scholarly journals A new non-mammalian eucynodont from the Chinle Formation (Triassic: Norian), and implications for the early Mesozoic equatorial cynodont record

2020 ◽  
Vol 16 (11) ◽  
pp. 20200631 ◽  
Author(s):  
Ben T. Kligman ◽  
Adam D. Marsh ◽  
Hans-Dieter Sues ◽  
Christian A. Sidor
Keyword(s):  
North Carolina ◽  
North America ◽  
Fossil Record ◽  
Upper Triassic ◽  
American Southwest ◽  
Biogeographic Pattern ◽  
Early Mesozoic ◽  
Chinle Formation ◽  
Sampling Biases ◽  
Shed Light

The Upper Triassic tetrapod fossil record of North America features a pronounced discrepancy between the assemblages of present-day Virginia and North Carolina relative to those of the American Southwest. While both are typified by large-bodied archosaurian reptiles like phytosaurs and aetosaurs, the latter notably lacks substantial representation of mammal relatives, including cynodonts. Recently collected non-mammalian eucynodontian jaws from the middle Norian Blue Mesa Member of the Chinle Formation in northeastern Arizona shed light on the Triassic cynodont record from western equatorial Pangaea. Importantly, they reveal new biogeographic connections to eastern equatorial Pangaea as well as southern portions of the supercontinent. This discovery indicates that the faunal dissimilarity previously recognized between the western and eastern portions of equatorial Pangaea is overstated and possibly reflects longstanding sampling biases, rather than a true biogeographic pattern.

Paleomagnetism of the Triassic Nikolai Greenstone, McCarthy Quadrangle, Alaska

1977 ◽  
Vol 14 (11) ◽  
pp. 2578-2592 ◽  
Author(s):  
J. W. Hillhouse
Keyword(s):  
British Columbia ◽  
High Temperature ◽  
North America ◽  
Vertical Axis ◽  
Upper Triassic ◽  
Present Position ◽  
Stable Component ◽  
South Central ◽  
Early Mesozoic ◽  
Lamellar Texture

Paleomagnetic evidence indicates that the extensive early Mesozoic basalt field near McCarthy, south-central Alaska, originated far south of its present position relative to North America. Results obtained from the Middle and (or) Upper Triassic Nikolai Greenstone suggest that those basalts originated within 15° of the paleoequator. This position is at least 27° (3000 km) south of the Upper Triassic latitude predicted for McCarthy on the basis of paleomagnetic data from continental North America. The Nikolai pole, as determined from 50 flows sampled at 5 sites, is at 2.2° N, 146.1° E (α95 = 4.8°). The polarity of the pole is ambiguous, because the corresponding magnetic direction has a low inclination and a westerly declination. Therefore, the Nikolai may have originated near 15° N latitude or, alternatively, as far south as 15° S latitude. In addition to being displaced northward, the Nikolai block has been rotated roughly 90° about the vertical axis. A measure of the reliability of this pole is provided by favorable results from the following tests: (1) Within one stratigraphic section, normal and reversed directions from consecutive flows are antipolar. (2) Consistent directions were obtained from sites 30 km apart. (3) Application of the fold test indicated the magnetization was acquired before the rocks were folded. (4) The magnetizations of several pilot specimens are thermally stable up to 550 °C. The stable component is probably carried by magnetite with lamellar texture, a primary feature commonly acquired by a basalt at high temperature during initial cooling of the magma. Geologic and paleomagnetic evidence indicates that the Nikolai is allochthonous to Alaska and that, together with associated formations in southern Alaska and British Columbia, it is part of a now disrupted equatorial terrane.

scholarly journals A thin-shelled reptile from the Late Triassic of North America and the origin of the turtle shell

2008 ◽  
Vol 276 (1656) ◽  
pp. 507-513 ◽  
Author(s):  
Walter G Joyce ◽  
Spencer G Lucas ◽  
Torsten M Scheyer ◽  
Andrew B Heckert ◽  
Adrian P Hunt
Keyword(s):  
New Mexico ◽  
North America ◽  
Fossil Record ◽  
De Novo ◽  
Upper Triassic ◽  
Late Triassic ◽  
Terrestrial Habitat ◽  
Turtle Shell ◽  
Shell Elements ◽  
Stem Lineage

A new, thin-shelled fossil from the Upper Triassic (Revueltian: Norian) Chinle Group of New Mexico, Chinlechelys tenertesta , is one of the most primitive known unambiguous members of the turtle stem lineage. The thin-shelled nature of the new turtle combined with its likely terrestrial habitat preference hint at taphonomic filters that basal turtles had to overcome before entering the fossil record. Chinlechelys tenertesta possesses neck spines formed by multiple osteoderms, indicating that the earliest known turtles were covered with rows of dermal armour. More importantly, the primitive, vertically oriented dorsal ribs of the new turtle are only poorly associated with the overlying costal bones, indicating that these two structures are independent ossifications in basal turtles. These novel observations lend support to the hypothesis that the turtle shell was originally a complex composite in which dermal armour fused with the endoskeletal ribs and vertebrae of an ancestral lineage instead of forming de novo. The critical shell elements (i.e. costals and neurals) are thus not simple outgrowths of the bone of the endoskeletal elements as has been hypothesized from some embryological observations.

