Nessie, more commonly known to the public as The Loch Ness Monster, is a friend of the Dinosaucers.
Nessie is an unevolved Elasmasaurus, who has survived in Loch Ness for 65 million years. It is unknown how this is comparable to the life span of the Dinosaucers and Tyrannos.
The Tyrannos gained knowledge of her through their Monster Monitor, and traveled to Loch Ness to recruit her to their cause. Genghis Rex commanded Plesio to charm her into becoming their ally. Because Nessie was lonely after so many years of being alone, she was easily taken in by him. Thus, she fell in love with Plesio deeply, even though their time together was short.
She speaks with a Scottish accent, obviously due to hearing the humans speak in the native area she resides. However, it is unknown if humans can actually understand her speech, or if only the Dinosaucers and Tyrannos can understand her.
Nessie together with Plesio
She can, however, communicate with the Sea Gulls in Loch Ness. The Dinosaucers tried to warn Nessie of Plesio's true intentions, but by that point she was too enthralled by him. It wasn't until the Loch's gulls befriended Teryx that she began to listen. Despite this, she even helped Plesio fossilize the Dinosaucers, both before and after the gulls warned her.
When The Tyrannos revealed themselves and their true nature, Nessie was completely heartbroken. However, Plesio's feelings for Nessie, despite his normal calculating nature, were indeed reciprocal. The Tyrannos by that point were holding her against her will, forcing her to join the Tyrannos or be fossilized. Plesio secretly freed the Dinosaucers, and also Nessie, making it look all accidental.
Despite this, Plesio and Nessie had to part ways, the former telling her that she'd regret going with him and becoming a Tyranno. Though brokenhearted, she understood his reasons. Teryx offered Nessie a chance to join the Dinosaucers, but she refused. However, she promised to remain in touch and become friends with the Dinosaucers.