Banksia strahanensis
Encyclopedia
Banksia strahanensis is an extinct
species of tree or shrub in the plant
genus
Banksia
. It is known only from a fossil
leaf and several fossil leaf fragments found in Early
to Middle
Pleistocene
sediment
at Regatta Point
in western Tasmania
. These are long and very narrow, with entire margins, superficially resembling leaves of the extant B. spinulosa
(Hairpin Banksia).
The fossils clearly belong to genus Banksia, section Oncostylis
, series Spicigerae
, the only difficulty being that all Oncostylis taxa have a visible network of veins on the upper leaf surface, whereas the fossil leaves appear not to. They are most similar to the leaves of B. spinulosa, differing only in the absence of surface venation; a longer petiole
; and the combination of narrow leaves with hairless undersides (all forms of B. spinulosa with leaves as narrow as those of B. strahanensis have hairy undersides). Because of these differences, the fossils are considered a separate species. The species is believed to represent an extinct lineage; it is unlikely to be an ancestor of any extant Banksia species, as the absence of leaf surface venation is thought to be an adaptation rather than a primitive state. Extinction was probably caused by the climatic and physical disruption of the Early Pleistocene Glaciations.
The fossils of B. strahanensis were discovered in sediment at Regatta Point during the early 1980s. A formal description was published in 1991 by Gregory J. Jordan and Robert S. Hill, who named the species after the nearby town of Strahan
. Hence the species' full name is "Banksia strahanensis Jordan & Hill". The holotype
and a number of other specimens are stored in the Department of Plant Science at the University of Tasmania
.
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 of tree or shrub in the plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Banksia
Banksia
Banksia is a genus of around 170 species in the plant family Proteaceae. These Australian wildflowers and popular garden plants are easily recognised by their characteristic flower spikes and fruiting "cones" and heads. When it comes to size, banksias range from prostrate woody shrubs to trees up...
. It is known only from a fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
leaf and several fossil leaf fragments found in Early
Early Pleistocene
Calabrian is a subdivision of the Pleistocene Epoch of the Geologic time scale. ~1.8 Ma.—781,000 years ago ± 5,000 years, a period of ~.The end of the stage is defined by the last magnetic pole reversal and plunge in to an ice age and global drying possibly colder and drier than the late Miocene ...
to Middle
Middle Pleistocene
The Middle Pleistocene, more specifically referred to as the Ionian stage, is a period of geologic time from ca. 781 to 126 thousand years ago....
Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
at Regatta Point
Regatta Point, Tasmania
Regatta Point is the location of a port and rail terminus in West Coast Tasmania, Australia- Port :Regatta Point is often assumed into the name of the locality across the bay in Macquarie Harbour, Strahan, Tasmania...
in western Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
. These are long and very narrow, with entire margins, superficially resembling leaves of the extant B. spinulosa
Banksia spinulosa
The Hairpin Banksia is a species of woody shrub, of the genus Banksia in the Proteaceae family, native to eastern Australia. Widely distributed, it is found as an understorey plant in open dry forest or heathland from Victoria to northern Queensland, generally on sandstone though sometimes also...
(Hairpin Banksia).
The fossils clearly belong to genus Banksia, section Oncostylis
Banksia sect. Oncostylis
Banksia sect. Oncostylis is one of four sections of subgenus Banksia subg. Banksia. It contains those Banksia species with hooked pistils. All of the species in Oncostylis also exhibit a top-down sequence of flower anthesis, except for Banksia nutans which is bottom-up.Banksia sect...
, series Spicigerae
Banksia ser. Spicigerae
Banksia ser. Spicigerae is a taxonomic series in the genus Banksia. It consists of the seven species in section Oncostylis that have cylindrical inflorescences. These range in form from small shrubs to tall trees. The leaves grow in either an alternate or whorled pattern, with various shape forms...
, the only difficulty being that all Oncostylis taxa have a visible network of veins on the upper leaf surface, whereas the fossil leaves appear not to. They are most similar to the leaves of B. spinulosa, differing only in the absence of surface venation; a longer petiole
Petiole (botany)
In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...
; and the combination of narrow leaves with hairless undersides (all forms of B. spinulosa with leaves as narrow as those of B. strahanensis have hairy undersides). Because of these differences, the fossils are considered a separate species. The species is believed to represent an extinct lineage; it is unlikely to be an ancestor of any extant Banksia species, as the absence of leaf surface venation is thought to be an adaptation rather than a primitive state. Extinction was probably caused by the climatic and physical disruption of the Early Pleistocene Glaciations.
The fossils of B. strahanensis were discovered in sediment at Regatta Point during the early 1980s. A formal description was published in 1991 by Gregory J. Jordan and Robert S. Hill, who named the species after the nearby town of Strahan
Strahan, Tasmania
-See also:* Convicts on the West Coast of Tasmania* Macquarie Harbour* Railways on the West Coast of Tasmania* West Coast Piners-Further reading:* *...
. Hence the species' full name is "Banksia strahanensis Jordan & Hill". The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
and a number of other specimens are stored in the Department of Plant Science at the University of Tasmania
University of Tasmania
The University of Tasmania is a medium-sized public Australian university based in Tasmania, Australia. Officially founded on 1 January 1890, it was the fourth university to be established in nineteenth-century Australia...
.