Bauruemys elegans ( Suárez, 1969a ), Kischlat, 1994

Gaffney, Eugene S., Meylan, Peter A., Wood, Roger C., Simons, Elwyn & De Almeida Campos, Diogenes, 2011, Evolution Of The Side-Necked Turtles: The Family Podocnemididae, Bulletin of the American Museum of Natural History 2011 (350), pp. 1-237 : 14-21

Bauruemys elegans ( Suárez, 1969a)

Podocnemis elegans Suárez, 1969a

Bauruemys elegans ( Suárez, 1969a) Kischlat, 1994

TYPE SPECIMEN: The number of the type specimen of this species is in some ambiguity, but we conclude with the assistance of our colleagues, G. Oliveira and P.S.R. Romano, that the type is MCT 1492-R, an associated shell and skull. The original author did not designate a holotype by number but he figured the shell, carapace, and plastron. However, the skull that was figured ( Suárez, 1969a: figs. 6, 7) does not belong to the type specimen; it is MCT 1753-R (figs. 11, 12), and should be considered a paratype based on the text of Suárez (1969a; P.S.R. Romano, personal commun.). Candeiro et al. (2006: 927) confusingly state ‘‘ holotype of B. elegans is UFRGS 148 and MN-V 4487, a postcranium….’’ Oliveira and Romano (2007) say (in translation) that although these specimens are representative of the species, they have concluded, following an extensive examination of the collections involved, that neither specimen should be referred to the type material of B. elegans . We agree that the type of Podocnemis elegans Suárez, 1969a , is MCT 1492-R, a skull (figs. 9, 10) and shell with scapulocoracoids, femur, and humerus. This identification is based on the shell figures in Suárez (1969a: figs. 2–4; 1969b: figs. 1–5).

The type skull, MCT 1492-R (figs. 9, 10), is dorsoventrally crushed and much of the bone is broken. The right side is better preserved than the left in general. The prefrontals are present but broken anteriorly. The frontals are both present with clear sutures. Both parietals are broken laterally and posteriorly. Portions of the jugal where it contacts the maxilla are present on both sides, but its posterior contacts are damaged or missing. Only small parts of the quadratojugals are identifiable, and the postorbitals are either missing (left) or broken and overlapped with the jugal and quadratojugal (right). Only a small portion of the anterior margins of the left squamosal are preserved and none of the right. The cheek emargination is partially preserved on the right side but badly damaged, and it is not determinable on the left side.

The premaxillae are represented only by a part of the horizontal plate visible in dorsal view. The left maxilla has the portion below the orbit preserved with the labial ridge intact, but its anterior portion is missing and its posterior margins broken. The right maxilla is more complete, but is covered ventrally by matrix, which helps hold it together along with some loose bone fragments on the ventral surface. The vomer is missing. The left palatine is cracked and missing its anterior margins but is otherwise intact. The right palatine is badly broken and represented only by the posteromedial piece.

The right quadrate is preserved medially, but the cavum tympani and processus articularis are gone. The left quadrate has a partially crushed and broken cavum tympani and the processus articularis present. The medial contacts of both quadrates are preserved. The left pterygoid is nearly complete except for some cracking and slight displacement. The right pterygoid lacks most of its lateral portion and is partially obscured by displaced bone fragments. On both sides, the cavum pterygoidei is preserved, although its margins are broken edges. The anteromedial part of the supraoccipital is preserved, but all of the crista supraoccipitalis is gone. Both exoccipitals are present but slightly broken along the margin of the foramen magnum, and the condylus occipitalis is broken off. The basioccipital is complete except for the condylus occipitalis. Both prootics are present and complete but mostly covered by matrix. The left opisthotic lacks some of its posterior process and the right one lacks all of it. The basisphenoid is complete, with clear sutures.

To the extent that it is preserved, the type skull agrees in detail with the other skulls ascribed to this species that are described below.

TYPE LOCALITY: ‘‘Tartaruguito’’ locality, near kilometer 736 of the old Sorocabana Railway branch, Pirapozinho, São Paulo State, Brazil, 22 ° 13 9 08 0 S, 51 ° 25 9 59 0 W ( Romano and Azevedo, 2007; also see Bertini et al., 2006, for map; Oliveira and Romano, 2007). Suárez (2002), Henriques et al. (2005), Henriques (2006), Bertini et al. (2006), discuss the taphonomy and depositional history of this locality.

HORIZON: Adamantina Fm. fide Suárez (2002), Bertini et al. (2006).

DIAGNOSIS: As for genus.

REFERRED MATERIAL: MCT 1753 -R, figured by Suárez (1969a: figs. 6, 7; 1969b: figs. 5, 6), but not associated with type specimen. This skull (described below, figs. 11, 12) is the best preserved of the Bauruemys we have seen ; all bones, except the vomer, are known from either one side or the other. The horizontal plates of the premaxillae are cracked and a few small pieces are missing. The crista supraoccipitalis is cracked and broken and has been repaired by reconstructing the available pieces. The result shows all the limits of the crista, but it is slightly deformed by crushing. Both temporal margins are dorsoventrally crushed but not collapsed, only depressed from the level of the skull roof. A small portion of the posteromedial part of the left parietal is missing. The posterior end of the right squamosal is missing. On the ventral surface, the pterygoid flanges are broken away and the floor of the cavum pterygoidei has been removed by preparation to expose the internal features of the cavum pterygoidei.

