142 



M.S.Y. LEE AND J.D. SCANLON 



in ventral view ( 1 ); anterodorsal, condyles facing very dorsally, 

 none of the articular surface is visible in ventral view (2). 

 Mesoleptos 0. 



174. Centra. Notochordal, i.e. perforated by persistent notochord 

 in adults (0); not notochordal, i.e. not perforated by persistent 

 notochord in adults (1). Mesoleptos 1. 



175. Centra. Amphicoelous (0); procoelous (1). Mesoleptos 1. 



176. Neural spines. Tall processes (0); low ridges ( 1 ). Mesoleptos 0. 



177. Zygosphenes and zygantra. Present (0); absent (1). 

 Mesoleptos (Visible on the MCSNT specimen). 



179. Intercentra on dorsal (thoracolumbar) vertebrae. Present 

 (0); absent (1). Mesoleptos 1. 



1 80. Number of presacral vertebrae. 23 to 25 (0); 22 or fewer ( 1 ); 

 26 (2); 27 to 50 (3); 50 to 119(4); 120 to 150(5), 150 or more 

 (6). Mesoleptos 3. 



182. Transverse processes of cervicals. On anterior end of cen- 

 trum (0); on middle of centrum (1). Mesoleptos 0. 



1 83. Hypapophyses on anterior presacrals. Only extending to the 

 posterior end of the sixth presacral at most (0); extending to the 

 seventh presacral or beyond (1). Mesoleptos 1. 



185. Anterior presacral vertebrae (excluding atlas and axis 

 intercentra). Not sutured or fused to preceding centrum (0); 

 sutured to preceding centrum (1); fused to preceding centrum 

 (2). Mesoleptos 2. 



1 86. Anterior presacral vertebrae Not sutured or fused to follow- 

 ing centrum (0); sutured to following centrum (1); fused to 

 following centrum (2). Mesoleptos 0. 



1 87. Pachyostosis of mid-dorsal vertebrae and ribs. Absent (0); 

 present (1). Mesoleptos 0. 



1 96. Body shape. Round, dorsal ribs smoothly curved (0); laterally 

 compressed, middle and distal regions of dorsal ribs totally 

 straight (1). Mesoleptos 1. 



198. Ribs. Proximal end without anteroventral pseudotuberculum 

 (0); proximal end with anteroventral pseudotuberculum (1). 

 Mesoleptos 0. 



199. Ribs. Proximal end without posterodorsal pseudotuberculum 

 (0); proximal end with posterodorsal pseudotuberculum (1). 

 Mesoleptos 0. 



200. Distally forked cloacal ribs ('lymphapophyses'). Absent (0); 

 present (1). Mesoleptos 0. 



201. Tail. Cylindrical or only slightly lateral compressed, trans- 

 verse processes well-developed, chevrons and neural spines 

 not elongated (0); very laterally compressed, transverse proc- 

 esses reduced anteriorly and absent posteriorly, chevrons and 

 neural spines elongated (1). Mesoleptos 1. 



203. Scapulocoracoid. Present and large (0); present but reduced 

 (1); absent (2). Mesoleptos 1. 



204. Emargination on anterodorsal edge of scapula. Absent (0); 

 present (1). Mesoleptos 0. 



205. Anterior (primary) coracoid emargination. Absent (0); 

 present (1). Mesoleptos 1. 



206. Posterior (secondary) coracoid emargination. Absent (0); 

 present (1). Mesoleptos 1. 



207. Clavicle. Present (0); absent (1). Mesoleptos (see text for 

 discussion of identity of this element). 



209. Clavicles. Rod-like, at most only slightly expanded proxi- 

 mally and with no notch or fenestra (0); greatly expanded 

 proximally, usually with notch or fenestra (1). Mesoleptos 

 (see text for discussion of identity of this element). 



218. Forelimbs. Large (0); small (1), absent (2). Mesoleptos 1. 



222. Pelvis. Present and large (0); present and small ( 1 ); absent (2). 

 Mesoleptos 1. 



228. Hindlimbs. Well-developed (0); reduced (1); absent (2). 



Mesoleptos 1. 



234. Body proportions. Head moderately large with respect to 

 wide trunk region (0); head extremely small with respect to 

 wide trunk region (1 ). Mesoleptos 1. 



