THEROCEPHALIA

Huttenlocker, Adam, 2009, An investigation into the cladistic relationships and monophyly of therocephalian therapsids (Amniota: Synapsida), Zoological Journal of the Linnean Society 157 (4), pp. 865-891 : 887-888

THEROCEPHALIA (15 characters)

19. Posteroventral extension of the zygomatic arch just below the orbit slightly curved, having a distinctly concave ventral margin throughout its length (3).

36. Palatal fenestra for lower caniniform present and confluent with internal naris (1).

38. Portion of vomer separating the choanae expands anteriorly and is widest at its contact with the premaxilla (1). (From Hopson & Barghusen, 1986; van den Heever, 1994; specialized transverse bars contacting the maxilla are present in Whaitsiidae ).

43. Large suborbital vacuities bound by the palatine, pterygoid and ectopterygoid are present throughout ontogeny (1). (Absent in adults of Theriognathus and Euchambersia .)

44. Pterygoid bears a ventromedian tubercle/crest anterior to the interpterygoid vacuity (1).

46. Pterygoid flange expansion produces sharp, posteriorly projecting wings with slight posterolateral expansion, nearly contacting the zygomatic arch (2). (Reduced in Euchambersia , as it is in cynodonts.)

51. Epipterygoid ascending process is slightly expanded anteroposteriorly (1). (Modified from Kemp, 1972a; Hopson & Barghusen, 1986; extremely expanded in Theriognathus and Cynodontia , which were coded ‘2’.)

60. Dorsal process of stapes reduced/absent (1). (Apparently present in Viatkosuchus , as reported by Tatarinov, 1995a.)

71. Splenial laterally obscured by dentary (1). (From Sidor & Hopson, 1998; Sidor, 2003; either conv. in non- Procynosuchus cynodonts or plesiomorphic for Eutheriodontia with a primitive reversal in Procynosuchus , which displays a laterally exposed splenial and is coded ‘0’.)

84. Sharp anterior process of the dorsal iliac plate (ischial tuber) present above a ventral concavity (1).

85. Pubis and ischium orientation slightly horizontal, forming a broad puboischiatic plate (1).

87. Distinct trochanter minor of the femur present (1).

98. Stapedial foramen reduced/absent (2). (Modified from Hopson & Kitching, 2001; conv. in Anomodontia ; Viatkosuchus is coded ‘0’ for this character, as reported by Tatarinov, 1995a.)

103. Greatest width of zygomatic arch is at the back of the arch (1). (From Hopson & Kitching, 2001; conv. in cynognathian cynodonts.)

110. Lateral dentary sulcus extending from the coronoid process to the ramus present (1). (Shallow, but present in lycosuchids and scylacosaurids, as observed by van den Heever, 1994; completely absent in some non-akidnognathid ‘whaitsioids’ and coded ‘0’ for those taxa.)