A Linkage Among Pangean Tectonism, Cyclic Alluviation, Climate Change, and Biologic Turnover In the Late Triassic: The Record From The Chinle Formation, Southwestern United States

Atchley, Stacy C.; Nordt, Lee C.; Dworkin, Steven I.; Ramezani, Jahandar; Parker, William G.; Ash, Sidney R.; Bowring, Samuel A.

doi:10.2110/jsr.2013.89

Cited by 75 publications

(139 citation statements)

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“…Material of K. perfectus is common in Adamanian strata (Blue Mesa Member, lower Sonsela Member) of the park and rare in Revueltian strata (upper Sonsela Member, Petrified Forest Member), while material of A. gregorii demonstrates the inverse distribution pattern (Hunt and Lucas, 1993), which is thought to reflect a climate-associated transition from large metoposaurids to small ones (Parker and Martz, 2011;Atchley et al, 2013). Past workers have cited several features of A. gregorii, including its co-occurrence with a predominantly terrestrial assemblage, poorly developed lateral line system, elongate intercentra, and pelvic structure, as evidence of adaptations for a more terrestrial lifestyle that would have allowed for this transition (Hunt, 1993).…”

Section: Discussionmentioning

confidence: 99%

“…Given the pronounced seasonality that characterized the equatorial regions of the Upper Triassic, it would not be unexpected for aquatic taxa, particularly desiccationprone amphibians, to acquire adaptations that would allow them to tolerate more arid conditions during the dry season (Dubiel et al, 1991;Martz and Parker, 2010;Atchley et al, 2013;Nordt et al, 2015). For example, workers have postulated that M. diagnosticus, which features more robust forelimbs and musculature relative to Dutuitosaurus ouazzoui (two taxa with well-described articulated skeletons), may have been adapted for burrowing into lake sediments during the dry season .…”

Section: Discussionmentioning

confidence: 99%

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A juvenile Koskinonodon perfectus (Temnospondyli, Metoposauridae) from the Upper Triassic of Arizona and its implications for the taxonomy of North American metoposaurids

Gee

Parker²

2017

J. Paleontol.

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Abstract.-Metoposaurids are temnospondyl amphibians that are well known from Upper Triassic deposits in North America, Europe, India, and Africa. Two species of metoposaurids, Koskinonodon perfectus and Apachesaurus gregorii, are among the most common fossils found in the Petrified Forest National Park (PEFO) of the southwestern United States. The two are distinguished on the basis of several cranial traits and the morphology of their intercentra, and are more informally distinguished by their overall size and biostratigraphic range. While material of adult metoposaurids is extremely common in Upper Triassic deposits, described material of juveniles is very rare, which limits the study of ontogenetic trajectories that would assist in assessing whether diagnostic traits of the smaller A. gregorii are also ontogenetically influenced traits in juveniles of K. perfectus. Here we report on material from a juvenile specimen of K. perfectus from the Petrified Forest Member (Norian) of the Chinle Formation in the PEFO. This specimen is significant because it represents the highest known occurrence of the species within the PEFO, documents a rare occurrence of a juvenile specimen of a North American metoposaurid, and records a rare North American metoposaurid specimen that includes associated cranial and postcranial material. Additionally, the combination of cranial features diagnostic of K. perfectus and intercentra of proportions intermediate between K. perfectus and A. gregorii in this specimen raises questions about the utility of several characters for species discrimination in North American metoposaurids.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A juvenile Koskinonodon perfectus (Temnospondyli, Metoposauridae) from the Upper Triassic of Arizona and its implications for the taxonomy of North American metoposaurids

Gee

Parker²

2017

J. Paleontol.

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“…Results of this study suggest that two climate regimes affected the weathering intensity of Chinle sandstone and coincide with the two composite sequences previously identified by Atchley et al . () (Table ). Although all Chinle sandstones exhibit a decline in feldspar content, and an increase in secondary porosity, authigenic clay and pseudomatrix content, the extent and style of these changes can be used as a guide to understanding Late Triassic climates.…”

Section: Discussionmentioning

confidence: 99%

“…(B) Chinle Formation stratigraphy including lithostratigraphic, geochronological and sequence stratigraphic framework. Stacked bar chart shows lithological proportions within fluvial aggradational cycles ( FAC s) with age dated sandstone samples (modified from Atchley et al ., ).…”

