Tag Archives: Cretaceous

At first I was afraid, I was petrified…

Palaeontology is the study of old life. It doesn’t exactly jump for attention. We have something against old stuff. Even the iPad I’m typing on right now is a testament to our dislike of the old and our constant need for new and fresh. Anyone who has ever splashed out a few bucks on an original Atari 2600 (nerd reference alert) or a vintage 1980s stonewashed jacket knows that old has another connotation. It can also mean classic. Ok, maybe not the best examples of classics, but you get the drift. Today I decided to learn about the classics. The organism both great and humble that through multiple evolutionary combinations attained a form that enabled their survival for millions of years. Incidentally, I don’t consider humans part of this ‘classics’ subset. A few million years doesn’t quite pass muster.

A classic of human engineering, the jaguar

A plant classic, the monkey puzzle tree. A living fossils millions of years old. The oldest specimen alive to date is 800 years old. That’s what I call vintage

Since their origins in the Silurian period, land plants have been through a few ‘bad patches’. Probably the most commonly known is the Cretaceous extinction, or the dinosaur killer in common parlance. The end of the Cretaceous featured an unfortunate synchrony of very unpleasant geological and extraterrestrial events that must have made the living quarters a little unpalatable for most organisms. These events were, in no particular order, the impact of a large meteor in Mexico, eruption of the Deccan traps in India and unexplained anoxia of the oceans. Most people have heard of the chicxulub crater (probably not by name), but the other two events are almost muttered under the breath. I’d never heard of the Deccan traps or indeed the Siberian traps till my brother, who loves to give me nightmares, decided to tell me that lava can pour out of the ground for 30,000 years or more. Definitely beyond the timeline of most disaster movies. These events were so global in their effects that a layer of soot and a rare element, iridium, were deposited in the Earth. The soot and dust thrown up by the combination of volcanism and impact shock waves would have blocked sunlight and rendered it almost impossible for plants to photosynthesise. And therein lies the mystery. Without photosynthesis, how could plants survive and yet some species came through the extinction event unscathed. Without plants, how could animals survive and yet some did. For reasons that are not fully understood, some plants and animals emerged from one of the worst global environmental catastrophes and many others did not.

Letter on possible causes of oceanic anoxia

Eddie: What if we’re the last animals left alive? We’ll have to repopulate the earth.
Crash: How are we supposed to do that? Everyone here is either a dude or our sister.

Now I’ll get to the concept of a classic. The earth has undergone several climatic upheavals which should have led to total extinctions, yet some species persist. These are the species on the edge. The survivors. Evolution is not a steady stream of linear changes but rather it follows a more punctuated pattern. Extreme conditions seem to force evolutionary change. Following the major extinctions of the Cretaceous and Permian, life flourished with apparent ease and new species quickly filled ecological niches. Some species such as crocodiles, mammals, ferns seem to have the ability to weather the storm of changes and maintain their ecological foothold. This doesn’t necessarily equate to them having a more complex or sophisticated body plan but rather that they have a robustness of design. In particular plants have an incredible arsenal of survival skills. Many plants can adjust leaves, stems and roots to cope with low water levels. Some plants can withstand fires and indeed rely on being razed to the ground to disperse their seeds. Plants have developed a particularly formidable arsenal of chemical substances which can be used to prevent herbivory, to signal to other plants and to initiate reproduction. The gamete carrying pollen of angiosperms is particularly tough when subjected to environmental challenge. Even when doused with hydrofluoric acid (breaking bad fans will recall its destructive force), pollen has retained it’s viability. It seems unsurprising in this case that angiosperms recovered well from the late
Cretaceous extinction.
For our sake, I hope the Deccan traps stay quiet, and that meteors swing past us and our oceans remain relatively oxygen rich. I wouldn’t like to anticipate the odds of our survival. We are newbies, with all the fragility that that entails and we are facing into a period of serious environmental change. The mystery of life came through catastrophic extinction events is something we should be taking heed of, to safeguard our own future.


The day the world nearly died



Extreme plants


Svalbard world seed bank- just in case, but who’ll be around to sow them?

When is a hole not a hole?

I’d been harboring a secret dread of stomatal counts since the very first day in UCD. The idea of manicuring a leaf and plucking off the varnish looking for tiny holes just seemed, well, a bit tedious, a bit fiddly and destined for failure. Amanda, yet another super-friendly and helpful Ph.D. (must be something in the water), brought us some beautiful Ginkgo leaves, which we subsequently butchered with a backed-blade (sorry Ginkgos). Obtaining the prints was blissfully easy. Paint, dry, lift with tape and onto a slide. What can I say, all those days spent, to quote my mother, “wasting your time putting on that stupid nail varnish” paid off. After a brief discussion on how to count stomata, (not the 1, 2, 3 bit!), we headed with nervous anticipation into the microscopy room. Slides focused and primed for action, we added our little counting boxes and off we went. Amanda’s infectious laughter, reminiscent of a kid who’s just discovered bubbles, provided the perfect backdrop to our little stomata counting party. Wow, there they were as clear as day and all you had to do was count ’em up, scale ’em up and you could tell how much carbon dioxide was present in the atmosphere. The images are astounding, like really pretty, flowery wallpaper.


My little fluorescent flowers (stomata to the uninitiated)

We take a glance at some triassic leaves. Two things are obvious. There’s a lot of holes of unknown origin and its very difficult to discern which ones are stomata. We leave this count to Amanda’s superior experience. Amanda gives us the counts for the fossils and added to our own data, we can now determine that the carbon dioxide level was approximately 200 ppm above present values. I am immediately struck by how accessible and relatively simple this technique is, although I can envisage many debates about statistics and sampling.

http://www.denison.edu/sustainability/duarb-253.html All about Ginkgos

At lunch Amanda pulls out a cup decorated in Ginkgo leaves. Now that’s dedication! After lunch, having passed our leaf grinding initiation yesterday, we move up a level. Isotope analysis. Another relatively simple method (except for the scary equations) to indirectly determine carbon dioxide levels based on how heavy isotopes of carbon are incorporated into plants. Today we get to grind in glass. Tomorrow, grinding with one hand while hopping on a pogo stick. Filtering our tiny pile into grindings into a 2cm wide glass vial turns out to be a little challenging, particularly while being observed. I’m doing oh so well and then boom crumbled leaf everywhere. I look pityingly at Amanda. This will be her life for the foreseeable future. Earlier on we were regaled with tales of fastest stomatal counts, Aidan is top of the leader board by Amanda’s tally. This job definitely wasn’t designed for speed. Amanda shows us the isotope analysis ‘boats’, teeny-weeny containers (like the ends of fuses) into which individual leaf grindings must be poured. Where’s Tinkerbell when you need her…..

I take off to the local library, realising the time has come to tackle an actual paleobotany book. I find the Science section. Dinosaurs, dinosaurs, dinosaurs, fossils, fossils, fossils, geology. Huh? Where’s the plant fossils? I consider complaining, especially since the pathway to the library is lined with fossil-impregnated limestone paving (Talk about false advertising). I settle on a generic fossil tome, remembering that Jenny has promised us a look at her own book. Towards the end, I find 8 pages in a 255 page book, dedicated to plants. I’m glad Jenny is around, making sure our humble producers aren’t consigned to a dusty shelf.

http://www.ucd.ie/plantpalaeo/porter.html Amanda’s bio

Our ultra clean high tech bench

Ginkgo biloba (or Rocky Balboa as I call it, mainly due to its comeback kid nature. See reference above)

Plastosaurus Rex, a victim of the late Cretaceous peak oil crisis