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The Ordovician is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period 485.4 million years ago (Ma) to the start of the Silurian Period 443.8 Mya.
The PaleozoicEra is the first of three geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic and ends 251.9 Ma at the start of the Mesozoic Era. The Paleozoic is subdivided into six geologic periods :
The Silurian is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago (Mya), to the beginning of the Devonian Period, 419.2 Mya. The Silurian is the shortest period of the Paleozoic Era. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out.
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, fungi and protozoa.
The embryophytes are a clade of plants, also known as Embryophyta or land plants. They are the most familiar group of photoautotrophs that make up the vegetation on Earth's dry lands and wetlands. Embryophytes have a common ancestor with green algae, having emerged within the Phragmoplastophyta clade of freshwater charophyte green algae as a sister taxon of Charophyceae, Coleochaetophyceae and Zygnematophyceae. Embryophytes consist of the bryophytes and the polysporangiophytes. Living embryophytes include hornworts, liverworts, mosses, lycophytes, ferns, gymnosperms and angiosperms. Embryophytes have diplobiontic life cycles.
The Marchantiophyta are a division of non-vascular land plants commonly referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information.
Paleobotany, also spelled as palaeobotany, is the branch of botany dealing with the recovery and identification of plant remains from geological contexts, and their use for the biological reconstruction of past environments (paleogeography), and the evolutionary history of plants, with a bearing upon the evolution of life in general. A synonym is paleophytology. It is a component of paleontology and paleobiology. The prefix palaeo- or paleo- means "ancient, old", and is derived from the Greek adjective παλαιός, palaios. Paleobotany includes the study of terrestrial plant fossils, as well as the study of prehistoric marine photoautotrophs, such as photosynthetic algae, seaweeds or kelp. A closely related field is palynology, which is the study of fossilized and extant spores and pollen.
Cooksonia is an extinct group of primitive land plants, treated as a genus, although probably not monophyletic. The earliest Cooksonia date from the middle of the Silurian ; the group continued to be an important component of the flora until the end of the Early Devonian, a total time span of 433 to 393 million years ago. While Cooksonia fossils are distributed globally, most type specimens come from Britain, where they were first discovered in 1937. Cooksonia includes the oldest known plant to have a stem with vascular tissue and is thus a transitional form between the primitive non-vascular bryophytes and the vascular plants.
The Andean-Saharan glaciation, also known as the Early Paleozoic Ice Age (EPIA), the Early Paleozoic Icehouse, the Late Ordovician glaciation, the end-Ordovician glaciation, or the Hirnantian glaciation, occurred during the Paleozoic from approximately 460 Ma to around 420 Ma, during the Late Ordovician and the Silurian period. The major glaciation during this period was formerly thought only to consist of the Hirnantian glaciation itself but has now been recognized as a longer, more gradual event, which began as early as the Darriwilian, and possibly even the Floian. Evidence of this glaciation can be seen in places such as Arabia, North Africa, South Africa, Brazil, Peru, Bolivia, Chile, Argentina, and Wyoming. More evidence derived from isotopic data is that during the Late Ordovician, tropical ocean temperatures were about 5 °C cooler than present day; this would have been a major factor that aided in the glaciation process.
The evolution of plants has resulted in a wide range of complexity, from the earliest algal mats of unicellular archaeplastids evolved through endosymbiosis, through multicellular marine and freshwater green algae, to spore-bearing terrestrial bryophytes, lycopods and ferns, and eventually to the complex seed-bearing gymnosperms and angiosperms of today. While many of the earliest groups continue to thrive, as exemplified by red and green algae in marine environments, more recently derived groups have displaced previously ecologically dominant ones; for example, the ascendance of flowering plants over gymnosperms in terrestrial environments.
Tortilicaulis is a moss-like plant known from fossils recovered from southern Britain, spanning the Silurian-Devonian boundary. Originally recovered from the Downtonian of the Welsh borderlands, Tortilicaulis has since been recovered in the famous Ludlow Lane locality.
