Devonzeit

Devonzeit, also known in English as the Devonian period, is a division of the Paleozoic Era spanning roughly 419 to 359 million years ago. It follows the Silurian and precedes the Carboniferous and is named after Devonshire in England, where rocks of this age were first studied. The period is notable for extensive marine diversification, particularly of fish, and for the early colonisation of land by plants and arthropods.

Marine environments during Devonzeit were dominated by a wide array of jawed and jaw‑less fishes, including placoderms, early sharks, and lobe‑filled sarcopterygians that gave rise to tetrapods. Coral reefs expanded, and limestone deposits from warm, shallow seas are widespread in the stratigraphic record. Terrestrial ecosystems saw the emergence of vascular plants such as Cooksonia and early lycophytes, which formed the first extensive land‑based vegetation and contributed to soil development. Arthropods, especially early insects and myriapods, also began to exploit terrestrial niches.

The period experienced considerable climatic fluctuations, with evidence of both greenhouse conditions and cooler intervals. A major extinction event toward the close of Devonzeit, often termed the Late Devonian extinction, affected predominantly marine life, reducing reef diversity and altering fish populations. The causes are debated, with hypotheses including sea‑level changes, anoxia, and bolide impacts.

Geologically, Devonzeit deposits are characterised by sedimentary sequences of sandstones, shales, and limestones, often rich in fossils that illuminate early vertebrate evolution and the advent of terrestrial flora. The period’s legacy includes the foundations for later terrestrial ecosystems and the evolutionary pathways that led to amphibians and, eventually, tetrapod domination of land.