Fig. 28. Restoration of probable appearance of Amphibamus grandiceps Cope on the basis of the material described herewith. × 1.5.
In the type specimen the matrix in the orbit was blackened as if by the pigmentum nigrum of the choroid. The same has been noticed in other specimens. Professor Cope thought this indicated that the animal was nocturnal.
There are many characters in Amphibamus which seem to approximate the reptilian type of structure. Among these may be mentioned the character of the articular surfaces of the limb bones, the intercentral position of the ribs, the incipient double-headedness and the curvature of the ribs, the presence of a cartilaginous calcified pubis, the length of the limbs, and the clawed character of the phalanges.
Amphibamus was a low, flat, short, and undoubtedly a creeping, crawling animal, possibly spending a portion of its time in the water; but it could not have been a swimmer. It was one of nature's first attempts at constructing a land vertebrate.
Measurements of Amphibamus grandiceps Cope.
Collection of Mr. L. E. Daniels, of Rolling Prairie, Indiana:
| mm. | |
| Entire length of specimen | 62 |
| Posterior width of head | 15 |
| Length of head | 15 |
| Posterior height of skull | 3 |
| Length of orbit | 5 |
| Width of orbit | 3.5 |
| Interorbital width | 4 |
| Width of skull in front of orbits | 11 |
| Width of skull just back of orbits | 16 |
| Length of presacral region of the vertebral column | 30 |
| Length of tail | 13 |
| Length of fore limb | 13.5 |
| Length of humerus | 4 |
| Length of radius and ulna | 3 |
| Length of right hand as preserved | 3.5 |
| Length of rib along curve | 5.5 |
| Length of hind limb | 17 |
| Length of ilium | 4 |
| Length of vertebral centrum | 1.75 |
| Length of portion of scapula (?) preserved | 4.5 |
| Length of foot | 6.5 |
| Width of impression of body midway | 16 |
| No. 794 (1234), Yale University Museum: | |
| mm. | |
| Length of skeleton | 67 |
| Length of skull | 15 |
| Posterior width of skull | 15 |
| Depth of tympanic notch | 4 |
| Width of tympanic notch | 6 |
| Long diameter of the orbit | 7 |
| Transverse diameter of the orbit | 5.5 |
| Interorbital width | 4.5 |
| Diameter of pineal foramen | .75 |
| Length of cervical series of vertebræ | 9 |
| Length of dorsal series | 35 |
| Length of caudal series | 13 |
| Length of a centrum of the dorsal series | 1.5 |
| Length of dorsal rib | 3.5 |
| Length of arm | 20 |
| Length of humerus | 7 |
| Length of radius and ulna | 4 |
| Width of carpal space | 3 |
| Length of third digit | 5 |
| Length of leg | 25 |
| Length of ilium | 3 |
| Length of femur | 9 |
| Length of tibia and fibula | 5 |
| Length of carpal space | 4 |
| Length of 1st digit | 3 |
| Length of 2d digit | 4.5 |
| Length of 4th digit | 7 |
| 3 ventral scutellæ in 1 mm. | |
Amphibamus thoracatus Moodie.