Cathaymyrus is an Early Cambrian

Cambrian

The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...

 cephalochordate known from the Chengjiang locality in Yunnan Province, China. It had a long segmented body with no distinctive head. The segments resemble the v-shaped muscle blocks found in similar cephalochordates such as Amphioxus. A long linear impression runs along the "back" of the body looking something like a chordate notochord

Notochord

The notochord is a flexible, rod-shaped body found in embryos of all chordates. It is composed of cells derived from the mesoderm and defines the primitive axis of the embryo. In some chordates, it persists throughout life as the main axial support of the body, while in most vertebrates it becomes...

. Cathaymyrus is related to Pikaia

Pikaia

Pikaia gracilens is an extinct animal known from the Middle Cambrian Burgess Shale of British Columbia. -Discovery:It was discovered by Charles Walcott and was first described by him in 1911. It was named after Pika Peak, a mountain in Alberta, Canada. Based on the obvious and regular segmentation...

, another cephalochordate from the Burgess Shale

Burgess Shale

The Burgess Shale Formation, located in the Canadian Rockies of British Columbia, is one of the world's most celebrated fossil fields, and the best of its kind. It is famous for the exceptional preservation of the soft parts of its fossils...

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