bilaterians
Was the “ancestor of all animals” really identified recently?
Researchers: Program for limb development may have been in “in the bilaterian common ancestor”
What? Doug Axe draws attention to a new paper at Evolution News and Science Today which suggests that “the genetic program for limb development predates limbs.” Abstract: Cephalopod mollusks evolved numerous anatomical innovations, including specialized arms and tentacles, but little is known about the developmental mechanisms underlying the evolution of cephalopod limbs. Here we report that all three axes of cuttlefish limbs are patterned by the same signaling networks that act in vertebrates and arthropods, although they evolved limbs independently. In cuttlefish limb buds, Hedgehog is expressed anteriorly. Posterior transplantation of Hedgehog-expressing cells induced mirror-image limb duplications. Bmp and Wnt signaling, which establishes dorsoventral polarity in vertebrate and arthropod limbs, is similarly polarized in cuttlefish. Inhibition of the dorsal Bmp signal Read More ›