Paleobotany

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A fossil Betula leopoldae (birch) leaf from the Early Eocene of Washington state, approximately 49 million years ago Betula leopoldae SRIC SR02-22-19.jpg
A fossil Betula leopoldae (birch) leaf from the Early Eocene of Washington state, approximately 49 million years ago

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", [1] and is derived from the Greek adjective παλαιός, palaios. [2] 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.

Contents

Paleobotany is important in the reconstruction of ancient ecological systems and climate, known as paleoecology and paleoclimatology respectively. It is fundamental to the study of green plant development and evolution. Paleobotany is a historical science much like its adjacent, paleontology. Because of the understanding that paleobotany gives to archeologists, it has become important to the field of archaeology as a whole. primarily for the use of phytoliths in relative dating and in paleoethnobotany. [3]

The study and discipline of paleobotany was seen as far back as the 19th century. Known as the “Father of Paleobotany”, French botanist Adolphe-Theodore Brongniart was a sufficient figure in this emergence of Paleobotany, known for his work on the relationship between the living and extinct plant life. This work not only progressed paleobotany but also the understanding of the earth and its longevity in actuality and the organic matter that existed over the earth’s timeline. Paleobotany also succeeded in the hands of German paleontologist Ernst Friedrich von Schlothiem, and Czech nobleman and scholar, Kaspar Maria von Sternberg. [4] [5]

Paleoecology

As paleobotany is the specification of fossilized plant life and the environment in which they thrived in, paleoecology is the study of all once-living organisms and the interactions held in the environments they once existed in, before becoming extinct. [6]

Paleoecology is a similar study to that of paleontology, but paleoecology uses more methodology from the biological sciences and geological sciences [7] rather than from an anthropological standpoint as paleontologists do.

Paleopalynology

Paleopalynology, more commonly known as palynology, is the science and study of ancient palynomorphs: particles sized between 5 and 500 micrometers. [8] This would be an inclusion of pollen and spores and any other micro-organic matter. Paleopalynology is simply paleobotany on a much smaller scale, the two in close association with each other.

Similar to paleobotany, we can tell a great deal of information about the environment and biome at the time these particles existed prehistorically. These particles also help geologists identify and date the rock strata of sedimentary rocks. It is also used to find natural oils and gas within these rock layers for extraction. [9] Besides uncovering documentation of our past environmental conditions, palynology can also tell us about animal diets, historical standings of human allergies, and reveal evidence in crime cases.[ citation needed ]

Overview of the paleobotanical record

Macroscopic remains of true vascular plants are first found in the fossil record during the Silurian Period of the Paleozoic era. Some dispersed, fragmentary fossils of disputed affinity, primarily spores and cuticles, have been found in rocks from the Ordovician Period in Oman, and are thought to derive from liverwort- or moss-grade fossil plants. [10]

An unpolished hand sample of the Lower Devonian Rhynie Chert from Scotland Rhynie chert.jpg
An unpolished hand sample of the Lower Devonian Rhynie Chert from Scotland

An important early land plant fossil locality is the Rhynie chert, found outside the village of Rhynie in Scotland. The Rhynie chert is an Early Devonian sinter (hot spring) deposit composed primarily of silica. It is exceptional due to its preservation of several different clades of plants, from mosses and lycophytes to more unusual, problematic forms. Many fossil animals, including arthropods and arachnids, are also found in the Rhynie chert, and it offers a unique window into the history of early terrestrial life.

Plant-derived macrofossils become abundant in the Late Devonian including tree trunks, fronds, and roots. The earliest tree was once thought to be Archaeopteris , which bears simple, fern-like leaves spirally arranged on branches atop a conifer-like trunk, [11] although it is now known to be the recently discovered Wattieza . [12]

Widespread coal swamp deposits across North America and Europe during the Carboniferous Period contain a wealth of fossils containing arborescent lycopods up to 30 m tall, abundant seed plants, such as conifers and seed ferns, and countless smaller, herbaceous plants.

