Not true. Oreopithecus was a bipedal hominoid with a precision grip who was adapted to an aquatic setting for at least 2 million years on the isolated island of Tuscany-Sardinia in the Mediterranean. Harrison & Rook, Function, Phylogeny, and Fossils: Miocence Hominoid Evolution and Adaptations. 1997 “The remains of Oreopithecus bambolii are extremely abundant in VI, and this species represents one of the commonest mammals at the site…..Evidence for a primarily aquatic setting and a humid forested environment is provided by the extensive lignite accumulations, the common occurrence of skeletal remains in anatomical connection, the abundance of fossil crocodiles, chelonians, and freshwater mollusks, and the occurrence of otters…..The area was evidently poorly drained, and the forested areas were interspersed with numerous freshwater pools and shallow lakes. pg 335 “Interestingly, there is also a corresponding decline in the abundance of Oreopithecus in V2, which might simply imply a relatively narrow ecological preference by this taxon for swampy, forested habitats.” pg. 336 “Another possibility is that Oreopithecus was exploiting aquatic or wetland plants, such as water lilies, reeds, sedges, cattail, pond weeds, horsetails, and stoneworts, all of which are abundantly represented in the pollen spectrum from Baccinello.” pg. 341,
Let me rephrase myself, no known hominid has become specialized for aquatic feeding behaviour for an extensive period of evolutionary time that has relevance for the Aquatic Ape Hypothesis as it applies to modern humans. As far as we know, all of our ancestors over the past 6-8 million years lived in woodlands, savannas, and maybe rainforests.
You mean hominin. And Hurzeler and others have suggested that Oreopithecus was a hominin. Cranio-dentally, Oreopithecus is extremely similar to Sahelanthropus. And it had a foot that was similar to that of Ardipithecus. The last semiaquatic phase ended approximately 2.6 million years ago, IMO. They are the result of island isolation. I should also note that humans have kidneys like marine mammals. Humans are the only Catarrhine primate that has kidneys with medullary pyramids, a feature that is nearly universal in the kidneys of marine mammals. Marcel F. Williams