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New Herpetological Species and Records from the
Norden Bridge Fauna (Miocene: Late Barstovian)
of Nebraska
J. Alan Holman
Michigan State University
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Transactions of the Nebraska Academy of Sciences and Aliated Societies
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1982. Transactions
of
the Nebraska Academy
of
Sciences, X:31-36.
NEW
HERPETOLOGICAL SPEOES
AND
RECORDS
FROM
THE NORDEN BRIDGE FAUNA (MIOCENE: LATE BARSTOVIAN)
OF
NEBRASKA
J.
Alan Holman
Museum
Michigan State University
East Lansing, Michigan
48824
New herpetological species and records from
the
Late Barstovian
Norden Bridge Quarry, Brown County, Nebraska, are reported. New
species include a softshell turtle and a watersnake. Forms reported from
the fauna for
the
fIrst time include the boid snake Geringophis depres-
sus,
the colubrid snakes Ameiseophis robinsoni, Nebraskophis skinneri,
Neonatrix elongata, and Salvadora paleolineata, and an indeterminate
viperid snake. The caudal vertebra and humerus
of
the salamander
Ambystoma
minshalli are described and fIgured for the fIrst time.
Genera
of
the snakes are archaic and have been previously reported
only from Arikareean
to
Late Barstovian times.
t t t
INTRODUCTION
The Norden Bridge Quarry has been one
of
the most
productive Late Tertiary herpetological sites in North America
(HoIman and Sullivan, 1981: Table 1, p. 142-143). The
present paper reports new herpetological species and records
that are mainly the result
of
collections made
by
Michigan
State University Museum field parties from 1974 through
1979.
The site lies in Brown
County, Nebraska, near the Norden-
Johnstown Road, about
274
m south
of
the Norden Bridge
across the Niobrara River, at
an
elevation
of
661 m in SE *
SW
% Sec. 33, T. 33 N.,
R.
23
W.,
Brown County, Nebraska.
It lies in the lowermost part
of
the Valentine Formation and
represents a heretofore unnamed lithologic unit whose
mam-
malian remains indicate Late Barstovian
as
well
as
Claren-
donian relationships (Morris F. Skinner, personal communi-
cation). The fauna represents Late Barstovian times based
on
31
the presence
of
certain herpetological forms
not
reported from
Clarendonian sites (HoIman, 1973b). Future collecting will
likely reveal new herpetological material since additional
excavations at the Norden Bridge Quarry are underway.
SYSTEMATIC PALEONTOLOGY
Class Amphibia
Order Caudata
Family Ambystomatidae
Genus
Ambystoma
Tschudi, 1838
Ambystoma
minshalli Tihen and Chantell, 1963
Material. Six vertebrae (including three
trunk
vertebrae,
one caudal vertebra, and two vertebrae
of
uncertain position),
and one right humerus (Michigan
State University Vertebrate
Paleontology Number 944).
Remarks. The
trunk
vertebrae do
not
differ in any impor-
tant
way from those
of
the type material described
by
Tihen
and
Chantell (1963:509-510). The caudal vertebra and hu-
merus (Fig. 1)
of
this important species have
not
heretofore
been illustrated and described.
The caudal vertebra has the following noteworthy
char-
acteristics.
In
dorsal view,
it
is
about
twice as long as wide.
The prezygapophyseal articular surfaces are ovaloid. The
cen-
trum
extends anteriorly between the prezygapophyseal artic-
ular surfaces. The neural spine
is
poorly developed and
is
in
the
form
of
a very weak keel. The posterior end
of
the neural
32
J.
A.
Holman
FIGURE
1.
Ambystoma
minshalli,
MSUVP
944. A-C.
Caudal
vertebra in dorsal, ventral, and lateral view.
D.
Humer-
us in lateral
view.
Projections equal 2 mm; that below C
applies equally to A-C. Anterior right in A and
B;
left in
C.
arch
is
truncated. The right postzygapophysis
is
missing. The
tip
of
the left postzygapophysis extends posterior to the
neural arch.
In lateral view, the rib-bearing processes are broken. The
neural arch
is
almost flat with only a very slight upsweep in
its posterior portion. In ventral
view,
the centrum
is
elongate,
constricted in its middle, and amphicoelous. In posterior view,
the top
of
the neural arch
is
slightly convex. The round cotyle
is
larger than the neural canal. In anterior view, the top
of
the
neural arch
is
slightly convex. The
sub
rounded cotyle
is
much
larger than the neural canal.
