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

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 middle 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) Miocene. This paper documents a late Clarendonian (10 Ma) and a latest Hemphillian (5 Ma) Local Faunas (LFs) 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 (Ceratogualus anecdotus, Pseudhipparion skinneri, Calippus cf. cerasinus, and Cormohipparion cf. ingennum) is late Clarendonian. The mainly reworked Lake Corpus Christi LF includes the horses Dinohippus cf. mexicanus, Astrohippus stockii, Pseudhipparion simpsoni, Nannippus 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.