Terrestrialisation (Precambrian–Devonian)

Abstract

The emergence of plants and animals from the sea on to land – terrestrialisation – was one of the major advances in the history of life on Earth. Evidence for early colonisation is poor, but the fossil record reveals that by mid‐Palaeozoic times, complex terrestrial ecosystems had become established. The first phase of land colonisation by organisms may have started in the Precambrian, some 2.6 gigaannums (Ga) ago, in the form of microbially bound alluvial sands. The second phase began in earnest in Ordovician times, when early land plants, in the form of bryophyte‐like spores, first appear in the fossil record. By the Silurian, true vascular plants were present, and these green swards were inhabited by mainly detritivorous and predatory arthropods. By the late Devonian, true forests had developed, but it was not until the latest Palaeozoic that modern‐type terrestrial ecosystems, with abundant herbivores in the food chain.

Key Concepts:

  • Organisms need to be overcome many physiological barriers when colonising the land from the sea.

  • Conditions on the early Earth (∼4.6–1.0 Ga) were inhospitable to terrestrial life.

  • Microbial crusts were likely the earliest land life.

  • Higher plants appeared on land in the Ordovician period; vascular plants in the Silurian.

  • The first land animals (Silurian) were detritivorous and predatory arthropods.

  • Modern‐type ecosystems, with abundant herbivory and vertebrates, came in the latest Palaeozoic.

Keywords: arthropod; Devonian; ecosystem; tracheophyte; land colonisation

Figure 1.

Reconstructions of early land plants. (a) Cooksonia from the Late Silurian; (b) Zosterophyllum from the Lower Devonian; (c) Psilophyton from the Lower Devonian. Note the increase in stature and complexity through time.

Figure 2.

The mite Protacarus crani from the Rhynie chert. Left lateral view of holotype specimen. Reproduced from Hirst S (1923) On some arachnid remains from the Old Red Sandstone (Rynie Chert Bed, Aberdeenshire). Annals and Magazine of Natural History12: 455–474.

Figure 3.

The trigonotarbid Palaeocharinus sp. in Rhynie chert. Left lateral view of approximate sagittal section, anterior to left. This specimen is <1 mm long; Rhynie trigonotarbids range up to 5 mm in length.

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References

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Further Reading

Beerbower R (1985) Early development of continental ecosystems. In: Tiffney BH (ed) Geological Factors and the Evolution of Plants. New Haven, CT: Yale University Press.

Selden PA and Edwards D (1989) Colonisation of the land In: Allen KC and Briggs DEG (eds) Evolution and the Fossil Record, chap. 6, pp. 122–152. London: Belhaven Press.

Selden PA and Jeram AJ (1989) Palaeophysiology of terrestrialisation in the Chelicerata. Transactions of the Royal Society of Edinburgh: Earth Sciences 80: 303–310.

Selden PA and Nudds JR (2012) Evolution of Fossil Ecosystems, 2nd edn. London: Manson Publishing.

Shear WA and Selden PA (2000) Rustling in the undergrowth: animals in early terrestrial ecosystems In: Gensel PG and Edwards D (eds) Plants Invade the Land: Evolutionary and Environmental Perspectives. New York: Columbia University Press.

Shear WA, Selden PA, Rolfe WDI, Bonamo PM and Grierson JD (1987) New terrestrial arachnids from the Devonian of Gilboa, New York (Arachnida: Trigonotarbida). American Museum Novitates 2901: 1–74.

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How to Cite close
Selden, Paul(Sep 2012) Terrestrialisation (Precambrian–Devonian). In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0001641.pub3]