Aplocheilidae Indian Ocean to Thailand Aplocheilus McClelland, 1839 Pachypanchax Myers, 1933 Bleeker, 1859 Cynolebiidae South America, Europe, Asia Cynolebiini Hoedeman, 1961 Cynopoecilini Costa, 1990 Kryptolebiinae Costa, 2004 Neofundulini Costa, 1990 Plesiolebiina Rachoviini Costa, 1990 Rivulini Myers, 1925 Hoedeman, 1961 (Cynolebiidae was formerly Rivulidae (Myers 1925)

Nothobranchiidae Africa Adamantini Huber, 2000 Callopanchini Huber, 2000 Epiplateini Huber, 2000 Nothobranchiini Garman, 1895 Garman, 1895 †Kenyaichthyidae Kenya The evolution of fish can be seen in the way the tail fin and more important;y the bones that drove it. Sharks and rays have a backbone that goes right the way to the end of the fin. Gar, a primitive fish all its own, have the same arrangement but with the beginnings of a lower tail bone structure. Later, fishes evolved to have the backbone connected to a bony plate and that bony plate then drove the rays of the tail fin. Over a long period of time this caudal plade reduced in size and ended up being one more piece of the backbone, right at the end and no longer involved with any fin rays.. Instead the fin rays of the tail mesh directly with  the fin rays of the backbone, overall a more efficient and stronger design. Altner & Reichenbacher 2015 The only fossil Aplocheilid Killifish known has been placed in this genus representing an unknown archaic lineage. The triangular plural caudal plate (shown here in red) is a characteristic of ancient fishes (even Coelacanths are more evolved than this), while more modern fish have a tiny vestigial bone where the hyplural used to be and it ends up in fact becoming one of the last pieces of the tailbone. In modern fish the rays of the backbone mesh with ther tail fin rays while in ancient fish the tailbone connects to the caudal/hypural plate which in turn connects to the fin rays of the tail fin. Only half a dozen species of killifish have a large hypural plate like this and they share thet in common with the extinct genus KLanyaichtghys. WHat's curious about this is that the fossil samples used to describe this species all showed varying degrees of evolution in the hypural plate and while there is variation in a similar way in living killifish, it is nowhere near as pronounced here. It might on the other hand represent four different fish at four different stages of evolution that appear to have lived at the same time - just as they do today - in the same place.