Revised Biostratigraphy of the Middle Miocene to Earliest Pliocene Goliad Formation of South Texas

Abstract

The fluvial Goliad Formation crops out along the coastal plain of South Texas. In the 1950s-60s, the Lapara Creek Fauna, from low in the section and including virtually all the then known Goliad fossils, was assigned to the early Clarendonian (12 Ma) North American Land Mammal Age (NALMA). A Labahia Mission Fauna, based only on a tooth and leg bone that were never described, was placed in the succeeding early to mid- dle Hemphillian NALMA. At that time the Miocene-Pliocene boundary was placed at about 13 Ma, which meant the Goliad Formation was Pliocene in age, a correlation still followed by some. In the 1970s, the Mio-Pliocene boundary was set at about 5.5 Ma, and the Goliad was reassigned to the middle (Lapara Creek) to late (Labahia Mission) Mio- cene. This paper documents a late Clarendonian (10 Ma) Local Fauna (LF) and a latest Hemphillian (5 Ma) LF in the Goliad. The Dinero LF occurs high in the section, below the caliche that caps the Goliad. The concurrent range zone of its taxa (Ceratogaulus anecdotus, Pseudhipparion skinneri, Calippus cf. cerasinus, and Cormohipparion cf. in- gennum) is late Clarendonian. The mainly reworked Lake Corpus Christi LF includes the horses Dinohippus cf. mexicanus, Astrohippus stockii, Pseudhipparion simpsoni, Nan- nippus cf. beckensis, N. aztecus, and Neohipparion eurystyle. These support a latest Hemphillian age (early Pliocene) for the caliche cap of the Goliad. The Lapara Creek Fauna correlates with the Textularia "W" benthic foraminiferal biozone; the Dinero LF to the Bolivina-Cibicides biozone; and the Lake Corpus Christi LF to the Bigenerina "6" biozone.

Full text

Revised Biostratigraphy of the Middle Miocene to Earliest Pliocene
Goliad Formation of South Texas
Jon A. Baskin1 and Richard C. Hulbert, Jr.2
1Department of Biological and Health Sciences, Texas A&M University – Kingsville, Kingsville, Texas 78363
2Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611
ABSTRACT
The fluvial Goliad Formation crops out along the coastal plain of South Texas. In
the 1950s-60s, the Lapara Creek Fauna, from low in the section and including virtually
all the then known Goliad fossils, was assigned to the early Clarendonian (12 Ma) North
American Land Mammal Age (NALMA). A Labahia Mission Fauna, based only on a
tooth and leg bone that were never described, was placed in the succeeding early to mid-
dle Hemphillian NALMA. At that time the Miocene-Pliocene boundary was placed at
about 13 Ma, which meant the Goliad Formation was Pliocene in age, a correlation still
followed by some. In the 1970s, the Mio-Pliocene boundary was set at about 5.5 Ma, and
the Goliad was reassigned to the middle (Lapara Creek) to late (Labahia Mission) Mio-
cene. This paper documents a late Clarendonian (10 Ma) Local Fauna (LF) and a latest
Hemphillian (5 Ma) LF in the Goliad. The Dinero LF occurs high in the section, below
the caliche that caps the Goliad. The concurrent range zone of its taxa (Ceratogaulus
anecdotus, Pseudhipparion skinneri, Calippus cf. cerasinus, and Cormohipparion cf. in-
gennum) is late Clarendonian. The mainly reworked Lake Corpus Christi LF includes
the horses Dinohippus cf. mexicanus, Astrohippus stockii, Pseudhipparion simpsoni, Nan-
nippus cf. beckensis, N. aztecus, and Neohipparion eurystyle. These support a latest
Hemphillian age (early Pliocene) for the caliche cap of the Goliad. The Lapara Creek
Fauna correlates with the Textularia “W” benthic foraminiferal biozone; the Dinero LF
to the Bolivina-Cibicides biozone; and the Lake Corpus Christi LF to the Bigenerina “6”
biozone.