scholarly journals The oldest vertebrate trace fossils from Comb Ridge (Bears Ears Region, southeastern Utah)

2017 ◽  
Author(s):  
Robert J Gay ◽  
Xavier A Jenkins ◽  
Taormina Lepore
Keyword(s):  
Trace Fossils ◽  
Upper Triassic ◽  
River Channel ◽  
American Southwest ◽  
Chinle Formation ◽  
Western Colorado ◽  
The Us ◽  
Indian Creek ◽  
Body Fossil ◽  
The Church

Vertebrate trace fossils are common in Upper Triassic deposits across the American southwest. These ichnofauna are dominated by Grallator, Brachychirotherium, and Pseudotetrasauropus, and lack ichnotaxa traditionally considered to be Early Jurassic in age, such as Eubrontes and Anomoepus. While known from Indian Creek and Lisbon Valley, Utah, vertebrate trace fossils have not been previously reported from Comb Ridge, Utah. This is significant considering that lithostratigraphic work has been ongoing at Comb Ridge since the 1990s in the elsewhere fossiliferous ‘Big Indian Rock Beds’, in the US Highway 163 roadcut that transects Comb Ridge. 2016 fieldwork by the Museums of Western Colorado: Dinosaur Journey recovered two sandstone slabs that had been dislodged from a river channel sand in the Church Rock Member of the Chinle Formation. The slabs preserve the first documented Triassic vertebrate trace fossils from Comb Ridge: a single pes impression of the ichnogenus Grallator, and several manus and at least one pes impression of a small archosaur. We tentatively refer this second track set to the ichnogenus Brachychirotherium. Taken together, these specimens provide evidence for a more diverse vertebrate fauna in the Church Rock Member of the Chinle Formation at Comb Ridge than indicated by the current body fossil record.

scholarly journals The oldest vertebrate trace fossils from Comb Ridge (Bears Ears Region, southeastern Utah)

2017 ◽  
Author(s):  
Robert J Gay ◽  
Xavier A Jenkins ◽  
Taormina Lepore
Keyword(s):  
Trace Fossils ◽  
Upper Triassic ◽  
River Channel ◽  
American Southwest ◽  
Chinle Formation ◽  
Western Colorado ◽  
The Us ◽  
Indian Creek ◽  
Body Fossil ◽  
The Church

Vertebrate trace fossils are common in Upper Triassic deposits across the American southwest. These ichnofauna are dominated by Grallator, Brachychirotherium, and Pseudotetrasauropus, and lack ichnotaxa traditionally considered to be Early Jurassic in age, such as Eubrontes and Anomoepus. While known from Indian Creek and Lisbon Valley, Utah, vertebrate trace fossils have not been previously reported from Comb Ridge, Utah. This is significant considering that lithostratigraphic work has been ongoing at Comb Ridge since the 1990s in the elsewhere fossiliferous ‘Big Indian Rock Beds’, in the US Highway 163 roadcut that transects Comb Ridge. 2016 fieldwork by the Museums of Western Colorado: Dinosaur Journey recovered two sandstone slabs that had been dislodged from a river channel sand in the Church Rock Member of the Chinle Formation. The slabs preserve the first documented Triassic vertebrate trace fossils from Comb Ridge: a single pes impression of the ichnogenus Grallator, and several manus and at least one pes impression of a small archosaur. We tentatively refer this second track set to the ichnogenus Brachychirotherium. Taken together, these specimens provide evidence for a more diverse vertebrate fauna in the Church Rock Member of the Chinle Formation at Comb Ridge than indicated by the current body fossil record.

scholarly journals A new species ofCoahomasuchus(Archosauria, Aetosauria) from the Upper Triassic Pekin Formation, Deep River Basin, North Carolina

2016 ◽  
Vol 91 (1) ◽  
pp. 162-178 ◽  
Author(s):  
Andrew B. Heckert ◽  
Nicholas C. Fraser ◽  
Vincent P. Schneider
Keyword(s):  
North Carolina ◽  
New Species ◽  
North America ◽  
Upper Triassic ◽  
The Other ◽  
Anterior Portion ◽  
City Formation ◽  
The North ◽  
A New Species ◽  
Rare Instance

