Taxi with young children?

I am traveling with a 1 and 4 year old in January and wondering about car seat requirements in PV. Do I need to have carseats for each of them to take a taxi from the airport to Nuevo Vallarta?

There is no car seat requirement in PV. If you are worried about not having them in a car seat, you can take your own down (but not all taxis will have seat belts to secure them). You can rent baby gear (pretty much anything you would need baby wise) down there, http://www.lotsfortotsmexico.com. Your other option is there are transportation services that you can arrange transportation with that offer car seats. So it is up to you to make the decision if you want them in a car seat or not.