scholarly journals An elongate hadrosaurid forelimb with biological traces informs the biogeography of the Lambeosaurinae

2020 ◽  
pp. 1-9
Author(s):  
Chase Doran Brownstein ◽  
Immanuel Bissell
Keyword(s):  
New Jersey ◽  
North America ◽  
Late Cretaceous ◽  
North American ◽  
American West ◽  
Atlantic Coastal Plain ◽  
Western Interior Seaway ◽  
Terrestrial Vertebrates ◽  
Both Bones ◽  
Atlantic Coastal

Abstract Although the fossil record of the Late Cretaceous eastern North American landmass Appalachia is poor compared to that from the American West, it includes material from surprisingly aberrant terrestrial vertebrates that may represent relictual forms persisting in relative isolation until the end of the Mesozoic. One intriguing question is to what extent eastern and western North American faunas interspersed following the closure of the Western Interior Seaway during the Maastrichtian Stage of the Late Cretaceous ca. 70 Ma. Isolated remains from the Atlantic Coastal Plain in New Jersey have been preliminarily identified as the bones of crested lambeosaurine hadrosaurids, a derived clade known from the Cretaceous of Asia, western North America, and Europe, but have not been formally described. We describe the partial forelimb of a large hadrosaurid from the late Maastrichtian New Egypt Formation of New Jersey. The ulna preserves multiple deep scores identifiable as shark feeding marks, and both bones show ovoid and circular marks attributable to invertebrates. This forelimb is very similar to another partial antebrachium from the same area that shows evidence of septic arthritis. Both these specimens and a complete humerus from the same unit are closely comparable to the lower forelimbs of lambeosaurines among hadrosaurid dinosaurs. Although the absence of lambeosaurine synapomorphies observable on the New Egypt Formation forelimbs precludes their definite referral to Lambeosaurinae, they show that a morphotype of large hadrosauromorph with distinctly elongate forelimbs existed in the latest Maastrichtian of eastern North America and allow for a revision of the latest Cretaceous biogeography of crested herbivorous dinosaurs.

scholarly journals Dinosaurs from the Santonian–Campanian Atlantic coastline substantiate phylogenetic signatures of vicariance in Cretaceous North America

2021 ◽  
Vol 8 (8) ◽  
pp. 210127
Author(s):  
Chase Doran Brownstein
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Coastal Plain ◽  
Fossil Record ◽  
Atlantic Coastal Plain ◽  
Terrestrial Vertebrates ◽  
Small Juvenile ◽  
The Poor ◽  
Atlantic Coastal ◽  
Early Late

During the Cretaceous, diversifications and turnovers affected terrestrial vertebrates experiencing the effects of global geographical change. However, the poor fossil record from the early Late Cretaceous has concealed how dinosaurs and other terrestrial vertebrates responded to these events. I describe two dinosaurs from the Santonian to Early Campanian of the obscure North American paleolandmass Appalachia. A revised look at a large, potentially novel theropod shows that it likely belongs to a new clade of tyrannosauroids solely from Appalachia. Another partial skeleton belongs to an early member of the Hadrosauridae, a highly successful clade of herbivorous dinosaurs. This skeleton is associated with the first small juvenile dinosaur specimens from the Atlantic Coastal Plain. The tyrannosauroid and hadrosaurid substantiate one of the only Late Santonian dinosaur faunas and help pinpoint the timing of important anatomical innovations in two widespread dinosaur lineages. The phylogenetic positions of the tyrannosauroid and hadrosaurid show Santonian Appalachian dinosaur faunas are comparable to coeval Eurasian ones, and the presence of clades formed only by Appalachian dinosaur taxa establishes a degree of endemism in Appalachian dinosaur assemblages attributable to episodes of vicariance.

scholarly journals Prootic anatomy of a juvenile tyrannosauroid from New Jersey and its implications for the morphology and evolution of the tyrannosauroid braincase

2018 ◽  
Author(s):  
Chase D Brownstein
Keyword(s):  
Phylogenetic Analysis ◽  
North America ◽  
Northern Hemisphere ◽  
Late Cretaceous ◽  
Coastal Plain ◽  
Fossil Record ◽  
Atlantic Coastal Plain ◽  
Western Interior Seaway ◽  
Large Predator ◽  
Atlantic Coastal

Among the most recognizable theropods are the tyrannosauroids, a group of small to large carnivorous coelurosaurian dinosaurs that inhabited the majority of the northern hemisphere during the Cretaceous and came to dominate large predator niches in North American and Asian ecosystems by the end of the Mesozoic era. The clade is among the best-represented of dinosaur groups in the notoriously sparse fossil record of Appalachia, the Late Cretaceous landmass that occupied the eastern portion of North America after its formation from the transgression of the Western Interior Seaway. Here, the prootic of a juvenile tyrannosauroid collected from the middle-late Campanian Marshalltown Formation of the Atlantic Coastal Plain is described, remarkable for being the first concrete evidence of juvenile theropods in that plain during the time of the existence of Appalachia and the only portion of theropod braincase known from the landmass. Phylogenetic analysis recovers the specimen as an “intermediate” tyrannosauroid of similar grade to Dryptosaurus and Appalachiosaurus. Comparisons with the corresponding portions of other tyrannosauroid braincases suggest that the Ellisdale prootic is more similar to Turonian forms in morphology than to the derived tyrannosaurids of the Late Cretaceous, thus supporting the hypothesis that Appalachian tyrannosauroids and other vertebrates were relict forms surviving in isolation from their derived counterparts in Eurasia.

