Rats were medium-sized, long-tailed rodents, a number of which lived in sewers and underground tunnels in the present.
A rat was scavenging in the London Underground tunnel by Arsenal Station, when it was attacked from behind and devoured by a Carboniferous Arachnid.
Five years before 2011 (circa 2006), when a baby Kaprosuchus was flushed down into the sewer, it came across a rat so it attacked and ate the rodent.
Helen Cutter speculated that in the future, species descended from rats were among the dominant predators.
When a Silurian Millipede ran past Connor Temple, he initially thought it was a rat, and exclaimed that rats really freaked him out.