There is nothing new under the sun and the world is born fresh at every moment. Holding both of those ideas at once will help you grab the overarching thesis of this very long series, which is eating up a significant percentage of the history herbivory.
The next important milestone in the history of herbivory comes around the mid-Cretaceous, about a hundred million years ago, with the diversification of the angiosperms on their road to global domination. But before we get to important events in geologic epochs I am going to rehash my inconsequential week. Yes, that means once again it is time for my least favorite (of two) sections in this blog, the Almanac Section, where I tell you what actually happened in my week.
This week I made the trek down to California to give Byron, Ben and the other people of Grounded Land and Livestock a much-needed break. They have done a fantastic job down there. Byron Palmer and I are partners in that business and the most rewarding part of it is seeing the amazing changes that happen on the land when you put in the work to move animals around. And sometimes that is a lot of work. For instance, at Cayetanna.
Cayetanna, is a rugged little ranch that we have leased for the last three years. Its boundaries are drawn on the ridge lines so that the ranch encompasses an entire sub-drainage of San Antonio Creek. This is a legacy from the way the Spanish drew property lines 250 years ago. Since we have this entire drainage, we are able to see the scarcely-believable-impacts possible when you do a little better with your cattle management.
Early in the morning last Saturday, I went out to move the most rugged pasture we have, a six hundred acre pasture I call ‘the wilderness.’ Now, six hundred acres is not that big but because of a combination of long steep slopes, rocks, and dense brush, you have to travel on foot. Well, maybe you can travel on four-wheeler or horse, but I can definitely only do it on foot. And the gates are positioned in places where the cattle have to go to some unusual places in order to find their way out of the pasture. I could move the gates… but then I wouldn’t be able to do as much of this, my favorite job, of all the jobs I do. And I wouldn’t be able to complain about it.
At first light as I was riding the four-wheeler out to find the cattle I went past some of the little drainages that I have been looking at for the past three years. The third year of management is a fun one. There are all kinds of very rapid changes in the land. When we first started managing this property, its steep hillsides were gashed with deep erosion gullies that bled red soil into San Antonio Creek. Those gullies are in the process of transforming into gentle meandering creeks, as soil builds up in the bottom of them, anchored by grass and clover and iris roots. After each rainstorm, you can see the places where the next layer of soil has been deposited, often several
inches at a time. I wondered how many tons of soil are now captured in these fresh hanging meadows. These are the effect (and cause) of dramatic hydrologic changes and we desperately need some science to quantify and untangle the different causal factors involved.
Moving on, I went up to the top of the pasture, where I took this picture, and as usual, found some cattle.
They love it at the top. I spent the rest of that day following those cattle until they found more cattle and following them until they found more cattle and following them until they found the gate. And then I did the same thing the next day. And the next.
We went round and round, some groups doing three or four loops, plunging down to the bottom of a thousand-foot canyon to go back up a thousand-foot canyon, over and over. During this time I had a lot of opportunities to look around. I had the chance to see how much more open all the vegetation was now compared to three years ago. There are big swathes of Serpentine soil in that pasture, and the scrub oak and toyon are thinner, the grass more robust in between. Again, the mechanisms for this change are far from clear. Even the deep dark canyons of bay and oak have more plants in the understory. The leaflitter-and-fern-filled forests are turning into savannas, dominated by grass and wildflowers. The human embryo records all the evolutionary changes of our species in nine months. In the same way, when you start managing land with herbivores you have the opportunity to watch the evolution of pro-herbivore ecosystems in fast forward.
The other thing I contemplated, while I climbed over rocks and trees, in what became the pouring rain, to get the last seven cattle out of this pasture, was the soundness of this current business model. Okay, that was fun, now lets quick stop thinking about that before we do anything stupid. Or smart. Back to the Cretaceous.
As I’ve said before, remember that the term ‘flowering plant’ is just a name. There were plenty of other plants that essentially flowered, and 100 million years ago there were plants like the Bennitaleans that had big showy things that can only be described as ‘flowers.’ But Angiosperms grabbed a big chunk of the earth’s ecosystems from these other plants. As far as major divisions of life go, plant or animal, the Angiosperms are one of the youngest groups on the planet. You could call them late-bloomers. Oh, man. I’m turning into my father.
As we talked about last week, no one should imagine the world before Angiosperms as having blank spots wherever we currently see flowering plants. Even functions that are carried out almost exclusively by angiosperms today, such as mega-fauna dispersed seeds and megafauna adapted vegetative patterns, were performed quite happily by more ‘primitive’ plants. Last week we talked about horsetails and my experience with them. But I probably have more experience with ferns. Ferns were likely the other major component of the herbaceous layer in early Mesozoic savannas.
In, for instance, Northern California, when you start grazing a place with a lot of trees, Cayetanna would be a good example, you are bound to encounter ferns. These ferns have different responses to herbivory. For instance at Cayetanna ‘sword ferns’ and bracken ferns. Sword ferns are extremely sensitive to grazing, or to any kind of surface damage, such as fire. Bracken ferns, in contrast, do very well with a certain amount of grazing, even if grazers don’t always do well with them as there can be a toxicity problem. Even maidenhair ferns which seem very fragile and sensitive do alright with grazing, where it removes taller vegetation. Is the ‘sword fern’ a more ancient pre-herbivore phenotype? I don’t know.
