407 B
407 B
Bilateria
- A 3rd germ layer on top of Eumetazoa, the mesoderm
- Bilaterally symmetric
- The Urbilaterian:
- MRCA of the Bilaterians
- Must have been extremely unspecialized to give rise to both deuterostomia and protostomia
- Anterior to Posterior positioning controlled by hox-genes
- In this case, they're called Hox cluster genes