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The evolution of fishes took place over a timeline which spans the Cambrian to the Cenozoic, including during that time in particular the Devonian, which has been dubbed the "age of fishes" for the many changes during that period. The Late Devonian extinctions played a crucial role in shaping the evolution of fish, or vertebrates in general. [1]
Young sporophytes of the common moss Tortula muralis. In mosses, the gametophyte is the dominant generation, while the sporophytes consist of sporangium-bearing stalks growing from the tips of the gametophytes Sporophytes of moss during spring In flowering plants, the sporophyte comprises the whole multicellular body except the pollen and ...
A subclass of the Osteichthyes, the ray-finned fish (Actinopterygii), have become the dominant group of fish in the post-Paleozoic and modern world, with some 30,000 living species. The bony (and cartilaginous) fish groups that emerged after the Devonian were characterised by steady improvements in foraging and locomotion.
In biology, evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organization , from kingdoms to species , and individual organisms and molecules , such as DNA and proteins .
Since tongues are only found in tetrapods, it is assumed that they evolved as a result of the more gravity-bound environment of the land, which requires an extra force of muscles to drive the food inside, from the exaptation of gill muscles, specifically the ventral ones (see hypobranchial eminence and pharyngeal arches).
The male gametophyte of the species has been formally described, [6] which was assigned to a new form taxon Lyonophyton rhyniensis, but is now properly referred to as an Aglaophyton gametophyte. The Rhynie chert bears many examples of male and female gametophytes, which are loosely similar in their construction to the sporophyte phase, down to ...
Mosaic evolution – Evolution of characters at various rates both within and between species; Parallel evolution – Similar evolution in distinct species; Quantum evolution – Evolution where transitional forms are particularly unstable and do not last long; Recurrent evolution – The repeated evolution of a particular character
Alternation of generations is defined as the alternation of multicellular diploid and haploid forms in the organism's life cycle, regardless of whether these forms are free-living. [6] In some species, such as the alga Ulva lactuca , the diploid and haploid forms are indeed both free-living independent organisms, essentially identical in ...