Callistomordax kugleri, Schoch, 2008

Schoch, Rainer R., 2008, A new stereospondyl from the German Middle Triassic, and the origin of the Metoposauridae, Zoological Journal of the Linnean Society 152 (1), pp. 79-113 : 80-84

CALLISTOMORDAX KUGLERI SP. NOV.

1985 ‘Metoposaurier-Vorfahr’ Kugler & Bartholomä (1985: 16).

1988 ‘oldest undoubted Morales (1988: 23 a). metoposaurid’

1993 ‘probably a latiscopid’ Hunt (1993: 90).

1998 Almasauridae gen. nov. Schoch & Werneburg sp. nov. (1998: 637).

2000 Almasauridae gen. nov. Schoch & Milner (2000: sp. nov. 120, fig. 85).

Holotype: SMNS 82035 , a nearly complete skeleton. The skull, exposed in dorsal view, has a length of 137 mm (from tip of premaxilla to back rim of postparietal), and the length of the preserved skeleton is 1. 23 m.

Type horizon: Top of Untere Graue Mergel (Bed 6 of Schoch, 2002a), Lower Keuper (Erfurt Formation), Longobardian (Upper Ladinian), Middle Triassic.

Type locality: Vellberg (Schumann quarry), northern Baden-Württemberg, southern Germany.

Referred material: From type locality: SMNS 90516 , anterior two-thirds of skeleton with complete skull in dorsal view (153 mm); SMNS 55385 , isolated, complete skull (148 mm; Figs 2A , 5 ); SMNS 90519 , isolated left humerus ( Fig. 7 D–F ); SMNS 90520 , parts of skeleton including well-preserved pectoral and pelvic girdle ( Fig. 7A, B, H, I ) and crushed skull (145 mm); SMNS 90700 , articulated skeleton lacking posterior half of tail, but including well-preserved girdles, appendages, and skull (125 mm) in ventral view ( Fig. 7C ); MHI-K1, a nearly complete postcranial skeleton including one humerus and both hind limbs; MHI-K2, fairly complete, small postcranial skeleton with pectoral girdle; MHI-K3, disarticulated large postcranial skeleton with scapulocoracoid ( Fig. 7G ), interclavicle, humerus, radius, and ilium; MHI-K4, small skull (95 mm); MHI-K5, slightly disarticulated skull with good snout region (160 mm). From Ummenhofen quarry: SMNS 90506 , posterior part of trunk, pelvic elements, and hind limb ( Fig. 9 ). From Kupferzell locality: SMNS 81713 , isolated articular; SMNS 84115–84118 , 90521 , isolated intercentra ( Fig. 8C–L ); SMNS 84119 , atlas ( Fig. 8A, B ) .

Stratigraphic range: Albertibank through Untere Graue Mergel, Lower Keuper (Erfurt Formation), Langobardian, Middle Triassic.

Etymology: In honour of Werner Kugler, private collector of Crailsheim, who found and prepared the first specimen. His general contributions to our understanding of Lower Keuper vertebrates have been outstanding.

Diagnosis: Autapomorphic character states are as follows: (1) frontals co-ossified, with single medial anterior tip and blunt posterior end ( Figs 1A , 4B ); (2) pterygoid distinct by very broad and flat quadrate ramus combined with a particularly slender and narrow palatine ramus ( Figs 1B , 5 ); (3) subtemporal windows nearly round and wider than the basicranial region ( Fig. 1B ); (4) anterior palate very short, with vomers and palatines dominated by huge fangs the sockets of which occupy most of the bone surfaces, and minute, obliquely orientated choanae ( Figs 1B , 5 ); (5) palatal and symphyseal fangs laterally compressed and keeled; (6) intercentra forming open crescents with high flanks (except when fused to pleurocentra, then giving a disc-shaped compound bone, see Fig. 8C, D ) with pointed upper ends and a massive, anteroposteriorly elongated ventral portion that has a quadrangular outline ( Fig. 8C–J ); (7) shaft of cleithrum curved in semilunar fashion ( Fig. 7H, I ).

Derived characters shared with other taxa:

1. Callistomordax and the Metoposauridae : clavicle extending well posteriorly on interclavicle, with the radial arrangement of the ornament pointing posteromedially.

