Interrelationships of basal synapsids: Cranial and postcranial morphological partitions suggest different topologies

Journal of Systematic Palaeontology

Volumn 10, Issue 4, 2012, Pages 601-624

  Benson, Roger B J ^a  

^a UNIVERSITY OF CAMBRIDGE   (United Kingdom)

Author keywords

'Pelycosauria'; Character conflict; Phylogenetics; Synapsida

Indexed keywords

CARBONIFEROUS; CRANIUM; FOSSIL RECORD; LIZARD; MORPHOLOGY; PERMIAN; PHYLOGENETICS; TERRESTRIAL ECOSYSTEM; TOPOLOGY;

AMNIOTA; ANIMALIA; EUPELYCOSAURIA; MAMMALIA; REPTILIA; SYNAPSIDA; THERAPSIDA; VERTEBRATA;

EID: 84866469379     PISSN: 14772019     EISSN: 14780941     Source Type: Journal    
DOI: 10.1080/14772019.2011.631042     Document Type: Article

References (142)

1. Amson, E. & Laurin, M. 2011. On the affinities of Tetraceratops insignis, an Early Permian synapsid. Acta Palaeontologica Polonica, 56, 301-312.
2. Anderson, J. S. & Reisz, R. R. 2004. Pyozia mesenensis, a new, small varanopid (Synapsida, Eupelycosauria) from Russia: "pelycosaur" diversity in the Middle Permian. Journal of Vertebrate Paleontology, 24, 173-179.
3. Bakker, R. T. 1986. The dinosaur heresies. Kensington, New York, 481 pp.
4. Bell, W.A. 1966. Carboniferous plants of eastern Canada. Geological Survey of Canada, Paper 66-11, 1-76.
5. Bennett, S. C. 1996. Aerodynamics and thermoregulatory function of the dorsal sail of Edaphosaurus. Paleobiology, 22, 496-506.
6. Benson, R. B. J. 2010. A description of Megalosaurus bucklandii (Dinosauria: Theropoda) from the Bathonian of the UK and the relationships of Middle Jurassic theropods. Zoological Journal of the Linnean Society of London, 158, 882-935.
7. Berman, D. 1978. Ctenospondylus ninevehensis, a new species (Reptilia, Pelycosauria) from the Lower Permian Dunkard Group of Ohio. Annals of the Carnegie Museum, 47, 493-514.
8. Berman, D. & Reisz, R. R. 1982. Restudy of Mycterosaurus longiceps (Reptilia, Pelycosauria) from the Lower Permian of Texas. Annals of the Carnegie Museum, 51, 423-453.
9. Berman, D. S., Reisz, R. R., Bolt, J. R & Scott, D. 1995. The cranial anatomy and relationships of the synapsid Vara-nosaurus (Eupelycosauria: Ophiacodontidae) from the Early Permian of Texas and Oklahoma. Annals of the Carnegie Museum, 64, 99-133.
10. Berman, D. S., Sumida, S. S. & Lombard, R. E. 1997. Biogeog-raphy of primitive amniotes. Pp. 85-139 in S. S. Sumida & K. L. M. Martin (eds) Amniote Origins. Academic Press, San Diego.
11. Berman, D., Reisz, R. R., Martens, T. & Henrici, A. C. 2001. A new species of Dimetrodon (Synapsida: Sphenacodontidae) from the Lower Permian of Germany records first occurrence of genus outside North America. Canadian Journal of Earth Sciences, 38, 803-812.
12. Botha-Brink, J. & Modesto, S. P. 2007. A mixed-age classed 'pelycosaur' aggregation from South Africa: earliest evidence of parental care in amniotes? Proceedings of the Royal Society of London B, 274, 2829-2834.
13. Botha-Brink, J. & Modesto, S. P. 2009. Anatomy and relationships of the Middle Permian varanopid Heleosaurus scholtzi based on a social aggregation from the Karoo Basin of South Africa. Journal of Vertebrate Paleontology, 29, 389-400.
