The bacterial and algal mats were joined early in the period by primitive plants that created the first recognizable soils and harbored some arthropods like mites, scorpions and myriapods. The reasons for the Late Devonian extinctions are still unknown, and all explanations remain speculative. This period started about 419 million years ago and ended 358.9 million years ago. The Kellwasser and Hangeberg events were the two longest episodes of the mass extinction. Lily-like crinoids (animals, their resemblance to flowers notwithstanding) were abundant, and trilobites were still fairly common. Some of the outer shell has broken away revealing the chambered structure. Plant Life. [57][60] Land plants as well as freshwater species, such as our tetrapod ancestors, were relatively unaffected by the Late Devonian extinction event (there is a counterargument that the Devonian extinctions nearly wiped out the tetrapods[61]). The oceans experienced episodes of reduced dissolved oxygen levels, which likely caused the extinction of many species, especially marine animals. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. [41], By the Devonian Period, life was well underway in its colonization of the land. Devonian Period, in geologic time, an interval of the Paleozoic Era that follows the Silurian Period and precedes the Carboniferous Period, spanning between about 419.2 million and 358.9 million years ago. Brachiopods (ToL: Brachiopoda
