Name: Eusthenopteron
Phonetic: You-sten-op-teh-ron.
Named By: J.‭ ‬F.‭ ‬Whiteavis‭ ‬-‭ ‬1881.
Classification: Chordata,‭ ‬Vertebrata,‭ ‬Sarcopterygii,‭ ‬Tetrapodomorpha,‭ ‬Osteolepidida,‭ ‬Tristichopteridae.
Species: E.‭ ‬foordi‭ (‬type‭)‬,‭ E. jenkinsi, ‬E.‭ ‬savesoderberghi.
Type: Carnivore.
Size: Various sizes known,‭ ‬potentially up to‭ ‬1.8‭ ‬meters long.
Known locations: Canada,‭ ‬Quebec,‭ ‬Miguasha.‭
Time period: Givetian to Frasnian of the Devonian.
Fossil representation: Known from thousands of Specimens.

       The most notable features of Eusthenopteron are the powerfully built pectoral and pelvic fins.‭ ‬This led to early speculation that Eusthenopteron could use these fins to crawl out of the water and onto land.‭ ‬This in turn led to Eusthenopteron being classed by some as a link to the early tetrapods.
       Today however,‭ ‬Eusthenopteron is more widely accepted to have stayed in the water,‭ ‬but developed the parts that would allow for the evolution of legs.‭ ‬Reinforcement for this view comes from the study of transitional fossils such as Tiktaalik,‭ ‬which seems to suggest that primitive legs would have evolved in creatures that were still primarily aquatic.‭ ‬These continuing adaptations including primitive fingers and leg joints for navigating dense weeds and shallow waters,‭ ‬also proved useful for terrestrial locomotion as well.
       Eusthenopteron did still have some of the features that would become present in later terrestrial amphibians.‭ ‬The teeth displayed folded enamel like the labyrinthodonts,‭ ‬and it also had internal nostrils.‭ ‬The bones of the pectoral fins also display clear upper and lower portions with bones that are analogous to a humerus,‭ ‬ulna and radius.‭ ‬The pelvic fins also have a similar arrangement but the bones here would be the equivalent of a femur,‭ ‬tibia and fibula.‭

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
- On some remarkable fossil fishes from the Devonian rocks of Scaumenac Bay, in the Province of Quebec - Joseph Frederick Whiteaves - 1881.
- Juvenile specimens of Eusthenopteron foordi Whiteaves, 1881 (Osteolepiform rhipidistian, Pisces) from the Late Devonian of Miguasha, Quebec, Canada. - H. P. Schultze - 1984.
- Vertebral development in the Devonian Sarcopterygian fish Eusthenopteron foordi and the polarity of vertebral evolution in non-amniote tetrapods - S. Cote, R. Carroll, R. Cloutier & L. Bar-Sagi - 2002.
- A microanatomical and histological study of the paired fin skeleton of the Devonian sarcopterygian Eusthenopteron foordi - M. Laurin, F. J. Meunier, D. Germain & M. Lemoine - 2007.
- A microanatomical and histological study of the fin long bones of the Devonian sarcopterygian Eusthenopteron foordi - François J. Meunier & Michel Laurin - 2012.
- The humerus of Eusthenopteron: a puzzling organization presaging the establishment of tetrapod limb bone marrow. - Proceedings of the Royal Society B: Biological Sciences, 281 (1782): 20140299. - S. Sanchez, P. Tafforeau & P. E. Ahlberg - 2014.


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