INTRODUCTION
The youngest Tertiary vertebrate faunas of the northwestern Gulf Coast are from the Goliad Formation and
its equivalents, which crop out along the coastal plain of Texas into Louisiana. Because the Goliad contains the
Evangeline aquifer and uranium deposits, it has been well studied in the subsurface (Solis, 1981; Arredondo and
Thomann, 1996), where it is approximately 400 ft thick. Fossiliferous exposures of the Goliad Formation, with
few exceptions, are in South Texas, especially in Bee and Live Oak counties (Fig. 1). Quinn (1955) and Wilson
(1956) established the vertebrate biostratigraphic units for the Miocene of the Texas Coastal Plain and Wilson
(1956) summarized the nomenclatural history of the lithostratigraphic and biostratigraphic units now assigned to
the Goliad Formation. Tedford et al. (1987, 2004) correlated the Miocene vertebrate faunas of North America,
including those of the Texas Gulf Coast, with the succession of North American Land Mammal Ages
(NALMAs).
Tertiary mammal fossils from South Texas were first reported by Dumble (1894) as coming from the Lapara
division, later the Lapara Beds (Dumble, 1903). The fragmentary remains were identified by the paleontologist
Baskin, J. A., and R. C. Hulbert, Jr., 2008, Revised biostratigraphy of the middle Miocene to earliest Pliocene Goliad For-
mation of South Texas: Gulf Coast Association of Geological Societies Transactions, v. 58, p. 93-101.
93

Baskin and Hulbert
Figure 1. Map of study area. 1 (Bridge Ranch) and 2 (Farish Ranch), Lapara Creek Fauna; 3, Dinero
LF; 4, Labahia Mission Fauna; 5, Lake Corpus Christi LF. Exposures of the Goliad Formation out-
lined in red indicated by Mg. Live Oak, Bee, and Goliad counties outlined with dashed lines.
E. D. Cope as equivalent in age to those that he had described from the Blanco Beds of the Texas Panhandle.
Deussen (1924) renamed the Lapara Beds the Lapara Sand and stated that its fossils indicated a “middle Pliocene
(Blanco) age.” Plummer (1933) formally proposed the name Goliad Formation (Plummer noted the name had
been introduced at a meeting of the San Antonio Geological Society in 1932 by Howeth and Martin) and included
the Lapara Member as its lowermost unit. The sands of the Lapara Member contained the teeth and bones of a
rhinoceros and small horse collected by A. Deussen, which led Plummer (1933) to assign the Goliad Formation
to the Pliocene.
The relative age of the Lapara Member of the Goliad Formation has been accurately known since at least the
1940s; the absolute age (by correlation), since the 1960s. Extensive fossil collections were first made in Live
Oak and Bee counties by Works Progress Administration (WPA) crews of the Bureau of Economic Geology of
the University of Texas in the 1930s. Sellards (1940) described a gomphothere (an extinct elephant-like mammal
with upper and lower tusks) and noted the presence of horses from the Farish Ranch LF, which he assigned to the
Pliocene. Weeks (1945) reported that C. L. Camp of the Museum of Paleontology, University of California,
Berkeley, correlated the Goliad Formation fossils with Clarendonian and Hemphillian faunas of the Texas Pan-
handle. Quinn (1955) provided the first extensive description of Lapara fossils. He concluded that the Lapara
Creek Fauna was older than the early Clarendonian Burge Fauna of Nebraska and therefore was latest Barstovian
in age, which at that time was correlated with the late Miocene. Patton (1969) reassigned the Lapara Creek Fauna
to the early Clarendonian NALMA, which was then considered early Pliocene. The following species of horses
are known from the Lapara Creek Fauna (Quinn, 1955; Forsten, 1975; Webb and Hulbert, 1986; Hulbert, 1987,
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Revised Biostratigraphy of the Middle Miocene to Earliest Pliocene Goliad Formation of South Texas
1988a, 1988b): Hypohippus affinis, Neohipparion affine, Pseudhipparion curtivallum, Calippus placidus, C.
regulus, C. martini, Protohippus supremus, Cormohipparion occidentale, and C. ingenuum. These horses and
other mammalian fossils (Tedford et al., 1987) confirm the early Clarendonian NALMA assignment of the La-
para Creek Fauna.