Measurements and ratios are as follow: length
of
centrum
3.6 mm, width
of
centrum anteriorly
1.1
mm, width through
postzygapophyses
3.0 mm, length through zygapophyses
4.8 mm. Ratio
of
centrum length to anterior centrum width
is
3.27.
The humerus has the following important characteristics.
In lateral view, the head
is
ovaloid and depressed. Below the
head
is
an excavated area. The crista ventralis
is
about one and
one-half times the length
of
the width
of
the head and
is
sharp·
ly produced from the shaft. On the anterior portion
of
the
shaft, just below the crista ventralis,
is
a distinct protuberance.
The distal end
of
the bone
is
divided into rather indistinct
external and internal condyles. The greatest length
of
the bone
is
7.1
mm.
This species
was
originally described from the Norden
Bridge Quarry
by
Tihen and Chantall
(I963)
and was listed
by Holman (1973b).
Order Anura
Family Bufonidae
Genus Bufo Laurenti, 1768
Bufo hibbardi Taylor, 1936
Material. Right ilium,
MSUVP
1013.
RemIJrks. This ilium
is
assigned to the species
B.
hibbardi
on the basis
of
the height and shape
of
the dorsal prominence.
Bufo
cf. hibbardi was reported from the Norden Bridge Quarry
by Estes and Tihen (1964) and Bufo hibbardi
was
reported
from the Norden Bridge Quarry by Holman (1973b).
Bufo kuhrei Holman, 1973
Material. Proximal portion
of
a right tibiofibula,
MSUVP
890.
RemIJrks. Bufo kuhrei
was
previously known only on the
basis
of
a single large ilium from the Norden Bridge fauna
(Holman, 1973b). The tibiofibula from the present collection
represents a toad
of
equal or perhaps even larger
size
than the
one represented by the type. In fact, the tibiofibula is about
as
large
as
that
of
the "giant toad," Bufo marinus, from which
it
differs in being much more anteroposteriorly flattened. The
greatest width through proximal end
of
the fossil
is
8.9 mm.
This measurement in
five
modern adult Bufo marinus ranges
from
8.1
to 9.6 mm with a mean
of9.1
mm.
Class
Reptilia
Order Testudines
Family Trionychidae
Genus Trionyx Geoffroy,
1809
Trionyx quinni n. sp.
Etymology. The specific name
is
in memory
of
James
Quinn, native Nebraskan and vertebrate paleontologist.
Holotype.
MSUVP
952 (Fig. 2 A and
B).
A left hypoplas-
tron collected by Alisa Griggs, J.
A.
Holman, Mark PodeU,
and
Carl Wellstead, July 1976.
Hypodigm. (Figs. 2-5). Type and left hypoplastron,
MSUVP
953; left hypoplastron,
MSUVP
954; right hypoplas-
tron,
MSUVP
955; two fragmentary pieces
of
a right hyo-
plastron,
MSUVP
956; six fragmentary pieces
of
pleural bones,
MSUVP
957. These bones were collected in 1971, 1974,
1975, and 1976
by
Michigan State University Museum field
parties.
FIGURE
2.
A-H. Left hypoplastra
of
species
of
Trionyx;
left-hand figures in dorsal
view,
right-hand figures
in
ventral
view.
A and
B.
Holotype
of
Trionyx quinni
n.
sp.,
MSUVP
952. C and
D.
Trionyx ferox. E and
F.
Trionyx muticus. G-H.
Trionyx spinifer. Projections equal 5 nun. Posterior toward
top in all.
FIGURE 3. A-D. Left hypoplastra
of
Trionyx quinni
n.
sp;left in dorsal
view,
right in ventral
view.
A and
B.
MSUVP
953. C and
D.
MSUVP
954. Projections equal 10 mm.
~os
terior toward right in A and
C;
left in
Band
D.
Miocene herpetofauna from Norden Bridge
33
FIGURE 4. A and
B.
Piece
of
left hypoplastron
of
Trionyx quinni
n.
sp.,
MSUVP
955. C and
D.
Piece
of
left
hyoplastron
of
Trionyx quinni
n.
sp.,
MSUVP
956; left in
dorsal
view,
right in ventral
view.
Projections equal 10 mm.
