Name: Holoptychius.
Phonetic: Hol-op-tie-ke-us.
Named By: Louis Agassiz‭ ‬-‭ ‬1835/39/43‭?
Classification: Chordata,‭ ‬Sarcopterygii,‭ ‬Porolepiformes,‭ ‬Holoptychiidae.
Species: H.‭ ‬americanus,‭ ‬H.‭ ‬flemingi,‭ ‬H.‭ ‬giganteus,‭ ‬H.‭ ‬halli,‭ ‬H.‭ ‬hopkinsii,‭ ‬H.‭ ‬nobilissimus.
Diet: Carnivore/Piscivore.
Size: Between 0.5 and 2.5 meters long with‭ ‬some variation between species.
Known locations: Possibly worldwide with some known locations including Belgium,‭ ‬Russia and the United Kingdom.
Time period: Givetian of the Devonian through to the Bashkirian of the Carboniferous.
Fossil representation: Many individuals.

       Holoptychius seems to have been a particularly widespread genus of lobe-finned fish.‭ ‬Like relative genera,‭ ‬the body was streamlined with most of the fins in a more rearward placement on the body.‭ ‬The scales were fairly large and round,‭ ‬and the tail was asymmetrical with an upper lobe far more greatly developed than the lower.‭ ‬Because fish are driven by a‭ ‬rearward propulsion of the tail they have a tendency to nosedive into the depths,‭ ‬but the effect is magnified far greater if the upper lobe of the tail is more strongly developed.‭ ‬To counter this effect,‭ ‬the pectoral fins‭ (‬the forward pair near the head‭) ‬are angled to act as hydroplanes to counter this down pitching.‭ ‬The pectoral fins of Holoptychius are particularly large suggesting that Holoptychius were particularly fast swimmers.

More information on the above fish can be found on their corresponding pages; Ceratodus, Chinlea, Dipnorhynchus, Dipterus, Eusthenopteron, Gooloogongia, Griphognathus, Gyroptychius, Holoptychius, Hyneria, Macropoma, Mandageria, Osteolepis, Panderichthys, Rhizodus, Strunius, Tiktaalik (upper estimate).

Further reading
-‭ ‬A synopsis of the classification of the British Palaeozoic rocks,‭ ‬with a systematic description of the British Palaeozoic fossils.Fasciculus‭ ‬3,‭ ‬Mollusca and Palaeozoic fishes‭ ‬-‭ ‬F.‭ ‬M'Coy‭ ‬-‭ ‬1855.


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