Lungfish tooth plates (Sarcopterygii, Dipnoi) from the Late Cretaceous (Santonian) Eutaw Formation of Alabama and Mississippi, USA

2018 ◽  
Vol 93 (3) ◽  
pp. 531-542
Author(s):  
T. Lynn Harrell ◽  
Dana J. Ehret
Keyword(s):  
New Jersey ◽  
North America ◽  
Late Cretaceous ◽  
Fossil Record ◽  
American West ◽  
The United States ◽  
Diagnostic Value ◽  
Western Interior Seaway ◽  
Eutaw Formation ◽  
New Occurrences

AbstractLungfish are a poorly represented component of the Mesozoic fossil record in North America, as most lungfish fossils consist of rare, isolated dental plates that are of little diagnostic value due to their conservative nature. In eastern North America, the paucity of lungfish fossils in Late Cretaceous strata is further compounded by the occurrence of geologic units that are primarily marine in origin, unlike the Late Jurassic to mid-Cretaceous fluvial deposits of the American west that contain comparatively more specimens. Lungfish fossils from the eastern side of the Late Cretaceous Western Interior Seaway (Appalachia) have previously been reported from the Cenomanian Woodbine Formation of northeast Texas and the Campanian Mount Laurel Formation of New Jersey. Here we report two new occurrences of eastern North American lungfish tooth plates from the Santonian Eutaw Formation of Alabama and Mississippi. These two specimens are referred to Ceratodus frazieri Ostrom, 1970 and Ceratodus carteri Main et al., 2014, species that are better known from the mid-Cretaceous of the Western Interior of North America. This discovery is the first published record of lungfish of any age from the states of Alabama and Mississippi. It partially bridges the temporal gap in the fossil record between the Cenomanian lungfish of Texas and the Campanian lungfish of New Jersey and extends the biogeographic range of Late Cretaceous lungfish to the eastern Gulf Coastal Plain of the United States.

scholarly journals Prootic anatomy of a juvenile tyrannosauroid from New Jersey and its implications for the morphology and evolution of the tyrannosauroid braincase

2018 ◽  
Author(s):  
Chase D Brownstein
Keyword(s):  
Phylogenetic Analysis ◽  
North America ◽  
Northern Hemisphere ◽  
Late Cretaceous ◽  
Coastal Plain ◽  
Fossil Record ◽  
Atlantic Coastal Plain ◽  
Western Interior Seaway ◽  
Large Predator ◽  
Atlantic Coastal

Among the most recognizable theropods are the tyrannosauroids, a group of small to large carnivorous coelurosaurian dinosaurs that inhabited the majority of the northern hemisphere during the Cretaceous and came to dominate large predator niches in North American and Asian ecosystems by the end of the Mesozoic era. The clade is among the best-represented of dinosaur groups in the notoriously sparse fossil record of Appalachia, the Late Cretaceous landmass that occupied the eastern portion of North America after its formation from the transgression of the Western Interior Seaway. Here, the prootic of a juvenile tyrannosauroid collected from the middle-late Campanian Marshalltown Formation of the Atlantic Coastal Plain is described, remarkable for being the first concrete evidence of juvenile theropods in that plain during the time of the existence of Appalachia and the only portion of theropod braincase known from the landmass. Phylogenetic analysis recovers the specimen as an “intermediate” tyrannosauroid of similar grade to Dryptosaurus and Appalachiosaurus. Comparisons with the corresponding portions of other tyrannosauroid braincases suggest that the Ellisdale prootic is more similar to Turonian forms in morphology than to the derived tyrannosaurids of the Late Cretaceous, thus supporting the hypothesis that Appalachian tyrannosauroids and other vertebrates were relict forms surviving in isolation from their derived counterparts in Eurasia.

scholarly journals Theropod hindlimbs with feeding and other traces reveal ecosystem dynamics in the Maastrichtian of eastern North America

2018 ◽  
Author(s):  
Chase D Brownstein
Keyword(s):  
New Jersey ◽  
North America ◽  
Atlantic Coastal Plain ◽  
Ecosystem Dynamics ◽  
Eastern North America ◽  
Terrestrial Vertebrate ◽  
Past Life ◽  
Atlantic Coastal ◽  
Tibia Shaft ◽  
Tooth Marks

