scholarly journals Early archosauromorph remains from the Permo-Triassic Buena Vista formation of NorthEastern Uruguay

2014 ◽  
Author(s):  
Martin Ezcurra ◽  
Pablo Velozo ◽  
Melitta Meneghel ◽  
Graciela Piñeiro
Keyword(s):  
South America ◽  
Mass Extinction ◽  
Cervical Vertebrae ◽  
Terrestrial Ecosystems ◽  
Early Evolution ◽  
Early Triassic ◽  
Late Permian ◽  
Unique Combination ◽  
Buena Vista ◽  
The Impact

The Permo-Triassic archosauromorph record is crucial to understand the impact of the Permo-Triassic mass extinction on the early evolution of the group and its subsequent dominance in Mesozoic terrestrial ecosystems. However, the Permo-Triassic archosauromorph record is still very poor in most continents and hampers the identification of global macroevolutionary patterns. Here we describe cranial and postcranial bones from the Permo-Triassic Buena Vista Formation of northeastern Uruguay that contribute to increase the meagre early archosauromorph record from South America. A basioccipital fused to both partial exoccipitals and three cervical vertebrae are assigned to Archosauromorpha based on apomorphies or a unique combination of characters. The archosauromorph remains of the Buena Vista Formation probably represent a multi-taxonomic assemblage composed of non-archosauriform archosauromorphs and a ‘proterosuchid-grade’ animal. This assemblage does not contribute in the discussion of a Late Permian or Early Triassic age for the Buena Vista Formation, but reinforces the broad palaeobiogeographic distribution of ‘proterosuchid grade’ diapsids in Permo-Triassic beds worldwide.

scholarly journals Early archosauromorph remains from the Permo-Triassic Buena Vista formation of NorthEastern Uruguay

2014 ◽  
Author(s):  
Martin Ezcurra ◽  
Pablo Velozo ◽  
Melitta Meneghel ◽  
Graciela Piñeiro
Keyword(s):  
South America ◽  
Mass Extinction ◽  
Cervical Vertebrae ◽  
Terrestrial Ecosystems ◽  
Early Evolution ◽  
Early Triassic ◽  
Late Permian ◽  
Unique Combination ◽  
Buena Vista ◽  
The Impact

The Permo-Triassic archosauromorph record is crucial to understand the impact of the Permo-Triassic mass extinction on the early evolution of the group and its subsequent dominance in Mesozoic terrestrial ecosystems. However, the Permo-Triassic archosauromorph record is still very poor in most continents and hampers the identification of global macroevolutionary patterns. Here we describe cranial and postcranial bones from the Permo-Triassic Buena Vista Formation of northeastern Uruguay that contribute to increase the meagre early archosauromorph record from South America. A basioccipital fused to both partial exoccipitals and three cervical vertebrae are assigned to Archosauromorpha based on apomorphies or a unique combination of characters. The archosauromorph remains of the Buena Vista Formation probably represent a multi-taxonomic assemblage composed of non-archosauriform archosauromorphs and a ‘proterosuchid-grade’ animal. This assemblage does not contribute in the discussion of a Late Permian or Early Triassic age for the Buena Vista Formation, but reinforces the broad palaeobiogeographic distribution of ‘proterosuchid grade’ diapsids in Permo-Triassic beds worldwide.

scholarly journals Morphological selectivity of the Permian-Triassic ammonoid mass extinction

Geology ◽  
2021 ◽  
Author(s):  
Xu Dai ◽  
Dieter Korn ◽  
Haijun Song
Keyword(s):  
Multidimensional Scaling ◽  
Mass Extinction ◽  
Nonmetric Multidimensional Scaling ◽  
Morphological Data ◽  
Early Triassic ◽  
Late Permian ◽  
Scaling Method ◽  
Data Set ◽  
Rapid Diversification ◽  
The Impact

Ammonoids suffered a diversity bottleneck during the Permian-Triassic mass extinction (PTME) and experienced a rapid diversification in the Early Triassic. However, the kinds of ammonoids that were more likely to survive the PTME and that fueled subsequent diversification are still poorly known. We compiled a comprehensive morphological data set and used the nonmetric multidimensional scaling method to reveal the impact of the PTME on the morphological selectivity of ammonoids. Our results show that postextinction taxa occupied a quite different morphospace when compared with the pre-extinction assemblages. The survivors were mainly smooth and weakly ornamented forms, while the late Permian species were dominated by coarsely ornamented forms. Contrary to previously recognized nonselective patterns, these results suggest a morphological selectivity of the Permian-Triassic crisis. Newcomers in the Griesbachian were mainly compressed and smooth forms. This morphological shift from the coarsely ornamented ammonoids dominating the Changhsingian to the smooth ammonoids dominating the Griesbachian possibly suggests an ecological turnover of ammonoids during the PTME.

