scholarly journals Non-dinosaurian dinosauromorphs from the Chinle Formation (Upper Triassic) of the Eagle Basin, northern Colorado: Dromomeron romeri (Lagerpetidae) and a new taxon, Kwanasaurus williamparkeri (Silesauridae)

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7551 ◽  
Author(s):  
Jeffrey W. Martz ◽  
Bryan J. Small
Keyword(s):  
Articular Surface ◽  
Upper Triassic ◽  
Late Triassic ◽  
New Taxon ◽  
Dietary Specialization ◽  
Sister Clade ◽  
Chinle Formation ◽  
Northern Colorado ◽  
Land Vertebrate ◽  
Early Late

The “red siltstone” member of the Upper Triassic Chinle Formation in the Eagle Basin of Colorado contains a diverse assemblage of dinosauromorphs falling outside of Dinosauria. This assemblage is the northernmost known occurrence of non-dinosaurian dinosauromorphs in North America, and probably falls within the Revueltian land vertebrate estimated biochronozone (215–207 Ma, middle to late Norian). Lagerpetids are represented by proximal femora and a humerus referable to Dromomeron romeri. Silesaurids (non-dinosaurian dinosauriforms) are the most commonly recovered dinosauromorph elements, consisting of dentaries, maxillae, isolated teeth, humeri, illia, femora, and possibly a scapula and tibiae. These elements represent a new silesaurid, Kwanasaurus williamparkeri, gen. et sp. nov., which possesses several autapomorphies: a short, very robust maxilla with a broad ascending process, a massive ventromedial process, a complex articular surface for the lacrimal and jugal, and 12 teeth; 14 dentary teeth; an ilium with an elongate and blade-like preacetabular process and concave acetabular margin; a femur with an extremely thin medial distal condyle and a depression on the distal end anterior to the crista tibiofibularis. The recognition of K. williamparkeri further demonstrates the predominantly Late Triassic diversity and widespread geographic distribution across Pangea of the sister clade to Asilisaurus, here named Sulcimentisauria. Silesaurid dentition suggests a variety of dietary specializations from faunivory and omnivory in the Middle Triassic and early Late Triassic (Carnian), to herbivory in the Late Triassic (Carnian and Norian), with the latter specialization possibly coinciding with the radiation of Sulcimentisauria across Pangea. The extremely robust maxilla and folidont teeth of K. williamparkei may represent a strong herbivorous dietary specialization among silesaurids.

scholarly journals An enigmatic Arthropoda from the Upper Triassic (Carnian) southwestern Gondwana (Argentina)

2019 ◽  
Vol 94 (2) ◽  
pp. 279-290 ◽  
Author(s):  
María B. Lara ◽  
Bárbara Cariglino ◽  
Ana M. Zavattieri ◽  
Iracema Zacarías
Keyword(s):  
New Genus ◽  
Upper Triassic ◽  
Late Triassic ◽  
New Taxon ◽  
Delta Plain ◽  
Ecological Implications ◽  
Fish Remains ◽  
Potrerillos Formation ◽  
Warm Temperate ◽  
Early Late

AbstractThe presence of a new taxon, Duraznovis gallegoi new genus new species is reported and described from an early Late Triassic (Carnian) deposit in Argentina. Two specimens, recovered from the Quebrada del Durazno locality, uppermost levels of the Potrerillos Formation, Cuyana Basin (Mendoza), are represented by the molds of their shield and imprints of soft parts. The identity of these specimens appears enigmatic but closely resembles in the possession of a generalized arthropod morphology and a distinctive combination of characters, to living and fossil representatives of xiphosurans (Chelicerata) and notostracans (Branchiopoda). The new fossils are associated with a rich biota comprising abundant insects, spinicaudatans, plants, and scarce fish remains living in semipermanent swamps and/or ponds within a delta plain environment with intermittent episodes of flooding, in a warm temperate and humid megamonsoonal climate during Triassic times. In this context, we analyze the taphonomic and ecological implications of their presence. Lastly, these unique specimens at the Quebrada del Durazno locality adds to the diversity of the biota, revealing the importance of this site as an exceptional paleontological Triassic deposit.UUID: http://zoobank.org/8d1194c2-170c-4b7a-b0c6-5c08b0974d95

The Late Triassic (Norian) Adamanian–Revueltian tetrapod faunal transition in the Chinle Formation of Petrified Forest National Park, Arizona

2010 ◽  
Vol 101 (3-4) ◽  
pp. 231-260 ◽  
Author(s):  
William G. Parker ◽  
Jeffrey W. Martz
Keyword(s):  
National Park ◽  
Upper Triassic ◽  
Late Triassic ◽  
Western North America ◽  
Faunal Turnover ◽  
Chinle Formation ◽  
Petrified Forest National Park ◽  
Land Vertebrate ◽  
Age Constraints ◽  
Petrified Forest

