Relating to or characteristic of actinopterygian fish, having ray-supported fins.
From actinopterygian plus the adjectival suffix -ous, meaning 'of or relating to ray-finned fish.'
When you see a goldfish, tuna, or salmon, you're looking at an actinopterygious fish—the fact that their fins are supported by delicate rays instead of fleshy lobes made them vastly more adaptable than their ancient cousins.
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