Gee et al.—New early Permian vertebrate locality 92(6):1092–1106


root traces and potential burrow fills are common and give the caliche nodules a ‘vuggy’ appearance. Frosted quartz grains dominate in the sand fraction with minor amounts of orthoclase and lithic fragments. The alluvium that caps the Vale Formation at the Mud Hill


locality is composed of Cretaceous material removed from the Callahan Divide, south of the locality. Clasts of conglomerates, sandstones, and limestones along with a diverse marine fossil assemblage are found in a matrix of loosely cemented quartz sand. The sands and conglomerates originate from the Antlers Sandstone, whereas the limestone and marine fossils are derived from the Edwards Limestone. The marine fossils are commonly fragmented and are representative of the molluscan dominated assemblage found in the Edwards Limestone. Material at the Mud Hill locality was collected from several


sites (Figs. 1, 3): D1: vertebrate collection site in a bank northeast of an


excavation for dam construction, north of a small water tank, south of Olhausen Road (32.335881°N, −99.799503°W); D2: vertebrate collection site in a bank south of a large tank, south of Olhausen Road (32.334817°N, −99.800989°W), which can be covered by an adjacent water tank in extremely wet weather; and D3: vertebrate collection site on a hillside exposure, north of Olhausen Road (32.337454°N, −99.801463°W). The D3 site is on private property that is not associated with the Olhausen Estates; collections were made under a private agreement with the landowner.


Materials and methods


All materials (Table 2) come from the Mud Hill locality on the Olhausen Estate near Abilene, Texas (Figs. 1–3, S1). An iso- lated diadectid centrum was collected from the estate by JO in the early 1970s, but the first bonebed site (D1) was not dis- covered until 1997 by Jacob and James Olhausen. The D2 site was found in 1998 by Robert Burt, and the D3 site was found in 2007 by Dale Ostlien. All three sites were periodically explored and partially excavated following their initial discovery. Because the sites were not excavated in a systematic fashion and without a quarry map, materials that are presently disarticulated could in fact have been associated at some point (e.g., right and left partial captorhinid mandibles). Initial excavation, sorting, and preparation of some of the


material was conducted by the family at the estate, primarily Jo Helen Cox, following collection; upon loan of the material to RRR, preparation of specimens in a formal laboratory was conducted with pin vises and air scribes by students at the University of Toronto Mississauga under the supervision of DS. Specimen photographs were taken by DS with a Canon EOS 40D digital SLR camera and a Leica DVM6 tilting microscope with Leica Application Suite X (LAS X) software; figures were compiled using Adobe Photoshop and Illustrator CS6.


Repositories and institutional abbreviations.—All specimens are deposited in the Texas Memorial Museum(TMM)in Austin, Texas, USA. Other institutions referenced in the text are: CNHM-UR=Chicago Natural History Museum (Field Museum of Natural History), Chicago, Illinois; UCLA VP= University of California Los Angeles, Vertebrate Paleontology,


Systematic Paleontology Superclass Tetrapoda Goodrich, 1930


Tetrapoda indet. and Diplocaulinae gen. indet. sp. indet. Figure 4.1


Description.—This intriguing, although unfortunately poorly preserved, specimen is a diminutive partial skeleton of a tetra- pod cemented to the skull roof of a diplocauline (TMM 43628- 8) noted below from the D2 site (Fig. 4.2, 4.3). The general contours of an elongate, rounded skull with a posterolateral projection on the right side can be made out, but the small size of the specimen in conjunction with weathering and encrusting obscures all other details. A series of vaguely vertebrae- appearing elements is associated with the skull and extends posteriorly to the margin of the diplocaulid skull, but as with the former, no details can be resolved that would further inform the identification.


Subclass Lepospondyli Zittel, 1888 Order Nectridea Miall, 1875 Nectridea indet. Figure 5


Description.—This specimen (TMM 43628-7) comprises the postorbital margin of a nectridean, with the fragment being roughly symmetrical, but with better preservation of the ele- ments on the left side of the skull; it was collected from the D2 site. It is broken off anterior to the pineal foramen, and the


1095


Table 2. Specimens from Mud Hill described herein, with site of recovery, taxonomic identification, and recovered material.


Specimen number


Site Taxonomy


TMM 43628-1 D2 Varanops brevirostris (Williston, 1911)


TMM 43628-2 D1 Diadectes sp. indet. TMM 43628-3 D1 Diadectes sp. indet.


Elements Dentary


Premaxilla, maxilla, dentary


Partial skeleton (see Campione and Reisz, 2010)


TMM 43628-5 D2 cf. Diadectes sp. indet. Postcrania (tarsus) TMM 43628-6 D3 cf. Diadectes sp. indet. Postcrania (vertebrae) TMM 43628-7 D2 Nectridea indet.


TMM 43628-4 D1 cf. Diadectes sp. indet. Postcrania (limbs, vertebrae, girdles)


TMM 43628-8 D2 Diplocaulinae gen. indet. sp. indet.


TMM 43628-10 D3 Hapsidopareiontidae gen. indet. sp. indet.


TMM 43628-9 D2 cf. Diplocaulus sp. indet.


TMM 43628-11 D3 Captorhinidae gen. indet. sp. indet.


TMM 43628-12 D3 Captorhinidae gen. indet. sp. indet.


TMM 43628-13 D3 cf. Captorhinikos chozaensis Olson, 1954c


Skull, partial mandible, clavicles


Skull, mandibles Skull, mandibles Humerus


Skull, mandibles, indet. tetrapod skull and vertebrae


Partial mandibles Premaxilla, mandible


Los Angeles, California; USNM=United States National Museum (now National Museum of Natural History, Smithso- nian Institution), Washington, DC.


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