Posterior toward left in A and
C;
right in
Band
D.
Locality. Norden Bridge Quarry, Valentine Formation,
Brown
County, Nebraska.
Diagnosis. Hypoplastron with
(I)
moderately concave
posterior margin; (2) short, wide, striated posteromedial
processes; (3) notch between posteromedial processes
inter-
secting sculptured area; (4) sculpturing well developed; and
(5) posterolateral processes short and wide.
Description
of
the Holotype. In ventral view, the bone
is
heavily sculptured. Its posterior margin
is
moderately concave.
The lateral part
of
this hypoplastron
is
broken and thus the
posterolateral processes are missing (these processes present
in
MSUVP
955, Fig. 4 A and
B).
The tips
of
the posteromedial
processes are broken off, but the shape
of
the remaining
34 J.
A.
Holman
c
FIGURE 5. A and
B.
Piece
of
right hyoplastron
of
Trionyx quinni
n.
sp.,
MSUVP
956. C and
D.
Fragmentary
right pleural bone
of
Trionyx quinni
n.
sp.; left in dorsal
view,
right in ventral
view.
Projections equal
10
mm.
Posterior
toward top in A and
B;
toward bottom in C and
D.
parts
is
short and wide, and the notch between them intersects
the sculptured area
of
the bone. The greatest length
of
the
bone, through the middle
of
the concavity
of
the posterior
margin,
is
12.3
mm
Discussion. The hypoplastra
of
the three modern North
American species,
Trionyx ferox,
T.
mu
tic
us,
and
T.
spinifer
are
all
separable from one another (Fig. 2 C-H). The hypoplas-
tra
of
the new species,
T.
quinni,
is
separable from
all
of
the
modern species by more than one character, yet it mainly
appears to have a composite
of
the characters found in the
modern forms.
It
may indeed be that
T.
quinni
is
near the
ancestry
of
the three modern species.
The posterior margin
of
the hypoplastron
is
not
as
strong-
ly concave
as
in
T.
ferox and
T.
muticus,
but
on the other
hand it
is
more concave than in
T.
spinifer.
The posteromedial processes
are
striated
as
in
T.
ferox
and
T.
spinifer,
but
these processes are smooth in
T.
muticus.
The posteromedial processes are short and wide
as
in
T.
muticus,
but
these processes are much longer in
T.
ferox and
T.
spinifer.
The notch between the posteromedial processes intersects
the sculptured area
as
in
T.
muticus and
T.
spinifer,
but
this
notch does not intersect the sculptured area in
T.
ferox.
The sculpturing
is
deep
as
in
T.
ferox, differing from
T.
muticus and
T.
spinifer where this sculpturing
is
not
so
deep.
Other elements
of
the hypodigm (Figs. 2-5) are not par-
ticularly diagnostic except that they show rather heavy sculp-
turing
as
in modern
T.
ferox rather than the lighter sculpturing
of
T.
muticus and
T.
spinifer.
Carapace and pastron fragments
of
an unidentified species
of
Trionyx were previously reported from the Norden Bridge
Quarry by Holman (1973b). These
(MSUVP
728) are now
tentatively assigned to
T.
quinni.
Order Squamata
Family Scincidae
Genus
Eumeces Wiegmann, 1834
Eumeces
sp.
Material. Left dentary,
MSUVP
966.
Remarks. Other material
of
this genus
of
lizard
was
previously reported from the Norden Bridge Quarry by
Hol-
man (1976) and by Holman and Sullivan (1981). The material
eventually may be shown to represent a new species.
Family Boidae
Genus
Geringophis Holman, 1976
Geringophis depressus Holman, 1976
Material. One trunk vertebra,
MSUVP
893.
Remarks. This
is
the first record
of
this very distinctive
genus from north-central Nebraska.
It
has previously been
reported from the Early Miocene
of
Wyoming and western
Nebraska and from the Late Miocene
of
southeastern
Ne-
braska (Holman, 1979). Geringophis depressus differs from
G.
yatkolae Holman, 1977,
of
the Early Miocene Harrison
Formation
of
western Nebraska in having (1) a more depressed
neural arch, (2) a
less
depressed condyle, (3) a broadly
U-
shaped rather than V-shaped posterior border
of
the neural
arch, (4) a thicker hemal keel, and (5) stronger sub central
ridges. The fossil agrees with
G.
depressus in
all
of
these
characters.
