the holotype specimen of vancleavea campi from

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centra and partial centra, fragments of proximal, and one distal, ... Axial Skeleton .... P-R, Distal left humerus in distal (P), cranial (Q) and caudal (R) views.

Heckert, A.B., and Lucas, S.G., eds., 2005, Vertebrate Paleontology in Arizona. New Mexico Museum of Natural History and Science Bulletin No. 29.

THE HOLOTYPE SPECIMEN OF VANCLEAVEA CAMPI FROM PETRIFIED FOREST NATIONAL PARK, ARIZONA, WITH NOTES ON THE TAXONOMY AND DISTRIBUTION OF THE TAXON

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ADRIAN P. HUNT, SPENCER G. LUCAS and JUSTIN A. SPIELMANN New Mexico Museum of Natural History and Science, 1801 Mountain Road NW, Albuquerque, NM 87104-1375

Abstract—Vancleavea campi is an unusual archosauriform taxon present throughout the AdamanianApachean interval of the Chinle Group. We photographically illustrate and redescribe the holotype from the Adamanian (latest Carnian) Blue Mesa Member of the Petrified Forest Formation at Petrified Forest National Park. Vancleavea campi displays apomorphies that include tall, narrow osteoderms with a bifurcate base and a smooth surface texture and smooth, flat osteoderms with a dorsal ridge, as well as the combination of these derived-aspect osteoderms with underived-aspect limb and girdle elements. Vancleavea has aquatic adaptations including dorsally-directed (non-terminal) external nares, an elongate body with short limbs and upright-standing osteoderms (sculling tail), although many specimens of this taxon are found in association with terrestrial faunas. Keywords: Archosauriform, Vancleavea, Adamanian, Revueltian, Apachean, terrestrial, aquatic INTRODUCTION Long and Murry (1995) named Vancleavea campi for a partial skeleton (PEFO 2427) of an unusual armored reptile from the Adamanian interval of the Blue Mesa Member of the Petrified Forest Formation in Petrified Forest National Park, Arizona. This aberrant reptile combines primitive-aspect postcrania with specialized osteoderms. Subsequently, Hunt et al. (2002) recognized that Vancleavea is a widespread taxon (Fig. 1) and that specimens of it had first been collected by E. C. Case in 1912. The purposes of this paper are to: (1) photographically illustrate for the first time, and to redescribe, the holotype of Vancleavea campi (Figs. 2-4); (2) to assess the validity and relationships of this taxon; and (3) to discuss its stratigraphic and geographic distribution. Institutional abbreviations: GR, Ruth Hall Museum of Paleontology, Ghost Ranch; MNA, Museum of Northern Arizona, Flagstaff; NMMNH, New Mexico Museum of Natural History and Science, Albuquerque; PEFO, Petrified Forest National Park, Arizona; SMU, Southern Methodist University, Dallas; UCMP, University of California Museum of Paleontology, Berkeley; UMMP, University of Michigan Museum of Paleontology, Ann Arbor; YPM, Yale Peabody Museum, New Haven. HOLOTYPE OF VANCLEAVEA CAMPI Long and Murry (1995, p. 195-198, figs. 197-198) described the holotype of Vancleavea campi in detail, and the following description draws heavily from their work. Long and Murry (1995, figs. 197-198) provided line drawings of selected bones, but no photographic illustrations of the holotype. The holotype (PEFO 2427; Figs. 2-4) consists of a large number of vertebral centra and partial centra, fragments of proximal, and one distal, limb elements, portions of all the pelvic elements and partial osteoderms. The holotype was collected over a area of eight square feet over a period of three years (Long and Murry, 1995) and so it is reasonable to question whether it all pertains to one individual. We believe, that with one exception noted below, all the elements represent one skeleton because: (1) the centra are of consistent size and show variation that can be parsimoniously considered to represent gradational morphologies; (2) the limb bones and girdle elements are of comparable size and all pertain to a reptile which is conspicuously less derived than most Late Triassic tetrapods

