The Scottish Lakes

Migration or survival for thousands of years? 

Given there is sufficient archaeological evidence to say both creatures went extinct millions of years ago, and the unlikeliness of either animal surviving undetected until a couple thousand years ago, it seems as though Nessie is not a lone dinosaur. This is science's take on it, requiring biological evidence of either dinosaur to prove otherwise, and to their credit, Loch Ness itself was formed around 10,000 years ago by a receding glacier. If Nessie is a Plesiosuchus, Plesiosaur, or related dinosaur from millions of years ago, then likely she had to move into the Loch after its creation. Life without doubt is full of strange enough phenomena.

Maybe Niseag could be one of those rare animals who survived in the deep ocean despite science claiming the improbable. The world's ocean system is vast and plenty large enough to sustain a breeding population of dinosaurs who managed to survive a catastrophic extinction event 65 million years ago. In fact, many ocean dwelling creatures may have been protected during the initial fallout long enough for food chain cycles to replenish, and it wouldn't be out of the ordinary for life to flourish through catastrophe once again.

There is perhaps yet another angle to help explain Nessie. By constructing certain elements of local folklore we discover characteristics of a beast which might be responsible for stimulating Nessie sightings. Starting with the name, Ness - Loosely translates to a cape, promontory, headland, fore-land, Naze (Eastern England Headland), or head. Niseag, as referred to by Saint Columba, is a Scottish Gaelic female name for Little Ness. Possibly a significant clue here - Little head. 

Many eyewitness accounts and photographs describe a creature with a smaller head at the end of what could be described as a long neck. Hence a suggested identification of a plesiosaur even though we know these dinosaurs had to overcome tremendous odds to be placed in Loch Ness by the 20th century. Known species in Scottish lakes don't fit Ness descriptions very well, but what if perhaps a known species from another location moved into Scottish territory, using the lochs as safe haven due to increased human population in the previous area?