''Protoplotus'' (meaning "original '' Plotus''") is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

waterbird A water bird, alternatively waterbird or aquatic bird, is a bird that lives on or around water. In some definitions, the term ''water bird'' is especially applied to birds in freshwater ecosystems, although others make no distinction from seabi ...

that inhabited Indonesia during the early-mid

Cenozoic The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three g ...

, most likely during the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

. It contains a single species, ''P. beauforti'' (named after

Lieven Ferdinand de Beaufort Lieven Ferdinand de Beaufort (March 23, 1879 in Den Treek, Leusden – 11 May 1968 in Amersfoort) was a Dutch biologist who, in 1903, participated in the North New Guinea Expedition. In the 1920s he was director of the Zoological Museum of ...

) known from a largely complete, well-preserved skeleton from the Sangkarewang Formation of Indonesia. It is the only member of the family Protoplotidae and, depending on age, one of the earliest known

Suliformes The order Suliformes (, dubbed "Phalacrocoraciformes" by ''Christidis & Boles 2008'') is an order of birds recognised by the International Ornithological Congress, International Ornithologist's Union. Regarding the recent evidence that the tradit ...

. ''Protoplotus'' was a rather small waterbird that inhabited the freshwater rift lake where the Sangkarewang Formation would be deposited. It closely resembled and likely had a similar lifestyle to modern

cormorant Phalacrocoracidae is a family of approximately 40 species of aquatic birds commonly known as cormorants and shags. Several different classifications of the family have been proposed, but in 2021 the International Ornithologists' Union (IOU) ado ...

s and

darter The darters, anhingas, or snakebirds are mainly tropical waterbirds in the family Anhingidae, which contains a single genus, ''Anhinga''. There are four living species, three of which are very common and widespread while the fourth is rarer and c ...

s, and for a while was considered to belong to the Anhingidae. However, more recent studies have found it to be distinct from both, and it is now placed in its own family, which is though to be related to both cormorants and anhingas. Uniquely, the single fossil skeleton of ''Protoplotus'' preserves

gastrolith A gastrolith, also called a stomach stone or gizzard stone, is a rock held inside a gastrointestinal tract. Gastroliths in some species are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. In ...

s. This suggests that it may have seasonally switched its diet from fish to fruit.

References

{{Taxonbar, from1=Q84236669, from2=Q84236712, from3=Q33136220 † Eocene birds Fossils of Indonesia Fossil taxa described in 1931 Prehistoric bird genera Extinct animals of Indonesia