A type of extinct fish or a fossil specimen, possibly related to Crossopterygii classification in ichthyology.
From 'cross-' + 'opt' (possibly from Greek 'opsis', meaning appearance or vision). This appears to be a specialized paleontological or taxonomic term with limited historical documentation.
Obscure scientific words like this remind us that taxonomy is constantly being refined—what scientists called a 'crossopt' a century ago might be classified completely differently today!
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