On a spring day in May 2020, 11-year-old Ruby Reynolds set out for the shores of the River Severn near the village of Blue Anchor so that she and her father, Justin, could go fossil hunting.

Paleontologists recently uncovered the fossil of Kretzoiarctos beatrix, an omnivorous ancestor of the modern giant panda, that lived around 11 million years ago. This discovery, made at the ...