ABSTRACTRecent stratigraphic revisions of the Upper Triassic Chinle Formation of Petrified Forest National Park, in conjunction with precise and accurate documentation of fossil tetrapod occurrences, clarified the local biostratigraphy, with regional and global implications. A significant overlap between Adamanian and Revueltian faunas is rejected, as is the validity of the Lamyan sub-land vertebrate faunachron. The Adamanian–Revueltian boundary can be precisely placed within the lower Jim Camp Wash beds of the Sonsela Member and thus does not occur at the hypothesised Tr-4 unconformity. This mid-Norian faunal turnover, may coincide with a floral turnover, based on palynology studies and also on sedimentological evidence of increasing aridity. Available age constraints bracketing the turnover horizon are consistent with the age of the Manicouagan impact event. The rise of dinosaurs in western North America did not correspond to the Adamanian–Revueltian transition, and overall dinosauromorph diversity seems to have remained at a constant level across it. The paucity of detailed Late Triassic vertebrate biostratigraphic data and radioisotopic dates makes it currently impossible to either support or reject the existence of globally synchronous Late Triassic extinctions for tetrapods.

Ichthyosaurs from the Upper Triassic (Carnian–Norian) of the New Siberian Islands, Russian Arctic, and their implications for the evolution of the ichthyosaurian basicranium and vertebral column

2021 ◽  
pp. 1-24
Author(s):  
Nikolay G. ZVERKOV ◽  
Dmitry V. GRIGORIEV ◽  
Andrzej S. WOLNIEWICZ ◽  
Alexey G. KONSTANTINOV ◽  
Evgeny S. SOBOLEV
Keyword(s):  
Vertebral Column ◽  
Cervical Vertebrae ◽  
Upper Triassic ◽  
Late Triassic ◽  
Phylogenetic Position ◽  
New Taxon ◽  
Russian Arctic ◽  
Micro Computed Tomography ◽  
New Siberian Islands ◽  
Group Relationships

ABSTRACT The first ichthyosaurian specimens discovered from the Upper Triassic of the Russian Arctic (Kotelny Island, New Siberian Islands) are described herein. They include the remains of large- to small-bodied ichthyosaurians originating from six stratigraphic levels spanning the lower Carnian to middle Norian. The material is mostly represented by isolated vertebrae and ribs, which are not possible to accurately diagnose, but also includes specimens comprising associated vertebrae and a fragmentary skeleton that preserves cranial remains (parabasisphenoid, fragmentary quadrate, partial mandible and hyoids). Based on vertebral and rib morphology, we identify the specimens as representatives of the following taxonomic groups: large-bodied shastasaurids, medium-sized indeterminate ichthyosaurians with a single rib facet in the presacral centra, and small euichthyosaurians with double rib facets present throughout the presacral vertebrae that likely represent toretocnemids and/or basal parvipelvians. In addition, the cranial and mandibular remains preserved in one of the specimens, ZIN PH 5/250, were studied using micro-computed tomography. Its mandible is highly similar to that of toretocnemids, whereas the parabasisphenoid demonstrates a peculiar combination of both plesiomorphic and derived character states, providing the first detailed data on this cranial element in a Late Triassic ichthyosaurian. Furthermore, the specimen also demonstrates a distinctive condition of rib articulation in the anteriormost presacral (cervical) vertebrae, which together with other features allows for the erection of a new taxon – Auroroborealia incognita gen. et sp. nov. Although the phylogenetic position of this taxon is uncertain due to its fragmentary nature, its anatomy, indicating toretocnemid or parvipelvian affinities, further supports the previously hypothesised sister-group relationships between these two clades. The morphology of the parabasisphenoid and vertebral column of the new taxon is discussed in broader contexts of the patterns of evolution of these skeletal regions in ichthyosaurs.

scholarly journals Osteology of the Late Triassic aetosaur Scutarx deltatylus (Archosauria: Pseudosuchia)

2016 ◽  
Author(s):  
William G Parker
Keyword(s):  
National Park ◽  
Vertebral Column ◽  
Upper Triassic ◽  
Late Triassic ◽  
Chinle Formation ◽  
Petrified Forest National Park ◽  
Petrified Forest

Aetosaurs are some of the most common fossils collected from the Upper Triassic Chinle Formation of Arizona, especially at the Petrified Forest National Park. Four partial skeletons collected from the park from 2002 through 2009 represent the holotype and referred specimens of Scutarx deltatylus. These specimens include much of the carapace, as well as the vertebral column, and shoulder and pelvic girldles. A partial skull represents the first aetosaur skull recovered from Arizona since the 1930s. Scutarx deltatylus can be distinguished from closely related forms Calyptosuchus wellesi and Adamanasuchus eisenhardtae not only morphologically, but also stratigraphically. Thus, Scutarx deltatylus is potentially an index taxon for the upper part of the Adamanian biozone.

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