Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Most of these probably had an endobenthic lifestyle, because their morphology is similar to that of extant taxa under such conditions [Corliss, 1991; Buzas et al., 1993; Jorissen et al., 2007].
Category: