Neochelys arenarum Broin, 1977

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 : 42-45

Neochelys arenarum Broin, 1977

TYPE SPECIMEN: MNHNP RI 45 , a shell ( Broin, 1977: text figs. 10–12; pl. 2, figs. 10, 11; see also for discussion and description) .

TYPE LOCALITY: Rians, Var, France ( Broin, 1977).

HORIZON: Sparnacian ( Broin, 1977).

DIAGNOSIS: Broin (1977), Schleich (1993), and Lapparent de Broin (2003a) give diagnoses for the numerous European shell-based species and further references. Broin (1977: figs. 11, 12) shows the anterior plastral lobe of arenarum Broin, 1977 , but with some individual variation, specimens all have the intergular scale separating the gular scales, in contrast to the condition in fajumensis Andrews, 1903 , discussed below. Only Neochelys arenarum is known from a skull that has been described and it is very similar to that of Neochelys fajumensis .

REFERRED MATERIAL: Same data as type: MNHNP RI 6 , nearly complete skull and jaws, slightly deformed, described and figured in Broin (1977: 70–83) ; MNHNP RI 7 , probably not deformed but with few sutures visible ; see list of other specimens in Broin (1977: 64); material from Rians , Var, France, in MDE: MDE R1 and MDE R2 , skull and lower jaw .

PREVIOUS WORK: The skull of this species is well described and figured in Broin (1977). A disarticulated basisphenoid associated with other Neochelys fragments is described and figured in Lapparent de Broin (2003a). Schleich (1993) described a new species, Neochelys franzeni , with associated skull material, which is not described. Other known but undescribed Neochelys skulls ( Jiménez Fuentes, 1988: 9, fig. 3; Lapparent de Broin, 2001: 170–171; 2003a: table 1) have been mentioned in the literature, but are apparently unavailable for study. The shell of Neochelys arenarum is described and figured in Broin (1977).

DISCUSSION: Although a number of species have been named, Broin (1977), Lapparent de Broin (2001), and some diagnosed comparatively in Broin (1977), Schleich (1993), and Lapparent de Broin (2003a), the shell characters distinquishing the various species seem to be within the individual variation of many recent species of Podocnemis , in our assessment.

Neochelys fajumensis ( Andrews, 1903) , new combination

Podocnemis fajumensis Andrews, 1903 . Podocnemis blanckenhorni Reinach, 1903 . Erymnochelys fajumensis (Andrews) Lapparent de

Broin, 2000a.

TYPE SPECIMEN: CGM 10202, anterior portion of plastron, collected by Beadnell, 1902, figured in Andrews (1903: pl. 8, fig. 2C; and Andrews, 1906: fig. 93) possibly now lost (Cyril Walker, R.C.W., unable to locate in Cairo Museum, personal commun.).

TYPE LOCALITY: ‘‘North of Birket-el- Qurun’’ Fayum Depression, Egypt ( Andrews, 1906: 292).

TYPE HORIZON: ‘‘In the Upper Eocene beds remains of another small Pleurodiran are not uncommon’’ ( Andrews, 1903: 121), who did not specifically designate a type locality or horizon. Later authors have reinterpreted the age assignment and concluded that fajumensis occurs only in the Oligocene part of the Jebel Qatrani Fm. ( Simons, 1968; Seiffert, 2006, q. v. for further references). The age of the Jebel Qatrani Fm. is a complex question with current evidence supporting only the base of the Jebel Qatrani as Eocene ( Seiffert, 2006). There is no direct evidence that any of the N. fajumensis material is Eocene, but as turtle distributions are frequently undocumented, this remains a possibility.

DIAGNOSIS: Six neurals, the first contacting nuchal; costals six, seven, eight meeting on midline; anterior end of nuchal very narrow, nuchal width-length about equal; intergular scale small, triangular or parallel sided, not completely separating gular scales, in contrast to all other Neochelys , or humeral scales on midline, barely extending onto entoplastron; differs from ‘‘Podocnemis’ ’ podocnemoides (von Reinach) in the gular and humeral scales meeting on the midline rather than being separated.

