I have a cycad plant-it is an ancient species, that was around in the time of the dinosaurs.
It is a fascinating plant-I have had it for 4 years now (its a hardy variety)-I keep it indoors during winter.
In four years, it has grown about an inch. Were ancient plants like these very slow growing? Or is this trait exclusive to the cycads?
I once saw a crocodile yawn, so I’m pretty sure that all dinosaurs that ever lived slept all day long.
Moving thread from Cafe Society to General Questions, where hopefully it will take root.
Crocodiles aren’t dinosaurs.
Fossilized trees from the Mesozoic era have rings comparable to today’s trees. Assuming that rings then corresponded to ‘growth’ and ‘steady state’ periods, that means they grew at about the same rate as trees today.
No, it isn’t.
It is a modern species that is descended from species that were around at the time of the dinosaurs, just like grass and gum trees and three toed sloths and every other species on the planet.
Your plant is not an ancient species. There is no reason to believe it is any more ancient than your lawn grass.
Speaking of actual ancient species, some of them would have been slow growing, just as your modern species is. That is a successful niche today and it would have been 1000 million years ago too. The vast majority of species were fast growing, just as they are today.
Many species of plants are slow growing.
I don’t know about species, but some extant plant genera do date back to the Mesozoic.
Ginkgos - the only surviving memberof their genus - have been arounda pretty long time, for example.
I doubt there is a definitive answer, some plants grow slowly and others quickly. Climatic conditions might have had an impact on average growth rates and the total amount of biomass the planet could support.
<Blake Style>
Can you please provide a cite showing that plants like this grew 1000 million years ago?
Why on earth would you believe that plants like that existed at that time?
</Blake Style>
Well, your point – it’s a modern species, albeit from an ancient lineage – is well taken. The odds, however, are in the cycad’s favor, since its lineage was around 150 million years before grass evolved, and cycads are AFAIK not noted for rapid evolution; if anything they’re very conservative.
The first land plants appear to be bryophytes from the Silurian’ vascuiar plants began in the earliest Devonian, just over 400 MYA.
True but with an important catch.
Paleozoic land floras were dominated by ferns, horsetails, and club mosses and their close relatives. They looked very much like trees as depicted by an imaginative 5-year-old.
After the post-Permian catastrophe, a Mesozoic fauna came in dominated by gymnosperms – conifers, ginkgoes, cycads, and several extinct groups. Ferns continued to be common.
With our big-animal-centric viewpoint, we tend to see the next transition as the K-T impact/traps event (65 MYA) that put paid to the (non-avian) dinosaurs and most of what used to be tagged ‘reptiles’, along with most cephalopods and a host of other creatures.
But nearly as important is the transition from Lower to Upper Cretaceous at 100 MYA. The Upper Cretaceous differed from the preceding epoch in three major ways: (1) almost all the dinosaurs we think of as typical Cretaceous dinosaurs – Tyrannosaurus, ankylosaurs, Triceratops, the duckbills, the ornithomimids, the dromaeosaurs, arose during it; (2) therian mammals – marsupials and placentals – arose and radiated during it, replacing all the Mesozoic mammals but the multituberculates and presumably the monotremes; and (3) angiosperms, flowering plants, a minor constituent of the Lower Cretaceous flora, became dominant over most niches, pressing conifers into a big-tree role and ferns into a forest-understory role and effectively suplanting everything else. This set the stage for the modern flora, although it didn’t develop until the evolution of grasses in the mid-Tertiary.
Although ferns and primitive vascular plants are capable of rapid growth, they had constraints on what niches they could fill (e.g., nothing arid). Gymnosperms characeristically are slower of growth – though there are of course numeous fast-growing ones as well. Angiosperms could regenerate after being grazed faster than gymnosperms and could outcompete ferns for most niches. A typical Southeast scene in the Upper Cretaceous would seem very familiar – piney woods with a few magnolias here and there, apparent squirrels scampering on the tree branches and opossums browsing the mast below for prey. Until a dinosaur passed through.
Eh? Ankylosaurs arose during the early Jurassic, ornithomimids during the late Jurassic, and dromaeosaurs in the mid-Jurassic.
The grass’s lineage has been around for exactly the same period of time. All life has a common ancestor. Any organism alive today has a lineage exactly as long as all others. There’s nothing about being a cycad that precludes and organism from speciation.
That should, or course, have been 100 million years ago.
Ferns continue to to thrive in arid environments even today. Ferns aren’t as *competitive *as vascular plants in an arid environment because of their mode of reproduction. But that isn’t to say that they aren’t just as *productive *in that environment. They have largely been displaced by flowering plants in all environments, but that is not the same as saying that they can’t thrive in those environments.