FIGURE 1. Distribution of Vancleavea campi in the Chinle Group of the southwestern United States. 1, Petrified Forest National Park: type locality of Vancleavea campi near Crocodile Hill and nearby localities in the Blue Mesa Member of the Petrified Forest Formation (Adamanian: late Carnian) and Zuni Well Mound, Dinosaur Hill and RAP Hill in the Painted Desert Member of the Petrified Forest Formation (Revueltian: early-mid Norian). 2, North Stinking Springs Mountain and Placerias quarry in the Blue Mesa Member of the Petrified Forest Formation (SS) and Bluewater Creek Formation (PQ) (Adamanian: late Carnian) south of Petrified Forest National Park. 3, Ghost Ranch area: Canjilon quarry in the Petrified Forest Formation (Revueltian: early-mid Norian) and Whitaker quarry in the Rock Point Formation (Apachean: Rhaetian). 4, Lamy locality in the Los Esteros Member of the Santa Rosa Formation (Adamanian: late Carnian). 5, Quay County localities: type Revueltian localities from the lower Bull Canyon Formation (Revueltian: early-mid Norian) and Gregory’s Quarry 2 in the Redonda Formation (Apachean: Rhaetian). 6, Crosby County locality in the Tecovas Formation (Adamanian: late Carnian).

and therefore can reasonably be assumed to represent the same taxon and individual; (3) there is no duplication of elements; and (4) the centra and girdle and limb elements are most parsimoniously considered to pertain to the same individual because they are of comparable size and there is no duplication of elements or mixing with specimens that obviously pertain to a different taxon (with the one exception noted below). Therefore, we consider that PEFO 2427 represents one skeleton.

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Axial Skeleton

There are no cervical vertebrae in the holotype specimen of Vancleavea campi. Three dorsal centra are well-preserved. The dorsal centra are platycoelous and elongate with a low dorsoventral height. In ventral view, the centra are hourglass-shaped with a narrow central width and a long, faint medial ridge. The articular ends are circular in cross section and vertical in orientation. Parapophyseal facets are situated on the neuro-central suture with the medial portion extending along much of the length of the centrum. The best preserved dorsal centrum (Fig. 2A-C; Long and Murry, 1995, figs. 197d-f) only preserves the parapophysis on the right side, as does another specimen (Fig. 2J-L). The most complete centrum (Fig. 2A-C) is 24 mm long, and the anterior and posterior dorsoventral heights at the articular surfaces are 14 mm and 15 mm respectively. Presumed anterior dorsal centra have prominent parapophyses (Fig. 2A-C, J-L; Long and Murry, 1995, fig. 197d-f), whereas posterior dorsals lack them (Fig. 2P-R). Only one sacral centrum is preserved in the holotype (Fig. 2D-F; Long and Murry, 1995, fig. 197Gg-h). This centrum is relatively shorter and less waisted than the dorsal centra. It is 22.5 mm long craniocaudally with diameters of the articular surfaces measuring 13.5 and 14 mm. In ventral view, there are two median ridges that are more prominent than the single one present in the dorsal centra (Fig. 2E; Long and Murry, 1995, fig. 197h). The articular ends of the sacral centra are shallowly concave, as is the case with the dorsal centra. The majority of centra pertain to the tail. Approximately 23 centra were recognized by Long and Murry (1995) as caudal in origin. Caudal centra are distinguished by prominent chevron facets and transverse processes (Fig. 2G-I, M-O, S-U, V-X; Long and Murry, 1995, fig. 197l-n, o-p). There are no complete transverse processes, but we conclude that they were prominent through the majority of the tail and that they were not short. The caudal centra are proportionally shorter and deeper in lateral view than the dorsal series. One centrum is interpreted as an anterior caudal because it has prominent tranverse processes but lacks distinct chevron facets (Fig. 2G-I). This centrum has two parallel ridges along its ventral margin. It is 21 mm long craniocaudally with anterior and posterior articular diameters of 14.1 and 16 mm respectively. The ventral surface is poorly preserved, but does not appear to have a complex morphology (cf. Long and Murry, 1995). Other caudal centra (Fig. 2M-O, S-U, V-X) have two prominent ventral ridges that are continuous with the chevron facets (Long and Murry, 1995, fig. 197m, o). Other occurrences of Vancleavea indicate that isolated centra are common. It appears that the neural arch was never fully fused to the centrum in Vancleavea. Pelvic Girdle The holotype of Vancleavea campi includes acetabular portions of the left ilium and the right and left pubes and ischia. The fragment of the left ilium (Fig. 3A-C; Long and Murry, 1995, fig. 198k-l) preserves a deep, imperforate acetabulum and the ventral portion of a posterodorsally-inclined supra-acetabular blade. In lateral view the iliac fragment is 24 mm in craniocaudal length and has a preserved dorsoventral height of 20 mm (to top of broken blade). There is no evidence of the attachment of the sacral ribs on the preserved portion of the ilium. The anterior edge of the supra-acetabular blade extends from about the midpoint of the acetabulum and is inclined posterodorsally at about 45˚. The acetabular portion of the ilium in lateral view is 12.5 mm in dorsoventral height and 19 mm in craniocaudal length. The pubis is represented by the proximal portions of the left (Fig. 3D-F; Long and Murry, 1995, fig. 198i-j) and right (Fig. 3G-I;

