is complete, contains 33-44 perforated scales, and runs along the midline of the body. The dentary bears a short lateral-line canal ending at or shortly behind mid-length, and altogether the lateral-line canals of the head are divided into at least two ossified tubes. All anostomids have an adipose fin; their dorsal fin contains one and 11, the anal fin one and 9, and the pelvic fins one and 8-9 hard and soft rays, respectively. Systematics and evolution This family is in all probability monotypic as traditionally defined. Several attempts to delimit subfamilies have taken place, and several of the proposed groupings indeed correspond to clades within this family. Leporellus has long been recognized as the basal-most living anostomid genus, due to its many plesiomorphies shared with the Chilodontidae and its peculiar apomorphies, and separated as a monotypic subfamily by some. A large clade of "modern" genera was treated as Anostominae by some authors; others considered that subfamily more inclusive. But the latter view is incorrect, as it includes a large number of lineages that are really basal members of the family and should not be treated as a subfamily (except monotypic ones, but these are generally avoided). Also, the huge assemblage usually treated under Leporinus is not monophyletic and in need of thorough study, to see how it is best divided. Depending on the exact relationships of Anostomoides, a Leporinus sensu lato clade could warrant recognition as another subfamily. Finally, Rhytiodus and Schizodon would almost certainly qualify as another subfamily, even if only the Anostominae warrant recognition otherwise. Evolution and fossil record The taxon Anostominae is also used to denote the entire family in outdated treatments, where the name "Anostomidae" is applied to the entire Anostomoidea (and sometimes even more distant relatives). In that respect, agreement is widespread today that the closest living relatives of the Anostomidae sensu stricto are the Chilodontidae headstanders, the toothless characins (Curimatidae) and the flannel-mouthed characins (Prochilodontidae). The origin of the Anostomidae can be quite confidently placed in the Paleogene, and somewhat less securely in late Paleogene, based on various evidence. For one, the biogeography of the family, with some very basal taxa found west of the Andes, indicates it was already well distinct when the northern part of that mountain range uplifted at the end of the Middle Miocene about 12 million years ago (Mya). Then, some scant but highly informative fossil evidence assigned