2. Callistomordax , Rileymillerus , and the Metoposauridae : lacrimal forms small element confined to the anterolateral margin of the orbit [ Bolt & Chatterjee, 2000 regarded this as a lateral exposure of the palatine (LEP), in analogy with dissorophoids].

3. Callistomordax and Almasaurus : cultriform process forms a prominent ventral keel, which rises from a ridge on the anterior portion of the basal plate, and terminates shortly posterior to the point where the parasphenoid is framed by posteromedial processes of the vomers; snout narrow, with the nares in the terminal position and located in close proximity.

Trigonosternum latum: Schmidt (1931) described and named a partial interclavicle from the Lower Keuper of Kölleda in Thuringia ( Germany) as a new genus and species, T. latum , which he referred to the Metoposauridae . Colbert & Imbrie (1956) have argued that the assignment of this fragment to metoposaurids is based on a misinterpretation caused by a wrong orientation of the interclavicle, which is followed here. The type and only specimen is not only indeterminate, but differs from the interclavicle of C. kugleri in ornamentation and overall shape ( Werneburg, 1990; Schoch & Milner, 2000).

Figures

Figure 1. Skull reconstruction of Callistomordax kugleri. A, Skull roof (dorsal view); B, palate (ventral view); C, occiput (posterior view); D, skull and mandible (lateral view); E, mandible (lateral view); F, mandible (medial view). (Please refer to the list at the end of the Introduction for a definition of the abbreviations.)

Figure 2. Skull material of Callistomordax kugleri. A, SMNS 55385 (ventral view); B, SMNS 55385 (dorsal view); C, SMNS 90520 (dorsal view); D, SMNS 90520 (ventral view); E, SMNS 82035 (type specimen, dorsal view). Dotted lines show poorly preserved sutures and/or fractures. (Please refer to the list at the end of the Introduction for a definition of the abbreviations.)

Figure 4. Skull material of Callistomordax kugleri. A, SMNS 90520 (dorsal view); B, SMNS 82035 (dorsal view). (Please refer to the list at the end of the Introduction for a definition of the abbreviations.)

Figure 5. Callistomordax kugleri, structure of palate and mandible exemplified by SMNS 55385 (ventral view). (Please refer to the list at the end of the Introduction for a definition of the abbreviations.)

Figure 7. Pectoral girdle of Callistomordax kugleri. A, interclavicle, SMNS 90520 (ventral view); B, interclavicle, SMNS 90520 (dorsal view); C, pectoral girdle, right mandible, and atlas in loose articulation, SMNS 90700 (ventral view); D–F, left humerus, SMNS 90519 – D, dorsal view, E, anterior view, F, ventral view; G, scapulocoracoid, MHI-K3 (lateral view); H, I, cleithrum, SMNS 90520 – H, medial view, I, lateral view. (Please refer to the list at the end of the Introduction for a definition of the abbreviations.)

Figure 8. Axial skeleton of Callistomordax kugleri. A, atlas, SMNS 84119 (anterior view); B, SMNS 84119 (posterior view); C, ‘stereospondylous’ anterior trunk intercentrum with pleurocentra firmly attached to intercentrum, SMNS 84115 (anterior view); D, same as C (posterior view); E, anterior trunk intercentrum, SMNS 84116 (anterior view); F, same as E (posterior view); G, posterior trunk intercentrum, SMNS 84117 (anterior view); H, same as G (posterior view); I, same as G (ventral view); J, same as E (ventral view); K, same as E (lateral view); L, same as G (lateral view); M, axis rib, SMNS 82035; N, trunk rib, SMNS 82035; O, caudal rib, SMNS 90700; P, trunk pleurocentrum, SMNS 90520; Q, anterior tail section, SMNS 82035. (Please refer to the list at the end of the Introduction for a definition of the abbreviations.)

Figure 9. Pelvic girdle of Callistomordax kugleri. A, femur, SMNS 90506 (dorsal view); B, femur, SMNS 90506 (ventral view); C, ilium, SMNS 90506 (lateral view); D, ischium, MHI-K2 (lateral view). (Please refer to the list at the end of the Introduction for a definition of the abbreviations.)