Anoxia may delay biotic recovery from the Late Ordovician mass extinction

Delayed biotic recovery from the end-Permian mass extinction has long been interpreted to result from environmental inhibition. Recently, evidence of more rapid recovery has begun to emerge, suggesting the role of environmental inhibition was previously overestimated. However, there have been few high-resolution taxonomic and ecological studies spanning the full Early and Middle Triassic recovery interval, leaving the precise pattern of recovery and underlying mechanisms poorly constrained. In this study, we document Early and Middle Triassic trends in taxonomic diversity, assemblage evenness, and size distribution of benthic foraminifers on an exceptionally exposed carbonate platform in south China. We observe gradual increases in all metrics through Early Triassic and earliest Middle Triassic time, with stable values reached early in the Anisian. There is little support in our data set for a substantial Early Triassic lag interval during the recovery of foraminifers or for a stepwise recovery pattern. The recovery pattern of foraminifers on the GBG corresponds well with available global data for this taxon and appears to parallel that of many benthic invertebrate clades. Early Triassic diversity increase in foraminifers was more gradual than in ammonoids and conodonts. However, foraminifers continued to increase in diversity, size, and evenness into Middle Triassic time, whereas diversity of ammonoids and conodonts declined. These contrasts suggest decoupling of recovery between benthic and pelagic environments; it is unclear whether these discrepancies reflect inherent contrasts in their evolutionary dynamics or the differential impact of Early Triassic ocean anoxia or associated environmental parameters on benthic ecosystems.

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Hirnantia Fauna from the Condroz Inlier, Belgium: another case of a relict Ordovician shelly fauna in the Silurian?

Journal of Paleontology ◽

10.1017/jpa.2021.74 ◽

2021 ◽

pp. 1-27

Author(s):

Sofia Pereira ◽

Jorge Colmenar ◽

Jan Mortier ◽

Jan Vanmeirhaeghe ◽

Jacques Verniers ◽

...

Keyword(s):

Sea Level ◽

Mass Extinction ◽

Late Ordovician ◽

Lake District ◽

Low Diversity ◽

Hirnantia Fauna ◽

And Sea Level

Abstract The end-Ordovician mass extinction, linked to a major glaciation, led to deep changes in Hirnantian–Rhuddanian biotas. The Hirnantia Fauna, the first of two Hirnantian survival brachiopod-dominated communities, characterizes the lower–mid Hirnantian deposits globally, and its distribution is essential to understand how the extinction took place. In this paper, we describe, illustrate, and discuss the first macrofossiliferous Hirnantia Fauna assemblage from Belgium, occurring in the Tihange Member of the Fosses Formation at Tihange (Huy), within the Central Condroz Inlier. Six fossiliferous beds have yielded a low-diversity, brachiopod-dominated association. In addition to the brachiopods (Eostropheodonta hirnantensis, Plectothyrella crassicosta, Hirnantia sp., and Trucizetina? sp.), one trilobite (Mucronaspis sp.), four pelmatozoans (Xenocrinus sp., Cyclocharax [col.] paucicrenulatus, Conspectocrinus [col.] celticus, and Pentagonocyclicus [col.] sp.), three graptolites (Cystograptus ancestralis, Normalograptus normalis, and ?Metabolograptus sp.), together with indeterminate machaeridians and bryozoans were identified. The graptolite assemblage, from the Akidograptus ascensus-Parakidograptus acuminatus Biozone, indicates an early Rhuddanian (Silurian) age, and thus, an unexpectedly late occurrence of a typical Hirnantia Fauna. This Belgian association may represent an additional example of relict Hirnantia Fauna in the Silurian, sharing characteristics with the only other known from Rhuddanian rocks at Yewdale Beck (Lake District, England), although reworking has not been completely ruled out. The survival of these Hirnantian taxa into the Silurian might be linked to delayed post-glacial effects of rising temperature and sea-level, which may have favored the establishment of refugia in these two particular regions that were paleogeographically close during the Late Ordovician–early Silurian.

