Eusthenopteron
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 -
Fran�ois 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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