On the whole, the anatomy of Sigillaria is closely related to that of the preceding group, and in fact a continuous series can be traced from the anatomically simplest species of Lepidodendron to the most modified Sigillariae.
The family Calamopityeae, allied anatomically to Lyginodendreae, is of Devonian and Lower Carboniferous age.
This plant may be regarded as anatomically the most primitive of the Medulloseae.
Anatomically the connexion of the family with the Pteridosperms (and through them, presumably, with some primitive group of Ferns) seems clear, but we have as yet no indications of the stages in the evolution of their reproductive organs.
The foot of the higher apes, though often spoken of as a hand, is anatomically not such, but a prehensile foot.