Psilophyton is a genus of extinct vascular plants. Described in 1859, it was one of the first fossil plants to be found which was of Devonian age. Specimens have been found in northern Maine, USA; Gaspé Bay, Quebec and New Brunswick, Canada; the Czech Republic; and Yunnan, China. Plants lacked leaves or true roots; spore-forming organs or sporangia were borne on the ends of branched clusters. It is significantly more complex than some other plants of comparable age and is thought to be part of the group from within which the modern ferns and seed plants evolved.
Ornatifilum is an artificial form genus, which is used to categorise any small, branched filaments with external ornamentation.
Polysporangiophytes, also called polysporangiates or formally Polysporangiophyta, are plants in which the spore-bearing generation (sporophyte) has branching stems (axes) that bear sporangia. The name literally means 'many sporangia plant'. The clade includes all land plants (embryophytes) except for the bryophytes whose sporophytes are normally unbranched, even if a few exceptional cases occur. While the definition is independent of the presence of vascular tissue, all living polysporangiophytes also have vascular tissue, i.e., are vascular plants or tracheophytes. Extinct polysporangiophytes are known that have no vascular tissue and so are not tracheophytes.
This article attempts to place key plant innovations in a geological context. It concerns itself only with novel adaptations and events that had a major ecological significance, not those that are of solely anthropological interest. The timeline displays a graphical representation of the adaptations; the text attempts to explain the nature and robustness of the evidence.
This article records new taxa of fossil plants that are scheduled to be described during the year 2015, as well as other significant discoveries and events related to paleobotany that are scheduled to occur in the year 2015.
Philippe Steemans is a Belgian geologist researcher, best known for his work on palynology. As a Senior Researcher of the National Fund for Scientific Research (NFSR) at the University of Liège, Belgium, in the Department of Geology, Steemans studies fossilised spores from Palaeozoic, mainly from their first occurrence in the Ordovician up to the Devonian.
Retispora lepidophyta is a spore type and an important biostratigraphic marker of the latest Devonian period. The last appearance of Retispora lepidophyta defines the Devonian-Mississippian boundary in Belgium and other places.
The Silurian-Devonian Terrestrial Revolution, also known as the Devonian Plant Explosion (DePE) and the Devonian explosion, was a period of rapid colonization, diversification and radiation of land plants and fungi on dry lands that occurred 428 to 359 million years ago (Mya) during the Silurian and Devonian periods, with the most critical phase occurring during the Late Silurian and Early Devonian.
This paleobotany list records new fossil plant taxa that were to be described during the year 2023, as well as notes other significant paleobotany discoveries and events which occurred during 2023.
References
- ↑ Steemans, P (2000). "Miospore evolution from the Ordovician to the Silurian". Review of Palaeobotany and Palynology. 113 (1–3): 189–196. doi:10.1016/S0034-6667(00)00059-2.
- ↑ Steemans, P.; Lepot, K.; Marshall, C.P.; Le Hérissé, A. and Javaux, E.J. (2010). "FTIR characterisation of the chemical composition of Silurian miospores (cryptospores and trilete spores) from Gotland, Sweden" (PDF). Review of Palaeobotany and Palynology. 162 (4): 577–590. doi:10.1016/j.revpalbo.2010.07.006.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ↑ Rubinstein, C.V.; Gerrienne, P.; de la Puente, G.S.; Astini, R.A.; Steemans, P. (2010). "Early Middle Ordovician evidence for land plants in Argentina (eastern Gondwana)". New Phytologist. 188 (2): 365–369. doi: 10.1111/j.1469-8137.2010.03433.x . hdl: 11336/55341 . PMID 20731783. S2CID 24070744.
- ↑ Badawy, A.S.; Mehlqvist, K.; Vajda, V.; Ahlberg, P. and Calner, M. (2014). "Late Ordovician (Katian) spores in Sweden: oldest land plant remains from Baltica". GFF. 136 (1): 16–21. doi:10.1080/11035897.2014.899266. S2CID 22198834.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ↑ Steemans, P.; Wellman, C.H. and Gerrienne, P. (2010). "Paleogeographic and paleoclimatic considerations based on Ordovician to Lochkovian vegetation". Geological Society, London, Special Publications. 339 (1): 49–58. Bibcode:2010GSLSP.339...49S. doi:10.1144/SP339.5. S2CID 140195843.
{{cite journal}}: CS1 maint: multiple names: authors list (link)