouw, 84(3): 241-245. Archived 2012-09-04 at the Wayback Machine
  6. 1 2 3 Gallagher, W. B. (2015). "Greensand mosasaurs of New Jersey and the Cretaceous–Paleogene transition of marine vertebrates". Netherlands Journal of Geosciences. 94 (1): 87–91. Bibcode:2015NJGeo..94...87G. doi:10.1017/njg.2014.30. ISSN   0016-7746.
  7. 1 2 3 Andrews, J. V.; Schein, J. P.; Friedman, M. (2023). "An earliest Paleocene squirrelfish (Teleostei: Beryciformes: Holocentroidea) and its bearing on the timescale of holocentroid evolution". Journal of Systematic Palaeontology. 21 (1). Bibcode:2023JSPal..2168571A. doi: 10.1080/14772019.2023.2168571 .
  8. Case, Gerard R. (1996-12-19). "A new Selachian Fauna from the Lower Hornerstown Formation (Early Paleocene/Montian) of Monmouth County, New Jersey". Palaeontographica Abteilung A: 1–14. doi:10.1127/pala/242/1996/1.
  9. 1 2 3 4 5 "PBDB Collection". paleobiodb.org. Retrieved 2024-11-12.
  10. "PBDB Collection". paleobiodb.org. Retrieved 2024-11-12.
  11. 1 2 3 4 5 6 7 "3.22 New Jersey, United States; 7. Hornerstown Formation," in Weishampel, et al. (2004). Page 586.
  12. Olsson, R.K. (1960). "Foraminifera of latest Cretaceous and earliest Tertiary age in the New Jersey coastal plain". Journal of Paleontology. 34: 1–58.
  13. Brochu, Christopher A.; Parris, David C.; Grandstaff, Barbara Smith; Denton, Robert K.; Gallagher, William B. (2012). "A new species of Borealosuchus (Crocodyliformes, Eusuchia) from the Late Cretaceous–early Paleogene of New Jersey". Journal of Vertebrate Paleontology. 32 (1): 105–116. doi:10.1080/02724634.2012.633585. ISSN   0272-4634.
  14. 1 2 Cossette, A. P., and C. A. Brochu. 2018. A new specimen of the alligatoroid Bottosaurus harlani and the early history of character evolution in alligatorids. Journal of Vertebrate Paleontology. DOI:10.1080/02724634.2018.1486321.
  15. Morgan, Donald J (December 2018). "PRESENCE OF A DYROSAURID NEOSUCHIAN IN THE SEVERN/BRIGHTSEAT FORMATION OF MARYLAND". The Journal of the Delaware Valley Paleontological Society. X: 91 to 104.
  16. 1 2 3 4 5 6 "PBDB Collection". paleobiodb.org. Retrieved 2024-11-12.
  17. Parris, David C. (1974). "Additional Records of Plesiosaurs from the Cretaceous of New Jersey". Journal of Paleontology. 48 (1): 32–35. ISSN   0022-3360.
  18. "PBDB Taxon". paleobiodb.org. Retrieved 2024-11-11.

Bibliography