Search results
Results from the WOW.Com Content Network
How the Snake Lost Its Legs: Curious Tales from the Frontier of Evo-Devo is a 2014 book on evolutionary developmental biology by Lewis I. Held, Jr. The title pays homage to Rudyard Kipling's Just So Stories, [1] [a] but the "tales" are strictly scientific, explaining how a wide range of animal features evolved, in molecular detail.
Snakes are a particularly good example for studying limb loss, as they underwent limb loss and regeneration multiple times throughout their evolution before they finally lost their legs for good. Much of the gene expression during embryonic development is regulated via spatiotemporal and chemotactic signaling, [ 20 ] as depicted by the image to ...
Many vertebrates are limbless, limb-reduced, or apodous, with a body plan consisting of a head and vertebral column, but no adjoining limbs such as legs or fins. Jawless fish are limbless but may have preceded the evolution of vertebrate limbs, whereas numerous reptile and amphibian lineages – and some eels and eel-like fish – independently lost their limbs.
While snakes are limbless reptiles, evolved from (and grouped with) lizards, there are many other species of lizards that have lost their limbs independently but which superficially look similar to snakes. These include the slowworm, glass snake, and amphisbaenians. [22]
Hox gene mutations have resulted in some tetrapods becoming limbless (snakes, legless lizards, and caecilians) or two-limbed (cetaceans, moas, and some lizards). [7] Nevertheless, these limbless groups still qualify as tetrapods through their ancestry, and some retain a pair of vestigial spurs that are remnants of the hindlimbs.
The hatching of the 107th tiny, wriggling snake at a Tennessee zoo marks the end of another year of efforts to save one of North America’s rarest snakes from extinction.
Pelvic spurs (also known as vestigial legs) are external protrusions found around the cloaca in certain superfamilies of snakes belonging to the greater infraorder Alethinophidia. [1] These spurs are made up of the remnants of the femur bone, which is then covered by a corneal spur, or claw-like structure. [ 1 ]
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!