This fossil record may be additional evidence for a Late
Barstovian rather than a
Clarendonian
age
for the Norden
Bridge fauna,
as
the very distinctive genus Geringophis
is
un-
reported from Clarendonian localities.
Family
Colubridae
Genus Ameiseophis Holman, 1976
Ameiseophis cf. Ameiseophis robinsoni Holman, 1976
Material. Trunk vertebra,
MSUVP
891.
Remarks. This distinctive form
has
previously been
re-
ported only from the Middle Miocene
of
Wyoming and the
Late Miocene
of
South Dakota (Holman, 1979). The very
strong hemal keel and sub central ridges are striking characters
of
the genus. The single vertebra
is
tentatively referred to the
previously described species
A. robinsoni. This record may be
another indication that the Norden Bridge fauna
is
of
Late
Barstovian
age,
as
Ameiseophis has not been reported from
Clarendonian localities.
Genus
Nebraskophis Holman, 1973
Nebraskophis skinneri Holman, 1973
Material. Trunk vertebra, University
of
Nebraska State
Museum Number 61037.
Remarks. This
is
the first report
of
this form from the
Norden Bridge fauna. The specimen
was
collected
by
J.
A.
Tihen and his field parties in the 1960s. The vertebra shows no
difference from the type, which
was
collected from the Late
Barstovian Egelhoff fauna across the Norden Bridge in Keya
Paha County, Nebraska (Holman, 1973a). Nebraskophis
skinneri
is
known only from the Late Miocene of north-
central and southeastern Nebraska (Holman, 1979).
Genus
Neonatrix Holman, 1973
Neonatrix elongata Holman, 1973
Material. Trunk vertebra,
MSUVP
967.
Remarks. This
is
the first defmite record
of
a species
of
this genus from the Norden
Bridge
fauna. This species has
elongate vertebra with very small hypapophyses.
It
has previ-
ously been reported only from the Middle Miocene
of
South
Dakota and Texas, and the Late Miocene
of
Nebraska and
Texas (Holman, 1979).
It
is
thought that this
is
a primitive
natricine genus.
Neonatrix magna
n.
sp.
Etymology. The specific name, Latin,
is
in
reference to
the relatively large
size
of
the fossil trunk vertebra.
Holotype. Trunk vertebra,
MSUVP
943 (Fig. 6). Collected
by
Alisa
Griggs,
J.
A.
Holman, Mark Podell, and Carl
Well-
stead in July 1976.
Locality. Norden Bridge Quarry, Valentine Formation,
Brown
County, Nebraska.
Diagnosis. A Neonatrix differing from the only previ-
ously known species, Neonatrix eiongata, in having its trunk
vertebra
(l)
larger, (2) with a shorter vertebral form, (3) with
a more vaulted neural arch, (4) with the ventral surface
of
the
Miocene herpetofauna from Norden
Bridge
35
FIGURE 6. Holotype trunk vertebra
of
Neonatrix
magna
n.
sp.,
MSUVP
943.
A.
Dorsal.
B.
Ventral.
C.
Lateral.
D. Posterior. Projection between C and D equals 2 mm and
applies equally to A-D.
hypapophysis bevelled, (5) with the condyle more compressed,
and (6) with the
sub
central ridges stronger.
Description
of
the Holotype. In anterior
view,
the cotyle
has its top broken, but it appears to be round and about the
same
size
as
the neural canal which
is
ftIled with sandy matrix.
The neural canal has its sides slightly convex laterally. The
zygosphene
is
straight dorsally. The prezygapophyses are
tilted slightly upward. The excavations on either side
of
the
cotyle are small. Each excavation has a
single
foramen in its
center. Both paradiapophyses are damaged.
In dorsal view, the centrum
is
about
as
long
as
it
is
wide.
The right prezygapophysis
is
missing; the tip
of
the left
zyga-
pophysis
is
broken, but appears to
have
been ovaloid. The
anterior edge
of
the zygosphene
is
slightly convex. The neural
spine
is
moderately thick and it has a slight posterior
over-
hang. The right diapophysis
is
broken, the left diapophysis
is
slightly produced laterally. There
is
no epizygapophyseal
spine.
In posterior view, the neural arch
is
highly vaulted. The
postzygapophyses are tilted slightly downward. The oval
condyle
is
slightly compressed and appears to
be
about the
same
size
as
the neural canal which
is
filled with matrix. The
hypapophysis projects only slightly below the condyle.
