Tuesday, December 17, 2013

Awesome Dead Shit: Prototaxites

When Amy has nightmares, they take one of two general forms: either all prosimians go extinct (OH GOD NO!) or it somehow involves giant mushrooms, of which she is irrationally opposed. So today to be an asshole, Meaghan is going to tell you all a lot about Prototaxites, the giant mushroom!

Prototaxites: Nature's threatening fungus-dildo




Prototaxites lived during the Silurian to the very early Devonian (or: 420-350 mya). This was right about when life forms were discovering that land was an okay place to be, but Prototaxites was massively larger than any of the land plants at the time (trees back then reached about 3 feet tall, mere shrubbery). Prototaxites has remained pretty enigmatic since Canadian scientist Charles Dawson found these huge, 20-foot-long spires in 1859.  See, unlike modern mushrooms, nobody's found any sort of fruiting structure. The lack of such a structure has caused Prototaxites to be interpreted as many different organisms: coniferous tree, lichen, algae, or even liverwort.

Woo, so identifiable! So distinct!
Ok, take a look at the image above. Notice how non-concentric those rings are? Here's a conifer for comparison:


Conifers grow a ring a year - the width changes with the relative harshness of the growth season. Prototaxites looks like it was haphazardly slapping on cells whenever it felt like it. Sporadic and irregular growth isn't a very conifer trait... but it is a pretty big fungal one. So that leaves lichen, algae, fungus, and liverwort left as possible culprits.

The liverwort one is fun. Essentially, liverwort often lives in big mats and then if the wind really gets it, it can be rolled up into a "log." So what's the problem with this theory? Check out the colored dots on the specimen below:

See how they are still concentric circles, and not spirals? If Prototaxites was really rolled-up liverwort, it should look like a less-delicious form of Meaghan's favorite Christmas treat, the Chocolate Roll:

Inspired by liverworts


Ok, what else makes it a fungus? One of the first approaches to figuring out wtf these things were was to look at thin slices of rock to see the cellular structure. Rudolf Schmid looked at slices of ancient shroom and found that there were elongated filaments with special pores in them, which resembled the pores and pits found in the cells of modern algae and fungus.

The most recent publications to support Prototaxites' status as a fungus looked at carbon isotopes. Plants have relatively 'light' isotopic signatures that remain somewhat constant throughout time and geography because they are consuming the same thing all the time (sunlight). However organisms that eat other organisms (herbivores, omnivores, carnivores, and decomposers) have erratic isotope signatures because it all depends on where they are and what's around them to eat. Prototaxites, like modern mushrooms, had a "I sometimes/frequently eat other organisms" isotope signature. 

No, this does not mean the Silurian was towered over by giant, carnivorous mushrooms (though that will undoubtedly feature heavily in Amy's nightmares from now on). What it does mean, however, is that Prototaxites was probably breaking down other plant matter like many mushrooms do today.

To conclude, here is a video of Amy ranting about how much she hates mushrooms. Fair warning (cough cough MOM): our favorite word starts with f and rhymes with duck, and we say it a whole lot in this clip.


Amy is going to blame alcohol for the factual inaccuracies in the above video but stands by her word that fungi are out to kill and eat us all.

SOURCES

http://geology.geoscienceworld.org/content/35/5/399.abstract
http://www.amjbot.org/content/97/7/1079.full
http://www.livescience.com/1461-prehistoric-mystery-organism-humongous-fungus.html
http://www-news.uchicago.edu/releases/07/070423.fungus.shtml
http://www.sciencemag.org/content/191/4224/287
http://www.sciencedirect.com/science/article/pii/S0034666701000586
http://www.sciencedirect.com/science/article/pii/0034666776900087
http://www.amjbot.org/content/97/2/268.short
http://coo.fieldofscience.com/2012/11/prototaxites-revisited.html