text: However this is not the earliest clear evidence of hair in the mammalian lineage , as fossils of the docodont Castorocauda , discovered in rocks dated to about , also have traces of fur .
simplified: However this is not the earliest clear evidence of hair in the mammalian lineage , as fossils of the docodont Castorocauda , discovered in rocks dated to about 164 mya , also have traces of fur .