0% HL, about equal in length to blind-side mandible; teeth conical and slightly lobate or truncate, largest are anterior becoming gradually smaller posteriorly, fewer on ocular-side premaxilla and dentary
, 4-10 on ocular-side premaxilla, 20-27 on blind-side premaxilla, 8-15 on ocular-side dentary
, 20-29 on blind-side dentary
; gill rakers of first arch moderately slender to broad and robust, 6-14 total, 1-6 on upper and 4-9 on lower arch; gill rakers of second arch broad and robust, 6-14 total, 0-4 on upper and 5-13 on lower arch; dorsal orbit round (nearly equal to eye length) to elliptical (posterior rim elongate and much greater than eye length), orbit lenth 22.
Color in alcohol: Ground color clear; snout, tip of dentary
, anterior portion of maxilla and top of head densely covered by small dark chromatophores, resulting in overall dark pigmentation; infraorbitals with scattered dark chromatophores; opercle with a dense concentration of relatively large dark chromatophores, forming a dark blotch; opercle translucent due to the loss of guanine pigmentation.
Its posterior maxillary and dentary
teeth have anteroposteriorly rather than transversely aligned crowns with serrated apical ridges (Sues and Baird 1998).
The differential diagnosis for this species provided by Carraway and Timm (2000) uses qualitative features of the glenoid fossa and measurements of the cranium and coronoid process of the dentary
that are not preserved in the Terapa specimens, so no comparisons can be made.
The caudolateral edge of the dentary
is irregular and invests laterally in the direction of the ventral rims of the coronoid and the supra-angular.
similar to that in left MI, with two long transversal ridges in anterior part.
10] General shape of the premaxilla and dentary
(Costa 1998a) (CI: 0.
TABLE 1 Measurements of Ludington, Michigan, Castoroides canadensis Right Dentary
Length of tooth row 74mm Greatest length of lower molar II 18 mm Greatest length of lower molar III 16 mm Greatest length of mandibular symphasis 75 mm Greatest length, tip of jaw through condyloid process 202 mm Greatest length of alveolus I 22mm Greatest length of alveolus IV 22 mm Greatest width of alveolus I 26mm Greatest width of alveolus IV 18 mm
The lower jaw was almost completely made up of dentary
bone; other minor components included the angular, surangular, and articular bones.
The Fragment extends posteriad from the point of the dentary
Measurements (Table 1) of the dentary
correspond well with data on Oreamnos harringtoni presented in and Mead & Lawler (1994).
I selected the dentary
to estimate variation in age and size of the Emeryville Acipenser since they were the most abundant, well-preserved element in the assemblage (Broughton 1995).
Diagnostic features separating it from other species of Protosuchus include the consistent presence of two caniniform teeth (rather than one) in each dentary
and the slender rather than deep anterior process of the jugal extending below the orbit (Clark 1986; Gow 2000).
75, length of dentary
(includes lower incisors); 11.
are minimal; the geo- graphically closest "Deuterodon" minor from Tapa-jos basin has an indistinct humeral spot and a longer anal fin; "Deuterodon" pedri from Minas Gerais seems closer morphologically, with the head shorter, and a few more premaxillary, maxillary and dentary