''Azolla primaeva'' is an extinct

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

of "

water fern Water fern is a common name for several plants and may refer to: * Salviniales, an order of aquatic ferns * ''Austroblechnum lanceolatum'', syn. ''Blechnum chambersii'', lance water fern * ''Austroblechnum patersonii'', syn. ''Blechnum patersonii'' ...

" in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Salviniaceae Salviniaceae (), is a family of heterosporous ferns in the order Salviniales. The Salviniaceae contain the two genera '' Azolla'' and '' Salvinia'', with about 20 known species in total. The oldest records of the family date to the Late Cretaceo ...

known from

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

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s from the

Ypresian In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by the Eocene Lutetian Age. The Ypresian i ...

stage (), found in southern

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost Provinces and territories of Canada, province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include ...

. The species was first described from poorly preserved material collected in the

Similkameen River The Similkameen River runs through southern British Columbia, Canada, eventually discharging into the Okanagan River near Oroville, Washington, in the United States. Through the Okanagan River, it drains to the Columbia River. The river is said ...

area near

Princeton, British Columbia Princeton (originally Vermilion Forks) is a town in the Similkameen region of southern British Columbia, Canada."The rich history of Princeton or how Vermilion Forks made it on the map...", Princeton 2008 Visitors Guide, p. 4. It lies just east o ...

and later noted from outcrops at Stump Lake northeast of Princeton. The fossils were described by David P. Penhallow in the 1890 volume ''On Fossil Plants from the Smilkameen Valley and Other Places in the Southern Interior of British Columbia''. Though the volume only lists

John William Dawson Sir John William Dawson (1820–1899) was a Canadian geologist and university administrator. Life and work John William Dawson was born on 13 October 1820 in Pictou, Nova Scotia, where he attended and graduated from Pictou Academy. Of Scot ...

as author, Dawson notes that the ''A primaevum'' description had been written by Penhallow. Due to the poor nature of the type specimen the species was placed in the

form genus Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships. Form classification, generally restricted to palaeontology, reflects uncertainty; the goal of s ...

'' Azollophyllum'' as ''Azollophyllum primaevum'' indicating its similarity to the modern genus, but at the same time acknowledging lack of detail needed to confirm its placement in the genus. Placement of the species was formally changed with the publication of a paper written by Chester A. Arnold based on new fossil specimens collected near the former mining camp of

Ashnola, British Columbia Ashnola is a locality and former railway point in the Similkameen Country of southern British Columbia, Canada, located at the confluence of the Ashnola River with the Similkameen. Ashnola Indian Reserve No. 10 is at the same general location, and ...

, approximately 8 miles south of Princeton along the Similkimeen River. The fossils were recovered from strata of the

Allenby Formation The Allenby formation is a sedimentary rock formation in British Columbia which was deposited during the Ypresian stage of the Early Eocene. It consists of conglomerates, sandstones with interbedded shales and coal. The shales contain an abund ...

, at the time considered

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but ...

age, but now known to be of the Early Middle Eocene. The specimens were studied by Arnold of the

University of Michigan , mottoeng = "Arts, Knowledge, Truth" , former_names = Catholepistemiad, or University of Michigania (1817–1821) , budget = $10.3 billion (2021) , endowment = $17 billion (2021)As o ...

who published the 1955 type redescription for ''A. primaeva'' in the ''Contributions from the Museum of. Paleontology, University of Michigan'', Volume 12. Arnold noted the new specimens to consist of leafy vegetation and roots often forming mats in the rock. The plants are accompanied by microspore massulae and

megasporangia A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cyc ...

Azolla primaeva aquatic mat SRIC SR 21-009-023 img1

At the time this paper was published, four species of ''Azolla'' had been described from the fossil record. The oldest species at that time was '' A. intertrappea'' from Eocene age strata in India and described in 1934 by

Birbal Sahni Birbal Sahni FRS (14 November 1891 – 10 April 1949) was an Indian paleobotanist who studied the fossils of the Indian subcontinent. He also took an interest in geology and archaeology. He founded what is now the Birbal Sahni Institute of Pal ...

and H. S. Rao. Also in 1934,

Roland W. Brown Roland Wilbur Brown (1893–1961) was an American paleobotanist and geologist. Biography Brown was born in 1893. In 1928, he was appointed as a geologist with the United States Geological Survey, where he remained until he retired in 1958. He als ...

described a similarly aged species, '' A. berryi'', from the

Middle Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "d ...

Green River Formation The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of intermountain lakes in three basins along the present-day Green River in Colorado, Wyoming, and Utah. The sediments are deposited in very fine ...

. An

species, '' A. prisca'', was published from the

London Clay The London Clay Formation is a marine geological formation of Ypresian (early Eocene Epoch, c. 56–49 million years ago) age which crops out in the southeast of England. The London Clay is well known for its fossil content. The fossils from t ...

s of England eight years earlier in 1926 by

Marjorie E.J. Chandler Marjorie is a female given name derived from Margaret, which means pearl. It can also be spelled as Margery or Marjory. Marjorie is a medieval variant of Margery, influenced by the name of the herb marjoram. It came into English from the Old F ...

and

Eleanor M. Reid Eleanor () is a feminine given name, originally from an Old French adaptation of the Old Provençal name ''Aliénor''. It is the name of a number of women of royalty and nobility in western Europe during the High Middle Ages. The name was introd ...

. The youngest of the fossil species was '' A. tertiaria'' described by

Edward W. Berry Edward Wilber Berry (February 10, 1875 – September 20, 1945) was an American paleontologist and botanist; the principal focus of his research was paleobotany. Early life Berry was born February 10, 1875, in Newark, New Jersey, and finished hi ...

in 1927 from Pliocene fossils found in the Esmeralda Formation of Nevada. Arnold notes that with the placement of ''A. primaeva'' into the genus ''Azolla'' means that its description in 1890 was actually the earliest species described from the fossil record. After comparing the new fossil specimens to both modern and fossil species as much as he was able with the descriptions available, Arnold noted ''A. primaeva'' to be close in morphology to the living '' A.filiculoides'' and the Eocene ''A. intertrappea'' of India. Fossil specimens of ''Azolla'' have been recovered from the closely related strata of the

Klondike Mountain Formation The Klondike Mountain Formation is an Early Eocene (Ypresian) geological formation located in the northeast central area of Washington state. The formation, named for the type location designated in 1962, Klondike Mountain north of Republic, Wash ...

around

Republic, Washington Republic is a city in Ferry County, Washington, United States. The population was 1,073 at the 2010 census, a 12.5% increase over the 2000 census. It is the county seat of Ferry County. It was the largest mining camp in the Republic Mining Di ...

, but have not been described to species.

References

{{Taxonbar, from=Q4832823 Salviniales Paleogene plants Plants described in 1890 Fossil taxa described in 1890 Eocene plants Freshwater plants Extinct flora of North America

† A dagger, obelisk, or obelus is a typographical mark that usually indicates a footnote if an asterisk has already been used. The symbol is also used to indicate death (of people) or extinction (of species). It is one of the modern descendan ...

Allenby Formation