How is the neck of the green velociraptor 10757 connected?
Looking at inventory for Velociraptor, included in 10757 set you've mentioned, there is a Technic Pin. Since all of the limbs have half of the pin molded into the parts this leaves us with Technic Pin that is used to connect body with a head piece.



Better pictured by this step from LEGO building instruction (thanks Syberion for the tip):