I found a dead cow , Scared the crap out of me...but I found it?

Well I have discovered some new trails around my house , in the woods. So I took my friend on them with me to find where they lead to. Well there's a deep creek and the farther you get , it shallows out. So once it got shallow enough we crossed over , so on our way back we crossed over somewhere else , and were going to climb back onto the trail using a fallen down tree. So while were in the middle of the creek I hear my friend gasp , so I turn around , just a few feet away is a HUGE dead cow. It blended in so well we didn't notice it before. At first we thought it was fake..but it wasn't. It was dead , and looked to be about 500 lbs or more. We got scared because well were only 13 , and we had no clue how it died or what killed it...so we left in a hurry. At its stomach there was a big hole and it had been eaten on all the inside....you could see its ribs poking out...Oh it was creepy! But we left soon enough. It seems to of been there for quite some time now...Farther down th creek across the deeper ends is a farm because I always hear the 'moo's' of cows. Is there anything I should do or call??? How do you think it died??? The creek was shallow with hardly a current...