Angiosperms (flowering plants) evolved during the Mesozoic, and flowering plant pollen and leaves first appeared during the Early Cretaceous, approximately 130 million years ago.

Plant fossils

A plant fossil is any preserved part of a plant that has long since died. Such fossils may be prehistoric impressions that are many millions of years old, or bits of charcoal that are only a few hundred years old. Prehistoric plants are various groups of plants that lived before recorded history (before about 3500 BC).

Preservation of plant fossils

Ginkgoites huttonii, Middle Jurassic, Yorkshire, UK. Leaves preserved as compressions. Specimen in Munich Palaeontological Museum, Germany. Gingkoites huttoni 1.jpg
Ginkgoites huttonii, Middle Jurassic, Yorkshire, UK. Leaves preserved as compressions. Specimen in Munich Palaeontological Museum, Germany.

Plant fossils can be preserved in a variety of ways, each of which can give different types of information about the original parent plant. These modes of preservation may be summarised in a paleobotanical context as follows.

  1. Adpressions (compressions – impressions). These are the most commonly found type of plant fossil. They provide good morphological detail, especially of dorsiventral (flattened) plant parts such as leaves. If the cuticle is preserved, they can also yield fine anatomical detail of the epidermis. Little other detail of cellular anatomy is normally preserved.
    Rhynia, Lower Devonian Rhynie Chert, Scotland, UK. Transverse section through a stem preserved as a silica petrifaction, showing preservation of cellular structure. Rhynia stem.jpg
    Rhynia , Lower Devonian Rhynie Chert, Scotland, UK. Transverse section through a stem preserved as a silica petrifaction, showing preservation of cellular structure.
  2. Petrifactions (permineralisations or anatomically preserved fossils). These provide fine detail of the cell anatomy of the plant tissue. Morphological detail can also be determined by serial sectioning, but this is both time consuming and difficult.
  3. Moulds and casts. These only tend to preserve the more robust plant parts such as seeds or woody stems. They can provide information about the three-dimensional form of the plant, and in the case of casts of tree stumps can provide evidence of the density of the original vegetation. However, they rarely preserve any fine morphological detail or cell anatomy. A subset of such fossils are pith casts, where the centre of a stem is either hollow or has delicate pith. After death, sediment enters and forms a cast of the central cavity of the stem. The best known examples of pith casts are in the Carboniferous Sphenophyta (Calamites) and cordaites (Artisia).
    Crossotheca hughesiana Kidston, Middle Pennsylvanian, Coseley, near Dudley, UK. A lyginopteridalean pollen organ preserved as an authigenic mineralization (mineralized in situ). Specimen in Sedgwick Museum, Cambridge, UK. Crossotheca nodule.JPG
    Crossotheca hughesiana Kidston, Middle Pennsylvanian, Coseley, near Dudley, UK. A lyginopteridalean pollen organ preserved as an authigenic mineralization (mineralized in situ). Specimen in Sedgwick Museum, Cambridge, UK.
  4. Authigenic mineralisations. These can provide very fine, three-dimensional morphological detail, and have proved especially important in the study of reproductive structures that can be severely distorted in adpressions. However, as they are formed in mineral nodules, such fossils can rarely be of large size.
  5. Fusain. Fire normally destroys plant tissue but sometimes charcoalified remains can preserve fine morphological detail that is lost in other modes of preservation; some of the best evidence of early flowers has been preserved in fusain. Fusain fossils are delicate and often small, but because of their buoyancy can often drift for long distances and can thus provide evidence of vegetation away from areas of sedimentation.

