LANDRY, S.O.; State University of New York, Binghamton: Surface Mass raio and Neck and Tail Elongation in Large Dinosaurs.

Exaggeratedly long necks and (to lesser degree) tails in dinosaurs appear to be restricted to those of extremely large size. This suggests that elongation may be a consequence of unfavorable surface-mass ratios for dissipating internally generated metabolic heat with increase in size. This consideration applies regardless of whether or not animals are endothermic or exothermic. A dinosaur, an elephant, or a pile of wet hay all have the same problem; getting rid of heat. To test this idea, it is necessary to estimate both the volume and the surface area of irregular shapes. An outline of the animal is divided into segments, each of which approximates the shape of a regular geometric solid, whose lateral area and volume can be calculated, and these totaled. This was done on drawings of Apatosaurus, Mamenchisaurus, Brachiosaurus, and the Therapsid, Titanophoneus (weight c. 1,000 kg.) The large forms clearly have a more favorable surface/mass ratio. Their long necks and tails are a consequence of large size. No further explanation is necessary.