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A Rare Danian (Early Paleocene) Chlamydoselachus (Chondrichthyes: Elasmobranchii) From the Takatika Grit, Chatham Islands, New Zealand

Abstract Chlamydoselachus teeth recorded from the Takatika Grit, Chatham Islands, Southwest Pacific, are Danian in age and represent a new species of Chlamydoselachidae and the oldest Cenozoic record in the world, once considered to be Lazarus taxon for the early Paleogene. The new species Chlamydoselachus tatere n. sp. is diagnosed by three prominent upright cusps that display weak ornamentation restricted to the base of the cusp, a cutting edge that reaches the root and lacks intermediate cusplets. The root is broader than long and is labiolingually shortened with a wide transverse notch and poorly differentiated lobes. The variable tooth morphology within these Chatham specimens confirms that the fossil taxon has a slight degree of intraspecific variation laterally within dentition. Posterolaterally, the cusps become more gracile with greater lingual inclination and increasing separation between cusps. Also, the root becomes labiolingually shorter and the transverse notch wider and shallower. The presence of the chlamydoselachians in the shallow marine Takatika Grit indicates that early in its evolutionary history the group may have inhabited shallow neritic environments and their teeth were more robust, possibly a reflection of the sharks predatory lifestyle.