Section: Geological Settingmentioning

confidence: 99%

“…Previous climate studies have used the character of palaeosols to recognize the pronounced wet climate that persisted during the early parts of Chinle deposition and the subsequent change to progressively drier conditions (Dubiel et al ., ; Tanner, ; Prochnow et al ., ; Tanner & Lucas, ; Dubiel & Hasiotis, ; Trendell et al ., ; Atchley et al ., ; Nordt et al ., ). The cause of the evolving Late Triassic climate may be the result of the cessation of monsoonal flow induced by orographic blockage during the uplift of the western Pangean Cordillerian arc system (Atchley et al ., ; Nordt et al ., ).…”

Section: Introductionmentioning

confidence: 99%

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Eogenetic diagenesis of Chinle sandstones, Petrified Forest National Park (Arizona, USA): A record of Late Triassic climate change

et al. 2017

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Fluvially derived tuffaceous Chinle sandstones from Petrified Forest National Park provide a well‐preserved Late Triassic archive of climate information. Petrographic analysis of 38 Chinle sandstones provides new insight into the depositional history and evolution of palaeoclimate during Chinle deposition. This study focuses on the relationship between climate and meteoric diagenesis as a guide for constraining climate change in western equatorial Pangea during the Late Triassic. Petrographic analysis of Chinle sandstones reveals their wide range of textural attributes, as well as pedogenic and shallow burial diagenetic features that occurred during the Late Triassic. These diverse petrological characteristics are indicative of the evolving Late Triassic climate, when placed into a well‐constrained stratigraphic and geochronological framework. The stratigraphic succession is characterized by variations in the abundance of framework grains, detrital matrix, weathering intensity of feldspar and volcanic rock fragments, and the mineralogy of clay cements. Climate records from Chinle palaeosol geochemistry indicate a progression from wet to dry conditions. This trend is also reflected in the meteoric diagenetic features of Chinle sandstones. During deposition of the lower Chinle, elevated rainfall promoted the weathering of labile volcanic detritus to kaolinite, whereas feldspars (especially plagioclase) were partially or completely dissolved. In the upper Chinle, a trend towards drier conditions favoured the formation of smectite and less feldspar dissolution resulting in a higher abundance of well‐preserved plagioclase grains. Shallow burial meteoric weathering reactions in Chinle sandstones reflect the evolving climate during the Late Triassic.

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Osteology of the Late Triassic Bipedal Archosaur Poposaurus gracilis (Archosauria: Pseudosuchia) from Western North America

Schachner

Irmis

Huttenlocker

et al. 2019

The Anatomical Record

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Poposaurus gracilis is a bipedal pseudosuchian archosaur that has been poorly understood since the discovery of the holotype fragmentary partial postcranial skeleton in 1915. Poposaurus. gracilis is a member of Poposauroidea, an unusually morphologically divergent clade of pseudosuchians containing taxa that are bipedal, quadrupedal, toothed, edentulous, and some individuals with elongated thoracic neural spines (i.e., sails). In 2003, a well preserved, fully articulated, and nearly complete postcranial skeleton of P. gracilis was discovered with some fragmentary cranial elements from the Upper Triassic Chinle Formation of Grand Staircase‐Escalante National Monument of southern Utah, USA. The aim of this work is to describe the osteology of this specimen in detail and compare P. gracilis to other closely related pseudosuchian archosaurs. The open neurocentral sutures throughout the majority of the vertebral column, the small size of this individual, and the presence of seven evenly spaced cyclic growth marks in the histologically sectioned femur indicate that this specimen was a skeletally immature juvenile, or subadult when it died. The pes of P. gracilis contains multiple skeletal adaptations and osteological correlates for soft tissue structures that support a hypothesis of digitigrady for this taxon. When coupled with the numerous postcranial characters associated with cursoriality, and the many anatomical traits convergent with theropod dinosaurs, this animal likely occupied a similar ecological niche with contemporaneous theropods during the Late Triassic Period. Anat Rec, 303:874–917, 2020. © 2019 American Association for Anatomy

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A Linkage Among Pangean Tectonism, Cyclic Alluviation, Climate Change, and Biologic Turnover In the Late Triassic: The Record From The Chinle Formation, Southwestern United States

Cited by 75 publications

References 60 publications

A juvenile Koskinonodon perfectus (Temnospondyli, Metoposauridae) from the Upper Triassic of Arizona and its implications for the taxonomy of North American metoposaurids

A juvenile Koskinonodon perfectus (Temnospondyli, Metoposauridae) from the Upper Triassic of Arizona and its implications for the taxonomy of North American metoposaurids

Eogenetic diagenesis of Chinle sandstones, Petrified Forest National Park (Arizona, USA): A record of Late Triassic climate change

Osteology of the Late Triassic Bipedal Archosaur Poposaurus gracilis (Archosauria: Pseudosuchia) from Western North America

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