They are the
Troodons !
They were very smart dinosaurs but there is no clue they had any kind of poison . However , as Laura describes in her diary (will meet her later in the game and he will later unlock those pages of the diary which is accessible through the Main menu) they probably got that anomaly due to the elements of the frog DNA dr Wu used to fill the gaps in the sequence of the dinosaurs' extracted DNA . They proved to be very dangerous and that's why Hammond decide they should .... well , I better not reveal the details ! Let him play the game and find out those details !