Paired appendages—the pectoral and pelvic fins of fishes and the forelimbs and hindlimbs of tetrapods—were a major innovation in vertebrate evolution. Their emergence greatly expanded the ways vertebrates could move through their environments and ultimately provided the developmental foundation ...
Source: [Phys.org](https://phys.org/news/2026-10-ancient-hox-code-reveals-developmental.html)