Rana catesbeiana (Linneaus 1758, Shaw 1802) extant, bull frog. Derived from a sister to Triadobatrachus, Rana is the last of this lineage and includes some 90 species.
Distinct from Triadobatrachus, the skull of Rana is more spade-shaped in dorsal view. The nasals extend laterally to the maxilla. The squamosal is reduced to a frame for the eardrum.
The presacral count is further reduced to 9. The tail vertebrae are fused into a single long bone, the urostyle, following the sacral vertebrae, but note that while the urostyle is long, it lies completely between the ilia and does not extend beyond the ischium.
A cartilaginous element, the suprascapula, extends dorsal to the scapula and roofs over the first few dorsal ribs. The radius and ulna fuse. The hand is larger. The thumb is absent. Only a vestigial stub sometimes remains of metacarpal 1. Digit 2 of the manus has one fewer phalanx probably by fusion. Digits 3 and 4 have two fewer phalanges.
The ilium is elongated to half the torso length. The femur is gracile and elongated. The tibia and fibula are fused. The tibiale (astragalus) and fibulare (calcaneum) further elongate the foot. No trace of pedal 2.1 is present. A small medial carpal spur is present.