Sea Conifers

 The sea conifers (Nepotsceae) are a clade of conifers that secondarily returned to the sea. Some species can be found in freshwater biomes, but the most impressive are those founds in marine ecosystems, some of which forming surreal undersea forests mirroring the land taiga.

The ancestors of the sea conifers began growing on coastoal swamps during the Cenomanian. The rise of sea levels and expansion of angiosperms on terrestrial biomes provided an excellent opportunity for these conifers to expand into aquatic biomes. Evidence of sea conifer swamps can be found on the coastlines of most continents across the Turonian, and fully marine species already formed underwater forests during the Campanian. The KT mass extinction event reduced sea conifer diversity by 56%, and the group did not recover susbtantially until the Eocene Thermal Maximum. Once they did, though, they quickly grew to stay, and the oceanic cooling events through the Cenozoic only cemented their place as competing seagrasses and corals diminuished in range.

The arrival of sea conifers to the seas had a tremenous impact on marine ecosystems, as it lead to several marine acidification events. This disrupted hard invertebrate communities and in turn lead to multiple extinction events. Among the most curious byproducts was the spread of thick-shelled brachiopods, which are now the dominant reef-building animals.

The ancestors of sea conifers ancestors were Cheirolepidiaceae-like species - their closest living relative is Sciadopitys, positing some interesting possibilities for cypress evolution. Their original bauplan was similar to that of swamp cypresses, but by the Campanian they had developed the modern aerenchyma that allowed them to fully breath underwater, alongside with larger and broader leaves in some species. Some species have become herb-like like seagrasses, but many retained their bark and strong roots, allowing them protection from predators and parasites as well as osmotic regulation. This allows some species to grow firmly even on land, allowing them to thrive in nearshore habitats and a few to even return to a secondarily terrestrial lifestyle on islands.

Like most conifers, their leaves are highly acidic, and underwater forests have few animal parasites like barnacles, though several seaweed can grow on their trunks and branches for a brief time, before being dislodged by shedding bark. Their pollen and seeds are carried by ocean currents, forming clouds similar to those of coral zygotes. Juveniles plants may be eaten by a variety of aquatic herbivores from fish to dugongs, but the adults are only significantly consumed by turtles, several species having developed robust beaks to process cones, tree bark and branches. Meiolaniids in particular have diversified alongside sea conifers, having produced a vast variety of specialists adapted to consume various parts of these plants. As the world's climate dropped in the Pliocene meiolaniid diversity became reduced, and in their stead some waterfowl have began to specialised in sea conifer consumption, but they are for now rare and mostly just leaf nibblers.

Of the 1,200 living species, about two thirds are threatened by pollution and deliberate destruction in order to cultivate more rich marine environments for fishery. Do buy corks made from sea conifer bark, though, it helps motivate people to protect these wonderous plants.