It is also possible that this was stitched together out of more than one negative. I recall seeing a 6-foot-ish panorama by I want to say Carleton Watkins of a village in Mexico at the foot of a volcano. It was spliced together from three or four negatives from an 18x22 or maybe 20x24 camera. It was so well executed that you could not tell where the seams in the image were except from the slight changes in perspective that came from rotating the camera. That was an albumen print from the 1870s, IIRC. This image certainly has a perspectival distortion that looks like it was made by either a swing-lens camera, a Cirkuit or at least a multi-negative shot spliced together.