Faunal similarity in Madagascan and South Indian Late Cretaceous vertebrate faunas

Vertebrate evolution on the Indian raft - Biogeographic conundrums

“…The vertebrate fauna of the Cauvery basin largely comes either from the early drift phase Lower Albian to Middle Turonian Karai Formation of the Uttatur Group (Blanford, 1862;Stoliczka, 1873;Lydekker, 1879;Gowda, 1967;Paul, 1973;Ayyasami and Das, 1990;Underwood et al, 2011;Verma et al, 2012), or from the late drift phase Upper Cretaceous (Maastrichtian) Kallamedu Formation of the Ariyalur Group (Lydekker, 1879;Yadagiri and Ayyasami, 1989;Gaffney et al, 2001;Prasad et al, 2013;Goswami et al, 2012Goswami et al, , 2013Halliday et al, 2016). In recent years, attempts have been made to ascertain the biotic affinities of the vertebrate taxa recovered from this basin (Underwood et al, 2011;Verma et al, 2012;Prasad et al, 2013;Goswami et al, 2013;Verma, 2015;Halliday et al, 2016Halliday et al, , 2017.…”

“…The Kallamedu fauna thus has clades that have pan-Gondwanan affinities (gondwanatherian mammals and abelisaurid dinosaurs) Prasad et al, 2013) or Madagascan affinities (Egertonia sp., Kurmademys, simosuchid crocodyliform) (Gaffney et al, 2001;Prasad et al, 2013;Halliday et al, 2016) on one hand and a clade of Laurasian affinity such as troodontid theropod dinosaur on the other hand. Halliday et al (2017) comparing fauna of all the Late Cretaceous localities of India and Madagascar demonstrated that the faunal composition of the Kallamedu Formation is distinct fromthat of the Deccan infra-and intertrappean beds, rather it shows greater faunal similarity with the Upper Cretaceous Maevarano Formation of Madagascar, despite the fact that the two landmasses were separated several million years ago.…”

“…Patriat and Segoufin (1988) had suggested a Late Cretaceous connection between Madagascar and India across the Seychelles Plateau and volcanic islands through which transoceanic dispersal were possible, a hypothesis supported later by Rage (1996). Using faunal similarity network analyses, Halliday et al (2017) demonstrated close Late Cretaceous faunal similarities between India and Madagascar and suggested trans-oceanic dispersal of terrestrial and freshwater taxa between the two landmasses across a series of islands. While debunking the southern Kerguelen Plateau terrestrial route, Ali and Aitchison (2008) felt that the only possible link between India and Africa was through the Seychelles, Amirante Ridge, Providence Bank and Madagascar.…”

Binary Coefficients Redux

“…However, since the publication of his papers, Halliday et al (2017) used his modified form of the Forbes coefficient in cluster analysis of Late Cretaceous vertebrates across India. Although the papers by Alroy and by Halliday et al describe ordination and cluster analysis of localities, the same problem of uneven sampling exists in analysis of taxa and their arguments and findings should have application in R-mode analysis as well.…”