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Gondwana

About: Gondwana is a research topic. Over the lifetime, 6078 publications have been published within this topic receiving 263050 citations. The topic is also known as: Gondwanaland.


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Journal ArticleDOI
TL;DR: A review of paleontological, phyletic, geophysical, and climatic evidence leads to a new scenario of land mammal dispersal among South America, Antarctica, and Australia in the Late Cretaceous to early Tertiary epochs as mentioned in this paper.
Abstract: A review of paleontological, phyletic, geophysical, and climatic evidence leads to a new scenario of land mammal dispersal among South America, Antarctica, and Australia in the Late Cretaceous to early Tertiary epochs. New fossil land vertebrate material has been recovered from all three continents in recent years. As regards Gondwana, the present evidence suggests that monotreme mammals and ratite birds are of Mesozoic origin, based on both geochronological and phyletic grounds. The occurrence of monotremes in the early Paleocene (ca. 62 Ma) faunas of Patagonia and of ratites in late Eocene (ca. 41-37 m.y.) faunas of Seymour Island (Antarctic Peninsula) probably is an artifact of a much older and widespread Gondwana distribution prior to the Late Cretaceous Epoch. Except for South American microbiotheres being australidelphians, marsupial faunas of South America and Australia still are fundamentally disjunct. New material from Seymour Island (Microbiotheriidae) indicates the presence there of a derived taxon that resides in a group that is the sister taxon of most Australian marsupials. There is no compelling evidence that dispersal between Antarctica and Australia was as recent as ca. 41 Ma or later. In fact, the derived marsupial and placental land mammal fauna of Seymour Island shows its greatest affinity with Patagonian forms of Casamayoran age (ca. 51–54 m.y.). This suggests an earlier dispersal of more plesiomorphic marsupials from Patagonia to Australia via Antarctica, and vicariant disjunction subsequently. This is consistent with geophysical evidence that the South Tasman Rise was submerged by 64 Ma and with geological evidence that a shallow water marine barrier was present from then onward. The scenario above is consistent with molecular evidence suggesting that australidelphian bandicoots, dasyurids, and diprotodontians were distinct and present in Australia at least as early as the 63-Ma-old australidelphian microbiotheres and the ancient but not basal australidelphian,Andinodelphys, in the Tiupampa Fauna of Bolivia. Land mammal dispersal to Australia typically has been considered to be at a low level of probability (e.g., by sweepstakes dispersal). This study suggests that the marsupial colonizers of Australia included already recognizable members of the Peramelina, Dasyuromorphia, and Diprotodontia, at least, and entered via a filter route rather than by a sweepstakes dispersal.

243 citations

Journal ArticleDOI
TL;DR: The Steptoean positive carbon isotope excursion (SPICE) as discussed by the authors is a global oceanographic event that confirms intercontinental correlations between different biogeographic realms based on agnostids and other blue-water trilobites.

239 citations

Journal ArticleDOI
TL;DR: In this paper, the authors reported age data on zircon, monazite, uraninite and huttonite from a suite of 29 samples covering four major granulite blocks in southern India using an electron microprobe technique.

239 citations

Journal ArticleDOI
Abstract: The Mozambique Ocean closed as Gondwana formed. Its suture has been identified in Madagascar (Betsimisaraka suture), but its continuation, into India, is controversial. The Palghat-Cauvery shear system appears an ideal candidate as it: (i) lies along strike of the Betsimisaraka suture in Gondwana; (ii) forms a high-pressure granulite belt; and (iii) separates crustal domains with different geological histories. However, existing age constraints have been used to suggest that the structure is Archaean/Palaeoproterozoic. Here we date metamorphic zircons using secondary ion mass spectrometry (535.0 ± 4.9 Ma) and monazites using electron probe micro-analysis (537 ± 9, 532 ± 8, 525 ± 10 Ma). No evidence for an earlier metamorphic event was found. The identification of Palghat-Cauvery high-pressure metamorphism as Cambrian, and recognition that it bounds crustal domains of contrasting origin, points to it being the southern continuation of the Betsimisaraka suture and southern margin of Neoproterozoic India.

238 citations

Journal ArticleDOI
TL;DR: In this article, the authors attempt to assemble the Early Phanerozoic paleomagnetic results in map-form so that in which they can be compared with the geological evidence.
Abstract: The maps are intended as an attempt to assemble the Early Phanerozoic paleomagnetic results in map-form so that in which they can be compared with the geological evidence. Relative longitude is estimated by minimizing relative motions among the continents. This approach also provides a useful means of discussing the "polarity problem" in constructing polar wander curves. Six stages are tentatively recognized: (1) at the end of the Precambrian the continental crust is assembled into a supercontinent with the Siberian Shield in the southern hemisphere adjacent to eastern Gondwana; (2) the supercontinent is fragmented in the Early Cambrian; (3) it is reassembled in the Late Silurian (Caledonian Orogeny); (4) undergoes internal adjustments in the Devonian by the sinistral rotation of Laurasia relative to Gondwana (Acadian Orogeny); (5) it breaks-up again in the Late Devonian; and (6) is reassembled in the Middle Carboniferous (Hercynian-Appalachian Orogeny). These succession of stages is regarded as the surfa...

238 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023269
2022497
2021307
2020281
2019293
2018230