14. Bramwell, C. D. & Fellgett, P. B. 1979. Thermal regulation in sail lizards. Nature, 242, 203-205.
15. Brinkman, D. & Eberth, D. A. 1983. The interrelationships of pelycosaurs. Breviora, 473, 1-35.
16. Brinkman, D. & Eberth, D. A. 1986. The anatomy and relationships of Stereophallodon and Baldwinonus (Reptilia, Pely-cosauria). Breviora, 485, 1-34.
17. Broom, R. 1937. A further contribution to our knowledge of the fossil reptiles of the Karroo. Proceedings of the Zoological Society, B107, 299-318.
18. Campione, N. E. & Reisz, R. R. 2010. Varanops brevirostris (Eupelycosauria: Varanopidae) from the Lower Permian of Texas, with discussion of varanopid morphology and interrelationships. Journal of Vertebrate Paleontology, 30, 724-746.
19. Carroll, R. L. 1964. The earliest reptiles. Zoological Journal of the Linnean Society of London, 45, 61-83.
20. Carroll, R. L. 1969. A middle Pennsylvanian captorhinomorph, and the interrelationships of primitive reptiles. Journal of Paleontology, 43, 151-170.
21. Case, E. C. 1905. Bathygnathus borealis Leidy, and the Permian of Prince Edward Island. Science, new series, 22, 52-53.
22. Case, E. C. 1907. Revision of the Pelycosauria of North America. Carnegie Institute, Washington, 176 pp.
23. Clark, J. & Carroll, R. L. 1973. Romeriid reptiles from the Lower Permian. Bulletin of the Museum of Comparative Zoology, 144, 353-407.
24. Conrad, J. & Sidor, C. A. 2001. Re-evaluation of Tetraceratops insignis (Synapsida: Sphenacodontia). Journal of Vertebrate Paleontology, 21, 42A.
25. Cope, E. D. 1878. Descriptions of extinct Batrachia and Reptilia from the Permian formations of Texas. Proceedings of the American Philosophical Society, 17, 505-530.
26. Cope, E. D. 1882. Third contribution to the history of the Verte-brata of the Permian formation of Texas. Proceedings of the American Philosophical Society, 20, 447-461.
27. Cope, E. D. 1895. The reptilian order Cotylosauria. Proceedings of the American Philosophical Society, 34, 436-457.
28. Credner, H. 1888. Die Stegocephalen und Saurier aus dem Rothliegenden des Plauen'schen Grundes bei Dresden. VII Theil: Palaeohatteria longicaudata Cred. Zeischrift der deustschen geologischen Gesellschaft, 40, 490-558.
29. Currie, P. J. 1977. A new haptodontine sphenacodont (Reptilia: Pelycosauria) from the Upper Pennsylvanian of North America. Journal of Paleontology, 51, 927-942.
30. Currie, P. J. 1979. The osteology of haptodontine sphenacodonts (Reptilia: Pelycosauria). Palaeontographica Abteilung A, 163, 130-168.
31. DeMar, R. 1970. A primitive pelycosaur from the Pennsylvanian of Illinois. Journal of Paleontology, 44, 154-163.
32. Dilkes, D. W. & Reisz, R. R. 1996. First record of a basal synap-sid ('mammal-like reptile') in Gondwana. Proceedings of the Royal Society of London B, 263, 1165-1170.
33. Eberth, D. A. 1985. The skull of Sphenacodon ferocior, and comparisons with other sphenacodontines (Reptilia: Pely-cosauria). New Mexico Bureau of Mines & Mineral Resources Circular, 190, 1-39.
34. Eberth, D. A. & Brinkman, D. 1983. Ruthiromia elcobriensis, a new pelycosaur from El Cobre Canyon, New Mexico. Breviora, 474, 1-26.
35. Efremov, J. A. 1938. Some new Permian reptiles of the USSR. Academy of Sciences URSS, C.R., 19, 121-126.
36. Efremov, J. A. 1956. American elements in the fauna of Permian reptiles of the USSR. Doklady Akademii Nauk SSSR, 111, 1091-1094.
37. Fox, R. C. 1962. Two new pelycosaurs from the Lower Permian of Oklahoma. University of Kansas Publications, Museum of Natural History, 12, 297-307.
38. Fox, R. C. & Bowman, M. C. 1966. Osteology and relationships of Captorhinus aguti (Cope) (Reptilia: Captorhinomorpha). University of Kansas Paleontological Contributions, Vertebrata, 11, 1-79.
