Hi Frikkie, You may get a more athoritative answer but, just in case not, a quick answer to your question about earliest orchids is that you probably need a few more zeros on the the number you give (try 65,000,000 !)
But you ask for "proof"rather than probability; as far as I am aware, the earliest fossil evidence of orchids comes from about 50,000,000 (50 million) years ago and so, if the identification is correct, that would constitute proof . However, orchids are notoriously rare in the fossil record, partly because land-plants generally don't grow in environment where they are as likely to be preserved as, say, marine shells which get preserved in sea floor sediment, and only woody ones stand much chance. Many are identified, maybe surprisingly, from pollen and spores which are astonishingly robust and small enough and numerous enough to escape damage and are likely to occur in rock samples of small size (cores).. Without getting bogged down in tangible proof of orchids specifically, there is plenty of evidence to date key events in plant evolution generally. For example, the first land plants, once thought to be Silurian (circa 400 million) have now been found earlier as Ordovician. Anyone that has examined Carboniferous coal (circa 300 million) will be aware of the variety of major plant groups already in evidence then and by the Jurassic there are easily recognisable groups like the Cycads for example and many of the coniferous trees found fossilised (say) at the Arizona Petrified Forest. Late 20th and early 21stC work using DNA analysis seems to be suggesting that orchids may stretch tenuously back into the earliest Cretaceous or the late Jurassic (in other words, well in excess of the end of the Cretaceous at 65 million y). I suggest you search web entries with DNA, gene sequencing, orchid. http://tolweb.org/tree?group=Monocotyledons&contgroup=Euangiosperms http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=18297 http://www.world-of-fungi.org/Mostly_Mycology/Diane_Howarth/evolution.htm Just going back to the 'proof' thing; one of the hazards of trying to give a scientific opinion about the question you ask is that it is so easy for anyone to challenge on the basis of 'not proven'. Less easy, of course to provide an alternative and as useful a hypothesis! In short, the present state of knowledge suggests that they are of Cretaceous origin along with many of their associated groups.Watch that space! Just another related point; you refer to 'land bridges' which are a rather quaint old idea. Bone up on Plate Tectonics, especially for the regions that you are interested in. Continental crustal plate movements are very relevant for the distribution of orchid species and much has happened in the patch you refer to! If you want more help come back to me direct (it is so easy to clog up the forum!) Cheers John Stanley (Retired Geologist/ biologist) > > Message: 1 > Date: Mon, 17 Jul 2006 15:56:05 +0200 > From: "Frikkie Marais" <[EMAIL PROTECTED]> > Subject: [OGD] Age of orchids > To: <[email protected]> > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset="windows-1252" > > Hi > > I hope someone can help me. I would like to know if orchids were already > in existence 65 000 years ago, when Africa and the Arabian Peninsula were > still linked via a land bridge? A reference to prove this would also be > appreciated. > > Regards > > Frikkie Marais > South Africa _______________________________________________ the OrchidGuide Digest (OGD) [email protected] http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
