Provenance of Upper Triassic strata in southwestern North America as suggested by isotopic analysis and chemistry of zircon crystals

2012 ◽  
Author(s):  
Nancy R. Riggs ◽  
Andrew P. Barth ◽  
Carlos M. González-León ◽  
Carl E. Jacobson ◽  
Joseph L. Wooden ◽  
...  
Keyword(s):  
North America ◽  
Isotopic Analysis ◽  
Upper Triassic

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.

An ichthyosaur forefin from the Triassic of British Columbia exemplifying Jurassic features

1991 ◽  
Vol 28 (10) ◽  
pp. 1553-1560 ◽  
Author(s):  
C. McGowan
Keyword(s):  
British Columbia ◽  
North America ◽  
Lower Jurassic ◽  
Upper Triassic ◽  
New Material ◽  
Important Site

New ichthyosaur material is reported from an Upper Triassic locality on Williston Lake, northeastern British Columbia. The paucity of ichthyosaurs from the Triassic of North America make this a potentially important site. An isolated forefin is described, which is unlike that of any Triassic species from North America but which compares closely with certain Lower Jurassic species from England and Germany. The new material suggests that the transition in the ichthyosaurian fauna at the close of the Triassic may have been less abrupt than was previously supposed.

Taxonomic affinities and paleogeography of Stromatomorpha californica Smith, a distinctive Upper Triassic reef-adapted demosponge

2009 ◽  
Vol 83 (5) ◽  
pp. 783-793 ◽  
Author(s):  
B. Senowbari-Daryan ◽  
G. D. Stanley
Keyword(s):  
North America ◽  
Shallow Water ◽  
Type Species ◽  
Upper Triassic ◽  
Northern Calcareous Alps ◽  
Late Triassic ◽  
Separate Species ◽  
Northern Calcareous ◽  
Siliceous Spicules ◽  
Horizontal Layers

Stromatomorpha californica Smith is a massive, calcified, tropical to subtropical organism of the Late Triassic that produced small biostromes and contributed in building some reefs. It comes from the displaced terranes of Cordilleran North America (Eastern Klamath terrane, Alexander terrane, and Wrangellia). This shallow-water organism formed small laminar masses and sometimes patch reefs. It was first referred to the order Spongiomorphidae but was considered to be a coral. Other affinities that have been proposed include hydrozoan, stomatoporoid, sclerosponge, and chambered sponge. Part of the problem was diagenesis that resulted in dissolution of the siliceous spicules and/or replaced them with calcite. Well-preserved dendroclone spicules found during study of newly discovered specimens necessitate an assignment of Stromatomorpha californica to the demosponge order Orchocladina Rauff. Restudy of examples from the Northern Calcareous Alps extends the distribution of this species to the Tethys, where it was an important secondary framework builder in Upper Triassic (Norian-Rhaetian) reef complexes. Revisions of Stromatomorpha californica produce much wider pantropical distribution, mirroring paleogeographic patterns revealed for other tropical Triassic taxa. Review of Liassic material from the Jurassic of Morocco, previously assigned to Stromatomorpha californica Smith var. columnaris Le Maitre, cannot be sustained. Species previously included in Stromatomorpha are: S. stylifera Frech (type species, Rhaetian), S. actinostromoides Boiko (Norian), S. californica Smith (Norian), S. concescui Balters (Ladinian-Carnian), S. pamirica Boiko (Norian), S. rhaetica Kühn (Rhaetian), S. stromatoporoides Frech, and S. tenuiramosa Boiko (Norian). Stromatomorpha rhaetica Kühn described from the Rhaetian of Vorarlberg, Austria shows no major difference from S. californica. An example described as S. oncescui Balters from the Ladinian-Carnian of the Rarau Mountains, Romania, is very similar to S. californica in exhibiting similar spicule types. However, because of the greater distance between individual pillars, horizontal layers, and the older age, S. oncescui is retained as a separate species. The net-like and regular skeleton of Spongiomorpha sanpozanensis Yabe and Sugiyama, from the Upper Triassic of Sambosan (Tosa, Japan), suggests a closer alliance with Stromatomorpha, and this taxon possibly could be the same as S. californica.