Beside a Lapara Creek Fauna, Quinn (1955) and Wilson (1956) also recognized a late Pliocene Labahia Mis-
sion Fauna from the Labahia Member of the Goliad. The fauna is based only on a horse tooth and leg bone that
were never described (Tedford et al., 1987; Baskin, 1991), and which are probably non-diagnostic. Tedford et al.
(1987) nonetheless assigned the Labahia Mission Fauna to the early to middle Hemphillian.
Up until the 1970s, the Clarendonian/Hemphillian Goliad Formation was considered Pliocene in age, a cor-
relation still followed by some (Finch, 1996; Paine and Murphy, 2000; Ambrose, 2007). The earliest correlation
of the Clarendonian NALMA with European marine stages was to the Pontian (Kleinpell, 1938; Wood et al.,
1941). Durham et al. (1954) correlated it with the preceding Sarmation. At that time, both European stages were
placed in the Pliocene. An absolute age chronology for NALMAs was reported by Evernden et al. (1964). Potas-
sium-argon dates for Clarendonian faunas in Nevada and California ranged from 9.9-11.7 Ma. This was at about
the Miocene-Pliocene boundary as it was understood at that time (Kulp, 1961). With the recognition that Lyell’s
Miocene included the Messinian Stage, the Miocene-Pliocene boundary was set at about 5.3 Ma (Berggren, 1969;
Berggren and Van Couvering, 1974). Correlation of NALMAs with European marine stages led to the recogni-
tion that the Clarendonian and almost all of the Hemphillian were Miocene in age. The Barstovian-Clarendonian
boundary is placed at about 12.5 Ma, while the Hemphillian-Blancan boundary is set at 4.8 Ma (Tedford et al.,
2004; Woodburne, 2006). The early Clarendonian Lapara Creek Fauna from the base of the Goliad, at about 12
Ma (Tedford et al., 1987), is late middle Miocene in age. Because the Labahia Mission LF was presumed to be
early to late Hemphillian in age, the top of the Goliad was considered late Miocene (Tedford et al., 1987). The
two additional fossil localities, discussed below, clarify the age of the Goliad Formation (Fig. 2). Specimens
described are curated in the vertebrate paleontology laboratory of the Texas Memorial Museum (TMM), Univer-
sity of Texas, Austin.
THE LATE CLARENDONIAN DINERO LOCAL FAUNA
Quinn (1955, his Figure 5) noted five major localities for the Lapara Creek Fauna, but included numerous
others. One of the minor localities is TMM 31263 (Dinero LF, “at Sweeney [sic] Switch on road cut hwy 9,
George West to Dinero Rd., Live Oak County” of Forsten, 1975, p. 66). Swinney Switch is located at the inter-
section of farm roads 534 and 3024 and TMM 31263 is in a road cut 1 km north of the intersection, 20 km north-
west of Mathis (Fig. 1). A photograph of the locality appears in Weeks (1945, his Figure 23). Fossils were re-
covered from coarse, cross-bedded sands that are held together by a calcite cement. The sand is just below the
calcrete cap of the Goliad and above a pink/red clay that has been identified as the middle member of the Goliad
Formation, the Lagarto Creek clay (Weeks, 1945). Nine specimens were originally cataloged from this locality,
mostly isolated horse teeth, many of them fragmentary. Twenty additional specimens, at least complete enough
to be identified to genus, have since been collected. This locality is approximately 10 km downdip from the early
Clarendonian Farish Ranch Local Fauna near Berclair. Although the Dinero site is topographically lower (150 ft
versus 220 ft at Farish Ranch), it is higher in the section because of the Gulf of Mexico-ward dip of the Gulf
Coast Tertiary. The concurrent range zone of the taxa from the Dinero LF is late Clarendonian (Fig. 3).
