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“Squalodon” errabundus
Kellogg, 1931. Barnes, 2006:31-34; as a species of
Allodelphinidae.
Emended diagnosis of species:
Until further species are described in the genus, the
diagnosis of the species shall remain identical to that of the genus.
Holotype:
USNM 11573, left petrosal, collected by Charles Morrice in 1924.
Type locality:
CAS locality 905, in the Sharktooth Hill Bonebed ―on a hill west of Round
Mountain, locally known as one of the Shark Tooth Hills. Near latitude 35
o
28' North, and
longitude 119
o
27' West, about 6.5 miles northeast of Bakersfield, 4 miles east of the Kern
River Oil Field and 0.5 miles north of Kern River, Kern County, California. Section 25,
Township 28 South, Range 28 East, Caliente Quadrangle, United States Geological Survey.‖
From CAS locality catalog.
Referred specimens:
USNM 11574, left petrosal from CAS locality 905 collected by
Charles Morrice in 1924; LACM 149588, cranium and mandible with associated right
petrosal and left tympanic bulla from LACM locality 4314 (field number L.G. Barnes 1818),
collected by Gregory Art in 1976.
Formation and age:
All known specimens of
Zarhinocetus errabundus
are from the
middle Middle Miocene age Sharktooth Hill Bonebed, which is in the upper part of the
marine Round Mountain Silt. The species is part of the Sharktooth Hill Local Fauna
(Mitchell, 1965:iii; and see Barnes, 1977:326-327; 2006), which is derived from the
Sharktooth Hill Bonebed, a horizon that bears densely packed fossils, and is widely exposed
in outcrops of the upper part of the Round Mountain Silt in the area northeast of Bakersfield
in Kern County, California. The age and stratigraphic relationships of the upper part of the
Round Mountain Silt, which includes the Sharktooth Hill Bonebed, are well known, and the
horizon is correlated with the Temblor Provincial mega-invertebrate stage of Addicott (1972),
the Relizian and/or Luisian foraminiferal stages, and the later part of the Barstovian North
American Land Mammal Age, and is approximately 15.3 million years old (Barnes, 1977;
Barnes and Mitchell, 1984; Tedford et al., 1987:156, 201, fig. 6.2 (chart in pocket); Tedford
et al., 2004:172, Figure 6.2; Prothero et al., 2008).
Geographic and geochronologic ranges:
Middle Middle Miocene, eastern North Pacific
coast in the area of central California.
Comments:
The odontocete,
Squalodon errabundus
Kellogg, 1931, was originally based
by Kellogg (1931) on a holotypic isolated left petrosal, USNM 11573, and a referred left
petrosal, USNM 11574, both of which were collected from the same locality in the
Sharktooth Hill Bonebed. Kellogg (1931:373) explained his referral of this new species to the
genus
Squalodon
by writing: ―The two ear bones hereinafter described are referred to the
genus
Squalodon,
for reasons which are almost indefinable, and yet all known squalodonts
have similar peculiarly shaped periotics. The subtle characters that distinguish the periotics of
squalodonts from those of other porpoises are apparent to anyone who has studied these
bones, although it is difficult to point out any tangible feature which will invariably identify
them.‖
The characters resembling
Squalodon
that Kellogg observed in the periotics that he called
Squalodon errabundus
are primitive characters that are shared by various primitive
Platanistoidea, the superfamily that is now interpreted as including the family
Squalodontidae. Kellogg (1931) stated that
“Squalodon”
errabundus
was the first
documented fossil occurrence of a squalodontid from the Pacific coast of North America.
Unquestioned squalodontids are known from the North Pacific. Squalodontid teeth have been
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