Azolla primaeva
Encyclopedia
Azolla primaeva is an extinct
species
of "water fern" in the Azollaceae family known from Eocene
fossil
s from the Ypresian
stage , found in southern British Columbia
.
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. Though the volume only lists John William Dawson
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
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.
The species placement 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 approximately 8 miles south of Princeton along the Similkimeen River. The fossils were produced from strata of the Allenby Formation, at the time considered Oligocene
age, but now known to be of the Early Middle Eocene
.
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
.
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 Rao. Also in 1934, Roland W. Brown described a similarly aged species, A. berry, from the Middle Eocene
Green River Formation
. An Oligocene
species, A. prisca, was published from the London Clay
s of England eight years earlier in 1926 by Chandler and 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. 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
around Republic, Washington
, but have not been described to species.
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of "water fern" in the Azollaceae family known from Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s from the Ypresian
Ypresian
In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene. It spans the time between and , is preceded by the Thanetian age and is followed by the Eocene Lutetian age....
stage , found in southern British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
.
The species was first described from poorly preserved material collected in the Similkameen River
Similkameen River
The Similkameen River runs through southern British Columbia, eventually discharging into the Okanogan River near Oroville, Washington in the United States. The river is approximately long, and its drainage basin is in area...
area near Princeton, British Columbia
Princeton, British Columbia
Princeton is a small town in the Similkameen region of southern British Columbia, Canada. It lies just east of the Cascade Mountains, which continue south into Washington, Oregon and California. The Tulameen and Similkameen Rivers converge here...
and later noted from outcrops at Stump Lake
Stump Lake
Stump Lake is a lake in the Nicola Country region of the South-Central Interior of British Columbia, Canada, located northeast from and of a similar size to Nicola Lake...
northeast of Princeton. The fossils were described by David P. Penhallow
David P. Penhallow
David Pearce Penhallow was a Canadian-American botanist, paleobotanist and educator.Born in Kittery Point, Maine, Penhallow graduated from Massachusetts Agricultural College in 1873 . When his former professor, William S...
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
John William Dawson
Sir John William Dawson, CMG, FRS, FRSC , was a Canadian geologist and university administrator.- Life and work :...
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 taxon
Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships...
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.
The species placement was formally changed with the publication of a paper written by Chester A. Arnold
Chester A. Arnold
Chester Arthur Arnold was an American paleobotanist, born June 25, 1901 in Leeton, Missouri and died on 19 November 1977.He was the son of farmers Elmer and Edith Arnold. Arnolds family moved to Ludlowville, New York and he attended Cornell University with the intent to study agriculture...
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 produced from strata of the Allenby Formation, at the time considered Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
age, but now known to be of the Early Middle Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
.
The specimens were studied by Arnold of the University of Michigan
University of Michigan
The University of Michigan is a public research university located in Ann Arbor, Michigan in the United States. It is the state's oldest university and the flagship campus 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
Sporangium
A sporangium is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. All plants, fungi, and many other lineages form sporangia at some point in their life cycle...
.
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
Birbal Sahni FRS was an Indian paleobotanist who studied the fossils of the Indian subcontinent, was also a geologist who took an interest in archaeology...
and Rao. Also in 1934, Roland W. Brown described a similarly aged species, A. berry, from the Middle Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
Green River Formation
Green River Formation
The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of intermountain lakes. The sediments are deposited in very fine layers, a dark layer during the growing season and a light-hue inorganic layer in winter. Each pair of layers is called a varve and...
. An Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
species, A. prisca, was published from the London Clay
London Clay
The London Clay Formation is a marine geological formation of Ypresian age which crops out in the southeast of England. The London Clay is well known for the fossils it contains. The fossils from the Lower Eocene indicate a moderately warm climate, the flora being tropical or subtropical...
s of England eight years earlier in 1926 by Chandler and Reid. The youngest of the fossil species was A. tertiaria described by Edward W. Berry
Edward W. Berry
Edward Wilber Berry was an American paleontologist and botanist, the principal focus of his research was paleobotany. Berry studied North and South American flora and published taxonomic studies with theoretical reconstructions of paleoecology and phytogeography. He started his scientific...
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
Azolla filiculoides
Azolla filiculoides is a species of Azolla, native to warm temperate and tropical regions of the Americas as well as most of the old world including Asia and Australia....
and the Eocene A. intertrappea of India. Fossil specimens of Azolla have been recovered from the closely related strata of the Klondike Mountain Formation
Klondike Mountain Formation
The Klondike Mountain Formation is an early Eocene geologic formation that records the sedimentation in the southern most of a string of highland subtropical/Temperate lakes in Washington state and British Columbia. The formation is best known for exceptionally well preserved plant and insect fossils...
around Republic, Washington
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.-History:...
, but have not been described to species.