{{Short description|Extinct species of aquatic plant}} {{speciesbox | fossil_range = {{fossilrange|50|49}} | image =Azolla primaeva 6-7-19 img1 cropped.jpg | image_caption = leaves and stems, Klondike Mountain formation | genus = Azolla | species = primaeva | authority = (Penhallow) Arnold, 1955<ref name="Arnold1955">{{cite journal |last1=Arnold |first1=C. A. |year=1955 |title=A Tertiary ''Azolla'' from British Columbia |journal= Contributions from the Museum of Paleontology, University of Michigan |volume=12 |issue=4 |pages=37–45 |url= http://deepblue.lib.umich.edu/bitstream/2027.42/48289/2/ID129.pdf}}</ref> | synonyms = ''Azollophyllum primaevum'' | extinct=yes }}
'''''Azolla primaeva''''' is an extinct species of "water fern" in the family Salviniaceae known from Eocene fossils from the Ypresian stage ({{Period span/brief|Ypresian}}), found in southern British Columbia.<ref name="Arnold1955"/>
The species was first described from poorly preserved material collected in the Similkameen River area near Princeton, British Columbia 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''.<ref name="Arnold1955"/> Though the volume only lists John William Dawson as author, Dawson notes that the ''A primaevum'' description had been written by Penhallow.<ref name="Arnold1955"/> Due to the poor nature of the type specimen the species was placed in the form genus ''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.<ref name="Arnold1955"/>
Placement of the species was formally changed with the publication of a paper written by Chester A. Arnold<ref name="Arnold1955"/> based on new fossil specimens collected near the former mining camp of Ashnola, British Columbia, approximately 8 miles south of Princeton along the Similkimeen River. The fossils were recovered from strata of the Allenby Formation, at the time considered Oligocene age,<ref name="Arnold1955"/> but now known to be of the Early Middle Eocene.<ref name="Little2009">{{cite journal |last1=Little |first1=S. A. |author2=Stockey, R. |author3=Penner, B. |year=2009 |title=Anatomy and development of fruits of Lauraceae from the Middle Eocene Princeton Chert |journal= American Journal of Botany |volume=96 |pages=637–651 |doi=10.3732/ajb.0800318 |issue=3 |pmid=21628220|s2cid=38272445 }}</ref>
The specimens were studied by Arnold of the University of Michigan 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.<ref name="Arnold1955"/> [[File:Azolla primaeva aquatic mat SRIC SR 21-009-023 img1.jpg|thumb|left|upright|Fossil mat of ''A. primaeva''<br/> Stonerose Interpretive Center]] 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 and H. S. Rao. Also in 1934, Roland W. Brown described a similarly aged species, ''A. berryi'', from the Middle Eocene Green River Formation. An Oligocene species, ''A. prisca'', was published from the London Clays of England eight years earlier in 1926 by Marjorie E.J. Chandler and Eleanor M. Reid. The youngest of the fossil species was ''A. tertiaria'' described by Edward W. Berry in 1927 from Pliocene fossils found in the Esmeralda Formation of Nevada.<ref name="Arnold1955"/> 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.<ref name="Arnold1955"/>
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.<ref name="Arnold1955"/> Fossil specimens of ''Azolla'' have been recovered from the closely related strata of the Klondike Mountain Formation around Republic, Washington, but have not been described to species.<ref name="Greenwood2005">{{cite journal |last1=Greenwood |first1=D. R. |year=2005 |title=Fossil biotas from the Okanagan Highlands, southern British Columbia and northeastern Washington State: climates and ecosystems across an Eocene landscape |journal=Canadian Journal of Earth Sciences |volume=42 |issue=2 |pages=167–185 |doi=10.1139/e04-100|bibcode=2005CaJES..42..167G |display-authors=etal}}</ref>
== References == {{Reflist|30em}} {{Wikispecies}}
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Category:Salviniales Category:Paleogene plants Category:Plants described in 1890 Category:Fossil taxa described in 1890 Category:Eocene plants Category:Freshwater plants Category:Extinct flora of North America † Category:Allenby Formation