39. Fracasso, M. A. 1980. Age of the Permo-Carboniferous Cutler Formation vertebrate fauna from El Cobre Canyon, New Mexico. Journal of Paleontology, 54, 1237-1244.
40. Fröbisch, J., Schoch, R. R., Müller, J., Schindler, T. & Schweiss, D. 2011. A new basal sphenacodontid synapsid from the Late Carboniferous of the Saar-Nahe Basin, Germany. Acta Palaeontologica Polonica, 56, 113-120.
41. Gaudry, A. 1880. Sur un reptile très perfectionné trouvé dans le terrain permien. Compte rendu hebdomadaire des séances de l'Académie des Sciences Paris, 91, 669-671.
42. Graybeal, A. 1998. Is it better to add taxa or characters to a difficult phylogenetic problem? Systematic Biology, 47, 9-17.
43. Haack, S. 1986. A thermal model of the sailback pelycosaur. Paleobiology, 12, 450-458.
44. Holmes, R. 1977. The osteology and musculature of the pectoral limb of small captorhinids. Journal of Morphology, 152, 101-140.
45. Holmes, R. 2003. The hind limb of Captorhinus aguti and the step cycle of basal amniotes. Canadian Journal of Earth Sciences, 40, 515-526.
46. Huene, F. von. 1905. Pelycosaurier im deutschen Muschelkalk. Neues Jahrbuch für Mineralogie, Geologie und Paläontologie, 20, 321-353.
47. Jewet, J. M., Bayne, C. K., Goebel, E. D. O,'Connor, H. G., Swineford, A. & Zeller, D. 1968. The stratigraphic succession in Kansas. Kansas Geological Survey Bulletin, 189, 1-81.
48. Kemp, T. S. 1982. Mammal-like Reptiles and the Origin of Mammals. Academic Press, London, 363 pp.
49. Kemp, T. S. 1988. Interrelationships of the Synapsida. Pp. 23-29 in M. J. Benton (ed.) The Phylogeny and Classification of the Tetrapods. Volume 2. Systematics Association Special Volume, 35B, 23-29.
50. Kemp, T. S. 2005. The Origin and Evolution of Mammals. Oxford University Press, Oxford, 342 pp.
51. Kemp, T. S. 2006. The origin and early radiation of the therapsid mammal-like reptiles: a palaeobiological hypothesis. Journal of Evolutionary Biology, 19, 1231-1237.
52. Ketchum, H. F. & Benson, R. B. J. 2010. Global interrelationships of Plesiosauria (Reptilia, Sauropterygia) and the pivotal role of taxon sampling in determining the outcome of phylo-genetic analyses. Biological Reviews, 85, 361-392.
53. Kissel, R. A. & Reisz, R. R. 2004. Synapsid fauna of the Upper Pennsylvanian Rock Lake Shale near Garnett, Kansas and the diversity patterns of early amniotes. Pp. 409-428 in G. Arratia, M. V. H. Wilson & R. Cloutier (eds), Recent Advances in the Origin and Early Radiation of Vertebrates. Pfeil Verlag, München.
54. Kitching, I. J., Forey, P. L., Humphries, C. J. & Williams, D. M. 1998. Cladistics: the theory and practice of parsimony analysis. 2nd edition. Oxford University Press, Oxford, 248 pp.
55. Lane, H. H. 1945. New mid-Pennsylvanian reptiles from Kansas. Transactions of the Kansas Academy of Sciences, 47, 381-390.
56. Langston, W. Jr 1965. Oedaleops campi (Reptilia: Pelycosauria) new genus and species from the Lower Permian of New Mexico, and the Family Eothyrididae. Bulletin of the Texas Memorial Museum, 9, 1-47.
57. Langston, W. Jr & Reisz R. R. 1981. Aerosaurus wellesi, new species, a varanopseid mammal-like reptiles (Synapsida: Pely-cosauria) from the Lower Permian of New Mexico. Journal of Vertebrate Paleontology, 1, 73-96.
58. Laurin, M. 1993. Anatomy and relationships of Haptodus garnet-tensis, a Pennsylvanian synapsid from Kansas. Journal of Vertebrate Paleontology, 13, 200-229.
