[ 71 J 



ART. VII. — Fossil Footprints of Connecticut River. By James Deane, M. D. 



Plates VIII and IX. 



The footprints of the new Red Sandstone of Connecticut river, clearly indicate 

 that birds existed in multitudes during the deposition of this rock. Their vestiges 

 are preserved v^ith such remarkable fidelity, that no difficulties occur in assigning 

 to them their true place in the scale of animal organization. Their relation to 

 existing types is susceptible of unquestionable proof upon the application of the laws 

 of comparison. It consists in the corresponding number and arrangement of the toes 

 and their appendages, and in the impress of the heel. The law of correllation of 

 structure, or rather of configuration of structure, is distinctly shown by several 

 figures in the accompanying plate VIII. The massive foot, fig. 2, and the more 

 slender one, fig. 1, illustrate this principle in the clearest manner. They are both 

 right feet, and the inner toe is distinguished by the impress of two articular lobes, 

 the middle three and the outer four, which with the terminal joint or that of the nail 

 is in exact correspondence with the phalangeal divisions of the feet of living birds. 

 Posteriorly to the toes is the impress of the distal extremity of the tarso-metatarsal 

 bone, and this completes the harmonious relations of the fossil footprint with that of 

 living birds having an equal number of toes. The comparison is corroborated by the 

 method of progression. The movement of the extinct birds is invariably by 

 successive and alternate steps of the right and left foot, each pointing in the direction 

 of its successor. It consequently happens that the inversion of the foot is in 

 proportion to the length of the step. When the step is comparatively long, the foot- 

 prints point directly forward and fall in a direct line or nearly so, whereas if the step 

 be short, each foot points more or less inward, and falls considerably outward of the 

 direct line of progression. It is so in living birds, and these are the points of 

 comparison that connect them with their remote ancestors. In rare instances the 

 impress of the dermoid papillae is exquisitely preserved. 



It is obvious that the footprints were impressed upon the margins of such bodies of 

 water as were subject to considerable fluctuations of level, and it is impossible to say 

 whether this disturbance was due to the action of tides or of floods. It is difficult to 

 understand how the strata should become sufficiently hardened by exposure during 

 the period between the ebbing and flowing of tides, to retain impressions. The birds 

 trod upon the impressible mud when in condition to retain the form of the foot, and 



