Hello! I am new to this forum, but quite interested in Trees, Gymnospermae(Division) particularly their cultivation indoors and their history. I write this post as a means for us to share our knowledge regarding these things. Here I go :) The first forests arouse during the Carboniferous period 360-300 mya as rainforests, they changed the climate on earth radically because the absorbtion of CO2 and they thus acted as a massive carbon sink, lowering the temperature enormously. The Carboniferous period is named after these first forest that created the first geological layer dominated by organic media. These first trees were Lycophyta(they would have looked very alien to us indeed), all these species of trees are extinct today(Clubmosses from which they probably arouse survive though so one can imagine how they would look). They were replaced by what seems to have been the predecessor or member of the family Araucariaceae(Coniferophyta/Pinophyta order) and the Cycadaphyta order(which probably existed together with the Lycophyta, but fossils are lacking). Anyway as far as I know Araucariaceae are to be considered the oldest family extant, being older than 300 million years. The species of Araucariaceae existing today is much younger, one has to remember that although some of our extant species have the same morphology as trees 300 million years ago, a species morphology is not necessarily an indication of age. Young species can inherit traits from old species, e.g Auracaria heterophylla, which is supposed to look similar to the the first Araucariaceae. Perhaps Araucariaceae should be moved to its own order such as the Cycadaphyta, but the molecular evidence does not support this. Gymnospermae contains 3 extant orders(in age order): Cycadaphyta, Ginkphyta and Coniferophyta/Pinophyta. The taxonomy of the early Gymnospermae is a topic which is far from clear though The oldest fossil I know of when it comes to a non-Araucariaceae is the Gingko biloba, the oldest Gymnospermae extant species at 270 million years during the Permian period. In Second place comes Sciadopitys verticillata at 230 million years during the Triassic period. I should mention that the Cycadaphyta order probably predates all of the other Gymnosperms as they show a direct link to ferns(molecular evidence I believe) and ferns predates trees, again I am very interested in early Cycadaphyta fossils(I haven't been able to confirm 300 millionish fossils yet). One should keep in mind that the fossil record this old is not representative of the whole population which is very exciting, since we might very well find more fossils of extant species of this age although it is unlikely(some species of the Cycadaceae family are likely candidates). Also I should mention that the early Araucariacea forests might be put outside the Araucariacea family, which is why I am very interested in fossils that are definately within the Araucariacea family. If so the question is what family are those trees that are definately are precursors to Araucariacea, but are supposedly much older than Coniferophyta/Pinophyta(in which Araucariacea is put)? Metasequoia glyptostroboides is often mention as a living fossil, but the oldest fossils I am aware of is from the late Jurassic period 200-145 million years ago when trees were much more evolved, same thing goes for Wollemia and Agathis (genera in the Araucariaceae). I am exhausted now so indoor Gymnospermae get its own post later. Please correct me or fill in the blanks, I want to learn. Regards, Araven
Totally forgot Gnetophyta which is also about 300 million years old. Kingdom, Clade, Division, Class, Order, Family, Genus, Species. It gets terribly confusing as some authors don't use Order and the Clades are a total mess. To make it even more complicated we have subdivisions, subclasses etc etc Clades based on different traits see Spermatophytes vs Tracheophytes... So to make it clear Gymnospermae is the Division, however Cycadaphyta, Ginkophyta, Gnetophyta and Coniferophyta/Pinophyta are Subdivisions not Orders...... I was using Division, Subdivisions, Families and Species no matter what I said :) Regards, Araven