59. Laurin, M. 1994. Re-evaluation of Cutleria wilmarthi, an Early Permian synapsid from Colorado. Journal of Vertebrate Paleontology, 14, 134-138.
60. Laurin, M. & Reisz, R. R. 1990. Tetraceratops is the oldest known therapsid. Nature, 345, 249-250.
61. Laurin, M. & Reisz, R. R. 1995. A reevaluation of early amniote phylogeny. Zoological Journal of the Linnean Society of London, 113, 165-223.
62. Laurin, M. & Reisz, R. R. 1996. The osteology and relationships of Tetraceratops insignis, the oldest known therapsid. Journal of Vertebrate Paleontology, 16, 95-102.
63. Leidy, J. 1854. On Bathygnathus borealis an extinct Saurian of the New Red Sandstone of Prince Edward Island. Proceedings of the Academy of Natural Sciences of Philadelphia, second series, 2, 327-330.
64. Lewis, G. E. & Vaughn, P. P. 1965. Early Permian vertebrates from the Cutler Formation of the Placerville area Colorado. Geological Survey Professional Paper, 503-C, C1-C46.
65. Li, J. & Cheng, Z. 1997. First discovery of eotitanosuchian (Therapsida, Synapsida) of China. Vertebrata PalAsiatica, 35, 268-282.
66. Liu, J., Rubidge, B. & Li, J. 2009. New basal synapsid supports Laurasian origin for therapsids. Acta Palaeontologica Polonica, 54, 393-400.
67. Liu, J., Rubidge, B. & Li, J. 2010. A new specimen of Biseridens qilianicus indicates its phylogenetic position as the most basal anomodont. Proceedings of the Royal Society of London B, 277, 285-292.
68. Lucas, S. G. 2006. Global Permian tetrapod biostratigraphy and biochronology. Pp. 65-93 in S. G. Lucas, G. Cassinis & J. W. Schneider (eds) Non-Marine Permian Biostratigraphy and Biochronology. Special Papers of the Geological Society of London, 265, 65-93.
69. Maddin, H. C., Evans, D. C. & Reisz, R. R. 2006. An Early Permian varanodontine varanopid (Synapsida: Eupely-cosauria) from the Richards Spur locality, Oklahoma. Journal of Vertebrate Paleontology, 26, 957-966.
70. Maddin, H. C., Sidor, C. A. & Reisz, R. R. 2008. Cranial anatomy of Ennatosaurus tecton (Synapsida: Caseidae) from the Middle Permian of Russia and the evolutionary relationships of Caseidae. Journal of Vertebrate Paleontology, 28, 160-180.
71. Maddison, D. R. & Maddison, W. P. 2001. MacClade 4.06 for OSX. Sinauer Associates Inc., Sunderland, Massachusetts.
72. Marsh, O. C. 1878. Notice of new fossil reptiles. American Journal of Science, 15, 409-411
73. Mazierski, D. M. & Reisz, R. R. 2010. Description of a new specimen of Ianthasaurus hardestiorum (Eupelycosauria: Edaphosauridae) and a re-evaluation of edaphosaurid phylogeny. Canadian Journal of Earth Sciences, 47, 901-912.
74. Milner, A. R. 1993. Biogeography of Palaeozoic tetrapods. Pp. 324-353 in J. A. Long (ed.) Palaeozoic Vertebrate Biostratigraphy and Biogeography. Belhaven Press, London.
75. Modesto, S. P. 1994. The Lower Permian synapsid Glaucosaurus from Texas. Palaeontology, 37, 51-60.
76. Modesto, S. P. 1995. The skull of the herbivorous synapsid Edaphosaurus boanerges from the Lower Permian of Texas. Palaeontology, 38, 213-239.
77. Modesto, S. P. 1998. New information on the skull of the Early Permian reptile Captorhinus aguti. PaleoBios, 18, 21-35.
78. Modesto, S. P. 1999. Colobomycter pholeter from the Lower Permian of Oklahoma: a parareptile, not a protorothyridid. Journal of Vertebrate Paleontology, 19, 466-472.
