Pseudooides fossils have a segmented middle like the embryos of segmented animals, such as insects, inspiring grand theories on how complex segmented animals may have evolved.
A team of paleontologists from the University of Bristol’s School of Earth Sciences and Peking University have now peered inside the Pseudooides embryos using X-rays and found features that link them to the adult stages of another fossil group.
It turns out that these adult stages were right under the scientists’ noses all along: they have been found long ago in the same rocks as Pseudooides.
Surprisingly, these long-lost family members are not complex segmented animals at all, but ancestors of modern jellyfish. Paper. (public access) – Baichuan Duan, Xi-Ping Dong, Luis Porras, Kelly Vargas, John A. Cunningham, Philip C. J. Donoghue. The early Cambrian fossil embryo Pseudooides is a direct-developing cnidarian, not an early ecdysozoan. Proceedings of the Royal Society B: Biological Sciences, 2017; 284 (1869): 20172188 DOI: 10.1098/rspb.2017.2188 More.
It’s interesting that the researchers here see little need to protect a Darwinian tree of life. Who knows, we may go on to discover many other useful pieces of information.
See also: Researchers: Sponges definitely oldest animals, not “anatomically complex” comb jellies