Protorosaurus Speneri
, one of the earliest known fossil reptiles, has been already studied and described by Baron Cuvier, Hermann von Meyer, Sir Richard Owen, and Professor Huxley. Occurring in the Kupferschiefer, and therefore of Primary age, the exact determination of its structure and affinities has become of some interest in relation to the great development of Reptilian life which characterises the succeeding Triassic period. The most interesting example of
Protorosaurus
is that originally obtained by Spener, which he described and figured in 1710, and regarded as the remains of a Crocodile. His view was confirmed by Link. But Kundmann of Breslau in 1737 interpreted the remains as those of a new type of large-headed fossil-lizard. This conclusion was substantially adopted by Cuvier, who in 1808 made the animal universally known as the fossil Monitor of Thuringia. Cuvier had never seen a specimen; and was dependent upon the figures published by Spener, Link, and Swedenborg, and a drawing, which he published, of a specimen preserved in the Royal Museum at Berlin. He remarks that the head is not without resemblance to that of the Nilotic Crocodile, and, as Spener only knew drawings of the exterior of tlie Crocodile, his identification was excusable. Cuvier goes on to argue that the number of teeth in the lower jaw of a Crocodile is at fewest fifteen, while in the upper jaw there would be seventeen or eighteen extending back to the middle of the orbit, whereas the fossil has only eleven teeth, which reach back to the anterior angle of the orbit. On this evidence the skull is interpreted as that of a Lacertilian, allied to the Monitor. The author goes on to show that other parts of the skeleton confirm the inference from the skull. Thus the hind limb has five digits, with the number of phalanges in them successively 2, 3, 4, 5, 3, which agrees with the Monitor. The correspondence extends to the larger bones of the extremities. Cuvier only detected two differences of specific value: first, the spinous processes of the dorsal vertebræ are much more elevated than in Monitors; and secondly, the foreleg is relatively longer in proportion to the femur and the foot. It is unnecessary to offer any detailed discussion of this interpretation, for the figure now given, when compared with Spener’s figure, shows that Cuvier had not the evidence fairly before him.
Determination of Individual Mesio-distal Sizes of Front Teeth Upper and Lower Jaw
