crossopterygian
noun
cros·sop·ter·yg·ian ˌkrȯ-ˌsäp-tə-ˈri-j(ē-)ən 
: any of a subclass (Crossopterygii) of bony fishes (such as a coelacanth) that have paired fins suggesting limbs, that may be ancestral to the terrestrial vertebrates, and that are mostly extinct
called also lobe-fin
crossopterygian adjective
Word History
Etymology
New Latin Crossopterygii, subclass name, from Greek krossoi fringe + pterygion, diminutive of pteryg-, pteryx wing, fin; akin to Greek pteron wing — more at feather
First Known Use
1861, in the meaning defined above