A NEWPALAEOCTOPUS(CEPHALOPODA: COLEOIDEA) FROM THE LATE CRETACEOUS OF VALLECILLO, NORTH‐EASTERN MEXICO, AND IMPLICATIONS FOR THE EVOLUTION OF OCTOPODA

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Abstract
Abstract: Palaeoctopus pelagicussp. nov. is described from the early Turonian Vallecillo Limestone in north‐eastern Mexico. The species represents the first record of a fossil octopod from the Americas and the second species of the genusPalaeoctopus. The holotype and only known specimen preserves one half of an originally bipartite gladius vestige. Soft parts are not preserved. The gladius vestige is distinguished fromP. newboldifrom the Santonian Limestone of Lebanon by the arrangement of fields, striation and reinforcements. The new material supports previous ideas suggesting that the paired stylets of modern Octopoda evolved through gradual reduction of aTeudopsis‐like gladius via a transitional stage similar toPalaeoctopus. The origin of Octopoda and Cirroctopoda likely dates back to a period between the Toarcian (180 Ma) and the early Turonian (93 Ma). Palaeoecological conditions in the Vallecillo ocean suggest thatP. pelagicussp. nov. inhabited the pelagic shelf. Hostile low oxygen conditions on the sea floor exclude a benthic mode of life forP. pelagicussp. nov.

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