Taxonomic diversity of marine animals decreased markedly during the end-Guadalupian and end-Permian mass extinctions, but conodonts were largely unaffected by these two major events. This conclusion ...is largely based on potentially problematic conodont taxonomy, but quantitative analyses of conodont morphology have received little attention, despite offering key insights into macroevolutionary dynamics. Polygnathacea conodonts seemingly evolved fast and had high morphological diversity, and are therefore ideal for exploring morphospace trends and disparity related to environmental change in conodonts. Here we compiled discrete character-taxon matrices to first refine phylogenetic interpretations and then explore morphological disparity in four related conodont families, the Anchignathodontidae, Sweetognathidae, Idiognathodontidae and Vjalovognathidae, from the Permian to Early Triassic. Our findings reveal morphological innovation and exploration of new morphospace after the end-Guadalupian mass extinction and end-Permian mass extinction. We also show that the smaller end-Guadalupian extinction event was more impactful, resulting in greater losses of morphological disparity and taxonomic diversity, than the larger end-Permian extinction event. Overall, our study reveals morphological disparity trends related to temporal evolutionary dynamics for conodonts during the geologically and environmentally turbulent Permian and Early Triassic. We show that conodonts are affected by extinction events during this interval in terms of morphological diversity, rather than simply taxonomic diversity.
•Conodont morphological disparity through mass extinctions in the Permian was analyzed quantitatively for the first time.•Shifting of morphospace suggests that conodonts were affected by both the end-Guadalupian and end-Permian mass extinctions.•Morphological innovation initiated by mass extinctions indicates that turbulent environments may have promoted evolution.•Exploration of conodont morphological disparity provides novel insights into dental morphology and ecological innovation.
The South Qinling Belt is a key area for understanding the collisional history of the South China and North China blocks during the Lopingian (late Permian) and Triassic. This paper establishes the ...first integrated timescale based on conodont biostratigraphy and δ13Ccarb records from a continuous end Permian to the end-Early Triassic succession at Yiwagou, South Qinling Platform (SQP). Ten Early Triassic conodont zones are established. They are, in ascending order, Hindeodus parvus, H. postparvus, Neospathodus dieneri, Eurygnathodus costatus and E. hamadai, Novispathodus waageni-Scythogondolella mosheri, Pachycladina-Parachirognathus assemblage, Triassospathodus hungaricus, Ns. robustispinus and T. clinatus zones. Our record of δ13Ccarb fluctuations shows close correspondence to known Early Triassic carbon isotope fluctuations and, in combination with the conodont data, helps achieve a high-resolution age model for the region. The use of E. costatus as a good auxiliary marker for the Induan-Olenekian boundary (IOB), within palaeolatitudes of 40°N-40°S, is supported but it can not replace the use of Nv. waageni, because the former is absent in higher-latitude and cooler regions. The conodont faunas from the Palaeo-Tethyan Yiwagou section closely resemble those from the Northern Yangtze Platform (NYP), but they differ somewhat from the contemporaneous Nanpanjiang Basin at species level. Thus, the Qinling Sea was likely well connected with the NYP in the Early Triassic, but was more isolated from the Nanpanjiang Basin. The remarkable reappearance of Hindeodus fauna around the IOB at Yiwagou implies that the shallow-water Qinling Sea was a refuge area for this genus long after its disappearance elsewhere.
•Conodont biostratigraphy and δ13Ccarb records from end Permian to the end-Early Triassic succession at Yiwagou, South Qinling Platform.•Discussion of index conodont for the Induan-Olenekian boundary.•Comparison of the conodont faunas between the eastern Paleo-Tethyan Yiwagou, South China and the western Paleo-Tethyan Europe.•The shallow-water Qinling Sea was a refuge area for Hindeodus fauna after Griesbachian.
The Guadalupian Epoch is marked by the formation of the Pangean supercontinent, global sea-level change, rifting and drifting of the Cimmerian continents, formation of large igneous provinces and ...dramatic biotic changes. A high-resolution biostratigraphic, chemostratigraphic and high-precision geochronologic framework of this critical transition is fundamental to understanding these events. Extensive studies of the latest Cisuralian and Guadalupian Series in both South China and North America reveal the same conodont lineages, but the conodont interval zones based on Jinogondolella within the Guadalupian Series are slightly diachronous. High-precision U-Pb geochronological studies (CA-ID-TIMS method) calibrate the base of the Guadalupian Series (base Roadian) at 273.01 ± 0.14 Ma. A previously reported age from an ash bed overlying the Emeishan flood basalts, 259.51 ± 0.21 Ma, is adopted for the Guadalupian/Lopingian boundary (GLB). Based on recently published geochronology and Bayesian age modeling from the Guadalupian Series, the base of the Capitanian is constrained at 264.28 ± 0.16 Ma and the base of the Wordian is interpolated to be 266.9 ± 0.4 Ma. The Illawarra Reversal is of early-middle Wordian age. Both North America and South China possess a distinct negative δ13Ccarb excursion of 3-5‰ at the latest Kungurian and early Roadian (LK-ER CIE), which coincides with the early stages of a significant 3rd order sea-level rise. The large end-Guadalupian δ13Ccarb negative excursion may have been affected by post-depositional diagenesis or a warming event associated with the Emeishan volcanism. The 87Sr/86Sr ratios in both regions declined from the latest Kungurian to the late Capitanian, but have different ratios and reveal several fluctuations in the middle Guadalupian. Measured δ18Oapatite values suggest that the Delaware Basin was 3-4°C cooler than the eastern Yangtze Block. Analysis of a new high-resolution database of marine taxa indicates only a minor pre-Lopingian diversity drop from 261.04 Ma to 259.98 Ma, which coincides with the peak Emeishan volcanism. The widely-perceived “end-Guadalupian mass extinction” in North America is evidently masked by, and possibly an artefact of, a stratigraphic truncation effect due to rapid lithofacies changes from limestone to laminated evaporites with the closure of the west Texas basins.