79. Modesto, S. P. & Reisz, R. R. 1990. A new skeleton of Ianthasaurus hardestii, a primitive edaphosaur (Synapsida: Pelycosauria) from the Upper Pennsylvanian of Kansas. Canadian Journal of Earth Sciences, 27, 834-844.
80. Modesto, S. P. & Reisz, R. R. 1992. Restudy of Permo-Carboniferous synapsid Edaphosaurus novomexicanus Williston and Case, the oldest known herbivorous amniote. Canadian Journal of Earth Sciences, 29, 2653-2662.
81. Modesto, S. P., Sidor, C. A., Rubidge, B. S. & Welman, J. 2001. A second varanopseid skull from the Upper Permian of South Africa: implications for Late Permian 'pelycosaur' evolution. Lethaia, 34, 249-259.
82. Moss, J. L. 1972. The morphology and phylogenetic relationships of the Lower Permian tetrapod Tseajaia campi Vaughn (Amphibia: Seymouriamorpha). University of California Publications in Geological Sciences, 98, 1-72.
83. Nixon, K. C. 1999. The parsimony ratchet, a new method for rapid parsimony analysis. Cladistics, 15, 407-414.
84. Nopcsa, F. 1923. Die Familien der Reptilien. Fortschritte der Geologie und Palaeontologie, 2, 1-210.
85. Ogg, J. G., Ogg, G. & Gradstein, F. M. 2008. The Concise Geologic Time Scale. Cambridge University Press, Cambridge, 177 pp.
86. Olson, E. C. 1954. Fauna of the Vale and Choza: 7. Pelycosauria: Family Caseidae. Fieldiana: Geology, 17, 193-204.
87. Olson, E. C. 1962. Late Permian terrestrial vertebrates, U.S.A. and U.S.S.R. Transactions of the American Philosophical Society, new series, 52, 1-223.
88. Olson, E. C. 1968. The family Caseidae. Fieldiana: Geology, 17, 221-349.
89. Olson, E. C. & Barghusen, H. 1962. Permian vertebrates from Oklahoma and Texas. Oklahoma Geological Survey Circular, 59, 1-68.
90. Olson, E. C. & Beerbower, J. R. 1953. The San Angelo Formation, Permian of Texas, and its vertebrates. Journal of Geology, 61, 389-423.
91. Orlov, Y. A. 1958. Predatory dinocephalians from the Isheevo fauna (titanosuchians). Trudy Palaeontological Institute of the Academy of Sciences, USSR, 125, 1-114 [in Russian].
92. Peabody, F. E. 1952. Petrolacosaurus kansensis Lane, a Pennsylvanian reptile from Kansas. University of Kansas Palaeonto-logical Contribution, Vertebrata, 1, 1-41.
93. Peabody, F. E. 1954. Pennsylvanian reptiles of Kansas. Geological Society of America Bulletin, 65, 1293.
94. Peabody, F. E. 1957. Pennsylvanian reptiles of Garnett, Kansas: edaphosaurs. Journal of Paleontology, 31, 947-949.
95. Poe, S. & Swofford, D. L. 1999. Taxon sampling revisited. Nature, 389, 299-300.
96. Price, L. I. 1935. Notes on the brain case of Captorhinus. Proceedings of the Boston Society of Natural History, 40, 377-386
97. Reisz, R. R. 1972. Pelycosaurian reptiles from the Middle Pennsylvanian of North America. Bulletin of the Museum of Comparative Zoology, 144, 27-62.
98. Reisz, R. R. 1975. Pennsylvanian pelycosaurs from Linton, Ohio and Nyírany, Czechoslovakia. Journal of Paleontology, 49, 522-527.
99. Reisz, R. R. 1980. Pelycosauria: a review of phylogenetic relationships. Pp. 553-592 in A. L. Panchen (ed.) The Terrestrial Environment and the Origin of Land Vertebrates. Academic Press, London.
100. Reisz, R. R. 1986. Pelycosauria. Encyclopedia of Paleoherpetology, 17A, 1-102.
101. Reisz, R. R. 2005. Oromycter, a new caseid from the Lower Permian of Oklahoma. Journal of Vertebrate Paleontology, 25, 905-910.