Long and Murry, 1995, fig. 198q-r) elements. The iliac articular surface is crescent-shaped and rugose, as is the corresponding area of the ilium (Fig. 3C, F, I). The pubis does not make a significant contribution to the acetabulum. The specimens are too fragmentary to determine whether or not the obturator foramen is enclosed. The ischium is represented by the proximal portions of the left (Long and Murry, 1995, fig. 198n-p) and right elements (Fig. 3J-L; Long and Murry, 1995, fig. 198s-t). The posteroventral edge of the acetabulum is deep, and the articular surface for the ilium is clearly delineated from the acetabulum. The acetabular portion of the ischium indicates that it contributed at least 5 mm of dorsoventral height and 6 mm of depth to the acetabulum. The ventrolateral portion of the right ischial fragment has a deep pit that Long and Murry (1995, p. 195) interpreted as the beginning of a “well-defined groove,” but we are uncertain whether or not this is a correct interpretation. The right ischial fragment in lateral view has a craniocaudal length of 21 mm and a dorsoventral height of 14 mm (Fig. 3J). Fore Limb The holotype includes the proximal (Fig. 3S-T; Long and Murry, 1995, fig. 198a-b) and distal extremities (Fig. 3Q-R; Long and Murry, 1995, fig. 198c-d) of a left humerus. The proximal humerus lacks the dorsolateral margin, and the deltopectoral crest is broken off. The medial condyle is well developed. The deltopectoral crest was relatively elongate and extended high up the laterocranial margin. The distal humerus has two distinct condyles, with the ulnare condyle larger than the radial. The humeral shaft is sub-circular in cross section. The distal fragment is 25 mm long with a maximum lateromedial width of 19 mm and a width at the broken shaft end of 6.5 mm. In distal view the distal humerus is 20 mm in lateromedial width and a maximum of 7.5 mm in craniocaudal length. Hindlimb The holotype specimen of Vancleavea campi includes the proximal (and possibly distal) end of a right femur and the proximal end of a right tibia. The proximal femur has a narrow shaft and a head that is only slightly offset (Fig. 3M-O; Long and Murry, 1995, fig. 198g-h). The femoral fragment is 44 mm long with a greatest width of 17.5 mm slightly distal to the proximal end. The width of the broken shaft is 7.5 mm. The proximal end is 17 mm in lateromedial width and 8.5 mm in craniocaudal length. The fourth trochanter is a low rugosity of relatively short length that terminates ventral to the proximal end of the femur. Long and Murry (1995) identified a fragment as a possible distal femoral condyle, but we are unclear as to the identity of this element (Fig. 4M-N). The proximal right tibia is of simple morphology, with a rounded, sub-triangular cross section (Fig. 4P-R). The fragment is 19 mm long with a maximum proximal width of 13 mm. The medial margin is convex, and the lateral is slightly concave posteriorly. The proximal end is (Fig. 4R) is subtriangualar in shape with maximum and minimum dimensions of 15 and 11 mm. Osteoderms There are three types of ostoderms in the holotype of Vancleavea campi, but all are represented by fragmentary specimens. The first morphotype (morphotype A) is a relatively flat and smooth plate with a dorsal ridge (Fig. 4C-F; Long and Murry, 1995, fig. 197t-u). The largest specimen (Fig. 4C-D) is 10 by 9 mm. The second morphotype (morphotype B) is a laterally compressed, sharp-keeled osteoderm with a bifurcate base. (Fig. 4A-B, G-J; Long and Murry, 1995, fig. 197, fig. q-s). These are narrow,

