Catostomid fishes appear to have 2n(-->4n?) approximately 100 chromosomes. The Cyprinidae, from which catostomids probably diverged before the Eocene, usually have 2n = 48 or 50 chromosomes. Preliminary cytophotometric measurements indicate an approximate doubling of DNA content of cells among catostomids.

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An analysis of the chromosomes of the rainbow trout, Salmo gairdneri, revealed one triploid individual among 18 specimens examined. The diploid specimens possessed 60 chromosomes, whereas the single triploid possessed approximately 90. Suppression of the second meiotic division followed by fertilization of the unreduced oocyte is the most likely mechanism by which triploidy was achieved in this fish.

To investigate the morphology and evolutionary origin of muscles in vertebrate limbs, we conducted anatomical dissections, computed tomography and kinematic analyses on the pectoral fin of the African coelacanth, Latimeria chalumnae. We discovered nine antagonistic pairs of pronators and supinators that are anatomically and functionally distinct from the abductor and adductor superficiales and profundi. In particular, the first pronator and supinator pair represents mono- and biarticular muscles; a portion of the muscle fibers is attached to ridges on the humerus and is separated into two monoarticular muscles, whereas, as a biarticular muscle, the main body is inserted into the radius by crossing two joints from the shoulder girdle. This pair, consisting of a pronator and supinator, constitutes a muscle arrangement equivalent to two human antagonistic pairs of monoarticular muscles and one antagonistic pair of biarticular muscles in the stylopod between the shoulder and elbow joints. Our recent kinesiological and biomechanical engineering studies on human limbs have demonstrated that two antagonistic pairs of monoarticular muscles and one antagonistic pair of biarticular muscles in the stylopod (1) coordinately control output force and force direction at the wrist and ankle and (2) achieve a contact task to carry out weight-bearing motion and maintain stable posture. Therefore, along with dissections of the pectoral fins in two lungfish species, Neoceratodus forsteri and Protopterus aethiopicus, we discuss the functional and evolutionary implications for the fin-to-limb transition and subsequent evolution of tetrapods. Anat Rec, 299:1203-1223, 2016. © 2016 Wiley Periodicals, Inc.

A review of the chondrichthyan and osteichthyan fish fossils found in Japan is provided in the form of a series of tabular compilations covering the Late Mesozoic and Cenozoic Era. On the basis of this compilation, considerable changes are recognized in the fish faunas over a period of time. At the end of the Cretaceous Period a number of cartilaginous fishes disappeared. From the Oligocene to the Miocene, modern sharks including the family Carcharhinidae increased, whereas the Hexanchidae and Lamnidae declined. Most Miocene teleostean fishes differ from the Recent congeners at the species level.