On Sunday I brought home a fragment of an animal skeleton from Seapoint Beach. At first it looked like a baby dragon, but that's just too much George R.R. Martin on the brain. Then I discounted a bird, and thought fish skull. I posted that thought and some pictures on Sunday. That got my friend JoAnne thinking about every possible bird, fish, mammal, invertebrate that she could think of, as was I.
Nothing seem to fit, until JoAnne's husband suggested that it might not be a skull. Well, that was it, I was thinking about the wrong part of the skeleton. With much searching on the Internet, I finally found a picture that matched my skeletal fragment. Thanks to Dr. Karen Petersen in the Department of Biology at the University of Washington in Seattle for the pictures of comparative vertebrate anatomy. If you check the website and compare them to the following pictures of my beach finding, you'll see the answer (my answer at the bottom of the post, so here's your chance to solve the puzzle before I do!).
The skeletal fragment from Seapoint Beach matches the gull pelvis shown on the website linked above. The roundish end is the anterior end of the ilium, which in birds is fused with the other pelvic bones: the ischium and the pubis, as this diagram shows. Well, that was fun, although as to which species of gull, I will leave to others to study.