Table 1. GLM results for acritarch genus diversity per 5° latitudinal band for the Cambrian stage 4, the Darriwilian, and the Hirnantian.

Only the two or three best models (i.e., with the lowest AICc value and highest Akaike weight) from all possible combination of the variables considered are shown here for each time interval. Empty cells indicate a variable not included in the corresponding model (i.e., a variable that does not increase the predictability of taxonomic richness). Neg. bin., negative binomial; CSA, continental shelf area (10⁶ km²); SST_an, mean annual SST; SST², squared SST; SST_diff, difference between summer and winter SST; SSS_an, mean annual SSS; SSS², squared SSS; SSS_diff, difference between summer and winter SSS; and ∅, not applicable (AICc not being computable for negative binomial GLMs). Dispersion = residual deviance/degrees of freedom, overdispersion when >1.

Temporal interval	Family	Dispersion	R2	CSA	SSTan	SST2	SSTdiff	SSSan	SSS2	SSSdiff	AICc	Akaike weight
Cambrian stage 4	Poisson	1.477	0.66				0.056		0.003		163	0.114
	Poisson	1.489	0.66				0.055	0.236			163	0.101
	Neg. bin.	1.092	0.66				0.053		0.003		164	∅
Darriwilian	Poisson	0.301	0.96		−0.071			16.815	−0.242		125	0.31
	Poisson	0.322	0.96			−0.001		12.758	−0.184		126	0.262
Hirnantian	Poisson	2.276	0.91	0.172	−0.244		0.271		0.017		123	0.303
	Poisson	2.279	0.91	0.175	−0.244		0.268	1.139			123	0.297
	Neg. bin.	1.202	0.92	0.199	−0.264		0.286		0.018		121	∅