Platinx is an extinct genus of marine ray-finned fish that inhabited the northern Tethys Ocean during the early to middle Eocene.

[1] It was the last surviving member of the ancient order Crossognathiformes, which was a dominant and successful group throughout the preceding Mesozoic era.

[2][3] It contains a single species, P. macropterus, whose remains are primarily known from the late Ypresian-aged rocks of Monte Bolca, Italy.

[4] However, specimens have also been recovered from the earliest-Ypresian Danata Formation of Turkmenistan (sometimes placed in their own distinct species, P. cognitus Daniltshenko, 1968, although these do not appear to be distinct enough from P. macropterus),[3] as well as incomplete remains from the middle Eocene of Syria.

[5] The extinct bonytongues Monopteros and Thrissopterus, which co-occur with Platinx in Monte Bolca, were for a time briefly reclassified as a species of Platinx (P. gigas), although they are now known to be distinct.