What is "burlingiidae"

The Burlingiidae constitute a family of trilobites of uncertain affinity, that lived during the Middle to lowest Upper Cambrian (Acadoparadoxides pinus- to Agnostus pisiformis-zone). Burlingiids have a cosmopolitan distribution, can be found in deposits that originate from outside the continental shelfs, and may have been planktonic. They are characterized by their oval shape, small size (less than ), proparian sutures, and non-functional articulations of the thorax. Uniquely the anterior borders of the pleura are raised, and there are between 8 and 15 thorax segments. Burlingiid trilobites have been found in Norway, Sweden, Northern Siberia, Eastern and South-eastern China, Australia (Tasmania), India (Himalayas) and the United Kingdom.