102. Reisz, R. R. 2007. The cranial anatomy of basal diadectomorphs and the origin of amniotes. Pp. 228-252 in J. S. Anderson & H.-D. Sues (eds) Major Transitions in Vertebrate Evolution (Life of the Past). Indiana University Press, Bloomington.
103. Reisz, R. R. & Berman, D. S. 1986. Ianthasaurus hardestii n. sp., a primitive edaphosaur (Reptilia, Pelycosauria) from the Upper Pennsylvanian Rock Lake Shale near Garnett, Kansas. Canadian Journal of Earth Sciences, 23, 77-91.
104. Reisz, R. R. & Berman, D. S. 2001. The skull of Mesenosaurus romeri, a small varanopseid (Synapsida: Eupelycosauria) from the Upper Permian of the Mezen River Basin, northern Russia. Annals of the Carnegie Museum, 70, 113-132.
105. Reisz, R. R. & Dilkes, D. W, 2003. Archaeovenator, a small varanopseid synapsid from the Upper Pennsylvanian of Kansas. Canadian Journal of Earth Sciences, 40, 527-539.
106. Reisz, R. R. & Laurin, M. 2004. A reevaluation of the enigmatic Permian synapsid Watongia and of its stratigraphic significance. Canadian Journal of Earth Sciences, 41, 377-386.
107. Reisz, R. R. & Modesto, S. P. 2007. Heleosaurus scholtzi from the Permian of South Africa: a varanopid synapsid, not a diapsid reptile. Journal of Vertebrate Paleontology, 27, 734-739.
108. Reisz R. R. & Tsuji, L. A. 2006. An articulated skeleton of Varanops with bite marks: the oldest known evidence of scavenging among terrestrial vertebrates. Journal of Vertebrate Paleontology, 26, 1012-1023.
109. Reisz, R. R., Heaton, M. J. & Pynn, B. R. 1982. Vertebrate fauna of Late Pennsylvanian Rock Lake Shale near Garnett, Kansas: Pelycosauria. Journal of Paleontology, 56, 741-750.
110. Reisz, R. R., Berman, D. S. & Scott, D. 1992a. The cranial anatomy and relationships of Secodontosaurus, an unusual mammal-like reptile (Synapsida: Sphenacodontidae) from the Early Permian of Texas. Zoological Journal of the Linnean Society of London, 104, 127-184.
111. Reisz, R. R., Scott, D. & Benedegem, J. van. 1992b. Atlas-axis complex of Secodontosaurus, a sphenacodontid mammallike reptile (Eupelycosauria: Synapsida) from the Lower Permian of Texas. Canadian Journal of Earth Sciences, 29, 596-600.
112. Reisz, R. R., Wilson, H. & Scott, D. 1997. Varanopseid synapsid skeletal elements from Richards Spur, a Lower Permian fissure fill located near Fort Sill, Oklahoma. Oklahoma Geology Notes, 57, 160-170.
113. Reisz, R. R., Dilkes, D. W. & Berman, D. S. 1998. Anatomy and relationships of Elliotsmithia longicepsBroom, a small synapsid (Eupelycosauria: Varanopseidae) from the Late Permian of South Africa. Journal of Vertebrate Paleontology, 18, 602-611.
114. Reisz, R. R., Godfrey, S. J. & Scott, D. 2009. Eothyris and Oedaleops: do these Early Permian synapsids from Texas and New Mexico form a clade? Journal of Vertebrate Paleontology, 29, 39-47.
115. Ricqles, A., de & Bolt, J. R. 1983. Jaw growth and tooth replacement in Captorhinus aguti (Reptilia: Captorhinomorpha): a morphological and histological analysis. Journal of Vertebrate Paleontology, 3, 7-24.
116. Rodbard, S. 1949. On the dorsal sail of Dimetrodon. Copeia, 1949, 244.
117. Romer, A. S. 1937. New genera and species of pelycosaurian reptiles. Proceedings of the New England Zoological Club, 16, 89-96.
118. Romer, A. S. 1946. The primitive reptile Limnoscelis restudied. American Journal of Science, 244, 150-188.
119. Romer, A. S. 1948. Relative growth in pelycosaurian reptiles. Pp. 45-55 in A. L. Toit (ed.) Robert Broom Commemorative Volume. South Africa Royal Society Special Publications, Capetown.
