2nd September 2026
Michael P., Taylor, University of Bristol, UK. <dino@miketaylor.org.uk>
Mathew J. Wedel, Western University of Health Sciences, California, USA.Dinosaur skeletons are overwhelmingly photographed, illustrated and interpreted in lateral view, and more rarely from other ground-level perspectives. This has quietly shaped a century of thinking about body shapes and proportions. From a maintenance balcony 15.8 m above the Jurassic Hall of the Carnegie Museum of Natural History, and from the floor beneath the mounts, we photographed the holotypes of two iconic sauropod holotypes: Diplodocus carnegii CM 84 and Apatosaurus louisae CM 3018. These dorsal and ventral perspectives have have never to our knowledge been previously published for any mounted sauropod skeleton. Because the two mounts stand side by side, are exceptionally complete, and represent the sister clades Diplodocinae and Apatosaurinae, they invite direct comparison.
Scaling the mounts to each other, the Apatosaurus torso is 1.47 times as wide as that of Diplodocus, and 11% longer (a difference attributable mostly to its much longer sacrum). It encloses 1.69 times the area in dorsal view. Combined with a torso about 1.20 times as tall, inferred from rib and hindlimb-bone lengths, this yields a torso volume — and so, plausibly, a body mass — 2.03 times that of Diplodocus, a much higher ratio than in any published estimate since 1985. The two torsos also differ in shape: Apatosaurus is broader across the shoulders than the hips, Diplodocus the reverse. Questions remain regarding how much this is due to real skeletal anatomy and how much to mounting decisions. Nevertheless, the tyranny of lateral view has obscured real and substantial morphological disparity.
[Slides to follow]