scholarly journals Anatomical notes and discussion of the first described aetosaurStagonolepis robertsoni(Archosauria: Suchia) from the Upper Triassic of Europe, and the use of plesiomorphies in aetosaur biochronology

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5455 ◽  
Author(s):  
William G. Parker
Keyword(s):  
Upper Triassic ◽  
Late Triassic ◽  
South American ◽  
Cervical Rib ◽  
Holotype Specimen ◽  
Surface Ornamentation ◽  
North And South ◽  
Detailed Work

Stagonolepis robertsoni, from the Late Triassic of Scotland, was the first named aetosaurian. Known mostly from a series of natural molds from two localities, the osteology of this taxon has been difficult to interpret. Detailed work on this material in the late 1950s resulted in a monograph that set the standard for the understanding of aetosaurians, makingStagonolepis robertsonithe best known aetosaurian; however, little has been done with this material since. Reanalysis of this material shows that despite its limitations the early 1960s reconstruction work depicts the preserved characteristics faithfully, especially in the skull. The first cervical rib is extremely anteroposteriorly elongate as inAlligator, a character not previously recognized in aetosaurians. Diapophyseal and zygapophyseal vertebral laminae are present in the cervical and trunk vertebrae. The ilium is autapomorphic with distinct pre- and post-processes of the iliac blade. The osteoderms differ from North and South American material that has been ascribed to the genus. Those assignments are based on plesiomorphies within Aetosauria, such as a radial ornamentation and a posteriorly located and medially offset dorsal eminence. Biostratigraphic correlations using taxonomic conclusions based on plesiomorphic characters should not be used. The holotype specimen ofS. robertsoniis currently diagnostic, in part because ventral osteoderms are not known for many aetosaurian taxa and the surface ornamentation of randomly distributed, closely packed oblong pits found inS. robertsoniis unique within Aetosauria.

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

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2411 ◽  
Author(s):  
William G. Parker
Keyword(s):  
Morphological Feature ◽  
National Park ◽  
Vertebral Column ◽  
Dorsal Surface ◽  
Upper Triassic ◽  
Late Triassic ◽  
Naming Convention ◽  
Holotype Specimen ◽  
Posteromedial Corner ◽  
Chinle Formation

Aetosaurians are some of the most common fossils collected from the Upper Triassic Chinle Formation of Arizona, especially at the Petrified Forest National Park (PEFO). Aetosaurians collected from lower levels of the park includeDesmatosuchus spurensis,Paratypothorax,Adamanasuchus eisenhardtae,Calyptosuchus wellesi, andScutarx deltatylus. Four partial skeletons collected from the park between 2002 and 2009 represent the holotype and referred specimens ofScutarx deltatylus. These specimens include much of the carapace, as well as the vertebral column, and shoulder and pelvic girdles, and a new naming convention proposed for osteoderms descriptions better differentiates portions of the carapace and ventral armor. A partial skull from the holotype specimen represents the first aetosaur skull recovered and described from Arizona since the 1930s. The key morphological feature distinguishingScutarx deltatylusis the presence of a prominent, triangular boss located in the posteromedial corner of the dorsal surface of the dorsal paramedian osteoderms.Scutarx deltatyluscan be distinguished from closely related formsCalyptosuchus wellesiandAdamanasuchus eisenhardtaenot only morphologically, but also stratigraphically. Thus,Scutarx deltatylusis potentially an index taxon for the upper part of the Adamanian biozone.

Systematics and paleobiogeography of Late TriassicGryphaea(Bivalvia) from the North American Cordillera

1992 ◽  
Vol 66 (1) ◽  
pp. 28-39 ◽  
Author(s):  
Christopher A. Mcroberts
Keyword(s):  
North American ◽  
Late Triassic ◽  
South American ◽  
Long Distance ◽  
Low Latitude ◽  
North American Cordillera ◽  
The North ◽  
North American Craton ◽  
Far Eastern ◽  
North And South

