Most Primitive Deuterostomes Found (540 mIllion Years Old)

[Virgilian]

Authors of a recent paper published in Nature--over at  Meiofaunal deuterostomes from the basal Cambrian of Shaanxi (China) by Jian Han, Simon Conway Morris, Qiang Ou, Degan Shu, and Hai Huang --describe the earliest, most primitive deuterostomes, which include of course such major groups as vertebrates, echinoderms, and hemichordates (acorn worms and graptolites).

 

They're from China. They're some 540 million years old, earliest Cambrian in geologic age. They had a mouth, but probably no actual anus. The newly discovered creatures have been named Saccorhytus coronarius gen. et sp. nov., from the Early Cambrian Kuanchuanpu Formation, South China.

 

The authors draw a couple of fascinating conclusions (among others):

 

"In Saccorhytus, however, diffusion across the body surface would have met any respiratory needs, suggesting that a transformation to specifically pharyngeal gills was linked to an increase in body size. If Saccorhytus lacked an anus, body openings may have originated to dispose of waste material."