The shell is very similar to that of Erymnochelys .

ETYMOLOGY: Presumably for the Fayum, Egypt.

REFERRED MATERIAL: AMNH 5086 (fig. 86), anterior plastral lobe; AMNH 5093, anterior plastral lobe (fig. 86); AMNH 5087, carapace. Apparently, most of the AMNH specimens came from three quarries: A, B, and C, in the lower Fossil Wood zone of the Jebel Qatrani Fm. ( Simons, 1968: 20; see also Moustafa, 1974, for map).

Similarly, the BMNH (including what was sent to Cairo and is now CGM) and YPM material are also probably from the early Oligocene part of the Jebel Qatrani Fm., according to Simons (1968: 19, 20). CGM 8790, shell; CGM 8509, anterior plastral lobe; BMNH R3103, anterior plastral lobe; BMNH R3435, anterior plastral lobe; YPM 6202, shell; YPM 6203, shell. The identifications are based almost entirely on the anterior plastral lobe morphology of the small intergular scale not separating the gulars or humerals.

We list all specimens found by the Duke parties because they provide evidence that the Neochelys skulls and jaws occur in close association with fajumensis shells in the Jebel Qatrani Fm. There is no documented case of an articulated set of cervicals connecting a skull with a shell, but the proximity of the skulls and shells is a matter of a few centimeters or less (D. Deblieux, E. Simons, personal obs.). Shell fragments of fajumensis are the commonest fossil in the Quarry L 41, Quarry M, and Quarry I localities, and only articulated shell material of some completeness was collected. Even the skeptical E.S.G. agrees that this skull-shell association should be accepted. Stratigraphic data for these quarries can be found in Bown and Kraus (1988: fig. 19, q. v. this paper for further references; see also Moustafa, 1974; Gingerich, 1992). The most recent age assessment for the Fayum stratigraphy ( Seiffert, 2006) indicates that Quarry L-41 is ca. 35.4 Ma (latest Eocene), Quarries A, B, and C are ca. 34.8, and Quarries I, M, and P are ca. 30.2– 29.5 Ma.

DPC 3146 (figs. 44, 45), skull, complete but lacking right temporal roof and cheek, right quadrate and squamosal, Quarry M, 82-1229; DPC 12143, laterally compressed skull, most elements present but considerably displaced by disarticulation, L-41, 92-461; DPC 15310, partial skull, most elements present but considerably displaced by disarticulation, loss of palate and left quadrate and otic area, L-41, 95-350; DPC no number, L-41, 99-245 (fig. 46), nearly complete skull, dorsoventrally flattened and slightly disarticulated but not extensively deformed; DPC 1697, partial skull, consisting of both premaxillae, maxillae, frontals, partial parietals, postorbitals, jugals, palatines, and basisphenoid, Quarry I, 77-39; DPC 3882, skull lacking snout and skull roof, Quarry I, 83- 252. These skulls listed above are from the Jebel Qatrani Fm., and are the basis (primarily DPC 3146) for the restorations in figures 42, 43.

DPC 6209, carapace, Quarry O, 86-861; DPC 2491, shell, Quarry R, 81-727; DPC 7747, shell, Quarry M, 85-986; DPC 9483, shell, Quarry I, 89-1028; DPC 4605, partial carapace, Quarry P, 83-1107; DPC 2149, disarticulated shell elements, Quarry M, 80- 854; DPC 10686, shell, L-41, 90-936; DPC 10434, partial shell, L-41, 90-531.