Direct documentation of the ecology of past life is often rare when the fossil record is comparatively poor, as in the case of the terrestrial fauna of the Maastrichtian of eastern North America. Here, I describe a femur and partial tibia shaft assignable to theropods from the Maastrichtian Big Brook locality of New Jersey. The former, identifiable to a previously undetected morphotype of large ornithomimosaur, bears several scrapes identifiable as the feeding traces of sharks, adding to the collection of terrestrial vertebrate remains bearing such marks from the state. The latter is littered with tooth marks and punctures from possibly multiple crocodyliform individuals, the first documented occurrence of such traces on dinosaur bone from the Maastrichtian of the Atlantic Coastal Plain. Additionally, its surface is dotted with likely traces of invertebrates, revealing a microcosm of biological interaction from the Maastrichtian New Jersey shoreline. Previously, the massive Campanian crocodylian taxon Deinosuchus rugosus and the slightly smaller Cenomanian-age Texas crocodyliform Deltasuchus motherali have been shown as important drivers of terrestrial vertebrate taphonomy in eastern North America. The report of crocodyliform bite marks on the ornithomimosaur metatarsal shaft in this manuscript reveals that crocodylians continued to play role in the taphonomy of large dinosaurs in eastern North America through the end of the Mesozoic. The preserved invertebrate traces add to the sparse record of their traces on dinosaur bone, and the presence of shark scrapes on the femur supports the “bloat-and-float” model of terrestrial vertebrate fossil deposition in eastern North America.

scholarly journals Theropod specimens from the Navesink Formation and their implications for the Diversity and Biogeography of Ornithomimosaurs and Tyrannosauroids on Appalachia

2017 ◽  
Author(s):  
Chase D Brownstein
Keyword(s):  
New Jersey ◽  
North America ◽  
Late Cretaceous ◽  
Phylogenetic Analyses ◽  
Eastern North America ◽  
Western Interior Seaway ◽  
Safe Haven ◽  
The Right

The sparse dinosaur record of eastern North America has rendered the dinosaurs of the Late Cretaceous landmass of Appalachia obscure. This landmass, isolated from the western landmass Laramidia by a great inland sea known as the Western Interior Seaway, may have been a safe haven for dinosaur species which would be replaced on Appalachia’s western contemporary. An excellent example of these isolated forms are the tyrannosaurs of Appalachia, which have not only been grouped outside Tyrannosauridae proper in phylogenetic analyses, but also bare distinct morphologies, including a gigantic manus in one form, from these ‘western tyrants’. However, Appalachian tyrannosaurs are only represented currently by the two valid taxa Dryptosaurus aquilunguis and Appalachiosaurus montgomeriensis, both which are only known from partial skeletons with few overlapping elements. Recently, the generic name Teihivenator was given to another tyrannosaur named “Laelaps” macropus by Cope (1868) by Yun (2017). However, examination of the specimens by the author show morphologies at odds with the morphological descriptions given by Yun (2017). The tyrannosaur named by Yun (2017), known from partial lower hindlimb elements including the portions of two metatarsals and a partial tibia, is shown herein to be a chimaera of ornithomimosaur and tyrannosauroid hindlimb elements. The several different dinosaur specimens which compose the syntypes of “Teihivenator” include three ornithomimosaur pedal phalanges with affinities to derived ornithomimid taxa, a proximal end of the right metatarsal II and a distal end of the right metatarsal II from either ornithomimosaurs or tyrannosauroids, and a partial tibia of a tyrannosauroid distinct from Dryptosaurus or Appalachiosaurus but nevertheless considered here to be from an indeterminate taxon based on the lack of observable autopomorphies and issues with the comparability of the specimen to other taxa. The specimens are nevertheless important for revealing further the theropod fauna of the Maastrichtian Navesink Formation of New Jersey, as well as for possibly increasing the diversity of tyrannosauroids and further illuminating the presence of ornithomimosaurs on Appalachia.

Lyell on the Geological Similarity of North America and Europe

1982 ◽  
Vol 1 (1) ◽  
pp. 45-47
Author(s):  
Leonard Wilson
Keyword(s):  
North America ◽  
Coastal Plain ◽  
North American ◽  
The United States ◽  
Atlantic Coastal Plain ◽  
Fossil Plants ◽  
Land Area ◽  
The North ◽  
The Difference ◽  
Atlantic Coastal

During his travels in America in 1841-1842 and 1845-1846, Charles Lyell was impressed by the difference of the living flora and fauna of North America from those of Europe. The fossil shells of the Cretaceous strata of New Jersey and of the Tertiary formations of the Atlantic Coastal Plain of the United States showed that North America had also constituted a separate biological region during the Cretaceous and throughout the Tertiary. By contrast, the fossil plants of North American coal formations were so closely similar to those of Europe that Lyell concluded that during the Carboniferous, Europe and North America must have formed a continuous land area. As evidence of a former land connection between North America and Europe, Lyell observed that the distribution of sediments among the strata of the Appalachians indicated that the Carboniferous strata of North America had been derived from land lying to the East — where the Atlantic Ocean now is. Similarly, the North American Silurian and other Paleozoic systems contained fossils similar to those of Europe, and their sediments were so distributed as to suggest that they had been derived from land lying to the East. Lyell pointed out the ancient uniformity of European and American fossil life, without being able to explain it.

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