Well, it seems to assume uniform change across all species, which is a creationist fantasy. As Steve said, there's no reason why one family cannot remain the same, and another changes, depending on environmental pressures..
As I was writing that post I thought the response would be that there must have been a time during which something else changed into turtles through environmental pressures. I think it's claimed that a transitional fossil has been found.
Nowt wrong with that. Some creatures are so well adapted to their environment that they haven't changed much in millions of years (crocodiles, as well as turtles, for example) while others have changed considerably.
I do find amusing the way fundies regularly say that some aspect of evolutionary theory is "desperation", when their own idiotic hypothesis is fuller of holes than a leaky colander. Spud's recent attempts to explain why the recurrent laryngeal nerve isn't an example of bad design look pretty desperate to me.
I haven't really said much, and I wasn't particularly serious about it, except to note that there is a common body plan in tetrapods which could be used to infer both I.D. and evolution.
I have seen other people on the net suggesting there are good reasons for the circuitous route. In particular, one doctor pointed out that it passes close to various lymph nodes, which means that if those nodes become enlarged due to a disease process, the nerve can be irritated causing hoarseness or cough. Thus it could be an early warning system, both to warn the owner and others that he is sick. If he has an infectious disease such as tuberculosis then this is clearly useful.
Try gently squeezing the sides of your trachea below the larynx. That's where the RLN is, and you might notice the need to cough. A possible defense mechanism in case of external pressure on the airway?
A possible analogy explaining how the design is necessary is where you are driving on a motorway and you pass the house you want to visit, but have to stay on the motorway until the next exit. You can't have an exit for every house you pass.
Here's a cross section of the human neck:
https://www.alamy.com/stock-photo-cross-section-through-neck-7710121.htmlThe vagus travels down the neck within a sheath containing the internal carotid artery and jugular vein. It may not be possible for it to branch while contained in this sheath.
Another point, which is neither here nor there but worth a mention, is that it isn't just the larynx that is wired backwards, but the whole trachea and the upper 1/3 of the oesophagus too. These seem to be a functional unit, necessary for swallowing and coughing. The muscles innervated by the RLN are concerned with the opening and closing of the airway and oesophagus, whereas the muscle innervated by the Superior laryngeal nerve is concerned with speech, allowing changes in pitch.
Lastly: if you view the circuitous route as a vestige of evolution, you may end up barking up the wrong tree, instead of encouraging research into the specific reasons for its design.