Chupacabras ("goatsuckers") were originally some form of mutie that appeared in Puerto Rico. After Silas Jamaivous arrived in 2094, he found some and sent them back in time to the late 1990's as test subjects for his work on a new gateway (one that he could use to go back in time himself). They were they found and captured by the US government, who took their DNA and combined it with other creatures, creating something completely new that survived past the holocaust and continued to plague the people of Puerto Rico.
Chupacabras were about four feet tall and bipedal. The head is similar to a horse's - oval-shaped, with a strong jaw, small nostrils, and a mouth full of needle teeth; the eyes are red with greenish-yellow, vertically-slitted pupils. Their hands and feet have three fingers and toes, all tipped with claws. They had a row of spines down the back, which can be used defensively as well as to impale victims. Chupacabras were capable of powerful leaps which, when combined with the small, bat-like wings under their arms, means they could glide for short distances. They could mesmerize their victims by projecting a rainbow of colours, as well as cloud the minds of those around them and cause fear and nausea, and are extremely hard to kill. (Dark Emblem, Crimson Waters)