how to get bio toxin in extinction map

[Slayrix]

Can't find it anywhere people said gatchas drop it but they don't, can't find it on the internet, so where do I get it.

[Boatabike]

If you use S+ you can make it in the grinder, other than that none on extinction map.

[Slayrix]

Originally posted by Boatabike:

If you use S+ you can make it in the grinder, other than that none on extinction map.

What is S+?

[Slayrix]

Originally posted by Boatabike:

If you use S+ you can make it in the grinder, other than that none on extinction map.

Also my rexes had it in thier inventory and idk how but they did some how, is it like a rare drop or something because that would make no since as to why my rexes had it in thier inventory, I was able to make 51 shock trank darts