scholarly journals A Hiatus Obscures the Early Evolution of Modern Lineages of Bony Fishes

2021 ◽  
Vol 8 ◽  
Author(s):  
Carlo Romano
Keyword(s):  
Mass Extinction ◽  
Fossil Record ◽  
Middle Triassic ◽  
Early Evolution ◽  
Early Triassic ◽  
Triassic Boundary ◽  
Bony Fishes ◽  
Extinction Event ◽  
Mass Extinction Event ◽  
The Impact

About half of all vertebrate species today are ray-finned fishes (Actinopterygii), and nearly all of them belong to the Neopterygii (modern ray-fins). The oldest unequivocal neopterygian fossils are known from the Early Triassic. They appear during a time when global fish faunas consisted of mostly cosmopolitan taxa, and contemporary bony fishes belonged mainly to non-neopterygian (“paleopterygian”) lineages. In the Middle Triassic (Pelsonian substage and later), less than 10 myrs (million years) after the Permian-Triassic boundary mass extinction event (PTBME), neopterygians were already species-rich and trophically diverse, and bony fish faunas were more regionally differentiated compared to the Early Triassic. Still little is known about the early evolution of neopterygians leading up to this first diversity peak. A major factor limiting our understanding of this “Triassic revolution” is an interval marked by a very poor fossil record, overlapping with the Spathian (late Olenekian, Early Triassic), Aegean (Early Anisian, Middle Triassic), and Bithynian (early Middle Anisian) substages. Here, I review the fossil record of Early and Middle Triassic marine bony fishes (Actinistia and Actinopterygii) at the substage-level in order to evaluate the impact of this hiatus–named herein the Spathian–Bithynian gap (SBG)–on our understanding of their diversification after the largest mass extinction event of the past. I propose three hypotheses: 1) the SSBE hypothesis, suggesting that most of the Middle Triassic diversity appeared in the aftermath of the Smithian-Spathian boundary extinction (SSBE; ∼2 myrs after the PTBME), 2) the Pelsonian explosion hypothesis, which states that most of the Middle Triassic ichthyodiversity is the result of a radiation event in the Pelsonian, and 3) the gradual replacement hypothesis, i.e. that the faunal turnover during the SBG was steady and bony fishes were not affected by extinction events subsequent to the PTBME. Based on current knowledge, hypothesis three is favored herein, but further studies are necessary to test alternative hypotheses. In light of the SBG, claims of a protracted diversification of bony fishes after the PTBME should be treated with caution.

Multiple Early Triassic greenhouse crises impeded recovery from Late Permian mass extinction

2011 ◽  
Vol 308 (1-2) ◽  
pp. 233-251 ◽  
Author(s):  
Gregory J. Retallack ◽  
Nathan D. Sheldon ◽  
Paul F. Carr ◽  
Mark Fanning ◽  
Caitlyn A. Thompson ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Early Triassic ◽  
Late Permian ◽  
Permian Mass Extinction

New material of Procolophon (Parareptilia: Procolophonoidea) from the Lower Triassic of Brazil, with remarks on the ages of the Sanga do Cabral and Buena Vista formations of South America

2006 ◽  
Vol 43 (11) ◽  
pp. 1685-1693 ◽  
Author(s):  
Sérgio Dias-da-Silva ◽  
Sean Patrick Modesto ◽  
Cesar Leandro Schultz
Keyword(s):  
South America ◽  
Lower Triassic ◽  
Dental Morphology ◽  
Early Triassic ◽  
Compelling Evidence ◽  
Buena Vista ◽  
New Material ◽  
Paraná Basin ◽  
Available Information ◽  
Parana Basin

We describe a large, fragmentary procolophonid skull and three large vertebrae from the Sanga do Cabral Formation, Paraná Basin, Lower Triassic of Brazil. Cranial and dental morphology allow us to refer the skull to the genus Procolophon; the fragmentary nature of the specimen, however, does not permit identification to species. The vertebrae are tentatively assigned to Procolophon. They are of a size expected for an individual represented by the skull, although the cranial and postcranial elements were not directly associated. The vertebrae are unusual for a procolophonid in exhibiting neural arches that are twice as broad as they are long, a dimension seen elsewhere among parareptiles only in pareiasaurs. A comparison of the manner of tetrapod preservation between the Sanga do Cabral and Katberg formations reveals that tetrapods in the former occur within conglomerates, whereas in the latter they are recovered mainly from mudstones. This taphonomic disparity may account for the absence in South America of the nearly cosmopolitan synapsid Lystrosaurus. The recent recognition of Permian tetrapods from the Buena Vista Formation of Uruguay, regarded widely to be a lateral equivalent of the Sanga do Cabral Formation, is assessed. We conclude that there is no compelling evidence of Permian tetrapods from the Buena Vista Formation and that the available information is suggestive of an Early Triassic age for that formation.