Evaluation of previously undescribed collections of Late TriassicGryphaeafrom the North American Cordillera increases the temporal range and geographic distribution of the genus.Gryphaea(Gryphaea)arcuataeformisKiparisova,G.cf.G.(Gryphaea)keilhauiBöhm, and a new species,G.(Gryphaea)nevadensis, occur in lower Carnian to upper Norian strata from Alaska, British Columbia, Oregon, and Nevada. The distribution is mostly primary with respect to the Upper Triassic North American Craton, and requires long-distance larval dispersal along the latitude of far-eastern Panthalassa. Unlike most modern oysters, the distribution of these Triassic gryphaeids may have been restricted to cool and deeper water environments.An early Carnian age ofGryphaea(Gryphaea)arcuataeformisplaces this species as the oldest knownGryphaea. When combined with late Carnian and Norian occurrences from the North and South American Cordillera, these data indicate that a low-latitude origin for the genus cannot be overlooked. Gryphaeids survived the end-Triassic extinction event presumably by living in refugia.

RESOLVING SOURCE-TO-SINK DYNAMICS BY MULTI-PROXY DATA FROM THE NORTH AND SOUTH AMERICAN CONTINENTAL SEDIMENTARY ARCHIVES

2020 ◽  
Author(s):  
Barbara Carrapa ◽  
◽  
Andrea Stevens Goddard ◽  
Scott Meek ◽  
Peter G. DeCelles
Keyword(s):  
South American ◽  
Proxy Data ◽  
The North ◽  
Source To Sink ◽  
North And South

The nasal cavity of two traversodontid cynodonts (Eucynodontia, Gomphodontia) from the Upper Triassic of Brazil

2021 ◽  
pp. 1-16
Author(s):  
Arymathéia Santos Franco ◽  
Rodrigo Temp Müller ◽  
Agustín G. Martinelli ◽  
Carolina A. Hoffmann ◽  
Leonardo Kerber
Keyword(s):  
Nasal Cavity ◽  
Fossil Record ◽  
Nasal Septum ◽  
Internal Surface ◽  
Nasolacrimal Duct ◽  
Upper Triassic ◽  
Late Triassic ◽  
Southern Brazil ◽  
Dorsal Region ◽  
Left And Right

Abstract Traversodontidae is a group of Triassic herbivorous/omnivorous cynodonts that represents the most diversified lineage within Cynognathia. In southern Brazil, a rich fossil record of late Middle/mid-Late Triassic cynodonts has been documented, with Exaeretodon riograndensis Abdala, Barberena, and Dornelles, 2002 and Siriusgnathus niemeyerorum Pavanatto et al., 2018 representing two abundant and well-documented traversodontids. The present study provides a comparative analysis of the morphology of the nasal cavity, nasal recesses, nasolacrimal duct, and maxillary canals of both species using computed tomography, highlighting the changes that occurred in parallel to the origin of mammaliaforms. Our results show that there were no ossified turbinals or a cribriform plate delimiting the posterior end of the nasal cavity, suggesting these structures were probably cartilaginous as in nonmammaliaform cynodonts. Both species show lateral ridges on the internal surface of the roof of the nasal cavity, but the median ridge for the attachment of a nasal septum is absent. Exaeretodon riograndensis and S. niemeyerorum show recesses on the dorsal region of the nasal cavity, which increase the volume of the nasal cavity, potentially enhancing the olfactory chamber and contributing to the sense of smell. On the lateral sides of the nasal cavity, the analyzed taxa show a well-developed maxillary recess. Although E. riograndensis and S. niemeyerorum have roughly similar nasal cavities, in the former taxon, the space between the left and right dorsal recesses of the nasal cavity is uniform along its entire extension, whereas this space narrows posteriorly in S. niemeyerorum. Finally, the nasolacrimal duct of S. niemeyerorum is more inclined anteroposteriorly than in E. riograndensis.

scholarly journals Detrital zircon provenance of the Late Triassic Songpan-Ganzi complex: Sedimentary record of collision of the North and South China blocks: Comment and Reply: REPLY

Geology ◽  
2006 ◽  
Vol 34 (1) ◽  
pp. e107-e108
Author(s):  
A. L. Weislogel ◽  
S. A. Graham ◽  
E. Z. Chang ◽  
J. L. Wooden ◽  
G. E. Gehrels ◽  
...  
Keyword(s):  
South China ◽  
Detrital Zircon ◽  
Late Triassic ◽  
Sedimentary Record ◽  
The North ◽  
North And South

Some North and South American Bees.