Fossil-taxa

Plant fossils almost always represent disarticulated parts of plants; even small herbaceous plants are rarely preserved whole. The few examples of plant fossils that appear to be the remains of whole plants are in fact incomplete as the internal cellular tissue and fine micromorphological detail is normally lost during fossilization. Plant remains can be preserved in a variety of ways, each revealing different features of the original parent plant. [13]

Because of this, paleobotanists usually assign different taxonomic names to different parts of the plant in different modes of preservation. For instance, in the subarborescent Palaeozoic sphenophytes, an impression of a leaf might be assigned to the genus Annularia, a compression of a cone assigned to Palaeostachya, and the stem assigned to either Calamites or Arthroxylon depending on whether it is preserved as a cast or a petrifaction. All of these fossils may have originated from the same parent plant but they are each given their own taxonomic name. This approach to naming plant fossils originated with the work of Adolphe-Théodore Brongniart. [14]

For many years this approach to naming plant fossils was accepted by paleobotanists but not formalised within the International Rules of Botanical Nomenclature. [15] Eventually, Thomas (1935) and Jongmans, Halle & Gothan (1935) proposed a set of formal provisions, the essence of which was introduced into the 1952 International Code of Botanical Nomenclature. [16] These early provisions allowed fossils representing particular parts of plants in a particular state of preservation to be placed in organ-genera. In addition, a small subset of organ-genera, to be known as form-genera, were recognised based on the artificial taxa introduced by Brongniart mainly for foliage fossils. The concepts and regulations surrounding organ- and form-genera were modified within successive codes of nomenclature, reflecting a failure of the paleobotanical community to agree on how this aspect of plant taxonomic nomenclature should work (a history reviewed by Cleal and Thomas in 2020 [17] ). The use of organ- and fossil-genera was abandoned with the St Louis Code, and replaced by "morphotaxa". [18]

The situation in the Vienna Code of 2005 was that any plant taxon whose type is a fossil, except diatoms, can be described as a morphotaxon, a particular part of a plant preserved in a particular way. [19] Although the name is always fixed to the type specimen, the circumscription (i.e. range of specimens that may be included within the taxon) is defined by the taxonomist who uses the name. Such a change in circumscription could result in an expansion of the range of plant parts or preservation states that could be incorporated within the taxon. For instance, a fossil-genus originally based on compressions of ovules could be used to include the multi-ovulate cupules within which the ovules were originally borne. A complication can arise if, in this case, there was an already named fossil-genus for these cupules. If paleobotanists were confident that the type of the ovule fossil-genus and of the cupule fossil-genus could be included in the same genus, then the two names would compete as to being the correct one for the newly emended genus. In general, there would be competing priority whenever plant parts that had been given different names were discovered to belong to the same species. It appeared that morphotaxa offered no real advantage to paleobotanists over normal fossil-taxa and the concept was abandoned with the 2011 botanical congress and the 2012 International Code of Nomenclature for algae, fungi, and plants.

Fossil groups of plants

Lycopod axis (branch) from the Middle Devonian of Wisconsin. Lycopod axis.jpg
Lycopod axis (branch) from the Middle Devonian of Wisconsin.
Stigmaria, a common fossil tree root. Upper Carboniferous of northeastern Ohio. StigmariaOhioPennsylvanian.jpg
Stigmaria, a common fossil tree root. Upper Carboniferous of northeastern Ohio.
External mold of Lepidodendron from the Upper Carboniferous of Ohio. LepidodendronOhio.jpg
External mold of Lepidodendron from the Upper Carboniferous of Ohio.

Some plants have remained almost unchanged throughout earth's geological time scale. Horsetails had evolved by the Late Devonian, [20] early ferns had evolved by the Mississippian, conifers by the Pennsylvanian. Some plants of prehistory are the same ones around today and are thus living fossils, such as Ginkgo biloba and Sciadopitys verticillata . Other plants have changed radically, or became extinct.

Examples of prehistoric plants are:

Notable paleobotanists

See also

Related Research Articles

<i>Glossopteris</i> Genus of extinct seed ferns

Glossopteris is the largest and best-known genus of the extinct Permian order of seed plants known as Glossopteridales. The name Glossopteris refers only to leaves, within the framework of form genera used in paleobotany.