This report documents conodont biostratigraphic successions from the Sandu and Honghuayuan sections located in the southeastern and northern parts of the Guizhou Province. The Sandu section, ...palaeogeographically located close to the inner margin of the Jiangnan Slope, contains two proto-and paraconodont assemblages of the Miaolingian to early Furongian age recovered from the Sandu Formation and latest Furongian to early Tremadocian Cordylodus lindstromi and Cordylodus angulatus zones recovered from the overlying Guotang Formation. The Honghuayuan section, located within the Sichuan Basin in the central part of the Yangtze Platform, contains middle Tremadocian conodonts of the Rossodus manitouensis and Paltodus deltifer zones. This conodont zonation permits biostratigraphic correlation with the Miaolingian to Tremadocian successions in other parts of South China and biozonal successions across the world.
Systematic study of a brachiopod assemblage from the Upper Mississippian Tonka Formation in Carlin Canyon, Elko, Nevada, USA, led to the recognition of 13 species, representing 12 genera and seven ...orders: ?Antiquatonia sp., Flexaria sp., ?Marginatia sp., Echinoconchus sp. of the Productida, ?Orthotetes sp. of the Orthotetida, Rhipidomella sp., Schizophoria sp. of the Orthida, Cleiothyridina cf. sublamellosaHall, 1858, Composita sulcataWeller, 1914 of the Athyridida, Anthracospirifer shawi shawiGordon, 1975, Anthracospirifer aff. A. shawi of the Spiriferida, Punctospirifer sp. of the Spiriferinida, and Girtyella indianensisGirty, 1909 of the Terebratulida, with the addition of one undetermined linoproductid and one genus and possibly two undetermined species of the Delthyridina. The assemblage shares affinities with upper Chesterian (middle Serpukhovian) Carlinia phillipsi and C. amsdeniana associations from western North American units, though the presence of Composita sulcata makes it also close to uppermost Chesterian faunas (Rhipidomella nevadensis and Composita popsiensis zones, upper Serpukhovian). The recorded faunal association, in terms of composition at the genus-level, is characteristic of brachiopod Unit 16 of Carter (1990a). Unit 16 spans the middle Chesterian (Gnathodus bilineatus conodont Zone) to upper Chesterian (Rachistognathus muricatus conodont Zone), corresponding to the upper Visean–Serpukhovian interval. A monospecific Vogegnathus postcampbelli conodont assemblage from the same locality confirms a late Chesterian (Serpukhovian) age of the fauna.
The Smithian–Spathian transition (~249.2 Ma) is marked by profound environmental changes, carbon cycle perturbations, and the stepwise loss of nektonic biodiversity (ammonoids and conodonts). While ...biotic and abiotic changes have been intensely studied for the palaeosubtropics and palaeotropics, the global spatio-temporal pattern, including mid- to higher latitudes, remains unresolved. In this study, we present conodont and palynomorph data from the Lower Triassic Vikinghøgda Formation in the Stensiöfjellet section, Svalbard. Conodont samples from this sequence generally yielded relatively few specimens with one exception in the basal Vendomdalen Member, which proved exceptionally abundant and diverse. Most conodont samples of the Lusitaniadalen Member are typically dominated by middle to late Smithian segminiplanate forms, such as Scythogondolella spp. This exceptional horizon in the basal Vendomdalen Member, associated with the cosmopolitan ammonoid Bajarunia, indicates an earliest Spathian age. This sample presents the first-ever recorded conodont fauna from the earliest Spathian in the Boreal realm and associates segminiplanate with numerous segminate forms. The presence of an abundant and diverse segminate conodont fauna in northern mid-latitudes during the Early Triassic suggests that temperature was not the main regulator for their distribution, as opposed to segminiplanate forms, which were apparently more restricted to colder waters. Palynomorphs are poorly preserved but allow the discrimination of three assemblages. Association 1 is lycophyte spore dominated, and associations 2 and 3 are both dominated by bisaccate pollen. The change from lycophyte-dominated to a gymnosperm-dominated vegetation occurs just above the Wasatchites beds. A comparison with the records from the southern palaeosubtropics indicates that the vegetation shift was synchronous and coincided with the onset of a cooling episode, commencing in the latest Smithian.
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