England 260 (Jones 70*, Dunkley 57) beat West Indies 118 (Williams 54*, Bell 4-33) by 142 runs
In an improved performance with the ball and in the field after their heavy 142-run defeat in the series opener, West Indies managed to bowl England out for 260 in 48.1 overs, despite Jones' unbeaten 70 and 57 to Dunkley.
But Bell took two wickets from her first three deliveries, had 3 for 3 from two overs, and ended a seven-over first spell with 4 for 26 which left West Indies reeling at 50 for 6 inside the first 10 overs of their reply.
Playing just her fifth ODI and eighth international overall after making her debut in the June Test against South Africa, Bell exploited some eye-catching lateral movement from the outset.
She had Hayley Matthews, the West Indies captain, out driving at a fuller delivery outside off which sailed to Heather Knight at slip, and it was a similar delivery which accounted for Kycia Knight as Bell got one to move away from the left-hander and wicketkeeper Jones gathered.
Cross, a decade her senior at 31, struck with the first ball of her second over when she had Aaliyah Alleyne caught behind as West Indies lurched to 3 for 4 in the third over of their innings. Bell then struck Shemaine Campbelle on the pad with a yorker to claim her third and the hosts were in disarray at 8 for 4.
Cross produced the first short ball of her spell to find the bottom edge off Chedean Nation's attempted to pull and Jones did the rest to make it 28 for 5, then Shabika Gajnabi went chasing a short ball down the leg side to gift Bell her fourth wicket, and Jones her fourth catch of the match.
Dean chimed in with the wickets of Afy Fletcher and last batter Sheneta Grimmond to bookend Ecclestone's dismissal of Cherry-Ann Fraser with one that clipped the top of off-stump.
England elected to bat and made just one change, their hand forced by Alice Capsey's return home with a broken collarbone suffered while fielding on Sunday. Capsey had been promoted to open that game but her absence this time meant Emma Lamb returned to the role she held with distinction against South Africa in July before falling away during India's 3-0 sweep of their ODI series later in the summer, where her highest score was 21.
Lamb and Tammy Beaumont settled well enough, reaching 42 without loss but then Lamb was run out by Campbelle and, when Beaumont chipped Alleyne to Gajnabi at mid-on, England were 65 for 2.
Dunkley reached fifty top-edging a pull off Fraser for four as she and Knight put on 51 runs for the fourth wicket before Matthews had Knight caught behind. Dunkley departed when she side-stepped trying to slog-sweep Fletcher only to see her stumps splattered.
Jones picked up where Dunkley left off, however, easing her way to a 49-ball fifty. She lofted Fraser straight down the ground for her eighth four, but she was left stranded on 70 from 63 balls, her highest score since 2019 and only her second fifty this year. Matthews picked up the last two wickets - taking a return catch off Cross and deceiving Bell with one that clattered into middle and off - to end with 3 or 50 from 9.1 overs.
Despite failing to see out their allocation, England could take some assurance from the fact West Indies hadn't reached 200 in their previous nine ODI innings, but it was their opening bowlers who put the result beyond doubt.
Valkerie Baynes is a general editor at ESPNcricinfo