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Within- and among-genus components of size evolution during mass extinction, recovery, and background intervals: a case study of Late Permian through Late Triassic foraminifera

Paleobiology ◽

10.1666/11040.1 ◽

2012 ◽

Vol 38 (4) ◽

pp. 627-643 ◽

Cited By ~ 26

Author(s):

Brianna L. Rego ◽

Steve C. Wang ◽

Demir Altiner ◽

Jonathan L. Payne

Keyword(s):

Mass Extinction ◽

Extinction Risk ◽

Maximum Size ◽

Size Reduction ◽

Late Triassic ◽

Mass Extinctions ◽

Late Permian ◽

Biotic Recovery ◽

Size Evolution ◽

Selective Extinction

One of the best-recognized patterns in the evolution of organismal size is the tendency for mean and maximum size within a clade to decrease following a major extinction event and to increase during the subsequent recovery interval. Because larger organisms are typically thought to be at higher extinction risk than their smaller relatives, it has commonly been assumed that size reduction mostly reflects the selective extinction of larger species. However, to our knowledge the relative importance of within- and among-lineage processes in driving overall trends in body size has never been compared quantitatively. In this study, we use a global, specimen-level database of foraminifera to study size evolution from the Late Permian through Late Triassic. We explicitly decompose size evolution into within- and among-genus components. We find that size reduction following the end-Permian mass extinction was driven more by size reduction within surviving species and genera than by the selective extinction of larger taxa. Similarly, we find that increase in mean size across taxa during Early Triassic biotic recovery was a product primarily of size increase within survivors and the extinction of unusually small taxa, rather than the origination of new, larger taxa. During background intervals we find no strong or consistent tendency for extinction, origination, or within-lineage change to move the overall size distribution toward larger or smaller sizes. Thus, size stasis during background intervals appears to result from small and inconsistent effects of within- and among-lineage processes rather than from large but offsetting effects of within- and among-taxon components. These observations are compatible with existing data for other taxa and extinction events, implying that mass extinctions do not influence size evolution by simply selecting against larger organisms. Instead, they appear to create conditions favorable to smaller organisms.

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Llandovery (early Silurian) crinoids from Hiiumaa Island, western Estonia

Journal of Paleontology ◽

10.1017/jpa.2016.120 ◽

2016 ◽

Vol 90 (6) ◽

pp. 1138-1147 ◽

Cited By ~ 6

Author(s):

William I. Ausich ◽

Mark A. Wilson

Keyword(s):

Mass Extinction ◽

Late Ordovician

AbstractRhuddanian crinoid faunas are poorly known globally, making this new fauna from the Hilliste Formation of western Estonian especially significant. The Hilliste fauna is the oldest Silurian fauna known from the Baltica paleocontinent, thus this is the first example of the crinoid recovery fauna after the Late Ordovician mass extinction. Hiiumaacrinus vinni n. gen. n. sp., Protaxocrinus estoniensis n. sp., Eomyelodactylus sp., calceocrinids, and five holdfast types are reported here. Although the fauna has relatively few taxa, it is among the most diverse Rhuddanian faunas known. Similar to other Rhuddanian crinoid faunas elsewhere, the Hilliste crinoid fauna contains crinoids belonging the Dimerocrinitidae, Taxocrinidae, Calceocrinidae, and Myelodactylidae; most elements of the new fauna are quite small, perhaps indicative of the Lilliput Effect.

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Late Ordovician mass extinction

Mass Extinction ◽

10.1007/978-3-540-75916-4_2 ◽

2007 ◽

pp. 5-7 ◽

Cited By ~ 2

Author(s):

Ashraf M. T. Elewa

Keyword(s):

Mass Extinction ◽

Late Ordovician

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Extinction: Late Ordovician Mass Extinction

Encyclopedia of Life Sciences ◽

10.1038/npg.els.0001652 ◽

2001 ◽

Author(s):

Patrick John Brenchley

Keyword(s):

Mass Extinction ◽

Late Ordovician

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A new faunistic component of the Lower Triassic Panchet Formation of India increases the continental non-archosauromorph neodiapsid record in the aftermath of the end-Permian mass extinction

Journal of Paleontology ◽

10.1017/jpa.2021.100 ◽

2021 ◽

pp. 1-11

Author(s):

Martín D. Ezcurra ◽

Saswati Bandyopadhyay ◽

Kasturi Sen

Keyword(s):

Mass Extinction ◽

Lower Triassic ◽

Maximum Height ◽

Dorsal Margin ◽

Early Triassic ◽

Anterior Portion ◽

Continental Deposits ◽

Biotic Recovery ◽

Patterns And Processes ◽

Permian Mass Extinction

Abstract The fossil record of Early Triassic diapsids is very important to understand how the end-Permian mass extinction affected ecosystems and the patterns and processes involved in the subsequent biotic recovery. Vertebrate fossil assemblages of continental deposits in current-day South Africa, China, and Russia are the best source of information of this clade during the aftermath of the extinction event. Although considerably less sampled, the Induan continental rocks of the Panchet Formation of the Damodar Basin (eastern India) have also yielded a relatively diverse vertebrate assemblage composed of fishes, temnospondyls, synapsids, and a single proterosuchid taxon. Here, we report on a small isolated diapsid partial ilium (ISIR 1132) from the upper Panchet Formation. This specimen has a distinct morphology compared to other tetrapods that we know, including a shallow emargination on the dorsal margin of the anterior portion of the iliac blade, and ratio between height of iliac blade versus maximum height of iliac acetabulum at level of the dorsalmost extension of supraacetabular crest ≤0.45. Comparisons and a quantitative phylogenetic analysis found ISIR 1132 as a non-archosauromorph neodiapsid. This new specimen expands the reptile diversity in the Panchet Formation as well as for the rest of Gondwana, where Early Triassic non-archosauromorph neodiapsid species are extremely scarce.

