Palms and dinosaurs co-evolution

[Mauna Kea Cloudforest]

I was trimming my livistona the other day, I have to say, these things have the most awful armament, talk about razor blade sharp, especially saribus and australis and this got me wondering why the heck a palm would even evolve such a defense. it's not like it helps to repel any major contemporary mammal aside perhaps gorillas and elephants. Most mammals aren't big enough to even want to eat palm leaves. Certainly there aren't any mammals in Australia that are big enough to care.

So what's the evolutionary need for armament on just the petioles the type you find on livistona and brahea? Was it the giant vegetarian dinosaurs? Does the armament somehow keep them from eating the leaves?

I tried to read up on paleobotany, and it seems conifers were the dominant form of vegetation in the early Mesozoic Era, and the closest plant resembling a palm would be a cycad. So unlike the lovely Hollywood pictures, no palms during the dinosaur era. Palms were the first monocots to come along after the mass extinction, but the dinosaurs were gone by then.

So what sort of evolutionary force would produce spines on petioles?

[sarasota alex]

The oldest known palm fruits belonging to Hyphaenocarpon aegipticum and Nypa bartini are 112 myo. The oldest evidence of trunking palms (Palmoxylon andevagense and P. ligerinum) is 95 myo. The oldest known leaf is that of a Sabalites carolinensis and is 86 myo. The leaf is palmate. And since palmate leaved palms evolved from pinnate leaved palms by 86 myo both must have already been in existence. These are confirmed fossils. There are older fossils attributed to palms, but those are not universally accepted in the paleobotanical community.

Dinosaurs didn't go extinct until 66 myo. So they co-existed with palms for at least 56 million years, possibly longer.

Also Australia had a very diverse marsupial megafauna with many large herbivores that existed for tens of millions of years. Marsupial tapir (Palorchestes azael) lived until 11,000 years ago. Overall existed for almost 12 million years. It was 2.5 meters long and had hind legs strong enough to stand up. It had koala-like claws to pull down leaves and tongue anatomy points to giraffe-like feeding habits. There is your reason for the Livistona leaf armament.

[PANGEA EXPRESS]

im sure a dino would have no problem with gnawing at those petioles lol

I always figured some palms had spines as a symbiotic relationship with smaller fruit spreading critters. For example the palm would provide a safe protected environment for a bird nest while the bird eats the fruits and spreads the seeds.

just one possibility.

[tropicbreeze]

Evolution is a continuous process. Do you think this may be a new evolutionary trend - a Livistona growing as an epiphyte in the fork of a Eucalyptus?

[Zeeth]

The oldest known palm fruits belonging to Hyphaenocarpon aegipticum and Nypa bartini are 112 myo. The oldest evidence of trunking palms (Palmoxylon andevagense and P. ligerinum) is 95 myo. The oldest known leaf is that of a Sabalites carolinensis and is 86 myo. The leaf is palmate. And since palmate leaved palms evolved from pinnate leaved palms by 86 myo both must have already been in existence. These are confirmed fossils. There are older fossils attributed to palms, but those are not universally accepted in the paleobotanical community.

Dinosaurs didn't go extinct until 66 myo. So they co-existed with palms for at least 56 million years, possibly longer.

Also Australia had a very diverse marsupial megafauna with many large herbivores that existed for tens of millions of years. Marsupial tapir (Palorchestes azael) lived until 11,000 years ago. Overall existed for almost 12 million years. It was 2.5 meters long and had hind legs strong enough to stand up. It had koala-like claws to pull down leaves and tongue anatomy points to giraffe-like feeding habits. There is your reason for the Livistona leaf armament.

Out of curiosity, why is the thought that palmate leaves evolved from pinnate leaves? I had always assumed that palmate came first, and that pinnate evolved second, based off the fact that Phoenix have pinnate leaves in a subfamily of palmate and costapalmate palms, suggesting to me that they evolved to be pinnate from palmate ancestors (though admittedly this could have easily happened even if palmate leaves evolved from pinnate palms).

[Zeeth]

Also Axel, if you think the spines on Livistona are nasty, you should look at Acrocomia aculeata

[sarasota alex]

The oldest known palm fruits belonging to Hyphaenocarpon aegipticum and Nypa bartini are 112 myo. The oldest evidence of trunking palms (Palmoxylon andevagense and P. ligerinum) is 95 myo. The oldest known leaf is that of a Sabalites carolinensis and is 86 myo. The leaf is palmate. And since palmate leaved palms evolved from pinnate leaved palms by 86 myo both must have already been in existence. These are confirmed fossils. There are older fossils attributed to palms, but those are not universally accepted in the paleobotanical community.

Dinosaurs didn't go extinct until 66 myo. So they co-existed with palms for at least 56 million years, possibly longer.

Also Australia had a very diverse marsupial megafauna with many large herbivores that existed for tens of millions of years. Marsupial tapir (Palorchestes azael) lived until 11,000 years ago. Overall existed for almost 12 million years. It was 2.5 meters long and had hind legs strong enough to stand up. It had koala-like claws to pull down leaves and tongue anatomy points to giraffe-like feeding habits. There is your reason for the Livistona leaf armament.