Discovery of Upper Ladinian ammonoids at the type locality of the Lower Carnian Desatoyense Zone (South Canyon, New Pass Range, Nevada)

2008 ◽  
Vol 82 (1) ◽  
pp. 176-182 ◽  
Author(s):  
Marco Balini
Keyword(s):  
North America ◽  
Marine Invertebrates ◽  
Upper Triassic ◽  
Type Locality

South Canyon, located in the New Pass Range in central Nevada (Fig. 1), is one of the most important localities for Upper Triassic marine invertebrates in North America. This site yields very rich ammonoid faunas, as well as cnidarians (Muller, 1936; Stanley, 1979; Roniewicz and Stanley, 1998), foraminifers (Gazdzicki and Stanley, 1983), bivalves (Waller and Stanley, 1998, 2005; Hopkin and McRoberts, 2003), and brachiopods.

scholarly journals First record of Mesozoic terrestrial vertebrates from Lithuania: phytosaurs (Diapsida: Archosauriformes) of probable Late Triassic age, with a review of phytosaur biogeography

2012 ◽  
Vol 150 (1) ◽  
pp. 110-122 ◽  
Author(s):  
STEPHEN L. BRUSATTE ◽  
RICHARD J. BUTLER ◽  
GRZEGORZ NIEDŹWIEDZKI ◽  
TOMASZ SULEJ ◽  
ROBERT BRONOWICZ ◽  
...  
Keyword(s):  
North America ◽  
Arid Regions ◽  
First Record ◽  
Upper Triassic ◽  
Late Triassic ◽  
Early Triassic ◽  
Baltic Region ◽  
Terrestrial Vertebrates ◽  
Terrestrial Vertebrate

AbstractFossils of Mesozoic terrestrial vertebrates from Lithuania and the wider East Baltic region of Europe have previously been unknown. We here report the first Mesozoic terrestrial vertebrate fossils from Lithuania: two premaxillary specimens and three teeth that belong to Phytosauria, a common clade of semiaquatic Triassic archosauriforms. These specimens represent an uncrested phytosaur, similar to several species within the generaPaleorhinus,Parasuchus,RutiodonandNicrosaurus. Because phytosaurs are currently only known from the Upper Triassic, their discovery in northwestern Lithuania (the Šaltiškiai clay-pit) suggests that at least part of the Triassic succession in this region is Late Triassic in age, and is not solely Early Triassic as has been previously considered. The new specimens are among the most northerly occurrences of phytosaurs in the Late Triassic, as Lithuania was approximately 7–10° further north than classic phytosaur-bearing localities in nearby Germany and Poland, and as much as 40° further north than the best-sampled phytosaur localities in North America. The far northerly occurrence of the Lithuanian fossils prompts a review of phytosaur biogeography and distribution, which suggests that these predators were widely distributed in the Triassic monsoonal belt but rarer in more arid regions.

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.

Upper Triassic Invertebrates from the Antimonio Formation, Sonora, Mexico

1994 ◽  
Vol 68 (S36) ◽  
pp. 1-33 ◽  
Author(s):  
George D. Stanley ◽  
Carlos González-León ◽  
Michael R. Sandy ◽  
Baba Senowbari-Daryan ◽  
Peter Doyle ◽  
...  
Keyword(s):  
North America ◽  
North American ◽  
Weak Link ◽  
Upper Triassic ◽  
Marine Fauna ◽  
Western Tethys ◽  
The North ◽  
Tethys Realm ◽  
First Occurrence ◽  
North American Craton

