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A new middle Eocene sirenian (Mammalia, Protosirenidae) from India

2009; E. Schweizerbart; Volume: 252; Issue: 3 Linguagem: Inglês

10.1127/0077-7749/2009/0252-0257

2363-717X

Sunil Bajpai, Daryl P. Domning, Debi P. Das, V. P. Mishra,

Fish biology, ecology, and behavior

Ashokia antiqua is a new genus and species of protosirenid sirenian based on a subadult skull from the early middle Eocene (Lutetian) Harudi Formation of Kutch district, Gujarat State, western India. While more derived than prorastomids, and more primitive than trichechids or dugongids, in comparison with other protosirenids it displays a mosaic of primitive and derived character states that places it at the evolutionary grade of a relatively primitive protosirenid. Cladistically, its sister group may be an unnamed genus and species of protosirenid from the Lutetian of Libya, which shares with it several synapomorphies of the zygomatic arch and ear region. This relationship with the unpublished Libyan form reinforces a pattern in Eocene paleobiogeography previously noted by SAGNE (2001): generically-distinct and endemic sirenian faunas on the north and south shores, respectively, of the former Tethys Seaway. The Kutch sirenian fauna, with Eotheroides, Eosiren, Protosiren, and now a relative of the Libyan protosirenid, resembles the fauna from North Africa, while the European genera Halitherium, Prototherium, and Sirenavus are absent - as predicted by SAGNE's (2001) hypothesis.