<span class="mw-page-title-main">Rhynie chert</span> Early Devonian sedimentary deposit exhibiting extraordinary fossil detail or completeness

The Rhynie chert is a Lower Devonian sedimentary deposit exhibiting extraordinary fossil detail or completeness. It is exposed near the village of Rhynie, Aberdeenshire, Scotland; a second unit, the Windyfield chert, is located some 700 m away. The Rhynie chert contains exceptionally preserved plant, fungus, lichen and animal material preserved in place by an overlying volcanic deposit. The bulk of the Devonian fossil bed consists of primitive plants, along with arthropods, lichens, algae and fungi.

<span class="mw-page-title-main">Zosterophyll</span> Group of extinct land plants

The zosterophylls are a group of extinct land plants that first appeared in the Silurian period. The taxon was first established by Banks in 1968 as the subdivision Zosterophyllophytina; they have since also been treated as the division Zosterophyllophyta or Zosterophyta and the class or plesion Zosterophyllopsida or Zosteropsida. They were among the first vascular plants in the fossil record, and had a world-wide distribution. They were probably stem-group lycophytes, forming a sister group to the ancestors of the living lycophytes. By the late Silurian a diverse assemblage of species existed, examples of which have been found fossilised in what is now Bathurst Island in Arctic Canada.

<i>Protosalvinia</i> Devonian fossil plant of uncertain affinity

Protosalvinia is a prehistoric plant found commonly in shale from shoreline habitats of the Upper Devonian period. The name Protosalvinia is a misnomer. The name literally means early Salvinia, and was given in the erroneous belief that the fossils were an earlier form of the living aquatic fern Salvinia. It is no longer believed that the fossils come from a fern, but deciding exactly what the fossils represent is still a matter of debate.

<i>Sigillaria</i> Extinct genus of spore-bearing plants

Sigillaria is a genus of extinct, spore-bearing, arborescent lycophyte, known from the Carboniferous and Permian periods. It is related to the more famous Lepidodendron, and more distantly to modern quillworts.

<i>Wattieza</i> Extinct genus of ferns

Wattieza was a genus of prehistoric trees that existed in the mid-Devonian that belong to the cladoxylopsids, close relatives of the modern ferns and horsetails. The 2005 discovery in Schoharie County, New York, of fossils from the Middle Devonian about 385 million years ago united the crown of Wattieza to a root and trunk known since 1870. The fossilized grove of "Gilboa stumps" discovered at Gilboa, New York, were described as Eospermatopteris, though the complete plant remained unknown. These fossils have been described as the earliest known trees, standing 8 m (26 ft) or more tall, resembling the unrelated modern tree fern.

Ornatifilum is an artificial form genus, which is used to categorise any small, branched filaments with external ornamentation.

<span class="mw-page-title-main">Polysporangiophyte</span> Spore-bearing plants with branched sporophytes

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.

<i>Aglaophyton</i> Extinct (Devonian) prevascular land plant

Aglaophyton major was the sporophyte generation of a diplohaplontic, pre-vascular, axial, free-sporing land plant of the Lower Devonian. It had anatomical features intermediate between those of the bryophytes and vascular plants or tracheophytes.

<i>Rhynia</i> Extinct species of vascular plant

Rhynia is a single-species genus of Devonian vascular plants. Rhynia gwynne-vaughanii was the sporophyte generation of a vascular, axial, free-sporing diplohaplontic embryophytic land plant of the Early Devonian that had anatomical features more advanced than those of the bryophytes. Rhynia gwynne-vaughanii was a member of a sister group to all other eutracheophytes, including modern vascular plants.

<i>Horneophyton</i> Extinct genus of early plants

Horneophyton is an extinct early plant which may form a "missing link" between the hornworts and the Rhyniopsida. It is a member of the class Horneophytopsida. Horneophyton is among the most abundant fossil organisms found in the Rhynie chert, a Devonian Lagerstätte in Aberdeenshire, UK. A single species, Horneophyton lignieri, is known. Its probable female gametophyte is the form taxon Langiophyton mackiei.

