This document is a supplement to Dinosauria, second edition, edited by David B. Weishampel,
Peter Dodson, and Halszka Osmolska (Berkeley: University of California Press, 2004). For other
supplements and for more information about the book, please visit http://dinosauria.ucpress.edu.
Appendix 18.1
Character Description
Basal Ornithopoda
Characters winnowed and/or modified and rescored from Norman (1984a), Sereno (1986),
Weishampel and Heinrich (1992), and Coria and Salgado (1996b).
1. External contact between premaxilla and lacrimal: absent (0); present (1).
2. Ventral edge of premaxilla offset ventrally relative to the border of the maxilla: not offset
(0); offset ventrally (1).
3. External antorbital fenestra shape: subtriangular (0); subcircular (1).
4. Antorbital fossa size: >10% of skull length (0); 15 (1).
5. Maxillary crowns: apex central (0); offset distally (1).
6. Maxillary crown enamel: equally thick lingually and bucally (0); asymmetrical thickness (1).
7. Dentary tooth count: 16 (1).
8. Dental cingulum between root and crown: absent (0); present (1).
9. Dentary crown bearing an elevated primary ridge: absent (0); present (1).
10. Dentary tooth crown enamel: equally thick (0); asymmetrical (1).
11. Dorsal vertebral count: 16 (1).
12. Rib curvature: strong (0); shallow (1).
13. Ossified sternal ribs: absent (0); present (1).
14. Ossified hypaxial tendons in the tail: absent (0); present (1).
15. Dorsal margin of scapula blade: curved (0); flattened (1).
16. Scapular neck: narrow (0); wide (1).
17. Deltoclavicularis muscle scar: narrow (0); large (1).
18. Scapulocoracoid suture: unfused (0); fused (1).
19. Humerus:scapula: equal in length (0); humerus 50% (1).
20. Postacetabular process of the ilium: short (0); long (1).
21. Brevis shelf on ilium: absent (0); present (1).
22. Lateral surface of the ischial peduncle of the ilium: not broadly swollen (0); broad swelling
(1).
23. Prepubic process of pubis: short and blunt (0); elongate and rodlike (1).
24. Obturator process of ischium: absent (0); present (1).
25. Obturator process position: near middle of shaft (0); proximally positioned (1).
26. Ischial shaft: rounded in cross section (0); flattened along much of length (1).
27. Femoral shape: gracile (0); robust (1).
28. Femoral shape: curved in lateral view (0); straight (1).
29. Cranial and greater trochanter: separated by cleft (0); fused together (1).
30. Femoral pit adjacent to fourth trochanter: absent (0); present (1).