Osteology and phylogeny of small-bodied hadrosauromorphs from an end-Cretaceous marine assemblage

2020 ◽  
Vol 191 (1) ◽  
pp. 180-200
Author(s):  
Chase Doran Brownstein
Keyword(s):  
New Jersey ◽  
North America ◽  
Late Cretaceous ◽  
Eastern Coast ◽  
Eastern North America ◽  
Post Mortem ◽  
Western North America ◽  
Dominant Group ◽  
Dinosaur Extinction ◽  
Depositional Setting

Abstract The timing of non-avian dinosaur decline is one of the most debated subjects in dinosaur palaeontology. Dinosaur faunas from the last few million years of the Mesozoic appear far less diverse than those from earlier in the Cretaceous, a trend that could suggest non-avian dinosaur extinction occurred gradually. However, the limited nature of the latest Cretaceous dinosaur record outside western North America has obscured patterns in dinosaur diversity just before the extinction. Here, I describe two associated skeletons and several isolated fossils recovered from the New Egypt Formation of New Jersey, a latest Maastrichtian unit that underlies the K–Pg boundary. The larger skeleton appears to be a small-bodied adult from a lineage outside Hadrosauridae, the dominant group of these animals during the Maastrichtian, that persisted along the eastern coast of North America. Smaller specimens are identifiable as juvenile hadrosauromorphs. These results substantiate an important assemblage of herbivorous dinosaurs from the poorly-known Cretaceous of eastern North America. The marine depositional setting for these skeletons demonstrates that proposed ecosystem preferences among hadrosauromorphs may be biased by post-mortem transportation, and the adult skeleton has implications for assessing the proposed relictual nature of Late Cretaceous eastern North American vertebrates.

scholarly journals New records of theropods from the latest Cretaceous of New Jersey and the Maastrichtian Appalachian fauna

2019 ◽  
Vol 6 (11) ◽  
pp. 191206 ◽  
Author(s):  
Chase Doran Brownstein
Keyword(s):  
New Jersey ◽  
North America ◽  
Fossil Record ◽  
New Records ◽  
The Other ◽  
Eastern North America ◽  
Western North America ◽  
Northeastern North America ◽  
Terrestrial Vertebrate ◽  
Postcranial Remains

The faunal changes that occurred in the few million years before the Cretaceous–Palaeogene extinction are of much interest to vertebrate palaeontologists. Western North America preserves arguably the best fossil record from this time, whereas terrestrial vertebrate fossils from the eastern portion of the continent are usually limited to isolated, eroded postcranial remains. Examination of fragmentary specimens from the American east, which was isolated for the majority of the Cretaceous as the landmass Appalachia, is nonetheless important for better understanding dinosaur diversity at the end of the Mesozoic. Here, I report on two theropod teeth from the Mount Laurel Formation, a lower-middle Maastrichtian unit from northeastern North America. One of these preserves in detail the structure of the outer enamel and resembles the dentition of the tyrannosauroid Dryptosaurus aquilunguis among latest Cretaceous forms in being heavily mediolaterally compressed and showing many moderately developed enamel crenulations. Along with previously reported tyrannosauroid material from the Mt Laurel and overlying Cretaceous units, this fossil supports the presence of non-tyrannosaurid tyrannosauroids in the Campanian–Maastrichtian of eastern North America and provides evidence for the hypothesis that the area was still home to relictual vertebrates through the end of the Mesozoic. The other tooth is assignable to a dromaeosaurid and represents both the youngest occurrence of a non-avian maniraptoran in eastern North America and the first from the Maastrichtian reported east of the Mississippi. This tooth, which belonged to a 3–4 m dromaeosaurid based on size comparisons with the teeth of taxa for which skeletons are known, increases the diversity of the Maastrichtian dinosaur fauna of Appalachia. Along with previously reported dromaeosaurid teeth, the Mt Laurel specimen supports the presence of mid-sized to large dromaeosaurids in eastern North America throughout the Cretaceous.

scholarly journals The first reported ceratopsid dinosaur from eastern North America (Owl Creek Formation, Upper Cretaceous, Mississippi, USA)

2017 ◽  
Author(s):  
Andrew A. Farke ◽  
George E. Phillips
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Depositional Environment ◽  
Upper Cretaceous ◽  
Eastern North America ◽  
Western North America ◽  
Western Interior Seaway ◽  
Double Root ◽  
Union County ◽  
Dentary Tooth

Ceratopsids (“horned dinosaurs”) are known from western North America and Asia, a distribution reflecting an inferred subaerial link between the two landmasses during the Late Cretaceous. However, this clade was previously unknown from eastern North America, presumably due to limited outcrop of the appropriate age and depositional environment as well as the separation of eastern and western North America by the Western Interior Seaway during much of the Late Cretaceous. A dentary tooth from the Owl Creek Formation (late Maastrichtian) of Union County, Mississippi, represents the first reported occurrence of Ceratopsidae from eastern North America. This tooth shows a combination of features typical of Ceratopsidae, including a double root and a prominent, blade-like carina. Based on the age of the fossil, we hypothesize that it is consistent with a dispersal of ceratopsids into eastern North America during the very latest Cretaceous, presumably after the two halves of North America were reunited following the retreat of the Western Interior Seaway.

scholarly journals The first reported ceratopsid dinosaur from eastern North America (Owl Creek Formation, Late Cretaceous, Mississippi, USA)

2017 ◽  
Author(s):  
Andrew A. Farke ◽  
George E. Phillips
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Depositional Environment ◽  
Eastern North America ◽  
Western North America ◽  
Western Interior Seaway ◽  
Double Root ◽  
Union County ◽  
Dentary Tooth

