Little Big Bones - Baby makes Five???

While preparing the 4th braincase I have encountered several small bones that appear to be from an infant Thalattosaur. They are two centrums (one from last year), what could be a leg bone and what could be a pelvic girdle bone. Here are some pictures:

Here is a plain centrum recovered in 2013. It shows the 'hour glass' scar where the neural arch connects, but no neural arch was found. In most cases the arches separate from the centrums at the cartilage joint. Without the neural arch it wasn't clear if this was just a bone at the end of the tail (from a larger animal) or a bone from a very small animal.

 Here is the recently found centrum with a partial neural arch attached. With the neural arch it must be one of the body backbones (instead of the tail). Thus it must be from a  very small individual = our 5th  animal! I hope we can find the skull for this one.

 Here's a top view of the small one and a normal sized one.

 Here is a different bone. It may be part of the pelvic girdle, though I'm not sure. The bones have 'growth areas' in three sides and a smooth saddle-curved surface on the side furthest from the camera. However, the nerve holes in the two bones don't correspond, so they may not be the same bone.

 Sincerely, Greg Carr