A diverse Upper Triassic tropical marine fauna from northwestern Sonora, Mexico, includes 31 taxa of tropical invertebrates including scleractinian corals, spongiomorphs, disjectoporoids, “hydrozoans,” thalamid and nonthalamid sponges, spiriferid and terebratulid brachiopods, gastropods, bivalves, coleoids, and anomuran microcoprolites. They occur within the late Karnian to Norian part of the Antimonio Formation (Antimonio terrane), which is juxtaposed against a fragmented portion of the North American craton. Most of the fauna is also known from the Tethys region. Sixteen Sonoran taxa co-occur in the western Tethys and five have never been known outside this region. Four additional taxa (one identified only at genus level) are geographically widespread. Some taxa occur in displaced terranes of North America, especially in west-central Nevada (Luning Formation). A weak link exists with the California Eastern Klamath terrane but stronger ties exist with Peru. Among Sonoran sponges,Nevadathalamia polystomawas previously recognized only from the Luning Formation, western Nevada. SpongesCinnabaria expansa, Nevadathalamia cylindrica, and a coral,Astraeomorpha sonorensisn. sp., are also known from Nevada. The coralsDistichomeandra austriaca, Chondrocoenia waltheri, Pamiroseris rectilamellosa, andAlpinophyllia flexuosaco-occur in central Europe. Two new taxa, a spongiomorph hydrozoan,Stromatoporidium lamellatumn. sp., and a disjectoporoid,Pamiropora sonorensisn. sp., have distinct affinities with the Tethys. The geographically widespread North American brachiopod,Spondylospira lewesensis, andPseudorhaetina antimoniensisn. gen. and sp. are among the Sonoran fauna. The Sonoran coleoid (aulacocerid)Dictyoconites(Dictyoconites) cf.D. reticulatumoccurs in the Tethys realm andCalliconitescf.C. drakeiis comparable with a species from the Eastern Klamath terrane.Calliconites millerin. sp. is the first occurrence of the genus outside Sicily. The bivalvesMyophorigonia jaworskii, M. salasi, andPalaeocardita peruvianaare known from Sonora and Peru. Eight gastropod taxa includeGuidoniacf.G. intermediaandG.cf.G. parvula, both previously known from Peru, andEucycloscala subbisertusfrom the western Tethys. The gastropods are unlike those already known from other North American terranes.

scholarly journals Giant alatoform bivalves in the Upper Triassic of western North America

Palaeontology ◽  
1999 ◽  
Vol 42 (1) ◽  
pp. 1-23 ◽  
Author(s):  
T. E. Yancey ◽  
G. D. Stanley, Jr
Keyword(s):  
North America ◽  
Upper Triassic ◽  
Western North America

Triassic notostracans in the Newark Supergroup, Culpeper Basin, northern Virginia

1986 ◽  
Vol 60 (5) ◽  
pp. 1086-1096 ◽  
Author(s):  
Pamela J. W. Gore ◽  
Alfred Traverse
Keyword(s):  
North America ◽  
Shallow Water ◽  
Upper Triassic ◽  
Anal Plate ◽  
Fish Scales ◽  
Newark Supergroup ◽  
Caudal Rami

Fossilized notostracan carapaces and abdominal fragments are present in the Upper Triassic (Rhaetian) Bull Run Formation in the Culpeper Basin near Manassas, Virginia. Over 250 notostracan carapaces and carapace fragments and three abdominal fragments with attached caudal rami were collected from light olive-gray, grayish-red, and brownish-gray shales in three on-strike localities. Carapace and abdomen are attached in one specimen. The Culpeper Basin notostracans have a rudimentary supra-anal plate and are identified as Triops cf. cancriformis. Their carapaces are indistinguishable from those of modern forms.Relatively few notostracan fossils are known and none have been reported previously from the Triassic of North America. Triassic notostracans, however, have been reported from Europe and Africa. Fossil notostracans have been reported from North America only once previously, from the Permian of Oklahoma.The notostracans are associated with conchostracans (Cyzicus sp.), ostracodes (Darwinula sp.), fish scales, insects, plant fragments, and stromatolites.The notostracan-bearing beds are present at the top of a transgressive-regressive sequence, indicating that the notostracans inhabited shallow water near the edge of a perennial lake. Palynology indicates that these beds are most likely mid- to late-Rhaetian in age.

Sign in / Sign up

Export Citation Format

Share Document