But around 100 + million years ago, the first Angiosperms start to give them some competition. The big problem is that we have a gaping hole in the fossil record where it comes to plants and the Cretaceous. We mostly know about these first angiosperms from their fossil pollen, which limits how much we can know about… basically everything. We don’t even know if they were herbaceous or woody plants.
This problem is further compounded by the very nature of many Angiosperms, the fact that they are pollinated by insects. Insect pollinated plants are poorly represented in the pollen record if they show up at all. When all we have is a pollen record we are going to know very little about the insect-pollinated portion of the ecosystem.
However, from what we can scrape together many researchers postulate that they were herbaceous and these plants are described time and time again as ‘weedy’ plants. Whenever the word ‘weed’ is used to describe a plant that is not psychoactive, there are biases at play, and this is no exception. “Disturbed” is the term used to describe the habitat that these plants occupy, another potentially pejorative term. What could have ‘disturbed’ the habitat to foster these ‘weedy’ species?
Well, the Cretaceous was also a period of diversification in dinosaur species. That’s one idea. Could the diversification of dinosaurs and the diversification of angiosperms be related? We don’t know.
The two groups that we must talk about even on this whirl-wind history of herbivory are the ceratopsians and the hadrosaurs. The ceratopsians were a group from North America and Asia. In Ceratopsia, you got your Styracasaurs, you got your Centrosaurs, and of course, you got your Triceratops. Ceratopsians were low feeding herbivores. That is a trait they shared with the other major group, the Hadrosaurs or ‘duck-billed’ dinosaurs. However, I prefer to call ducks ‘Hadrosaur-billed dinosaurs.’ But that’s just me. You should see the looks I get from my duck hunters.
Hadrosaurs had the most complex dentition of any animal, before or since. One of the takeaways from our history of herbivory is that despite what common sense might tell us, herbivores are carnivores that learned to eat plants, not the other way around. In the evolutionary record, it is herbivores that have the most ‘derived’ traits, meaning they have changed most since our common evolutionary ancestors. So, despite our own human-centric feelings, I could argue that hadrosaur dinosaurs were the pinnacle of evolution. Evolution has been trying to recover from the set back of dinosaur extinction ever since.
In addition, in the modern world, the more complex the herbivore’s teeth, the more open their habitat. Whenever you hear experts talk about this in the modern world, you hear them say things like, ‘obviously this is because the grass is such difficult food.’ Is that obvious though? Difficult for whom? For you and me and those researchers, I suppose, but anyone who is familiar with modern ecosystems with large animals knows that grass is far easier for herbivores to eat than browse. I think that animals in grasslands have more complex teeth because in grasslands herbivores actually eat plant structural parts as a mainstay of their diet. In closed forest ecosystems, large animals (to the extent that they are even present) subsist mostly on fruit, nuts, roots, seeds, mushrooms, etc., and only fill the gaps with leaves and branches. In forests, large herbivores get only a tiny sliver of the total production of the ecosystem, whereas, in savannas with large herbivores, those animals consume a huge chunk of ecosystem production. What I am trying to say is that maybe it is possible that late Cretaceous ecosystems were very open. But this way I get to turn that one sentence into a whole paragraph.
Perhaps this is why the late Cretaceous is dominated by ceratopsians and hadrosaurs. As the ecosystem becomes more open, the high browsing long-necked Sauropods have less of an ecological advantage.
This is also of course when the largest and most amazing carnivores that ever existed lived. But this is a history of herbivory, so who cares about them.
Since we don’t know what these plants looked like we are free to speculate. Maybe one of these early ‘pro-herbivore’ Angiosperms was a kind of palmetto. We have evidence for palmettos in the Cretaceous and these plants actually have a many of the characteristics of a pro-herbivore plant, though I have never managed livestock in a place with palmettos, so I have little confidence in my knowledge of them. Another possibility would be a form of terrestrial water lily. That would be pretty cool to see. Some of our earliest evidence for Angiosperms comes in the form of water lily pollen. We have water lilies in our ditches here in Oregon and the cattle love then will grab them as far out as they can reach when the water goes down in the fall. This is important, a very common pattern that you see all across the evolutionary record. When a new, innovative taxon evolves and enters an ecosystem, they often dominate all the prime territory first. This leaves the previously dominant organisms clinging on in the periphery of the ecosystem, maybe on an island, in low fertility soils, or in aquatic environments.
Whatever the specific species, feel free to daydream about a late Mesozoic covered in a savanna whose understory is carpeted with an explosion of flowers magenta, and peach, and lavender, and aquamarine. Over these flowers roam huge herds of herbivores. On these flowers, the blood of herbivores is spilled by carnivores as big as a school bus. Pretty cool, huh?
Well cut it out, because next week we are going to move from pastoral French Impressionism to harsh Russian Brutalism. We will spend the entire blog post on the extinction of those dinosaurs and on the complete reorganization of the whole structure of the ecosystem.
(Post script: I can’t believe how long this post is. Bless you for getting to the end of it.)