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FIGURE 2. Centra from the holotype of Vancleavea campi (PEFO 2427) from the Blue Mesa Member of the Petrified Forest Formation, Chinle Group (Adamanian: St. Johnsian: late Carnian), Petrified Forest National Park, Arizona. A-C, Dorsal centrum in dorsal (A), ventral (B) and cranial (C) views. D-F, Sacral centrum in dorsal (D), ventral (F) and cranial (F) views. G-I, Anterior caudal centrum in right lateral (G), left lateral (H) and cranial (I) views. J-L, Anterior dorsal centrum in dorsal (J), ventral (K) and cranial (L) views. M-O, Caudal centrum in dorsal (M), ventral (N) and caudal (O) views. P-R, Posterior? dorsal centrum in right lateral (P), left lateral (Q) and cranial (R) views. S-U, Caudal centrum in right lateral (S), left lateral (T) and cranial (U) views. V-X, Caudal centrum in dorsal (V), left lateral (W) and cranial (F) views. Scale bar = 2 cm.

vertical osteoderms with a concave ventral margin. The morphotype B osteoderms have a smooth texture. The larger specimen (Fig. 4G-J), whose margins are all broken, has a preserved craniocaudal

length of 14 mm (assuming the long axis paralleled the skeletal axis), a height of 12 mm and a basal width of 6.5 mm (assuming that the concave side is ventral).

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FIGURE 3. Pelvic and limb material from the holotype of Vancleavea campi (PEFO 2427) from the Blue Mesa Member of the Petrified Forest Formation, Chinle Group (Adamanian: St. Johnsian: late Carnian), Petrified Forest National Park, Arizona. A-C, Partial left ilium in lateral (A) and medial (B) views and a ventral view of the pubic articular surface (C). D-F, Proximal left pubis in lateral (D), medial (F) and proximal (F) views. G-I, Proximal right pubis in lateral (G), medial (H) and proximal (I) views. J-L, Proximal right ischium in lateral (J), medial (K) and proximal (L) views. M-O, Proximal right femur in cranial (M), caudal (N) and proximal (O) views. P-R, Distal left humerus in distal (P), cranial (Q) and caudal (R) views. S-T, Proximal left humerus in caudal (S) and cranial (T) views. All scale bars = 2 cm.

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FIGURE 4. Osteoderms and limb material from the holotype of Vancleavea campi (PEFO 2427) from the Blue Mesa Member of the Petrified Forest Formation, Chinle Group (Adamanian: St. Johnsian: late Carnian), Petrified Forest National Park, Arizona. A-B, Osteoderm of morphotype B in lateral views. C-D, Osteoderm of morphotype A in ventral (C) and dorsal (D) views. E-F, Osteoderm of morphotype A in dorsal (E) and ventral (F) views. G-J, Osteoderm of morphotype B in lateral (G-H), dorsal (I) and ventral (J) views. K-L, Osteoderm of morphotype C in dorsal (K) and ventral (L) views. M-N, ?Possible distal femoral fragment. P-R, Proximal right tibia in medial (P), lateral (Q) and proximal (R) views. Scale bar = 2 cm.

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The third morphotype (morphotype C) is only represented by one specimen (Fig. 4K-L; Long and Murry, 1995, fig. 197v-w). It represents the broken base of an osteoderm with a narrow, rounded spinose process. The broken base is 13 mm by 14 mm in ventral view with a broken, spine which is 5 by 6 mm in ventral view. This specimen is indistinguishable from specimens of the diminutive aetosaur Acaenasuchus geoffreyi, which Heckert and Lucas (2002) considered to be a juvenile of Desmatosuchus haplocerus. We thus believe that this specimen should be removed from the holotype of Vancleavea campi. Other specimens indicate that osteoderms of morphotype A are usually trapezoidal in shape and that the dorsal ridge projects anterior to the main body of the osteoderm as a prominent, acute projection (Hunt et al., 2002). Preliminary description of a complete skeleton of Vancleavea (GR 138) by Small and Downs (2002) indicates that osteoderms herein designated morphotype B are positioned vertically on the tail and that osteoderms of morphotype A are imbricated over the remainder of the body.