36 J.
A.
Holman
In ventral
view,
the
sub
central ridges
are
strong. The
hypapophysis
is
narrow and ends well anterior to the end
of
the condyle. The bottom
of
the hypapophysis
is
bevelled.
In lateral
view,
the vertebra has a moderately shortened
form. The neural spine
is
broken,
but
it appears to have been
somewhat longer than high. The strong subcentral ridges are
straight. The hypapophysis
is
very short and wide and has a
pointed tip; it ends anterior to the end
of
the condyle and has
its ventral surface bevelled.
The length of the vertebra, through the posterior
zyga-
pophysis and the zygosphene,
is
5.8
mm.
Remarks. This snake
is
assigned to the genus Neonatrix
on the basis
of
its very poorly developed hypapophysis.
It
is
quite distinct from Neonatrix elongata, the only other
known species in the genus, in several vertebral characters, and
must have had much different habits.
Genus
Salvadora Baird and Girard, 1853
Salvador a paleolineata Holman, 1973
Material. Trunk vertebrae,
MSUVP
892 (2), and
MSUVP
968 (1).
Remarks. This species
was
described from the Egelhoff
local fauna in adjacent Keya
Paha County, Nebraska, by
Holman (1973a), but it has never been reported from the
Norden Bridge fauna. The species
is
rather widely distributed
in the Late Tertiary and
is
known from the Middle Miocene
of
Wyoming, South Dakota, and Nebraska, and the Late Miocene
of
South Dakota, Nebraska, and Texas (Holman, 1979).
Family Viperidae
Viperid indet.
Material. Trunk vertebra,
MSUVP
889.
Remarks. The vertebra
is
typically viperid in having the
hypapophysis much thicker than
in
the Elapidae, Hydro-
phiidae, and Natricinae. This
is
only the third record
of
the
Viperidae from a Late Barstovian locality; other records being
from the Late Barstovian
of
Texas and
of
southeastern
Ne-
braska (Holman, 1979).
DISCUSSION
The Norden Bridge Quarry has already yielded a large
Late Barstovian herpetofauna (Holm an and
Sullivan, 1981)
and it
is
remarkable that it continues to yield new species
and records. The addition
of
archaic snake genera Ameiseo-
phis, Geringophis, Nebraskophis,
and Neonatrix tend
to
confirm a Late Barstovian rather than a Clarendonian
age
for
the Norden Bridge fauna,
as
none
of
these genera has been
reported from
Clarendonian localities.
It
is
hoped that con-
tinued collecting at the Norden Bridge Quarry will yield more
information about the herpetologicallife
of
Nebraska in Late
Miocene times.
ACKNOWLEDGMENTS
Field assistance by Alsia Griggs, Raymond Holman,
Robert Holman, Mark
Podell, and Carl Wellstead
is
most
gratefully acknowledged. Robert Evander, Loring Kuhre, and
Morris
Skinner assisted the project in many ways. Jane Kamin-
ski made the drawings.
REFERENCES
Estes,
R,
and J.
A.
Tihen. 1964. Lower vertebrates from the
Valentine Formation
of
Nebraska. American Midland
Naturalist,
72:453-472.
Holman, J.
A.
1973a. Reptiles
of
the Egelhoff local fauna
(upper Miocene)
of
Nebraska. Contributions from the
Museum
of
Paleonto logy, University
of
Michigan, 24:
125-134.
__
. 1973b.
New
amphibians and reptiles from the Norden
Bridge fauna (upper Miocene)
of
Ne
braska. Michigan Aca-
demician,
6:149-163.
__
. 1976. The herpetofauna
of
the lower Valentine Forma-
tion, north-central Nebraska.
Herpetologica, 32:262-268.
__
. 1979. A review
of
North American Tertiary snakes.
Publications
of
the Museum-Michigan State University,
Paleontological Series,
1 :200-260.
__
, and R.
M.
Sullivan. 1981. A small herpetofauna from
the type section
of
the Valentine Formation (Miocene:
Barstovian),
Cherry County, Nebraska. Journal
of
Pale-
ontology, 55:138-144.
Tihen, J.
A., and
C.
J. Chantell. 1963. Urodele remains from
the Valentine Formation
of
Nebraska. Copeia, 1963:
505-510.
