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The group took quite a hit at the Cretaceous – Paleogene boundary ( K – T boundary ) , with only the Pleurotomariidae surviving the Cretaceous – Paleogene extinction event – and then only in deep waters .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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