TABLE 1. Distribution of Vancleavea campi from the Upper Triassic Chinle Group of the western United States. Lvf is land vertebrate faunachron. ���

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TAXONOMIC STATUS AND RELATIONSHIPS OF VANCLEAVEA CAMPI The holotype of Vancleavea campi is fragmentary, but it clearly represents a distinctive taxon. The apomorphies of this taxon are tall, narrow osteoderms with a bifurcate base and a smooth surface texture and smooth, flat osteoderms with a dorsal ridge. The combination of derived-aspect osteoderms with underivedaspect limb and girdle elements is also an apomorphy. Full description of the complete Ghost Ranch specimen (GR 138) will add other apomorphies to this taxon and serve as an extremely important and complete specimen of Vancleavea that will further validate the taxon. Small and Downs (2002) consider Vancleavea to be an archosauriform because of the presence of an ossified laterosphenoid, thecodont tooth implantation, dermal ostoederms and a fourth trochanter. They consider the absence of supratemporal, antorbital and external mandibular fenestrae to be apomorphic reversals. The coverage of the postcranial skeleton by hundreds of smooth, imbricated osteoderms (of morphotypes A and B) (Small and Downs, 2002) is also apomorphic. Other potential apomorphies apparent in GR 138 include a short, tall skull with a mandible as tall as the skull (Small and Downs, 2002). FUNCTIONAL MORPHOLOGY AND PALEOECOLOGY Vancleavea is widespread throughout the Chinle Group, but it is restricted to a small number of localities (Hunt et al., 2002). These localities are principally dominated by terrestrial tetrapods (e. g., Whitaker quarry at Ghost Ranch, NMMNH locality 1), although at least one locality may be more aquatic in aspect (North Stinking Springs Mountain: Polcyn et al., 2002, advocate an aquatic setting and Hunt et al., 2002, a more terrestrial fauna). The most important key to understanding the functional morphology of Vancleavea is the Ghost Ranch specimen (GR 138), which has only been described in a preliminary way (Downs and Davidge, 1997; Small and Downs, 2002). Small and Downs (2002) suggest that GR 138 represents an aquatic animal because of its dorsally-directed (non-terminal) external nares, elongate body with short limbs and upright-standing osteoderms [osteoderm morphotype B herein] that represent a “sculling tail.” Thus, morphologic evidence strongly favors an aquatic lifestyle, with aquatic adaptations such as non-terminal external nares (Small and Downs, 2002). However, taphonomic settings and faunal associations suggest a more terrestrial habit. It could be argued that the heavy armor covering is more consistent with a non-aquatic ecology. Ultimately, further study of the functional morphology of Vancleavea is needed.