1927 ◽  
Vol 20 (3) ◽  
pp. 393-400
Author(s):  
T. D. A. Cockerell
Keyword(s):  
South American ◽  
North And South

scholarly journals Balance Differences between North and South American Older Adults: A Cross-Sectional, Age and Sex Matched Study

2021 ◽  
Author(s):  
Matheus Almeida Souza ◽  
Daniel Goble ◽  
Paige Arney ◽  
Edgar Ramos Vieira ◽  
Gabriela Silveira-Nunes ◽  
...  
Keyword(s):  
Older Adults ◽  
High Risk ◽  
North American ◽  
Force Plate ◽  
South American ◽  
Risk Of Falling ◽  
Men And Women ◽  
Falls Risk ◽  
South Americans ◽  
North And South

This study aimed to characterize the risk of falling in low, moderate and high risk participants from two different geographical locations using a portable force-plate. A sample of 390 older adults from South and North America were matched for age, sex, height and weight. All participants performed a standardized balance assessment using a force plate. Participants were classified in low, moderate and high risk of falling. No differences were observed between South and North American men, nor comparing North American men and women. South American women showed the significantly shorter center of pressure path length compared to other groups. The majority of the sample was categorized as having low risk of falling (male: 65.69 % and female: 61.87 %), with no differences between men and women. Also, no differences were found between North vs. South Americans, nor for falls risk levels when male and female groups were compared separately. In conclusion, South American women had better balance compatible with the status of the 50-59 years’ normative age-range. The prevalence of low falls risk was ~ 61-65 % and the prevalence of moderate to high risk was ~ 16-19 %. The frequency of fall risk did not differ significantly between North and South Americans, nor between males and females.

scholarly journals A fresh look at Cladarosymblema narrienense, a tetrapodomorph fish (Sarcopterygii: Megalichthyidae) from the Carboniferous of Australia, illuminated via X-ray tomography

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12597
Author(s):  
Alice M. Clement ◽  
Richard Cloutier ◽  
Jing Lu ◽  
Egon Perilli ◽  
Anton Maksimenko ◽  
...  
Keyword(s):  
Original Description ◽  
Sister Group ◽  
Axial Skeleton ◽  
Phylogenetic Position ◽  
Micro Computed Tomography ◽  
Holotype Specimen ◽  
Freshwater Swamp ◽  
The Family ◽  
First Time ◽  
Detailed Work

Background The megalichthyids are one of several clades of extinct tetrapodomorph fish that lived throughout the Devonian–Permian periods. They are advanced “osteolepidid-grade” fishes that lived in freshwater swamp and lake environments, with some taxa growing to very large sizes. They bear cosmine-covered bones and a large premaxillary tusk that lies lingually to a row of small teeth. Diagnosis of the family remains controversial with various authors revising it several times in recent works. There are fewer than 10 genera known globally, and only one member definitively identified from Gondwana. Cladarosymblema narrienense Fox et al. 1995 was described from the Lower Carboniferous Raymond Formation in Queensland, Australia, on the basis of several well-preserved specimens. Despite this detailed work, several aspects of its anatomy remain undescribed. Methods Two especially well-preserved 3D fossils of Cladarosymblema narrienense, including the holotype specimen, are scanned using synchrotron or micro-computed tomography (µCT), and 3D modelled using specialist segmentation and visualisation software. New anatomical detail, in particular internal anatomy, is revealed for the first time in this taxon. A novel phylogenetic matrix, adapted from other recent work on tetrapodomorphs, is used to clarify the interrelationships of the megalichthyids and confirm the phylogenetic position of C. narrienense. Results Never before seen morphological details of the palate, hyoid arch, basibranchial skeleton, pectoral girdle and axial skeleton are revealed and described. Several additional features are confirmed or updated from the original description. Moreover, the first full, virtual cranial endocast of any tetrapodomorph fish is presented and described, giving insight into the early neural adaptations in this group. Phylogenetic analysis confirms the monophyly of the Megalichthyidae with seven genera included (Askerichthys, Cladarosymblema, Ectosteorhachis, Mahalalepis, Megalichthys, Palatinichthys, and Sengoerichthys). The position of the megalichthyids as sister group to canowindrids, crownward of “osteolepidids” (e.g.,Osteolepis and Gogonasus), but below “tristichopterids” such as Eusthenopteron is confirmed, but our findings suggest further work is required to resolve megalichthyid interrelationships.

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