Plesiosaurus

From TARDIS Index File, the free Doctor Who reference.

The Plesiosaurus was a large marine reptile that lived during the early part of the Jurassic period.

It was distinguished by its small head, long and slender neck, broad turtle like body, a short tail, and two pairs of large, elongated paddles. The plesiosaurus shown in Vorg's miniscope was brownish green and was mildly aggressive. It was intelligent enough to be controlled by the miniscope. (DW: Carnival of Monsters)

It's unknown how the plesiosaurus was caught in Vorg's miniscope. It's possible the Lurmans or the original owners of the miniscope had time travelling capabilities or the Plesiosaurus was simply from a relic population.

Aliens and Enemies of Season 10

The Three Doctors: Omega  • Gell guards  • Anti-matter Organism  • Time Lords Carnival of Monsters: Lurmans  • Drashigs  • Kalik  • Plesiosaurus  • Orum  • Inter Minorians Frontier in Space: Draconians  • The Master  • Ogrons  • Daleks  • Ogron eater  • Cross Planet of the Daleks: Daleks  • Dalek Supreme  • Thals  • Spiridonians  • Sponge-plants  • Eye-plants The Green Death: BOSS  • Giant Maggots  • Giant Flies  • Stevens  • Ralph Fell  • Elgin  • Hinks  • James