Table 2. Origination rates for bivalve functional groups.

Functional Group	Rate	N	AIC
suspension, epifaunal, immobile, cemented	0.030	45	406.2
suspension, infaunal asiphonate, mobile, unattached	0.033	70	619.1
suspension, infaunal siphonate, immobile, unattached	0.015	6	64.4
subsurface deposit, infaunal asiphonate, mobile, unattached	0.018	13	132.1
chemosymbiotic, infaunal siphonate, mobile, unattached	0.023	60	573.5
subsurface deposit, infaunal siphonate, mobile, unattached	0.019	19	190.1
surface deposit, infaunal siphonate, mobile, unattached	0.030	54	488.8
suspension, infaunal siphonate, mobile, unattached	0.042	325	2719.8
all carnivores	0.034	35	307.9
all photosymbionts	0.065	6	46.9
all borers	0.022	38	368.8
all swimmers	0.015	11	115.7
all byssate	0.020	115	1128.9

Origination rates (in genera per million years) for each functional group, as estimated from backwards survivorship curves [33], [34]. N indicates the number of genera in each group; it was necessary to combine some groups to achieve adequate sample sizes. AIC indicates the degree of support for the rate estimate.