Smilodonichthys Rastrosus: A New Pliocene Salmonid Fish from Western United States
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Date
1972-03
Authors
Cavender, Ted M.
Miller, Robert Rush
Journal Title
Journal ISSN
Volume Title
Publisher
Museum of Natural History, University of Oregon
Abstract
In western North America, the family Salmonidae
is comprised of a diverse number of
species (upwards of 30) belonging to seven
genera assigned to three subfamilies (Norden, 1961). Though more than half of these species
are endemic to the area, an astonishingly few fossil specimens have been discovered which
can help document the evolution that has taken
place in this group. An exception is the one
described in this paper which adds importantly
to our understanding of the past life of these
fishes.
Materials of this fossil salmonid were collected
over a period of fifty years from Pliocene,
Pacific-slope localities in California and
Oregon. As early as 1917, vertebrae, teeth and
skull fragments of an extremely large but unfamiliar
type of fish were unearthed, along with
mammalian remains, at Pinole, Contra Costa
County, California. Only within recent years,
however, has it been possible to identify these
with certainty as being the remains of an extinct
form of salmonid that once was distributed in
the coastal regions of the Pacific Northwest,
probably much the way that Pacific salmon
(Oncorhynchus) are today. In 1950 and again
in 1964, more complete specimens were discovered
of this unusual species from a Pliocene
gravel pit in northcentral Oregon. The last find
consisted of a large skull which is outstanding
for its completeness and detail of preservation.
It is a description of this skull that forms the
main context of the present paper and which
has allowed fruitful comparison to be made
with living salmonids.
The name Smilodonichthys rastrosus is proposed
for this previously undescribed species.
Because of its high degree of morphological
distinction from other members of the Salmonidae,
this species is made the type of a new
genus. A number of its osteological features indicate
a phyletic relationship closest to Oncorhynchus,
yet none of the extant species of that
genus approaches the fossil in the specialization
of its feeding mechanism.
Description
52 pages
Keywords
Oncorhynchus, Salmonidae, Pacific-slope, Smilodonichthys rastrosus