The fossil remains of three turtles and one penguin which was previously believed to be a turtle are described and compared to the New Zealand and global palaeobiota. The fossil remains are stored at the Canterbury Museum. The turtles are Cretaceous, Palaeocene, and Eocene aged while the Penguin is from the Miocene. X-ray computed tomography (CT scanning), comparative research using published descriptions, and measurements of skeletons were used to generate descriptions and determine systematics of each specimen. Raw CT data was refined using the Materialise Software Suite to create 3D models of each specimen component. The Cretaceous specimen, discovered within the body cavity of Mosasaurus mokoroa is the first Cretaceous New Zealand specimen assigned to the Panchelonidae and exhibits trace evidence of Mosasaur predation in the form of acid etching and teeth marks, the first from the Southern Hemisphere. The Palaeocene specimen is assigned to the macrobaenid family, previously only known from the high latitude regions of Asia, Canada, and North America. Comparison with marine turtle species found that the most comparable marine turtle was Osteopygis the postcrania of which belong to the Macrobaenidae. Comparison with macrobaenids show marked similarities in plastron morphology. While macrobaenids are exclusively freshwater species the specimen in this study is considered to have been washed out into the marine environment. The Eocene specimen is assigned to the species Eochelone monstigris previously known from the Northland region of New Zealand. Assignment of this species is primarily based upon similarities in size, humeral morphology, and geographic proximity. The Miocene penguin is assigned to the species Pygoscelis tyreei previously known from Motunau Beach New Zealand, confirming the presence of this species in the Middle Miocene. Assignment of this species has been made on the basis of comparative measurements of the holotype specimen stored at the Canterbury Museum.