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DISTRIBUTION OF VANCLEAVEA CAMPI Hunt et al. (2002) reported on the distribution of Vancleavealike reptiles. Here, we consider it most parsimonious to consider that most of these records pertain to Vancleavea campi. Upper Triassic nonmarine red beds are extensively exposed over much of the western United States. Lucas (1993) demonstrated that these units are genetically related and referred all these strata to the Chinle Group. These red beds are highly fossiliferous, especially with regard to tetrapods, and provide the best worldwide record to study the complex terrestrial faunal transition that was occurred during the Late Triassic. There are three superposed lithostratigraphic sequences within the Chinle Group that are readily correlated across western North America (Lucas, 1993). These sequences, the Shinarump-Blue Mesa, Moss Back-Owl Rock and Rock Point, each yield significant tetrapod fossil assemblages that include fossils of Vancleavea (Table 1). Lucas and Hunt (1993) named a series of land-vertebrate faunachrons (lvf) for the Late Triassic of western North America. Lucas (1998) provided formal definitions of the lvfs, defined type assemblages and defined their beginnings using first appearance data (FAD). These lvfs are, in ascending order, by age: Otischalkian (late Carnian), Adamanian (latest Carnian), Revueltian (earlymiddle Norian) and Apachean (late Norian-Rhaetian). Hunt (2001) and Hunt et al. (2005) divided the Reveultian into two sub-lvfs (the older Barrancan and younger Lucianoan) and the Adamanian into two sub-lvfs (the older St. Johnsian and younger Lamyan). Adamanian Localities Arizona The type specimen of Vancleavea campi was collected from the Blue Mesa Member of the Petrified Forest Formation within Petrified Forest National Park (Murry and Long, 1989; Fig. 1) (Adamanian: St. Johnsian). Long and Murry (1995) also referred specimens to Vancleavea from nearby localities within the Blue Mesa Member at Petrified Forest National Park, including centra and osteoderms (MNA and UCMP specimens). Polcyn et al. (2002) reported on specimens of an ”undescribed neodiapsid” that they considered to be similar to Vancleavea campi described by Downs and Davidge (1997) from the Apachean of New Mexico. These specimens derive from the Blue Mesa Member of the Petrified Forest Formation between the Petrified Forest National Park and St. Johns near North Stinking Springs Mountain (Fig. 1) (Adamanian: St. Johnsian). There are two SMU specimens of this taxon: (1) a partial skeleton with osteoderms;

and (2) isolated osteoderms. Both localities are in the same stratigraphic interval (Polcyn et al., 2002). The stratigraphically lowest Adamanian occurrence in Arizona is at the Placerias quarry, which lies south of St. Johns in the Bluewater Creek Formation (Lucas et al., 1997) (Adamanian: St. Johnsian). Both Kaye and Padian (1994, fig. 9.6) and Long and Murry (1995, fig. 197a-c) illustrated the same anterior dorsal centrum (MNA V 3669) from the Placerias quarry, which represents Vancleavea campi. Kaye and Padian (1994) also referred another dorsal centrum (V3670) to the same taxon. New Mexico Collections at GR and NMMNH include isolated osteoderms from the Adamanian Los Esteros Member of the Santa Rosa Formation in Santa Fe County that are assignable to Vancleavea campi (Fig. 1) (Adamanian: St. Johnsian). These osteoderms are thin and flat, with a dorsal ridge that terminates in a prong. Texas Long and Murry (1995) identified UMMP 7278, an anterior dorsal centrum collected by Case from the Tecovas Formation of West Texas (Adamanian: St. Johnsian) as pertaining to Vancleavea campi (Fig. 1). Revueltian Localities Arizona Hunt and Wright (1999) listed occurrences of Vancleavea campi from the Painted Desert Member of the Petrified Forest Formation at Petrified Forest National Park (Fig. 1) (Revueltian: Barrancan). These specimens are dominantly vertebral and derive from Zuni Well Mound, Dinosaur Hill and RAP Hill in the northern section of the park (Hunt et al., 2002, fig. 2i-k). Fragmentary osteoderms are common at several localities (Hunt et al., 2002, fig. 2l-q). New Mexico Hunt (2001) described specimens of Vancleavea campi from two localities in the type assemblage of the Revueltian lvf (Barrancan sub-lvf: Bull Canyon Formation) in east-central New Mexico near Tucumcari (Fig. 1). NMMNH locality 522 yielded a partial articulated skeleton including limb bones, vertebrae and osteoderms (NMMNH P-4984: Hunt et al., 2002, fig. 2G), and NMMNH locality 5 includes centra (NMMNH P-20852) associated as stomach contents with a skeleton of the phytosaur Pseudopalatus andersoni (Hunt, 1991, 1994, 2001). Other specimens assigned by Hunt (2001) to Reptilia indet. from NMMNH locality 1, also in the Bull Canyon Formation (Revueltian: Barrancan), actually pertain to the same taxon as NMMNH P-4984. These include several limb fragments as well