Heleosuchus: an enigmatic diapsid reptile from the Late Permian or Early Triassic of southern Africa

1987 ◽  
Vol 24 (4) ◽  
pp. 664-667 ◽  
Author(s):  
Robert L. Carroll
Keyword(s):  
Southern Africa ◽  
Cervical Vertebrae ◽  
Type Specimen ◽  
Early Triassic ◽  
Late Permian ◽  
Diagnostic Features ◽  
Anterior Trunk

The primitive diapsid reptile Heleosuchus griesbachi, from the Late Permian or Early Triassic of southern Africa, is redescribed on the basis of a new cast made from the type specimen. Few diagnostic features of the skeleton are preserved, making it difficult to establish specific affinities. No characters are known that are uniquely shared with archosauromorphs. In common with lepidosauromorphs, but in contrast with stem diapsids, cervical vertebrae 3–5 are shorter than the anterior trunk vertebrae, and the transverse processes are relatively short. Heleosuchus may be a member of the Eosuchia or an otherwise unrecognized lineage of primitive lepidosauromorphs. The possibility that this specimen shows thyroid fenestration of the pelvis and a shortened and (or) hooked fifth metatarsal cannot be unequivocally established.

scholarly journals The first data on the n-isotopic composition of the Permian and Triassic of North-Eastern Russia and their significance for palaeotemperature reconstructions

2019 ◽  
Vol 484 (2) ◽  
pp. 187-190
Author(s):  
Y. D. Zakharov ◽  
A. S. Biakov ◽  
M. Horacek ◽  
N. A. Goryachev ◽  
I. L. Vedernikov
Keyword(s):  
Isotopic Composition ◽  
Mass Extinction ◽  
Climatic Conditions ◽  
Early Triassic ◽  
Late Permian ◽  
Triassic Boundary ◽  
North Eastern ◽  
Increasing Temperature ◽  
Permian Triassic Boundary ◽  
Eastern Russia

It is proposed that oscillating temperature conditions in the late Wuchiapingian and early Changhsingian (Late Permian) followed in the Boreal Superrealm to less variable climatic conditions in the late Changhsingian and early Induan (the time of trap formation of the Siberian Platform), with stable trend of increasing temperature in the Early Triassic. The Problem of the absence of signs of mass extinction of marine organisms at the Permian-Triassic boundary in the Boreal Superrealm is discussed.

The Permo-Triassic transition in Spitsbergen: δ13Corg chemostratigraphy, Fe and S geochemistry, facies, fauna and trace fossils

1998 ◽  
Vol 135 (1) ◽  
pp. 47-62 ◽  
Author(s):  
P. B. WIGNALL ◽  
R. MORANTE ◽  
R. NEWTON
Keyword(s):  
Water Column ◽  
Mass Extinction ◽  
Marine Ecosystem ◽  
Trace Fossil ◽  
Lower Latitude ◽  
Early Triassic ◽  
Late Permian ◽  
Ecosystem Recovery ◽  
Triassic Boundary ◽  
Field Evidence

New δ13Corg analyses of two boundary sections between the late Permian Kapp Starostin Formation and the early Triassic Vardebukta Formation of western Spitsbergen confirm field evidence that their contact is a conformable one. Thus, contrary to previous reports, some Spitsbergen sections contain a complete record of the environmental and faunal changes during the crisis interval of the end Permian mass extinction. No environmental deterioration is recorded in the late Permian until near the end of the terminal Changxingian Stage, whereupon the abundant siliceous sponge fauna of the Kapp Starostin Formation disappears along with the deep-burrowing fauna responsible for the Zoophycus trace fossil. A low diversity dysaerobic trace fossil assemblage is briefly developed before a transition to finely laminated, pyritic facies immediately beneath the Permo-Triassic boundary. Analysis of the S/C ratios from the laminated strata suggests that free H2S was present in the water column (euxinic conditions) even in relatively nearshore settings subject to storm sandstone deposition. The mass extinction crisis in Spitsbergen is therefore coincident with the extensive development of oxygen-poor conditions in the water column and compares closely, both in timing and nature, with the crisis seen in lower latitude Tethyan settings. However, the subsequent aftermath and recovery in the Boreal sections of Spitsbergen was more rapid than in Tethys. Thus, a shoreface sandstone body within the Dienerian Stage contains an appreciable diversity of fauna (by the standards of the early Triassic), including bryozoans, calcareous algae and deep infaunal bivalves, that suggests the marine ecosystem recovery began earliest in higher palaeolatitudes.

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