It's possible that the builder used studs like that.
I'd explore with a hole, behind the TV. You can get a small, cheap drywall access panel from HD/Lowes (many sizes) to cover your hole behind the TV, or maybe cut a double gang size hole and fill with a LV ring, covered with a plate.
You'll need to cut drywall eventually, to get power behind the TV, and run your LV cables.
If it was recent construction, you could call the builder, and find out if the studs are nailed to the wall, or top/bottom plates were used.
If you're amenable to painting the wall, you can cut out a TV-sized hole, attach your own wood to the wall securely ('blocking'), and then re-drywall. It's an expensive TV, put some time and effort into the project. Or, call a local insured AV installer, and put him on the hook if it falls. I'm not sure how much effort the builder used to secure the studs to the wall, but behind a big sheet of drywall, I doubt the stud could be pulled from the wall by the weight of the TV.
It's odd that you bought the mount before the TV.
Do 60" TVs come with pedestals? You might want to return the mount and consider that, if you want to put off the project until football season is over.