All of the following are lower jaws and consist of the fused dentaries indistinguishable from the lower jaw of Neochelys arenarum Broin (1977 : fig. 18, pl.2). DPC 1699, Quarry M, 77-240; DPC 2003, Quarry I, 80-813; DPC 2223, Quarry M, 80, 311; DPC 2230, Quarry M, 80-345; DPC 2602, Quarry M, 81-586; DPC 2747, Quarry M, 81- 137; DPC 2754, Quarry M, 81-176; DPC 2779, Quarry P, 81-52; DPC 2858, Quarry M, 81-563; DPC 3249, Quarry I, 82-623; DPC 3261, Quarry M, 82-542; DPC 3261, Quarry M, 82-542; DPC 3308, Quarry M, 82-542; DPC 3308, Quarry I, 82-161; DPC 3442, Quarry M, 82-951; DPC 3862, Quarry M, 83- 464; DPC 3973, Quarry M, 83-431; DPC 4291, Quarry M, 83-1380; DPC 4400, Quarry M, 83-302; DPC 4413, Quarry M, 83-123; DPC 4495, Quarry M, 83-787; DPC 5068, Quarry M, 84-825; DPC 5193, Quarry I, 84- 867; DPC 5520, Quarry M, 85-990; DPC 5749, Quarry M, 85-193; DPC 5786, Quarry I, 85-141; DPC 5892, Quarry M, 85-309; DPC 6205, two lower jaws, Quarry M, 86- 933; DPC 6413, Quarry M, 86-336; DPC 6522, Quarry M, 86-95; DPC 6558, Quarry M, 86-332; DPC 7331, Quarry M, 87-300; DPC 7545, Quarry M, 87-758; DPC 7546, Quarry I, 87-780; DPC 7673, Quarry I, 87- 859; DPC 9352A, Quarry M, 89-384; DPC 9795, Quarry M, 89-330; DPC 10226, Quarry I, 90-107; DPC 10382, Quarry I, 90-347; DPC 10607, Quarry M, 90-1208; DPC 11192, two lower jaws, Quarry M, 91-362; DPC 11403, Quarry M, 91-780; DPC 12116, Quarry M, 92-407.

DISCUSSION: The identification of Neochelys in the Fayum extends the range of this genus outside Europe to North Africa. The skull material from the Egyptian early Oligocene units is hardly distinguishable from the European Eocene Neochelys . However, the identification of this material with the Oligocene species fajumensis , extends the temporal range of Neochelys , formerly known from the early to late Eocene of Europe (55–34 Ma), adding approximately another 5 Ma to the already long duration of this genus. The recognition of Neochelys in the Paleogene of North Africa also adds another piece to the biogeographic puzzle of Afro-European dispersal in the Paleogene ( Lapparent de Broin, 2003a).

The recognition of fajumensis as Neochelys is based not only on the hypothesis that the shells and skulls in the Duke quarries are associated, which is testable but not certain, but that the characters used to diagnose fajumensis actually are restricted to this single species. It is possible that these characters diagnose a wider group of taxa, as the shell characters in the Pelomedusoides (particularly the Podocnemididae ), tend to be conservative in comparison to the skulls (discussion above and in Gaffney et al., 2006). Furthermore, fajumensis (fig. 47) and the Duke material differ from all European Neochelys in having small intergular scales allowing the gular scales to contact on the midline. The anterior lobe in the Pelomedusoides is the most variable part of the shell and has figured prominently in pleurodire shell taxonomy. Unfortunately, it is also individually variable (E.S.G., P.A.M., R.C.W., personal obs.), and too much emphasis has been placed on this area for characters in our judgements. Even Andrews (1906) showed that there was variation in the anterior plastral lobe of his podocnemidids.

We conclude that there are no systematic differences between the shells in the Duke quarries associated with skulls of Neochelys , and the shells identified in the literature as fajumensis . One could still argue that this taxon is not Neochelys because all Neochelys known to date have the intergular scales separating the gular scales. But then one would have to argue either that the skulls are not Neochelys or that they are not associated with the shells.