235. Dorsal body osteoderms. Absent (0); present ( 1 ). Mesoleptos 

 0. 



236. Ventral body osteoderms. Absent (0); present ( 1 ). Mesoleptos 

 0. 



246. Epiphyses. Present on appendicular and axial skeleton (0); 

 present on appendicular, but absent on axial skeleton (1); 

 absent from both appendicular and axial skeleton. Mesoleptos 

 1. Note Haasiophis was incorrectly coded with state 1 in Lee 

 (2002); it has state 2. 



Appendix 2 Synapomorphies for Clades A-D in Fig. 3A 



Character number, consistency index and direction of change (if not 

 — > 1) listed in parentheses. 



Clade A: dolichosaurs, Adriosaurus, Mesoleptos, and 

 Ophidia 



*More than ten cervical vertebrae (181, 0.6, 2— »3), *Scapulocoracoid 

 reduced (203, 0.67), *interclavicle absent (210, 0.33), *forelimbs 

 small (218, 0.5), *pelvis reduced (222, 0.5), *hindlimbs small (228, 

 0.67). 



Clade B: Adriosaurus, Mesoleptos, and Ophidia 



*Premaxilla-maxilla contact mobile (5. 1.0), frontals paired (26. 

 0.14), postorbitofrontal ventral process large (36, 0.5, 1— »0), su- 

 pratemporal superficial (52, 0.67, 1 — »0), *body laterally compressed 

 (196, 0.5), pubis not expanded distally (227, 1.0). 



Clade C: Mesoleptos and Ophidia (snakes) 



* Vertebral condyles facing posteriorly ( 172, 1.0, 1— »0), *head small 

 with respect to trunk (234, 1.0). 



Clade D: Ophidia (snakes) 



Dorsal process of maxilla on middle or anterior of maxilla (8, 0.5, 

 1— >0), posterior process of maxilla long (10, 0.33, 1— >0), lacrimal 

 absent (11, 0.5), frontoparietal suture with sinuous contact (30, 0.2, 

 1— >0), pineal foramen absent (40. 0.17), parietal table reduced to 

 sagittal crest (42, 0.22, 1 — >0), suspensorial ramus of parietal reduced 

 (44, 0.5), upper temporal arch incomplete (45, 0.25), tympanic crest 

 absent (57, 0.29, 0— »2), parietal downgrowths contacing 

 parabasisphenoid (67, 1.0), optic foramina enclosed in bone (68, 1.0), 

 anterior brain cavity floored by frontals and cultriform process (69, 

 0.67, 0->2), trigeminal foramina bordered at least partly by parietal 

 (70, 1.0), supraoccipital on skull roof behind parietal (86, 0.5), 

 posttemporal fenestra closed (89, 0.5), opening of Jacobson's organ 

 enclosed by vomer and septomaxilla only (94, 0.4, 1— >2), vomer 

 medial to palatine (99, 1.0), palatine- vomer contact mobile (102. 

 1 .0), palatine long ( 1 03, 0.33, 1 — >0), palatine with distinct rectangu- 

 lar process ( 105, 1 .0), two or fewer mental foramina on lateral surface 

 of dentary (117, 1.0), posterior margin of lateral surface of dentary 

 deeply notched (123, 0.4, l-»2), dentary overlapped by surangular 

 ( 1 24, 1 .0, 0— >2), surangular extends far over lateral surface of dentary 

 (134, 1.0, 2— >3), articular fused with prearticular and surangular 

 (144, 0.25, 1— >0), retroarticular process short (145, 1, 0— >1), mar- 

 ginal teeth with medial and lateral carinae (153, 0.67, 1 — >2), palatine 

 teeth present (166, 0.33, 1— >0), palatine teeth long fangs (167, 1.0), 

 *at least 1 20 presacral vertebrae ( 1 80, 0.6, 3— >5), *lymphapophyses 

 present (200, 0.67).*shoulder girdle absent (203, 0.67, l->2), Clavi- 

 cle absent (207, 0.33), ossified sternum absent (213, 1.0), *forelimbs 

 absent (218, 0.5, 1— >2), scleral ossicles absent (241, 0.5), *appen- 

 dicular epiphyses absent (246, 0.67, 1— >2). 