Professor Dianne Edwards CBE, FRS, FRSE, FLS, FLSW is a palaeobotanist, who studies the colonisation of land by plants, and early land plant interactions.

<span class="mw-page-title-main">Medullosales</span> Extinct order of Late Carboniferous seed ferns

The Medullosales is an extinct order of pteridospermous seed plants characterised by large ovules with circular cross-section and a vascularised nucellus, complex pollen-organs, stems and rachides with a dissected stele, and frond-like leaves. Their nearest still-living relatives are the cycads.

<span class="mw-page-title-main">Lyginopteridales</span> Prehistoric plant order

The Lyginopteridales are an extinct group of seed plants known from the Paleozoic. They were the first plant fossils to be described as pteridosperms and, thus, the group on which the concept of pteridosperms was first developed; they are the stratigraphically oldest-known pteridosperms, occurring first in late Devonian strata; and they have the most primitive features, most notably in the structure of their ovules. They probably evolved from a group of Late Devonian progymnosperms known as the Aneurophytales, which had large, compound frond-like leaves. The Lyginopteridales became the most abundant group of pteridosperms during Mississippian times, and included both trees and smaller plants. During early and most of middle Pennsylvanian times the Medullosales took over as the more important of the larger pteridosperms but the Lyginopteridales continued to flourish as climbing (lianescent) and scrambling plants. However, later in Middle Pennsylvanian times the Lyginopteridales went into serious decline, probably being out-competed by the Callistophytales that occupied similar ecological niches but had more sophisticated reproductive strategies. A few species continued into Late Pennsylvanian times, and in Cathaysia and east equatorial Gondwana they persisted into the Late Permian, but subsequently became extinct. Most evidence of the Lyginopteridales suggests that they grew in tropical latitudes of the time, in North America, Europe and China.

<i>Pachypteris</i> Mesozoic pteridosperm leaf fossil

Pachypteris is a Mesozoic pteridosperm genus of fossil leaves. It has either been aligned with the peltasperms or the corystosperms.

Chester Arthur Arnold was an American paleobotanist, born June 25, 1901, in Leeton, Missouri, and died on 19 November 1977.

Psilophytopsida is a now obsolete class containing one order, Psilophytales, which was previously used to classify a number of extinct plants which are now placed elsewhere. The class was established in 1917, under the name Psilophyta, with only three genera for a group of fossil plants from the Upper Silurian and Devonian periods which lack true roots and leaves, but have a vascular system within a branching cylindrical stem. The living Psilotaceae, the whisk-ferns, were sometimes added to the class, which was then usually called Psilopsida. This classification is no longer in use.

<span class="mw-page-title-main">Mary Gordon Calder</span> Scottish paleobotanist

Mary Gordon Calder was a Scottish paleobotanist. She is known for her work on Carboniferous fossil plants and Jurassic conifers.

<i>Nilssonia</i> (plant) Fossil plant of gondwana supergroup of India

Nilssonia is a genus of fossil foliage traditionally assigned to the Cycadophyta either in Cycadales or their own order Nilssoniales, though the relationships of this genus with the Cycadales have been put into question on chemical grounds.

The barinophytes are a group of extinct vascular plants (tracheophytes). Their relationship with other vascular plants is unclear. They have been treated as the separate class Barinophytopsida, the order Barinophytales of uncertain class and as a family or clade Barinophytaceae within the zosterophylls. They have also been considered to be possible lycopodiopsids.