65 as centra (Hunt, 2001). Ziegler et al. (2005, fig. 4b) identified a dorsal centrum from the Mesa Montosa Member of the Petrified Forest Formation (Revueltian: Barrancan) in north-central New Mexico as Vancleavea sp. This specimen differs from other specimens of Vancleavea in a number of features including: (1) neural arch fused to the centrum; and (2) in lateral view the anterior articular surface projecting much more ventrally than the posterior facet. The Canjilon phytosaur quarry is located in the Petrified Forest Formation (Revueltian: ?Lucianoan) of north-central New Mexico (Hunt and Lucas, 1993a; Heckert et al., 2005; Fig. 1)). Recent excavations have yielded new specimens, including GR 148, which is an osteoderm of Vancleavea campi (Hunt and Downs, 2002). Apachean localities New Mexico There are two Apachean localities in New Mexico that yield Vancleavea campi. The most important specimen is the articulated skeleton (GR 138) from the Whitaker quarry in the Rock Point Formation at Ghost Ranch, north-central New Mexico (Downs and Davidge, 1997; Small and Downs, 2002; Fig. 1). This specimen is associated with a second specimen that is only partially prepared and was erroneously reported as a choristodere (Downs and Davidge, 1997). Osteoderms of Vancleavea are also found at J. T. Gregory’s quarry 2 in Apache Canyon in the Redonda Formation of eastcentral New Mexico (NMMNH, UMMP, YPM specimens) (Fig. 1). The Redonda specimens had previously been assigned to a sphenosuchian (e.g., Hunt and Lucas, 1993b). However, they have subsequently been correctly assigned to Vancleavea campi (e. g., NMMNH P-36150; Hunt et al., 2002, fig. 2H). CONCLUSIONS Vancleavea campi is an unusual archosauriform taxon that is present throughout the Adamanian-Apachean portions of the Chinle Group. The holotype possesses several apomorphies. The most complete specimen of this taxon is GR 138, which has not been fully described, but several other apomorphies are recognizable in this specimen. Vancleavea has aquatic adaptations including dorsally-directed (non-terminal) external nares, an elongate body with short limbs and upright-standing osteoderms (sculling tail), although many specimens of this taxon are found in association with terrestrial faunas. ACKNOWLEDGMENTS We thank Scott Williams and Bill Parker for access to collections. The Petrified Forest Museum Association provided partial funding for this project. Andrew Heckert and Kate Zeigler provided helpful reviews.

REFERENCES Downs, A. and Davidge, J., 1997, A choristodere from the Ghost Ranch Coelophysis quarry: Journal of Vertebrate Paleontology, v. 17, supplement to no. 3, p. 43A-44A. Heckert, A. B., and Lucas, S. G., 2002, Acaenasuchus geoffreyi (Archosauria: Aetosauria) from the Upper Triassic Chinle Group: Juvenile of Desmatosuchus haplocerus: New Mexico Museum of Natural History and Science Bulletin, v. 21, p. 205-214. Heckert, A. B., Lucas, S. G., Sullivan, R. M., Hunt, A. P. and Spielmann, J. A., 2005, The vertebrate fauna of the Upper Triassic (revueltian: early-mid Norian) Painted Desert Member (Petrified Forest Formation: Chinle Group) in the Chama Basin, northern New Mexico: New Mexico Geological Society Guidebook, v. 56, in press. Hunt, A. P., 1991, Two phytosaur (Reptilia: Archosauria) skeletons from the

Bull Canyon Formation (Late Triassic) of east-central New Mexico with preserved stomach contents: New Mexico Geology, v. 13, p. 93. Hunt, A. P., 1994, Vertebrate paleontology and biostratigraphy of the Bull Canyon Formation (Chinle Group, Upper Triassic), east-central New Mexico with revisions of the families Metoposauridae (Amphibia: Temnospondyli) and Parasuchidae (Reptilia: Archosauria) [Ph.D. dissertation]. Albuquerque, University of New Mexico, 403 p. Hunt, A. P., 1997, E. C. Case, J. T. Gregory and early explorations for fossils vertebrates in the Bull Canyon Formation (Upper Triassic) of eastern New Mexico: New Mexico Museum of Natural History and Science, Bulletin 11, p. 15-24. Hunt, A. P., 2001, The vertebrate fauna, biostratigraphy and biochronology of the type Revueltian land-vertebrate faunachron, Bull Canyon

