My field guides are all woefully out of date; my western Peterson’s is from the 80s, my easterns is from the early 90s. I’ve got the great Texas Snakes by Werler and Dixon but it’s so old it uses Elaphe for our ratsnakes…
I really need field guides that aren’t 20+ years old for the sake of taxonomic and range changes if nothing else. Amazon shows a whole host of them, but I don’t want to drop hundreds of dollars ordering them all. Are Peterson’s still the best for the US as a whole? Are there significantly better up to date guides for TX/NM/OK herps in particular (or CO so I can bone up before this summer)?
The new Peterson’s for eastern herps was a bit controversial to some. I find it annoying (especially the range maps) but still useful. In my experience, it is what most people use for broad coverage in the US. It does really well with introduced species actually. The taxonomy is certainly more up to date than the 3rd edition (which is what you probably have).
I think that Amphibians and Reptiles of Texas (2013) is the standard for full coverage of Texas, but I don’t have personal experience with it. Toby Hibbitts (@toby on iNat) has written a lot of field guides and is a curator on iNat itself. I don’t think he’s on the forum, but you could try a DM there.