The synonymy of Podocnemis blanckenhorni Reinach, 1903 , with Podocnemis fajumensis Andrews, 1903 , appears to be correct, but the synonymy with Dacquemys suggested by Williams (1954c) is clearly not. The proposed synonymy of Pelomedusa progaleata Reinach, 1903 , with fajumensis ( Lapparent de Broin, 2000a) is hard to support as the type material is inadequate for useful comparison. Pelomedusa progaleata Reinach, 1903 , is better considered as a nomen dubium.

DESCRIPTION OF THE SKULL: The description of the skull of Neochelys arenarum by Broin (1977) is extremely close to the Egyptian skulls and only differences are noted below. Our description is based mostly on DPC 3146 (figs. 42–45) with some information from DPC 99-245 and other cranial fragments listed above.

The skull figured by Broin, MNHNP RI 6 (1977: figs. 13–18, pl. 2), is one of a series available for this species. All of the skulls in the series are slightly deformed, and the figured skull is slightly wider and lower than the others, which are narrower and almost exactly the same shape as DPC 3146, particularly the apparently undeformed MNHNP RI 7. So the wide shape of the figured Neochelys arenarum seems to be due to preservation and is unique to that specimen.

The prefrontal-frontal suture in the Egyptian specimens is W-shaped in dorsal view (fig. 42) and in MNHNP RI 6 it is transverse. DPC 3146 has an interorbital groove, similar to that seen in Podocnemis , but with a much wider interorbital distance. The other Egyptian skulls, however, do not show this groove, although we have coded Neochelys as present and absent for this character. DPC 3146 has a more emarginate posterior temporal roof with a greater quadratojugal exposure along the edge than in Neochelys arenarum , but this is within the range of variation frequently seen in many turtles. What may be the only significant distinction between the Egyptian skulls and the Neochelys arenarum series is in the cheek. The quadratojugal in DPC 3146 has a greater exposure along the cheek emargination than in MNHNP RI 6 associated with a smaller anterior process of the quadrate. It is possible, however, that even this is due to breakage in DPC 3146. In any case, we have not seen consistent characters that would differentiate the French Neochelys skulls from the Egyptian Neochelys skulls. They would probably be placed in the same species, if only the skulls were known.

DESCRIPTION OF THE SHELL: The reconstruction of the shell of Neochelys fajumensis (fig. 47) is based on a number of specimens: YPM 6202, AMNH 5087, CGM 8790, CGM 10202, AMNH 5086, AMNH 5093, CGM 8509, BMNH R3103, BMNH R3435, and YPM 6203.

The carapace of Neochelys fajumensis is domed and oval in the uncrushed examples in both groups; there are eight costals and 11 peripherals. Peripherals 8–11 and the pygal (YPM 6203 and CGM 8690) bear a ridge on their inner surface, which can also be seen in DPC 2491, DPC 7747, DPC 2225 and DPC 9483. The nuchal is wider than long, with an unusually narrow anterior half, in both groups of specimens. The first neural is four sided, as in most pleurodires. There are either five (YPM 6202, AMNH 5087, CGM 8790), six (DPC 2491), or seven (DPC 6209, DPC 7747) neural bones. This is accompanied by either costals six to eight meeting on the midline or just costals seven and eight meeting on the midline.

The plastron of Neochelys fajumensis has an anterior lobe that is shorter than the posterior lobe and is squared off along its anterior margin. Small swellings are present marking each of the scale areas: intergular, gular, and humeral. The outer border of the posterior lobe curves medially in a gentle arc to the tips of the xiphiplastra. The entoplastron varies slightly from all four sutures being straight to having the posterior pair curved; their margin convex posteriorly. Mesoplastra are preserved in CGM 8790, DPC 2491, and DPC 7747. There is no sulcus on the mesoplastron. The anal notch varies from wide and semicircular to narrower and more V-shaped. On the inner surface of the posterior lobe, along the lateral margin just inside the body wall attachment ridge is a low ridge of thickened bone paralleling the margin. Narrow intergular scales not completely separating the gular scales is one of the diagnostic features used in the literature for ‘‘ Podocnemis’ ’ fajumensis .