- "Actually, they're more like prehistoric dogs this time, kind of cute dunno, not in a Raptor way, I'm just gonna shut up."
- ―Connor Temple[src]
|Home time period||Late Eocene - Early Miocene epoch|
|Deaths caused||Wedding planner|
Hyaenodons are fast and vicious dog-like creatures with jaws full of teeth, massive heads and large brains. Despite the name there is no close relation between Hyaenodons and Hyaenas, or even Dogs, although they share a common ancestor with these carnivores. Hyaenodons roamed around Europe, Asia, Africa and North America from the Late Eocene to the Early Miocene, during which they became apex predators.
Hyaeodons were among the largest terrestrial carnivorous mammals of their time, ranging from the size of a squirrel to a small rhinoceros (0.6 - 3 metres). The adult Hyaenodons that were encountered at the Miller wedding incursion were approximately two metres long, while the pups were approximately the size of a large puppy.
Typical of early carnivorous mammals, Hyaenodon has a massive skull, but only a small brain; it has a long skull with a narrow snout, its neck is shorter than its skull, while its body is long and robust and terminated in a long tail. Hyaenodons also have a powerful set of teeth, with a bite forçe of 1300 pounds of force, and a design in the jaws that allows the teeth to sharpen themselves throughout their entire life.
Parent Hyaenodons are known to be fiercely protective of their young, following and watching their pups wherever they go, and attacking and killing any others that come near the pups or vice versa. Usually, when a Hyaenodon family's pups are at their nest, the mother will stay with the young, while the father guards the surrounding area.
A male and female Hyaenodon and their three pups came through an Anomaly to the basement of a Stately Home in the Present, and made a nest in the basement under a wine stack. When a wedding planner found the Hyaenodon pups under the wine stack, the mother attacked and killed her. Later, when the ARC team arrived and searched the cellar, the male adult Hyaenodon stalked and then attacked the team, but was abruptly knocked out by Connor Temple with an EMD.
The ARC subsequently send the father Hyaenodon back through the Anomaly, while the mother and the pups remained hidden and unnoticed in their nest under the wine stack. At dusk, the Hyaenodon pups and the mother emerged from the nest, and one of the pups ventured out into the house grounds, while the mother and the other two pups remained in the basement. When the Hyaenodon mother came across Connor in the basement, it attacked and pursued him, forcing Connor to lock himself and two of the pups in a room from the mother Hyaenodon for the night. Connor then fed the pups wine to distract them, before trapping them in a wooden box.
The next day, the Hyaenodon pup in the grounds arrived outside the basement window, and Connor managed to draw its attention and fire a cork at its leg; causing it to yelp out in distress, and luring the mother Hyaenodon from the basement. Connor subsequently unlocked the Anomaly and sent the two captured Hyaenodon pups back through, and then attempted to capture the third one and send it back through as well, but it fled. The father Hyaenodon then came back through the unlocked Anomaly, and it and the mother followed their pup still in the Present up into the house. The two adult Hyaenodons then launched an attack on the wedding guests at the house, causing havoc.
One of the adult Hyaenodons attacked Abby Maitland and Emily Merchant, and pursued them throuh the grounds of the house. Abby and Emily were able to briefly injure the creature with medieval weapons from the house, and afterwards lured it into a van and locked it inside. The other adult and the pup in the house attacked Michael Miller and another wedding guest on the house stairs, but the adult Hyaenodon was knocked out and incapacitated when Jenny Lewis hit it and send it falling over the stair banister to the bottom floor with a large house appliance. The ARC team subsequently sent the three Hyaenodonsback through the Anomaly.
- Some fans have suggested that the Hyaenodon pups in Episode 4.6 were in fact born in the Present after the mother Hyaenodon came through the Anomaly while pregnant with them. However, the fact that the pups could already walk and open their eyes were open would suggest otherwise.
- A few fans have speculated that Hyaenodon may have influenced the legend of the Beast of Gevaudan, a giant, wolf-like creature.
- Despite its name, Hyaenodon is not related to the hyena.
- The ARC team constantly referred the the creatures as 'giant dogs' even after identifying them as Hyaenodon, though the two species weren't even related.
- In Primeval, Hyaenodon was depicted as being able to turn its wrists, something creodonts (the order Hyaenodons belong to) have never been able to do.