Can someone explain why the correct answer is D and while the other answers are wrong please. F. Bossuyt, M. C. Milinkovitch. Amphibians as indicators of early tertiary \"out-of-India\" dispersal of vertebrates. Science 292, 93 (2001) This tree depicts inferred relationships among some major frog groups with branches drawn proportional to absolute time. Error bars on internal nodes depict confidence intervals on the dates of estimated nodes. Assuming this tree and the associated ages are correct which of the following statements is true? No individual living before 70 million years ago is an ancestor of Raninae Raninae and Dicroglossinae shared a common ancestor about 75 million years ago The divergence of Raninae and Nyctibatrachinae occurred more recently than the 85 million year old separation of India from Madagascar The last common ancestor of Micrixalinae and Dicroglossinae lived before India and Madagascar separated (85 million years ago) Solution The separation of the Madagascar and India-Seychelles landmasses was initiated by a mantle plume generating large quantities of basaltic magma that quickly formed an obstacle for faunal interchange. Rhacophorine tree frogs, which radiated almost exclusively in the Oriental realm into about 300 species dispersed out of India. The only African rhacophorine genus (Chiromantis, not included in our analyses) was shown to be nested well within this Asian clade, so it must have reached Africa over land. Raninae (including the genus Rana) currently have a cosmopolitan distribution (except for southern South America and most of Australia). These analyses indicate lineage originated on the drifting insular block and radiated into more than 200 species, probably after its “out-of-India” dispersal . Consistent with this scenario, the earliest known European fossils of the genus Rana are only of Oligocene age (24 to 34 Ma), whereas much older fossils would likely have been found if the lineage originated in Africa or Eurasia. The Dicroglossinae form a third out-of-India lineage. They experienced their main radiation on Asia, and only a limited number of members (e.g., Hoplobatrachus) reached Africa. Because various lineages of ranid frogs originated between 130 and 88 Ma, it is likely that several of them were present on Madagascar when it broke up from the IndiaSeychelles landmass. Although fossils of ranids have not been found from the Latest Cretaceous of Madagascar, the importance of this negative evidence is difficult to evaluate given that the Madagascan fossil frog record from that period is extremely poor and is restricted to a northwestern site of the island.This divergencetime analyses here indicate that Mantellinae experienced their initial radiation on Madagascar around the K-T boundary. Madagascan representatives of other lineages experienced either competitive take-overs or, more probably, extinction or opportunistic replacements associated with global or local crises. The absence of extant .

1. Can someone explain why the correct answer is D and while the other answers are wrong please.
F. Bossuyt, M. C. Milinkovitch. Amphibians as indicators of early tertiary "out-of-India"
dispersal of vertebrates. Science 292, 93 (2001) This tree depicts inferred relationships among
some major frog groups with branches drawn proportional to absolute time. Error bars on
internal nodes depict confidence intervals on the dates of estimated nodes. Assuming this tree
and the associated ages are correct which of the following statements is true? No individual
living before 70 million years ago is an ancestor of Raninae Raninae and Dicroglossinae shared
a common ancestor about 75 million years ago The divergence of Raninae and Nyctibatrachinae
occurred more recently than the 85 million year old separation of India from Madagascar The
last common ancestor of Micrixalinae and Dicroglossinae lived before India and Madagascar
separated (85 million years ago)
Solution
The separation of the Madagascar and India-Seychelles landmasses was initiated by a mantle
plume generating large quantities of basaltic magma that quickly formed an obstacle for faunal
interchange.
Rhacophorine tree frogs, which radiated almost exclusively in the Oriental realm into about 300
species dispersed out of India. The only African rhacophorine genus (Chiromantis, not included
in our analyses) was shown to be nested well within this Asian clade, so it must have reached
Africa over land. Raninae (including the genus Rana) currently have a cosmopolitan distribution
(except for southern South America and most of Australia). These analyses indicate lineage
originated on the drifting insular block and radiated into more than 200 species, probably after its
“out-of-India” dispersal . Consistent with this scenario, the earliest known European fossils of
the genus Rana are only of Oligocene age (24 to 34 Ma), whereas much older fossils would
likely have been found if the lineage originated in Africa or Eurasia. The Dicroglossinae form a
third out-of-India lineage. They experienced their main radiation on Asia, and only a limited
number of members (e.g., Hoplobatrachus) reached Africa.
Because various lineages of ranid frogs originated between 130 and 88 Ma, it is likely that
several of them were present on Madagascar when it broke up from the IndiaSeychelles
landmass. Although fossils of ranids have not been found from the Latest Cretaceous of
Madagascar, the importance of this negative evidence is difficult to evaluate given that the
Madagascan fossil frog record from that period is extremely poor and is restricted to a
northwestern site of the island.This divergencetime analyses here indicate that Mantellinae
experienced their initial radiation on Madagascar around the K-T boundary. Madagascan

2. representatives of other lineages experienced either competitive take-overs or, more probably,
extinction or opportunistic replacements associated with global or local crises. The absence of
extant native ranid frogs on the Seychelles is likely related to the breakup of these islands from
India being caused by and hence, coinciding with the emergence of the mantle plume that
produced the gigantic Deccan trap volcanism.