Topic
Dicynodon
About: Dicynodon is a research topic. Over the lifetime, 62 publications have been published within this topic receiving 1929 citations.
Papers published on a yearly basis
Papers
TL;DR: The Permian-Triassic boundary is recognized from the last appearance of Dicynodon and from a series of negative excursions in the isotopic composition of carbon within therapsid tusks, pedogenic carbonate nodules, and organic matter as mentioned in this paper.
Abstract: Distinct assemblages of paleosols above and below the Permian–Triassic boundary in the Karoo Basin of South Africa are evidence for reorganization of ecosystems following this greatest of all mass extinctions. The Permian–Triassic boundary is recognized from the last appearance of Dicynodon and from a series of negative excursions in the isotopic composition of carbon within therapsid tusks, pedogenic carbonate nodules, and organic matter. The boundary is also marked by laminated beds with very weakly developed paleosols, a change from purple (10R) to brownish red (2.5YR) paleosols, and a thin (10-cm) claystone breccia of reworked soil clasts. Paleoclimatic changes include a shift from arid and highly seasonal paleoclimate inferred from diffuse and shallow calcareous nodules in Permian paleosols to semiarid and less seasonal paleoclimate inferred from deep and well-focused calcic horizons in Triassic paleosols. An earliest Triassic shift to warmer and wetter paleoclimate is also indicated by increased chemical weathering, abundance of lycopsids, and diversity of labyrinthodonts. Permian paleosols have root traces comparable to those of open shrubland and riparian woodland, whereas Triassic paleosols have root traces and profile forms like soils of open woodland. This is a significant paleoenvironmental change, but not as dramatic a change as would be expected from the devastating extinctions of 88% of fossil vertebrate genera. Latest Permian therapsid reptiles were diverse and ecologically specialized. In contrast, the principal earliest Triassic therapsid, Lystrosaurus , was a burrower with no specific habitat preference. Its short internal nares, barrel chest, and high neural spines would have given it greater aerobic scope than preexisting therapsids and may have been an advantage under conditions of hypercapnia and hypoxia. These adaptations and associated ecosystem changes are compatible with widespread vertebrate mortality by acidosis and pulmonary edema in a post-apocalyptic greenhouse created by the voluminous release of methane from shallow marine and permafrost clathrates.
232 citations
TL;DR: Lifestyle is inferred to have been terrestrial for the stem‐tetrapod Discosauriscus, the basal synapsid Dimetrodon, the dicynodont therapsid Dicynodon, an unindentified gorgonopsian, and the parareptile Pareiasaurus, which is modelled as being aquatic, but was more likely amphibious.
Abstract: Bone microanatomy appears to track changes in various physiological or ecological properties of the individual or the taxon. Analyses of sections of the tibia of 99 taxa show a highly significant (P
149 citations
TL;DR: In this paper, the authors report a large δ 13 C excursion at the Permian-Triassic boundary and no long-term permian Δ 13 C trends for samples from the interior of Pangea.
Abstract: The rate, timing, and pattern of change in different regions and paleoenvironments are critical for distinguishing among potential causes for the Permian-Triassic (P-T) extinction. Carbon isotopic stratigraphy can provide global chronostratigraphic control. We report a large δ 13 C excursion at the P-T boundary and no long-term Permian δ 13 C trends for samples from the interior of Pangea. Stratigraphic gaps between available samples limit the resolution of our δ 13 C curve, but the excursion is within a 15-m-thick zone of overlap between Permian and Triassic taxa. Sedimentological and taphonomic observations demonstrate that this 15 m interval does not represent geologically instantaneous deposition. Together these data support a rapid and globally synchronous P-T event, but suggest that it occurred over a geologically resolvable interval of time.
139 citations
1 Jan 2014
TL;DR: In this paper, a comprehensive taxonomic revision of the dicynodonts of the Luangwa Basin, taking into account specimens in all major museum collections and new material collected by their team in 2009, was presented.
Abstract: Dicynodont fossils were first collected in the Luangwa Basin, Zambia, in the 1920s, but limited detailed study and taxonomic uncertainty have obscured their biostratigraphic utility and their implications for topics such as dicynodont biogeography and the effects of the end-Permian extinction. Here we present a comprehensive taxonomic revision of the dicynodonts of the Luangwa Basin, taking into account specimens in all major museum collections and new material collected by our team in 2009. We recognize 14 dicynodont species from the Upper Permian Upper Madumabisa Mudstone: Pristerodon mackayi, Endothiodon sp., Diictodon feliceps, Compsodon helmoedi, Emydops sp., Dicynodontoides cf. D. nowacki, a new tusked cistecephalid, cf. Katumbia parringtoni, Kitchinganomodon crassus, Oudenodon bainii, Odontocyclops whaitsi, Dicynodon huenei, Syops vanhoepeni, and a new lystrosaurid. Previous reports of Lystrosaurus in the basin appear to be in error. In addition, we found no significant partitioning of dicynodont taxa in the northern and southern parts of the basin, despite substantial differences in preservation, indicating the presence of a single faunal assemblage in the Upper Permian. The Madumabisa dicynodont assemblage is best correlated with the Cistecephalus Assemblage Zone of South Africa. The shared presence of Dicynodon huenei and possibly Katumbia in the Luangwa Basin and the Ruhuhu Basin of Tanzania suggests that the Tanzanian Usili Formation also can be correlated with the Cistecephalus zone. Interestingly, the Madumabisa assemblage from Zambia is more similar to the coeval assemblage from South Africa, despite its closer geographic proximity to Tanzania. The Karoo and Ruhuhu basins also include more endemic species in the Permian than the Luangwa Basin. The Middle Triassic Ntawere Formation preserves four dicynodont species (Kannemeyeria lophorhinus, “Kannemeyeria” latirostris, Zambiasaurus submersus, Sangusaurus edentatus), which occur at two stratigraphic levels. The lower Ntawere assemblage resembles that of the Omingonde Formation of Namibia in the presence of Kannemeyeria lophorhinus and potentially Dolichuranus (if “K.” latirostris represents this taxon). The upper Ntawere assemblage shares the genus Sangusaurus with that of the Manda beds of Tanzania and includes the endemic Zambiasaurus. Comparisons of these assemblages to the Omingonde and Manda suggest that both are best correlated with the Cynognathus C subzone. When combined with data on other tetrapod taxa, our revised dicynodont assemblages contribute to an emerging picture of broad faunal similarity in southern and eastern Africa during the Late Permian, and increasing differentiation between the South African and other Karoo basins following the end-Permian extinction.
104 citations
TL;DR: The Dicynodon Assemblage Zone (DiAZ) of South Africa's Karoo Basin is one of the eight biostratigraphic zones of the Beaufort Group as discussed by the authors.
102 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2020 | 2 |
| 2019 | 2 |
| 2018 | 3 |
| 2017 | 1 |
| 2016 | 3 |
| 2015 | 2 |