Saccorhytus
| Saccorhytus Temporal range: | |
|---|---|
| Reconstruction of Saccorhytus coronarius | |
| Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Superphylum: | Ecdysozoa |
| Phylum: | †Saccorhytida |
| Family: | †Saccorhytidae Han et al., 2017 |
| Genus: | †Saccorhytus Han et al., 2017 |
| Species: | †S. coronarius |
| Binomial name | |
| †Saccorhytus coronarius Han et al., 2017 | |
Saccorhytus (from Latin saccus "bag" and Ancient Greek ῥύτις rhytis "wrinkle") is an extinct genus of animal possibly belonging to the superphylum Ecdysozoa, and it is represented by a single species, Saccorhytus coronarius (from Latin attributive coronarius "[of a] crown"). The organism lived approximately 540 million years ago in the beginning of the Cambrian period. Initially proposed as a deuterostome, which would have made it the oldest known species of this superphylum, it has since been determined to belong to a protostome group called the ecdysozoans.
Fossils of the species were first discovered in the Kuanchuanpu Formation of Shaanxi province of China by a team of scientists from the United Kingdom, China and Germany, and the findings were first published in January 2017.
A 2024 paper suggested it may instead be the non-feeding larva of a scalidophoran, tentatively linking it to Eokinorhynchus due to their shared bilateral sclerites. However, a 2025 paper refutes this, again proposing that Saccorhytida is a distinct group of stem-ecdysozoans and also suggesting Eolarva may be intermediate between saccorhytids and crown-group ecdysozoans.