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Ocean euxinia and climate change “double whammy” drove the Late Ordovician mass extinction

Geology ◽

10.1130/g40121.1 ◽

2018 ◽

Vol 46 (6) ◽

pp. 535-538 ◽

Cited By ~ 40

Author(s):

Caineng Zou ◽

Zhen Qiu ◽

Simon W. Poulton ◽

Dazhong Dong ◽

Hongyan Wang ◽

...

Keyword(s):

Climate Change ◽

Mass Extinction ◽

Late Ordovician

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Rebound from the Permian/Triassic mass extinction: evolutionary paleoecology of sequential early Triassic (Smithian to Spathian) marine paleocommunities

The Paleontological Society Special Publications ◽

10.1017/s2475262200008212 ◽

1992 ◽

Vol 6 ◽

pp. 261-261

Author(s):

Jennifer K. Schubert ◽

David J. Bottjer

Keyword(s):

Mass Extinction ◽

Lower Triassic ◽

Upper Permian ◽

Early Triassic ◽

Triassic Boundary ◽

Biotic Recovery ◽

The Status ◽

Life Habits ◽

Stalked Crinoids ◽

Permian Triassic Boundary

The Permian/Triassic mass extinction, the most devastating biotic crisis of the Phanerozoic, has aroused considerable scientific interest. However, because research has focused primarily on understanding the magnitude of diversity reduction and causal mechanisms, the nature and timing of biotic recovery in the Early Triassic are still poorly understood. Marine limestones in the Lower Triassic Moenkopi Formation, which disconformably overlies the Upper Permian of southeastern Nevada and southern Utah, provide a rare opportunity to study the aftermath of the mass extinction in shallow water carbonate environments.Two contemporaneous members of the Moenkopi record the first marine incursion from the northwest in the Early Triassic (Smithian), the very sparsely fossiliferous marginal marine Schnabkaib Member in Nevada and southwest Utah, and the Sinbad Limestone in central-southern Utah, a marine unit dominated by amalgamated and condensed fossil-rich beds. The Virgin Limestone member was deposited during a subsequent (Spathian) Early Triassic sea level rise, about 4-5 Ma following the Permian/Triassic boundary, and includes nearshore and inner shelf limestones characterized by fossiliferous storm beds.Because the fossiliferous limestones of the Smithian Sinbad and the Spathian Virgin were deposited in similar shallow subtidal settings, they provide an opportunity to compare and contrast the status of biotic rebound at different points along an Early Triassic “time transect.” Analysis of bulk samples reveals that the older Sinbad and younger Virgin are similar in each possessing 2-3 different benthic marine paleocommunities of low within-habitat species richness. There are, however, several important differences between the Sinbad and Virgin faunas. The richly fossiliferous Sinbad assemblages are primarily molluscan, composed of approximately 2-8 species of bivalves, which may or may not be accompanied by ammonoids and 0-11 species of gastropods. Small spines, possibly belonging to an echinoid, are numerous in some samples. Although bivalves are also abundant in Virgin Limestone assemblages, fossils of other higher taxa are well-represented, including abundant crinoid ossicles, common brachiopods, echinoid spines and plates, and rare ammonoids and gastropods. Sinbad faunas also appear to lack epibionts and borers, while they are present but not abundant in the Virgin.The addition from Sinbad to Virgin times of groups other than molluscs, with different life habits and strategies, most likely led to an increase in spatial partitioning and resource utilization, in particular the development of epifaunal tiering with the appearance of stalked crinoids in the Virgin. This pattern of earliest Triassic community dominance by molluscs followed by later more “Paleozoic-like” communities has been observed in other regions. Earliest Triassic paucity of epibionts and borers indicates significant reduction in the biotic component of taphonomic processes, including taphonomic feedback, when compared with other time intervals. Data from these Early Triassic assemblages thus indicate the initiation of both an evolutionary and an ecological rebound between Sinbad (Smithian) and Virgin (Spathian) times.

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