References

  1. ↑ Stearn, W.T. (2004). Botanical Latin (4th (p/b) ed.). Portland, Oregon: Timber Press. p. 460. ISBN   978-0-7153-1643-6.
  2. ↑ Liddell, Henry George & Scott, Robert (1940). "παλαιός". A Greek-English Lexicon. Oxford: Clarendon Press. Retrieved 2019-07-16.
  3. ↑ Cabanes, D. (2020). Phytolith Analysis in Paleoecology and Archaeology. In Interdisciplinary Contributions to Archaeology (pp. 255-288) doi: 10.1007/978-3-030-42622-4_11
  4. ↑ "Brongniart, Adolphe-Théodore". www.encyclopedia.com. Encyclopedia.com: FREE online dictionary. Retrieved 22 February 2017.
  5. ↑ Cleal, Christopher J.; Lazarus, Maureen; Townsend, Annette (2005). "Illustrations and illustrators during the 'Golden Age' of palaeobotany: 1800–1840". In Bowden, A. J.; Burek, C. V.; Wilding, R. (eds.). History of palaeobotany : selected essays . London: Geological Society of London. p.  41. ISBN   9781862391741.
  6. ↑ "Paleoecology". Digital Atlas of Ancient Life. Retrieved 2023-11-13.
  7. ↑ "Paleoecology | Encyclopedia.com". www.encyclopedia.com. Retrieved 2023-11-13.
  8. ↑ Traverse, Alfred (2008). Paleopalynology. Topics in geobiology (2. ed., printed with corr ed.). Dordrecht: Springer. ISBN   978-1-4020-5609-3.
  9. ↑ "Palynology". Paleobotany + Palynology. Retrieved 2023-11-13.
  10. ↑ Wellman, Charles H.; Osterloff, Peter L. & Mohiuddin, Uzma (2003), "Fragments of the Earliest Land Plants" (PDF), Nature, 425 (6955): 282–285, Bibcode:2003Natur.425..282W, doi:10.1038/nature01884, PMID   13679913, S2CID   4383813
  11. ↑ Meyer-Berthaud, Brigitte; Scheckler, S.E. & Wendt, J. (1999), "Archaeopteris is the Earliest Modern Tree", Nature, 398 (6729): 700–701, Bibcode:1999Natur.398..700M, doi:10.1038/19516, S2CID   4419663
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  13. ↑ Darrah, William C. (1936). "The Peel Method in Paleobotany". Botanical Museum Leaflets, Harvard University. 4 (5): 69–83. doi: 10.5962/p.295100 . ISSN   0006-8098. JSTOR   41762635.
  14. ↑ Brongniart (1822)
  15. ↑ Briquet, J. (1906), Règles internationales de la nomenclature botanique adoptées par le Congrès International de Botanique de Vienne 1905, Jena: Fischer, OCLC   153969885
  16. ↑ Lanjouw et al. 1952
  17. ↑ Cleal & Thomas 2010
  18. ↑ Greuter et al. 2000
  19. ↑ McNeill 2006
  20. ↑ Elgorriaga, A.; Escapa, I.H.; Rothwell, G.W.; Tomescu, A.M.F.; Cúneo, N.R. (2018). "Origin of Equisetum: Evolution of horsetails (Equisetales) within the major euphyllophyte clade Sphenopsida". American Journal of Botany. 105 (8): 1286–1303. doi: 10.1002/ajb2.1125 . PMID   30025163.
  21. ↑ "Edward Berry". www.nasonline.org. Retrieved 2024-01-07.
  22. ↑ "Professor William Gilbert Chaloner (Bill) and his contributions to palaeobotany – International Organisation of Palaeobotany" . Retrieved 2024-01-07.
  23. ↑ Dettmann, Mary E., "Isabel Clifton Cookson (1893–1973)", Australian Dictionary of Biography, Canberra: National Centre of Biography, Australian National University, retrieved 2024-01-07
  24. ↑ "Margaret Bryan Davis | Biography & Facts | Britannica". www.britannica.com. Retrieved 2024-03-06.
  25. ↑ "Harvard University Herbaria & Libraries". kiki.huh.harvard.edu. Retrieved 2024-01-07.
  26. ↑ "Dianne Edwards | Plant Fossil Names". www.plantfossilnames.org. Retrieved 2024-01-07.
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