Review of “Plant Evolution Tour” - Part 3
After reading about the arrival of the first multi-celled plants in Review of “Plant Evolution Tour” - Part 2, we took a slight diversion in Did Jesus Stick to the Creation Script? to explore how it could be that God didn’t record the actual development of life on earth, but did record (through Moses) the removal of its hindrances. What we concluded in Did Jesus stick to the Creation script? Yes! is that those areas of development not recorded in Genesis were handled by God the Father. We therefore turn back to our review of the “Plant Evolution Tour” to learn more about what science tells us about the development of plant life, looking as always for those places where our Heavenly Father may have left evidence of His handiwork.
Before plants could venture onto land, it was important that certain environmental changes be made to the Earth’s surface. Firstly the near-shore environments needed to be of adequate size and stable. Secondly, soils needed to develop. And thirdly, the climatic conditions needed to be appropriate to support terrestrial plant life.
We already know that Jesus set this in motion on Day 3 when He started Plate Tectonics 2.4 Ga. At this point, there was already sea algae growing. With the advent of land, it would provide opportunities for plant life to take a whole new spin. However, it wasn’t until 2 billion years later when the process would finally give way to the true beginnings of land plants.
There was significant tectonic activity during the Cambrian and Ordovician (543-443Ma). Rodinia fragmented and East Gondwana collided with West Gondwana, before they both collided with Laurasia to form the Pangea supercontinent about 320Ma. There were also significant changes in sea levels due to the ending of ice ages at around 650-590Ma, and this led to widespread flooding and the creation of shallow straits. Then, at about 440Ma, there was another period of glaciation (another ice age) and [the] water levels dropped again, with ocean levels decreasing by 70 metres. It is this period of time that indisputable evidence for the first land plants can be dated back to.
At first, the atmosphere was still quite warm due to all of the CO2. But while the high temperatures (40C) prevented plants from taking root enough to clean it up very quickly, the Earth cooled down in some regions by 450 Ma.
There are several hurdles that plants had to overcome to really conquer the land.
- They had to reproduce. In the water, sperm could swim to the egg and fertilize. On land, there was no water to swim through. Some plants reproduced with airborne spores, and most others through a process called “The Alternation of Generations”.
- Plants developed cuticles to prevent the loss of water
- Plants developed stomatal spores to regulate water loss
- Plants developed supported cells to compensate for lack of water, and to fight the wind and rain
- Roots allowed plants to absorb water and nutrients from the ground, as well as anchor them
The first true land plants didn’t grow that large:
- Cooksonia developed 428 Ma. It had no leaves, and grew 6.5 cm long
- Rhynia qwynne-vaughanii developed 400 Ma, and grew to about 18cm long
- Aglaophyton major developed 400 Ma, and grew to 20cm long
- Zosterophyllum developed 400 Ma, too, and grew to 30cm long
- Baragwanathia longifolia developed between 420 and 410 Ma, and grew to be 1 meter long
It is thought that these plants developed from green algae, but their ancestry isn’t clear. They might not even have a common ancestor, although “current thinking is that the Charophyaceae contains a common ancestor.”
It seems to me that a surprising amount of complexity developed once the conditions allowed it, once all hindrances were removed. These complexities built on previous complexities, but the odds of this additional complexity seems so unlikely. I mean, just because conditions on land would allow the survival of new species, why should that necessarily result in their quick appearance? Adequate conditions for life provides no obligation for it to appear, and yet it did, as soon as it could. While continental drift and glaciation took their sweet time providing just the right conditions, the plants themselves wasted no time at all taking advantage of this work. To me, it seems almost intentional, but then I’m not surprised, because I already know it was.