The two identifiable, non-horse specimens are a complete left upper 4th premolar (TMM 31263-6) and a
relatively complete lower 4th premolar (TMM 31263-10) of a mylagaulid. Mylagaulids are an extinct group of
burrowing rodents, the size of large prairie dogs. This is the first mylagaulid reported from the Gulf Coastal
Plain outside of Florida (Webb, 1966; Baskin, 1981; Bryant, 1991). In Texas, mylagaulids are known elsewhere
from the Clarendonian (Noble Ranch, Rowe Ranch) and Hemphillian (Higgins, Coffee Ranch, Axtel) of the
Texas Panhandle (Schultz, 1990a). Korth (2000) recognized five genera of mylagaulines from the middle to late
Miocene (Barstovian-Hemphillian NALMAs). The Dinero specimens resemble the illustrations of Ceratogaulus
cf. rhinocerus from the early Clarendonian Burge quarry (Korth, 2000, his Figure 15C) or of Ceratogaulus anec-
dotus from the late Clarendonian Merritt Dam Member of the Ash Hollow Formation (Korth 2000, his Figure
17A). Ceratogaulus is the only known horned-rodent, with a pair of horns growing from its nasal bones. In C.
rhinocerus, the width to length ratio of P4 is >0.70; in C. anecdotus, 0.64-0.66 (Korth, 2000). In the Dinero
specimen, it is 0.57, more similar to C. anecdotus.
95

Figure 2. Goliad Formation biostratigraphy.
Pseudhipparion skinneri was a small (body mass 61 kg, MacFaddden and Hulbert, 1990), three-toed horse
with high-crowned cheek teeth. It is represented at Dinero by 5 upper and 4 lower cheek teeth, including an asso-
ciated right P2 and P3 (TMM 31263-11). This species is known elsewhere from the late Clarendonian Merritt
Dam Member of the Ash Hollow Formation of Nebraska, and the Love Bone Bed of Florida, as well as localities
from the early Hemphillian of Florida (Webb and Hulbert, 1986). The early Clarendonian Lapara Creek Fauna
Pseudhipparion is P. curtivallum. Pseudhipparion hessei is known from the middle Clarendonian MacAdams
Ranch Fauna of the Texas Panhandle. The specimens from Dinero are considerably smaller and higher crowned
than P. curtivallum and P. hessei. The late Hemphillian P. simpsoni, which is known from the Lake Corpus
Christi LF, is much higher crowned and if worn to a similar height as the upper teeth from Dinero would have the
fossettes reduced to absent (Webb and Hulbert, 1986). The late Barstovian Pseudhipparion early species from
the Bone Valley of Florida (Webb and Hulbert, 1986) is somewhat smaller in size but lower crowned. The crown
height of an unworn M3 from Bone Valley is 28.3; of a slightly worn upper molar, 24.9. The least worn upper
tooth from Dinero (TMM 31263-12) has a crown height of 30.6, compared to a maximum of 45 for specimens
from Florida.
Baskin and Hulbert
96

Figure 3. Stratigraphic ranges of taxa from the Dinero LF. Timescale modified after Tedford et al.
(2004).
Revised Biostratigraphy of the Middle Miocene to Earliest Pliocene Goliad Formation of South Texas
Cormohipparion cf. ingenuum is a larger (body mass 139 kg), three-toed horse. Hulbert (1988b) referred
Nannippus ingenuus to Cormohipparion. The species ranges from Clarendonian to early Hemphillian. The type
is from the early Hemphillian of Florida and the best samples are from the late Clarendonian of Florida. Hulbert
(1988b) stated that only two specimens from Lapara Creek can confidently be referred to C. ingenuum. Forsten
(1975) identified two specimens from Dinero, (TMM 31263-2 and -7) as Neohipparion occidentale, but they
instead represent C. cf. ingenuum.
Calippus cf. cerasinus is a small (body mass 100 kg) horse. Calippus (Gramohippus) cerasinus is also
known from the latest Clarendonian Merritt Dam Member of the Ash Hollow Formation of Nebraska and the
Love Bone Bed of Florida (Hulbert, 1988a). It is much larger than the late Barstovian to mid Clarendonian C.
(Calippus) placidus and Clarendonian C. (Calippus) regulus, and smaller than the early to mid Clarendonian C.
(Gramohippus) martini, all three of which occur in the Lapara Creek Fauna (Hulbert, 1988a).
