The pelvis is beginning to take shape today. The surrounding rock comes away cleanly from the bone (what we call ‘good separation’), which makes for pretty fast work. Things slow down a bit when I hit weathered, flaky bone – because the bones have not been heavily mineralized, if the hard outer layer of bone (the cortex) comes off, the inner spongy bone can easily turn into powder. When I hit eroded areas, I must slow down and douse the spongy parts in a special glue called Vinac, which is mostly just plastic that dissolves in acetone.
Ankylosaur hips look pretty weird even for dinosaurs, so here’s a picture of a perfect complete specimen at the American Museum of Natural History. This pelvis belongs to a Euoplocephalus from Alberta, and this specimen was very important for my work on ankylosaur tail swinging as it preserves really nice muscle scars that let me map out the tail-swinging muscles. Tail swinging math can be found here! (The blue line on the scale bar is 10 cm long – ankylosaurs were REALLY fat animals!)