DGM uncataloged (collected 1969, Campos and Silva), carapace and plastron disarticulated with postcranial material in carapace part, including an eighth cervical vertebra.

MCZ 4123, a more complete skull than DGM uncataloged (above), but it is slightly more distorted and deformed by crushing (figs. 13, 14). MCZ 4123 has the vomer intact and the pterygoid flanges preserved on both sides. It is the only Bauruemys we have seen to have the flanges intact. The fossa nasalis has been deformed by lateromedial crushing, but the elements are all present and the only area lost is part of the horizontal plates of the premaxillae. The right prefrontal is crushed and displaced onto the frontal. As in DGM uncataloged, the posterior parts of the temporal roof have been pushed ventrally below the level of the skull roof, but the bones are missing only a few small pieces and the temporal margins are intact. Some missing areas of the parietals, left cheek, and supraoccipital have been filled in or repaired with resin.

AMNH 7888 consists of the skull, attached lower jaws, and attached fragments, including a centrum and phalange, to the

TABLE 1 Comparison of Skulls of Mesozoic and Early Tertiary Podocnemididae right of the crista supraoccipitalis. The skull is missing the vomer, both prefrontals, both frontals, anterior parts of the parietals, dorsal parts of the premaxillae, anterior parts of the maxillae, and some of the pterygoid flanges. Although the vomer is missing and the lower jaws are in place, the ventral surface of the premaxillae is well preserved and visible. The lower jaw is missing some pieces anteriorly.

AMNH 30643 consists of roughly the right half of a skull, showing the fossa orbitalis, the sulcus palatinopterygoideus, and the fossa temporalis. The right cheek, cavum tympani, crista supraoccipitalis, and temporal roof are missing. The occiput is damaged and it lacks the condylus occipitalis.

AMNH 30642 consists of roughly the left half of the skull without the snout region. The left otic chamber and cavum tympani are well preserved. The dorsal surface of the basicranium is exposed from the rostrum basisphenoidale anteriorly to the condylus occipitalis posteriorly, showing the area of the dorsum sellae and associated structures.

AMNH 30774, two partial lower right jaws and miscellaneous fragments associated with AMNH 30642 and AMNH 30643.

MN 4322-V, nearly complete skull, lacking the premaxillae, anterior parts of the maxillae, vomer, lateral parts of the pterygoids, and some of the occipital surfaces. The more internal areas are still encased in matrix.

MN 4323-V, partial skull, lacking the right quadrate, occipital surfaces, and much of the palate. It still has matrix on many of the surfaces.

MN 4324-V, posterior half of a skull, lacking everything anterior to the pterygoidpalatine suture. The center of the cavum cranii is exposed in the anterior surface of the break. The posterior temporal margin is preserved.

MN 4487-V, two cervical vertebrae referred to by Kischlat (1994: 348).

MCZ 4125, anterior half of a shell, with costals 1–4, neurals 1–4, anterior half of plastron with right mesoplastron. Only a few peripherals are preserved.

MCZ 4122, anterior margin of a shell, with the nuchal, peripherals 1–3, and the anterior plastral lobe.

MCZ 4127, right maxilla and palatine with ventral surfaces exposed.

MCZ 4128, partial skull lacking the prefrontals, frontals, postorbitals, and quadratojugals, left quadrate, on the dorsal surface. The posterior rami of the lower jaws are in place on the ventral surface. Most of the elements visible in ventral view are present, but are cracked and not well preserved.

MCZ 4129, partial skull consisting of the snout region exposed in ventral view and the otic chambers and cavum cranii exposed in a break.

MCZ 4124, small block of matrix with some limb elements in situ.

PREVIOUS WORK: Although Suárez (1969a) appears to be the legitimate publication for the type announcement for Podocnemis elegans , there are two other possible publications listed by Oliveira and Romano (2007) that contain a type announcement. One of these, not listed in our bibliography but listed in Oliveira and Romano (2007: 127), is a short paper that we interpret as an unpublished abstract, not a legitimate taxonomic description. The other, Suárez (1969b), has the same text and figures as Suárez (1969a) with a different page and figure arrangement, but exactly the same content. We do not know the relative dates of publication.

In addition to the generic name proposed in Kischlat (1994), Kischlat (1996a, 1996b), and Kischlat et al. (1994) provide other hypotheses about the relationships and geologic distribution of Bauruemys . Romano and Azevedo (2007) present a morphometric study of this species, possible due to the relatively large numbers of specimens available. They support the hypothesis of a single species in the sample studied.

DISCUSSION: Peirópolis B, the smaller of the two unnamed shell taxa from Peirópolis, is known only from isolated shell elements. It shares derived features with Bauruemys elegans , but is too poorly known to be referred to this species.

Kischlat (1994: 348) described two cervical vertebrae of Bauruemys elegans as lacking saddle-shaped or heterocoelous articulations (in the sense of Williams, 1950; Hoffstetter and Gasc, 1969). We have also examined these vertebrae and a number of similar cervicals in the uncataloged collections of the DNPM. The articulations are clearly similar to the cervical morphology of the outgroups, such as in Euraxemys and pelomedusids, in being a relatively simple, hemispherical, concave-convex articulation, not the more complex surface (‘‘saddle-shaped’’) seen in Podocnemis and Peltocephalus , and not the wide, surface seen in Turkanemys and Erymnochelys .