Once again, this may just be a result of selective pressure from angiosperms. Gymnosperms have largely been relegated to marginal environments of low fertility and aridity, to which they are better pre-adapted than angiosperms. Of course the survivors are largely going to be slower goring than the average angiosperm, because slow growth is favoured in environments of low fertility and aridity.
That doesn’t allow us to conclude that angiosperms that lived in productive regions exhibited similarly slow growth. If you did a comparison of angiosperms from environments of low fertility and aridity and angiosperms from more productive environments, you would likewise find slower average growth rates. But that’s a characteristic of the environment, not the clade.
While this was accepted wisdom for many decades, there is precious little evidence to support it, and it is being rethought by palaeoecologists. We know, for example, that even the sub-polar regions of the Cretaceous supported more animal biomass than many equatorial regions today. That strongly suggests that the vegetation then could recover *faster *than modern vegetation.
Angiosperms have numerous advantages over gymnosperms, but most of that advantage seems to be reproductive. They can produce small seeds and they can disperse genetic material rapidly and thus achieve great genetic diversity and win the arms race against animals.
Angiosperms appear to have been able to adopt a strategy of relying on chemical warfare. The diversity of toxins and unpalatable inclusions in angiosperms is much, much greater than in gymnosperms. When you compare chemical defences within clades, the difference is even more striking. A single genus of gymnosperms will include species that produce glycosides and cyanogenics and oxalates and a dozen other distinct chemical defences. In the gymnosperms the toxins will be amazingly conservative across entire families. What that means is that the angiosperms have diversified to avoid predation. Any specie of animal has to become a specialist in eating just one species to have any hope of keeping pace in the arms race, and very rapidly it loses the ability to eat many other plants. In contrast, the chemical defences of gymnosperms are so conservative that if an animal can eat one member of a family, it can almost certainly eat them all.
In the face of predation, gymnosperms only really have two options: recover fast or engage sclerophylly. Recovering fast is, of course, extremely wasteful of resources. Any gymnosperm that has to regrow 10% of its biomass every week isn’t never going to compete against a suite of angiosperm species that, on average, only need to replace 1%. Sclerophylly doesn’t work well in productive environments because it precludes responding to the environment itself. Tissue can only be produced once every few years, so as conditions change, you’re stuck with a one-size-fits-none body form. So in productive environments gymnosperms just couldn’t compete.
But sclerophylly is a great tactic for unproductive environments. It’s harder for animals to evolve a defence against leaves that are simply indigestible and spiky, and in those environments nutrients are too scarce to be able to grow new tissues in response to environmental fluctuations. One-size-fits-all is enforced on all plants. So in those environments the gymnosperms have managed to compete well precisely because they are slow growing.
The upshot being that most gymnosperms that have managed to compete with angiosperms are slow growing. But that doesn’t mean that all gymnosperms have always been slow growing. It just means that only the slow growing forms are competitive. In contrast angiosperms in productive environments actually get eaten less than gymnosperms, which is why they outcompete them.It’s not that they recover any faster, it’s that they avoid needing to recover.
Considering the competition in the Pre-Cambrian, just about any land plant, no matter how slow growing, would have been successful. 
It doesn’t answer the question about plants, but you may be interested to learn that a Jurassic therian mammal was published last year.
That’s impressive. How old is the little fella?
Actually, that’s not true at all. There are plenty of ancient species out there that are the exact same as they were millions (or in a few cases, hundreds of millions) of years ago.
Take the Horseshoe Crab for example. Or the crocodiles. Or any of the other “living fossils” that haven’t changed since their fossil ancestors left records.
Oh God.
We’ve debunked this nonsense at least 4 times in the last 3 months. And it keeps coming back.
The least you could have done is read your own link, which states outright that what you just posted is utterly incorrect. Since you didn’t bother to do so, it seems that this is willful ignorance, and I honestly don’t have the energy required to keep fighting willful ignorance on this topic.
So all I will just say is that everything you just posted is complete nonsense.
While the term “exact” in the other post is probably the wrong choice, this quote about the coelacanth seems to imply the post was substantially accurate if the term “exact” were replaced with “substantially the same”:
“The coelacanth is thought to have evolved into roughly its current form approximately 400 million years ago.[4]”
It keeps fighting back.
Note that there are several families, genera & species of coelacanth. The extant genus, Latimeria, is only the most recent genus. It remains very similar to earlier forms, but the fossil versions are classified as different genera/families because there are differences between them and the modern genus (or, more correctly, Latimeria was erected as a separate genus because the extant forms exhibited differences from the fossil forms). The overall form of coelacanths as a group has remained conservative over hundreds of millions years, but that is not the same as saying that one species has persisted, unchanged, for that whole time. Latimeria itself has no fossil record to speak of, so we don’t know exactly how old it is as a genus.