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Formation (Upper Triassic), east-central New Mexico: New Mexico Geological Society, Guidebook 52, p. 123-151. Hunt, A. P. and Downs, A., 2002, Taphonomy of the Late Triassic Canjilon phytosaur quarry (Petrified Forest Formation: Chinle Group), northcentral New Mexico: Data from new excavations: New Mexico Museum of Natural History and Science, Bulletin 21, p. 291-295. Hunt, A. P. and Lucas, S. G., 1993a, Stratigraphy and vertebrate paleontology of the Chinle Group (Upper Triassic), Chama basin, north-central New Mexico: New Mexico Museum of Natural History and Science, Bulletin 2, p. 61-69. Hunt, A. P. and Lucas, S. G., 1993b, Triassic vertebrate paleontology and biochronology of New Mexico: New Mexico Museum of Natural History and Science, Bulletin 2, p. 49-60. Hunt, A.P., Lucas, S.G. and Heckert, A.B., 2005, Definition and correlation of the Lamyan: a new biochronological unit for the nonmarine late Carnian (Late Triassic): New Mexico Geological Society, Guidebook 56, in press. Hunt, A. P. and Wright, J., 1999, New discoveries of Late Triassic dinosaurs from Petrified Forest National Park, Arizona; in Santucci, V. L. and McClelland, L., eds., National Park Service Paleontological Research. National Park Service Geological Resources Division Technical Report NPS/NRGRD/GRDTR-99/03, p. 96-99. Hunt, A.P., Heckert, A.B., Lucas, S.G, and Downs, A., 2002, The distribution of the enigmatic reptile Vancleavea in the Upper Triassic Chinle Group of the western United States, New Mexico Museum of Natural History and Science, Bulletin 21, 269-273. Kaye, F. T. and Padian, K., 1994, Microvertebrates from the Placerias quarry: A window on Late Triassic vertebrate diversity in the American Southwest; in Fraser, N. C. and Sues, H.-D., eds., In the Shadow of the Dinosaurs: Early Mesozoic Tetrapods: Cambridge, Cambridge University Press, p. 171-196. Long, R. A. and Murry, P. A., 1995, Late Triassic (Carnian and Norian)

tetrapods from the southwestern United States: New Mexico Museum of Natural History and Science, Bulletin 4, 254 p. Lucas, S. G., 1993, The Chinle Group: revised stratigraphy and chronology of Upper Triassic nonmarine strata in the western United States: Bulletin of the Museum of Northern Arizona, v. 59, p. 27-50. Lucas, S. G., 1998, Global Triassic tetrapod biostratigraphy and biochronology: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 143, p. 347-384. Lucas, S. G. and Hunt, A. P., 1993, Tetrapod biochronology of the Chinle Group (Upper Triassic), western United States: New Mexico Museum of Natural History and Science Bulletin, v. 3, p. 327-329. Lucas, S. G., Heckert, A. B. and Hunt, A. P., 1997, Stratigraphy and biochronology of the Late Triassic Placerias quarry, eastern Arizona (U.S.A.). Neues Jahrbuch für Geologie und Palaontologie Abhandlungen v. 203, p. 23-46. Murry, P. A. and Long, R. A., 1989, Geology and paleontology of the Chinle Formation, Petrified Forest National Park and vicinity, Arizona and a discussion of vertebrate fossils of the southwestern Upper Triassic; in Lucas, S. G. and Hunt, A. P., eds., Dawn of the Age of Dinosaurs in the American Southwest: Albuquerque, New Mexico Museum of Natural History, p. 29-64. Polcyn, M. J., Winkler, D.A., Jacobs, L. L., and Newman, K., 2002, Fossil occurrences and structural disturbance in the Triassic Chinle Formation at North Stinking Springs Mountain near St. Johns, Arizona: New Mexico Museum of Natural History and Science, Bulletin 21, p. 43-49. Small, B. and Downs, A., 2002, An unusual archosauriform from Ghost Ranch, New Mexico. Journal of Vertebrate Paleontology, v. 22, supplement to no. 3, 108A. Ziegler, K. E., Lucas, S. G. and Morgan, V. L., 2005, Vertebrate fauna of the Upper Triassic Mesa Montosa Member (Petrified Forest Formation, Chinle Group), Chama Basin, northern New Mexico: New Mexico Geological Society, Guidebook, v. 56, p. 335-340.

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