Paralbula, Blake, 1940

Sahni, Ashok, 1972, The vertebrate Fauna of the Judith River formation, Montana, Bulletin of the American Museum of Natural History 147 (6), pp. 319-416 : 345

? Paralbula sp.

Figure 7 R-U

Blake (1940) originally reported the genus from the Aquia Formation (lower Eocene) of Maryland. Current investigations, however, have revealed the presence of Paralbula not only in the Judith River Formation, Montana, but also in the Oldman Formation, Alberta. The teeth, which are fairly common in both formations, have been tentatively identified as belonging to? Paralbula sp. (Estes, personal commun.). The Judith River Formation specimens from Clambank Hollow are similar to those obtained from the Oldman Formation and consist of a mixture of thoroughly eroded to well-preserved teeth. The teeth vary in size and shape. Some are round, most are slightly convex, and a few are elongate or rectangular. AMNH 10100 has an average diameter of 2.5 mm. and AMNH 10101 has a length of 3.5 mm. (fig. 7R-U). The attachment surface of the teeth is slightly concave and is characterized by a few concentric layers. The larger teeth comprise the central part of the pharyngeal plate, whereas the smaller, more rounded ones form the peripheral areas. The isolated occurrence of the teeth makes it impossible to decipher the arrangement in which the teeth were stacked, and hence makes comment on their affinity to phyllodonts inadvisable at this time. The affinities and relationships of the Alberta and Montana occurrences of Paralbula are currently under study by Estes, at Boston University.

Figures

FIG. 7. A. AMNH 8446, ventral view of left discoglossid (A) humerus. B. Dorsal view. Both x 5. C. AMNH 8449, ventral view of left discoglossid (B) humerus. D. Dorsal view. Both x 5. E. AMNH 8450, ventral view of left discoglossid (C) humerus. F. Dorsal view. Both x 5. G. AMNH 8456, lateral view of distal portion of right discoglossid ilium, x 5. H. AMNH 8457, lateral view of distal portion of left discoglossid ilium, x 5. I. AMNH 8459, lateral view of distal portion of left discoglossid ilium, x 5. J. AMNH 8452, lateral view of distal portion of left pelobatid ilium, x 5. K. AMNH 8453, lateral view of distal portion of pelobatid ilium, x 5. L. AMNH 8460, external view of left discoglossid (C) maxilla. M. Internal view. Both x 5. N. AMNH 8462, external view of right discoglossid (B) maxilla. 0. Internal view. Both x 5. P. AMNH 8461, external view of left discoglossid (A) maxilla. Q. Internal view. Both x 5. R. AMNH 10100, occlusal view of?Paralbula sp. S. Basal view. Both x 10. T. AMNH 10101, occlusal view of?Paralbula sp. U. Basal view. Both x 1.0.