Ceratopsids (“horned dinosaurs”) are known from numerous specimens in western North America and Asia, a distribution reflecting the inferred subaerial link between the two landmasses during the Late Cretaceous. However, this clade was previously unknown from eastern North America, presumably due to limited outcrop of the appropriate age and depositional environment as well as the separation of eastern and western North America by the Western Interior Seaway during much of the Late Cretaceous. A dentary tooth from the Owl Creek Formation (late Maastrichtian) of Union County, Mississippi, represents the first reported occurrence of Ceratopsidae from eastern North America. This tooth shows a combination of features typical of Ceratopsidae, including a double root and a prominent, blade-like carina. Based on the age of the fossil, we hypothesize that it is consistent with a dispersal of ceratopsids into eastern North America during the very latest Cretaceous, after the two halves of North America were reunited following the retreat of the Western Interior Seaway.

scholarly journals The first reported ceratopsid dinosaur from eastern North America (Owl Creek Formation, Upper Cretaceous, Mississippi, USA)

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3342 ◽  
Author(s):  
Andrew A. Farke ◽  
George E. Phillips
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Depositional Environment ◽  
Upper Cretaceous ◽  
Eastern North America ◽  
Western North America ◽  
Western Interior Seaway ◽  
Double Root ◽  
Union County ◽  
Dentary Tooth

Ceratopsids (“horned dinosaurs”) are known from western North America and Asia, a distribution reflecting an inferred subaerial link between the two landmasses during the Late Cretaceous. However, this clade was previously unknown from eastern North America, presumably due to limited outcrop of the appropriate age and depositional environment as well as the separation of eastern and western North America by the Western Interior Seaway during much of the Late Cretaceous. A dentary tooth from the Owl Creek Formation (late Maastrichtian) of Union County, Mississippi, represents the first reported occurrence of Ceratopsidae from eastern North America. This tooth shows a combination of features typical of Ceratopsidae, including a double root and a prominent, blade-like carina. Based on the age of the fossil, we hypothesize that it is consistent with a dispersal of ceratopsids into eastern North America during the very latest Cretaceous, presumably after the two halves of North America were reunited following the retreat of the Western Interior Seaway.

FAUNAL RELATIONSHIPS BETWEEN EASTERN NORTH AMERICA AND EUROPE AS SHOWN BY INSECTS

1988 ◽  
Vol 120 (S144) ◽  
pp. 39-53 ◽  
Author(s):  
Gerald R. Noonan
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
North Atlantic ◽  
North American ◽  
Eastern North America ◽  
Western North America ◽  
The North ◽  
The North Atlantic ◽  
Fossil Data ◽  
Suitable Land

AbstractThe supercontinent of Pangaea, which once included most lands, fragmented during the Mesozoic. By the Late Cretaceous there were two northern land masses that were strikingly different from those of present day: Asiamerica consisting of present western North America and Asia; and Euramerica comprising Europe and eastern North America. Mild climates facilitated the spread of terrestrial organisms within each of these land masses, but epicontinental seas hindered movements between Europe and Asia and between eastern and western North America.The insects of Euramerica presumably once formed a fauna extending from eastern North America to Europe that differed from the fauna of Asiamerica. The opening of the North Atlantic separated insects in Europe from those in eastern North America. This produced vicarious patterns, with some insects of eastern North America now being more closely related phylogenetically to those of Europe than to those of western North America. Most groups of insects have not been examined for such trans-Atlantic vicariances, but studies reviewed in this paper suggest such relationships for some groups of Collembola, Hemiptera, Homoptera, Coleoptera, Diptera, and Hymenoptera.The last suitable land connections between Europe and eastern North America were severed approximately 20–35 million years ago. The insects separated by this severance evolved at different rates. Some groups split in this way have apparently undergone little evolution and have the same species on both sides of the North Atlantic, but other vicarious groups have differentiated into taxa that are now distinct at specific and supra-specific levels.The opening of the North Atlantic probably split both tropical- and temperate-adapted insects in Euramerica. However, without fossil data it is difficult to identify the biogeographical patterns resulting from such splitting of the tropical-adapted groups. Most presently recognized European and eastern North American vicarious patterns of insects were probably caused by division of Euramerica rather than dispersal across Beringia.

scholarly journals The first reported ceratopsid dinosaur from eastern North America (Owl Creek Formation, Upper Cretaceous, Mississippi, USA)

2017 ◽  
Author(s):  
Andrew A. Farke ◽  
George E. Phillips
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Depositional Environment ◽  
Upper Cretaceous ◽  
Eastern North America ◽  
Western North America ◽  
Western Interior Seaway ◽  
Double Root ◽  
Union County ◽  
Dentary Tooth

Ceratopsids (“horned dinosaurs”) are known from western North America and Asia, a distribution reflecting an inferred subaerial link between the two landmasses during the Late Cretaceous. However, this clade was previously unknown from eastern North America, presumably due to limited outcrop of the appropriate age and depositional environment as well as the separation of eastern and western North America by the Western Interior Seaway during much of the Late Cretaceous. A dentary tooth from the Owl Creek Formation (late Maastrichtian) of Union County, Mississippi, represents the first reported occurrence of Ceratopsidae from eastern North America. This tooth shows a combination of features typical of Ceratopsidae, including a double root and a prominent, blade-like carina. Based on the age of the fossil, we hypothesize that it is consistent with a dispersal of ceratopsids into eastern North America during the very latest Cretaceous, presumably after the two halves of North America were reunited following the retreat of the Western Interior Seaway.

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.

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.

Sign in / Sign up

Export Citation Format

Share Document