AbstractWe describe a new species of the aetosaurCoahomasuchus,C.chathamensis, based on an incomplete, but largely articulated, anterior portion of a skeleton recovered from a quarry in the Upper Triassic Pekin Formation of Chatham County, North Carolina. This is only the second documented occurrence ofCoahomasuchus, with the other being the holotype ofC.kahleorumHeckert and Lucas, 1999 from the Upper Triassic Colorado City Formation of Texas. Although much of the specimen is the same size as the holotype ofC.kahleorum, the dorsal paramedian osteoderms of the North Carolina taxon are considerably (~1.3×) wider than homologous counterparts inC.kahleorum, and the ventral thoracic osteoderms are also rectangular (~1.5× wider than long), rather than square, presumably to accommodate the wider body. This is a rare instance where two articulated specimens of closely related aetosaur species are available for direct comparison of homologous osteoderms. Isolated osteoderms with similar ornamentation from the same locality indicate thatC.chathamensismay have been one of the earliest aetosaurs to attain the broad osteoderm proportions (width:length >3.5:1) otherwise known solely from later branching, spinose taxa such asTypothorax. The co-occurrence ofLucasuchusandCoahomasuchusin both North Carolina and Texas supports past correlations indicating an Otischalkian (Carnian) age for these strata and demonstrates that plesiomorphic, non-spinose aetosaur genera were not necessarily endemic to a single basin in North America.

The earliest Elcanidae (Insecta, Orthoptera) from the Upper Triassic of North America

2018 ◽  
Vol 92 (6) ◽  
pp. 1028-1034 ◽  
Author(s):  
Yan Fang ◽  
A.D. Muscente ◽  
Sam W. Heads ◽  
Bo Wang ◽  
Shuhai Xiao
Keyword(s):  
North Carolina ◽  
North America ◽  
Posterior Margin ◽  
New Genus ◽  
Upper Triassic ◽  
New Genus And Species ◽  
X Ray ◽  
The North ◽  
The Family ◽  
Branch Formation

AbstractA new genus and species of the Elcanidae (Orthoptera, Elcanoidea), Cascadelcana virginiana n. gen. n. sp., is described based on a forewing specimen from the Upper Triassic (Norian) Cow Branch Formation in the Solite Quarry Lagerstätte near the North Carolina-Virginia boundary, USA. It is distinguished from other elcanid species by its RP+MA1 with six branches, M with two branches before stem MA1 fused with RP, and short CuA almost vertical against the posterior margin. This fossil represents the earliest definitive record of the family Elcanidae and the first orthopteran described from the Triassic of North America. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analyses show that the veins and a pterostigma-like structure on the wing of C. virginiana n. gen. n. sp. are preserved as carbonaceous compressions. The presence of a pterostigma-like structure in elcanids indicates that they may have evolved a particular flight mechanism distinct from those of other orthopterans.UUID: http://zoobank.org/49526c99-5da4-48e3-ba6e-7018b8f9b1ae

scholarly journals A new spider crab (Brachyura, Epialtidae) from the Castle Hayne Limestone Formation (Eocene), North Carolina, USA

2021 ◽  
Vol 73 (3) ◽  
pp. A261220
Author(s):  
Alessandro Garassino ◽  
Giovanni Pasini ◽  
Don Clements
Keyword(s):  
North Carolina ◽  
New Species ◽  
North America ◽  
South America ◽  
Fossil Record ◽  
Spider Crab ◽  
First Report

A new spider crab, Eoinachoides bretoni n. sp. (Epialtidae MacLeay, 1838) from the Comfort Member of the Castle Hayne Formation (Eocene) of Onslow County, North Carolina (USA), is herein described, representing the second spider crab recovered from this member. Although the new species does not enlarge the stratigraphical range for the genus which is currently restricted from the Eocene to Miocene, it is the first report in North America, extending the palaeogeographic distribution of Eoinachoides, limited currently in the fossil record of South America. In addition, an updated list of the species of the Castle Hayne Formation is herein provided.

scholarly journals The oldest vertebrate trace fossils from Comb Ridge (Bears Ears Region, southeastern Utah)

2016 ◽  
Author(s):  
Robert J Gay ◽  
Xavier A Jenkins ◽  
Taormina Lepore
Keyword(s):  
Trace Fossils ◽  
Upper Triassic ◽  
River Channel ◽  
American Southwest ◽  
The Body ◽  
Chinle Formation ◽  
Western Colorado ◽  
The Us ◽  
Body Fossil ◽  
The Church

Vertebrate trace fossils are common in Upper Triassic deposits across the American southwest. These ichnofauna are dominated by Grallator, Brachycheirotherium, and Pseudotetrasauropus and lack ichnotaxa traditionally considered to be Early Jurassic in age, such as Eubrontes and Anomoepus. While known from Indian Creek and Lisbon Valley, vertebrate trace fossils have not been previously reported from Comb Ridge. This is despite lithostratigraphic work having been conducted at the elsewhere-fossiliferous “Big Indian Rock Beds” at the US Highway 163 roadcut since the 1990s. 2016 fieldwork by the Museums of Western Colorado: Dinosaur Journey recovered two sandstone slabs that had been dislodged from a river channel sand in the Church Rock Member of the Chinle Formation. The slabs preserve the first documented vertebrate trace fossils from Comb Ridge: a single pes impression of the ichnogenus Grallator, and several manus and at least one pes impression of a small archosaur. We tentatively refer this second track set to the ichnogenus Brachychierotherium. Taken together, these specimens provide evidence for a more diverse vertebrate fauna in the Church Rock Member of the Chinle Formation at Comb Ridge than indicated by the body fossil record.

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