Scientists have now found that the Hox genes necessary for tetrapod development is present in a primitive fish (a paddlefish). Here’s part of what they write:
“Tetrapods have a second phase of Hox gene expression that happens later in development. During this second phase, hands and feet develop. Although this second phase is not known in zebrafish, the scientists found that it is present in paddlefish, which reveals that a pattern of gene activity long thought to be unique to vertebrates with hands and feet is in fact much more primitive.
This is the first molecular support for the theory that the genes to help make fingers and toes have been around for a long timeÃ¢â‚¬â€well before the 375-million-year-old Tiktaalik roseae, the newly found species discovered in 2004 by Shubin and colleagues. Tiktaalik provided a missing evolutionary link between fish and tetrapods and was among the first creatures that walked out of water onto land.” (Taken from PhysOrg.com. Here’s the link.)
Poor old Tiktaalik roseae! It’s fifteen minutes of fame is over. So much for “a missing evolutionary link”.