FROM RADIAL TO BILATERAL SYMMETRY. “The chordate sagittal plane is perpendicular to the sagittal plane primitive for the bilaterally symmetrical metazoans (Bilateria). The earliest metazoans, when symmetrical at all, were probably radial in symmetry. The axis of symmetry was vertical and the mouth, when present, opened either upward or downward.”
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linkedin post 2022-06-29 05:12:48
Nigel Fleming
September 21, 2022