At the beginning of the 21st century, the discovery of an involucrum on the auditory bulla of Indohyus, a small raoellid artiodactyl from the Indian subcontinent, triggered the phylogenetic gathering of Raoellidae with the Cetacea clade, making them pivotal in addressing questions surrounding the land-to-water transition in Artiodactyla. Micro CT scan investigations and newly collected material from the Kalakot area (Jammu and Kashmir, India), recently greatly increased our knowledge of the cranial and dental features of this group. Here we present new data on cranial morphology of Raoellidae deriving from micro CT scan investigations of Indohyus indirae and Khirtharia inflata. This new body of data comprises investigations of the endocast of the braincase, the complete middle ear including the ossicles and auditory bulla, the petrosal bone, and the cast of the bony labyrinth. It also includes the reconstruction of the complete anterior dentition. This study gives us a comprehensive picture of the features of the Raoellidae head and improves our understanding of their semiaquatic habits. This increased knowledge of raoellids further extends the list of features they share with the first archeocetes, calling into question the definition of the clade Cetacea.
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RBINS Staff Publications 2025 OA
Two species have been attributed to the genus Teretoctopus Robson, 1929: T. indicus Robson, 1929, the type species of the genus, and T. alcocki Robson, 1932. Of the four original T. alcocki syntypes, we relocate and redescribe the remains of two of them, and designate one of them the lectotype. Of three original T.indicus syntypes, it is probable that one is lost permanently, but the whereabouts of two of them remains unknown. What we can discern from remaining T. alcocki type material, augmented with descriptions of these specimens by Anne Massy and Guy Robson, is compared with what is known of the type species of this genus, T. indicus. A rediagnosis of the genus Teretoctopus is proffered, and relationships between this genus and others historically referred to as “inkless octopuses” are evaluated. While Teretoctopus has nomenclatural priority over Vulcanoctopus González et Guerra, 1998 and Muusoctopus Gleadall, 2004, for which it is possibly the senior synonym, and shares many characters and states with Ameloctopus Norman, 1992, further taxonomic resolution of relationships among these genera must await description and molecular analyses of accurately identified Teretoctopus specimens from the Gulf of Oman and northern Arabian Sea.
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RBINS Staff Publications 2026 OA