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THE LATEST HEMPHILLIAN LAKE CORPUS CHRISTI LOCAL FAUNA
The name Lake Corpus Christi Local Fauna is proposed for a mainly reworked assemblage recovered in the
lower Nueces River Valley, but whose source is the upper Goliad Formation. Baskin (1991) described early Plio-
cene horses from two late Pleistocene gravel pits along the Nueces River, approximately 10 km and 25 km down-
stream from exposures of the Goliad Formation. These include Dinohippus mexicanus, Astrohippus stockii, Nan-
nippus cf. beckensis, Nannippus aztecus, Pseudhipparion simpsoni, and Neohipparion eurystyle. Other trans-
ported specimens are an edentulous lower jaw of the four-tusked gomphothere Rhynchotherium, a calcaneum of
the rhinoceros Aphelops, and the proximal phalanx of the 2 m tall carnivorous bird Titanis (Baskin, 1995). Rhyn-
chotherium is known from the late Clarendonian to late Blancan (late Pliocene). The only known rhinoceros
from the Lapara Creek Fauna is Teleoceras (Prothero and Manning, 1987). Aphelops last occurs in the late
Hemphillian. Rare earth element dating showed that the Texas Titanis was the same age as the Hemphillian
horses (MacFadden et al., 2007). These taxa indicate that the Lake Corpus Christi LF is younger than the Mio-
cene-Pliocene boundary (5.5 Ma). This assemblage is most similar to that of the latest Hemphillian (Hh4, early
Pliocene, about 5 Ma) fauna from Yepómera, Mexico (MacFadden, 2006).
Unlike the reworked fossils previously described, which were all isolated teeth (Baskin, 1991), additional
latest Hemphillian fossils have since been recovered preserved in highly indurated calcrete by J. A. Baskin.
Among these are two partial Nannippus skulls, an edentuluous Rhyncotherium palate, and a partial upper denti-
tion of Dinohippus. In the region, highly indurated caliche only occurs at the top of the Goliad and is especially
well developed along the southern margins of Lake Corpus Christi, a reservoir created by the damming of the
Nueces River near Mathis, Texas. Further support for an upper Goliad source for the reworked fauna is provided
by a tooth of Neohipparion eurystyle found at Lake Corpus Christi by Alan Costello. Additionally, a palate of
the rhinoceros Aphelops was recovered just below the dam for Lake Corpus Christi, likely during construction of
the dam (Baskin, 1991). The large size of its teeth indicates a late Hemphillian age and the fragility of the speci-
men suggests it could not have been transported very far.
The calcrete at the top of the Goliad is a soil horizon that probably postdates the Lake Corpus Christi LF. It
is likely equivalent to the thick calcrete that separates the latest Hemphillian from Blancan faunas in the Texas
Panhandle (Schultz, 1990b), as well as the top of the Ogallala and its equivalents elsewhere (Hanneman and
Wideman, 2006), indicating a widespread climate of intense aridity that extended from the Great Plains to the
Gulf Coast in the early Pliocene.
CORRELATION WITH THE MARINE RECORD
Morton et al. (1988) correlated the Goliad Formation with the Bigerina humblei to Robulus “E” Gulf Coast
marine benthic foraminiferal zones, or middle to late Miocene. This is equivalent to middle Serravallian to
Messinian. For the present paper, the correlations of Fillon et al. (1997) are used. The Serravallian-Tortonian
boundary is now placed at 11.6 Ma (Hilgen et al., 2005). This indicates the base of the Goliad (early Clarendo-
nian Lapara Creek fauna) is better correlated with the Textularia “W” benthic foraminiferal zone (late Serraval-
lian); the Dinero LF to the Bolivina-Cibicides biozone (early Tortonian); and the Lake Corpus Christi LF to the
Bigenerina “6” biozone (early Zanclean).
ACKNOWLEDGMENTS
When I (JAB) first moved to Texas, Jack Wilson of UT Austin shared his knowledge of Goliad Formation
paleontology with me. Alan Costello, Frank Cornish, and Roger Steinberg donated fossils collected by them.
Ronny Thomas of TAMUK is responsible for collecting most of the reworked fossils from the Goliad Formation.
Mrs. Ruth Wright, Mr. Larry Wright, Mr. M. P. Wright IV, Mr. Mark Truesdale, and Mr. Greg Truesdale pro-
vided access to the Wright Materials sand and gravel quarries. Mr. George Sorensen graciously granted permis-
sion to collect from the sand and gravel pit on his property in Odem.
Baskin and Hulbert
98

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