120. Romer, A. S. & Price, L. I. 1940. Review of the Pelycosauria. Geological Society of America Special Paper, 28, 1-538.
121. Rubidge, B. S. & Sidor, C. A. 2001. Evolutionary patterns among Permo-Triassic therapsids. Annual Reviews in Ecology and Systematics, 32, 449-480.
122. Rydin, C. & Källersjö, M. 2002. Taxon sampling and seed plant phylogeny. Cladistics, 18, 485-513.
123. Sidor, C. A. 2003. Evolutionary trends and the origin of the mammalian lower jaw. Paleobiology, 29, 605-640.
124. Sidor, C. A. & Hopson, J.A.1998. Ghost lineages and "mammalness": Assessing the temporal pattern of character acquisition in the Synapsida. Paleobiology, 24, 254-273.
125. Sigogneau, D. & Tchudinov, P. K. 1972. Reflections on some Russian eotheriodonts (Reptilia, Synapsida, Therapsida). Palaeovertebrata, 5, 79-109.
126. Sikes, D. S. & Lewis, P. O. 2001. Beta software, Version 1. PAUPRat: PAUP implementation of the parsimony ratchet. Distributed by the authors. Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs.
127. Stovall, J. W., Price, L. I. & Romer, A. S. 1966. The postcranial skeleton of the giant Permian pelycosaur Cotylorhynchus romeri. Bulletin of the Museum of Comparative Zoology, 135, 1-30.
128. Sullivan, C. & Reisz, R. R. 1999. First record of Seymouria (Vertebrata: Seymouriamorpha) from Early Permian fissure fills at Richards Spur, Oklahoma. Canadian Journal of Earth Sciences, 36, 1257-1266.
129. Sumida, S. S. 1990. Vertebral morphology, alternation of neural spine height, and structure in Permo-Carboniferous tetrapods, and a reappraisal of primitive modes of terrestrial locomotion. University of California Publications, Zoology, 122, 1-129.
130. Sumida, S. S., Pelletier, V., Berman, D. & English, L. 2009. New information on the basal pelycosaurian-grade synapsid Oedaleops. Journal of Vertebrate Paleontology, Program and Abstracts, 2009, 188A.
131. * and other methods). Version 4.0b10. Sinauer Associates, Sunderland, Massachusetts.
132. Swofford, D. L. & Olsen, G. J. 1990. Phylogeny reconstruction. Pp. 411-501 in D. M. Hillis & C. Moritz (eds) Molecular Systematics. Sinauer Associates, Inc., Sunderland.
133. Vaughn, P. P. 1958a. On a new pelycosaur from the Lower Permian of Oklahoma, and on the origin of the Family Caseidae. Journal of Paleontology, 32, 981-991.
134. Vaughn, P. P. 1958b. A pelycosaur with subsphenoidal teeth from the Lower Permian of Oklahoma. Journal of the Washington Academy of Sciences, 48, 44-47.
135. Vaughn, P. P. 1969. Early Permian vertebrates from southern New Mexico and their paleozoogeographic significance. Los Angeles County Museum of Natural History Contributions in Science, 166, 1-22.
136. Watson, D. M. S. 1954. On Bolosaurus and the origin and classification of reptiles. Bulletin of the Museum of Comparative Zoology, 111, 1-449.
137. Watson, D. M. S. 1957. On Millerosaurus and the early history of the sauropsid reptiles. Philosophical Transactions of the Royal Society of London B, 240, 325-400.
138. Wilkinson, M. 2003. Missing data and multiple trees: stability and support. Journal of Vertebrate Paleontology, 23, 311-323.
139. Williston, S. W. 1911. American Permian Vertebrates. University of Chicago Press, Chicago, 145 pp.
140. Williston, S. W. 1912. Primitive reptiles. A review. Journal of Morphology, 23, 637-666.
141. Williston, S. W. 1913. The skulls of Araeoscelis and Casea, Permian reptiles. Journal of Geology, 21, 743-747.
142. Williston, S. W. & Case, E. C. 1913. Description of a nearly complete skeleton of Ophiacodon Marsh. Carnegie Institute of Washington Publication, 181, 37-59.