Fluvionectes
Name:
Fluvionectes
(River swimmer).
Phonetic: Flu-ve-o-nek-teez.
Named By: James A. Campbell, Mark T.
Mitchell, Michael J. Ryan & Jason S. Anderson -
2021.
Classification: Chordata, Reptilia,
Sauropterygia, Plesiosauria, Elasmosauridae, Elasmosaurinae.
Species: F. sloanae (type).
Diet: Piscivore/carnivore.
Size: Holotype roughly estimated to be about 5
meters long.
Known locations: Canada, Alberta - Dinosaur
Park Formation.
Time period: Campanian of the Cretaceous.
Fossil representation: Partial post cranial remains
including vertebrae, ribs partial pelvis and parts of the shoulder
girdle and left forelimb.
Fluvionectes
is a genus of elasmosaurid plesiosaur
that lived in North America
during the late Cretaceous. The first fossils of this genus were
recovered from the Dinosaur Park Formation in Canada, a location that
has yielded numerous though fragmentary and scattered plesiosaur fossil
for some time. Perhaps the most stand out fact about Fluvionectes
is
that the holotype fossils of this plesiosaur were recovered from what
was once a freshwater river. Most plesiosaur fossils are recovered
from marine deposits from the open sea, with a few lesser known ones
from estuaries where freshwater rivers emptied into the sea.
Fluvionectes
fossils in a freshwater habitat is proof that some plesiosaurs at least
ventured into freshwater rivers, though we do not know yet if this
was a visitation by a wandering plesiosaur, or if an actual
population of these plesiosaurs established themselves within the river
where they spent their entire lives. It is of course probable that
plesiosaurs could venture into freshwater environments given that they
breathed from the air. In modern times other air breathing creatures
usually associated with the sea such as seals, dolphins and even
whales have occasionally been observed venturing into freshwater
rivers. However, long term life in a river might eventually require
adaptation given that freshwater is typically less buoyant that
seawater.
While
the holotype fossils of Fluvionectes were found
scattered they do
actually represent most of the actual main body. Only the skull and
most of the neck are unknown meaning it is hard to accurately depict
the body length with certainty. The holotype was estimated by the
describers a mature individual about five meters long, though the
describers also mention other plesiosaur fossils in the Dinosaur Park
Formation that may come from slightly larger plesiosaurs about seven
meters long. Smaller size would be an advantage for plesiosaurs
inhabiting a river which would have likely been shallower with
possible tidal changes in depth and quite different from the
open sea.
Further reading
- A new elasmosaurid (Sauropterygia: Plesiosauria) from the
non-marine to paralic Dinosaur Park Formation of southern Alberta,
Canada. - PeerJ. - James A. Campbell, Mark T.
Mitchell, Michael J. Ryan & Jason S. Anderson -
2021.
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