Out of curiosity, why is the thought that palmate leaves evolved from pinnate leaves? I had always assumed that palmate came first, and that pinnate evolved second, based off the fact that Phoenix have pinnate leaves in a subfamily of palmate and costapalmate palms, suggesting to me that they evolved to be pinnate from palmate ancestors (though admittedly this could have easily happened even if palmate leaves evolved from pinnate palms).

I learned in on Palmtalk!

Dr. Dransfield actually elaborated on this here http://www.palmtalk.org/forum/index.php?/topic/21873-palmate-vs-pinnate/?p=365101 a few years ago. The accepted idea is that the earliest leaves were pinnate, then twice palmate palms evolved from pinnate and twice pinnate palms evolved from palmate. Basically Phoenix did evolve from palmate-leaved palms, but Phoenix, Arenga, Wallichia and Caryota are the only pinnate (or bi-pinnate) palms to do so. There rest of the pinnate palms were originally pinnate.

[Zeeth]

The oldest known palm fruits belonging to Hyphaenocarpon aegipticum and Nypa bartini are 112 myo. The oldest evidence of trunking palms (Palmoxylon andevagense and P. ligerinum) is 95 myo. The oldest known leaf is that of a Sabalites carolinensis and is 86 myo. The leaf is palmate. And since palmate leaved palms evolved from pinnate leaved palms by 86 myo both must have already been in existence. These are confirmed fossils. There are older fossils attributed to palms, but those are not universally accepted in the paleobotanical community.

Dinosaurs didn't go extinct until 66 myo. So they co-existed with palms for at least 56 million years, possibly longer.

Also Australia had a very diverse marsupial megafauna with many large herbivores that existed for tens of millions of years. Marsupial tapir (Palorchestes azael) lived until 11,000 years ago. Overall existed for almost 12 million years. It was 2.5 meters long and had hind legs strong enough to stand up. It had koala-like claws to pull down leaves and tongue anatomy points to giraffe-like feeding habits. There is your reason for the Livistona leaf armament.

Out of curiosity, why is the thought that palmate leaves evolved from pinnate leaves? I had always assumed that palmate came first, and that pinnate evolved second, based off the fact that Phoenix have pinnate leaves in a subfamily of palmate and costapalmate palms, suggesting to me that they evolved to be pinnate from palmate ancestors (though admittedly this could have easily happened even if palmate leaves evolved from pinnate palms).

I learned in on Palmtalk!

Dr. Dransfield actually elaborated on this here http://www.palmtalk.org/forum/index.php?/topic/21873-palmate-vs-pinnate/?p=365101 a few years ago. The accepted idea is that the earliest leaves were pinnate, then twice palmate palms evolved from pinnate and twice pinnate palms evolved from palmate. Basically Phoenix did evolve from palmate-leaved palms, but Phoenix, Arenga, Wallichia and Caryota are the only pinnate (or bi-pinnate) palms to do so. There rest of the pinnate palms were originally pinnate.

Thanks!

[Mauna Kea Cloudforest]

Alex, I had not heard about the giant marsupials, now it makes sense why there would be such nasty spines on livistona. Not so sure about dinosaurs co-existing with palms, though, as from what I read it seems the monocots didn't show up until after the first mass extinction, which included the extinction of the dinosaurs Keith, I was less puzzled by Acronomia, I think the Acronoma has a very contemporary mammalian defense system, the spines are everywhere and therefore should be effective at keeping rats and the likes out of the palm. Not much different from any other spiny plant these days. Livistona, on the other hand seems like it has an outdated adaptation which now just makes it annoying to prune the darn things.

Alex, thanks for that reference, this is very interesting. Quoting Dr. Dransfield's:

"The molecular phylogeny and the combined molecular and morphological phylogenies unequivocally provide evidence for the evolution of palmate leaves from pinnate leaves, at least twice, and the evolution of pinnate leaves from palmate twice. Thus Mauritia with a reduplicate palmate leaf arose out of the core of the pinnate leaved Calamoids, and the Coryphoids evolved out of the core pinnate leaved palms. Phoenix evolved out of the core of the Coryphoids (palmate to pinnate) as did the weird Caryotoids)."

So If I am understanding this right, the three separate evolutionary paths are

pinnate (Calamoids) -> Palmate (Mauritia)

pinnate (Calamoids) -> Palmate (Coryphoids) -> Phoenix

pinnate (Calamoids) -> Palmate (Coryphoids) -> Caryotoids

Which adds up to 2 x pinnate -> palmate and 2 x palmate -> pinnate.

I wonder where sabal fits in all this, it seems like an ancient genus, especially given the hardiness of this palm in places where it needs none, like Puerto Rico and the rest of the Caribbean and Central America. I bet those were pretty wide spread at one point in time.

[Funkthulhu]

Unneeded and biologically expensive morphology doesn't last long from an evolutionary standpoint. Things like spines and thorns may stick around for a bit longer, but if there are no herbivores to kill off spineless mutations the plants with those defenses don't have that much of an evolutionary advantage.

It probably varies from plant to plant, but spines on trunks don't necessarily defend against leaf eaters. I suspect a spiny trunk was developed to deter smaller climbing fruit-eaters from accessing the seeds before they were developed fully. Also, keep in mind that the mammalian Mega-fauna has only been extinct for 50-200k years, a blink of the eye geologically. Many of those large species were the key herbivore in their environment.

Smaller (especially island) species have gone extinct in only the last few centuries. Most ecosystems are still trying to adapt to these losses. Some may not recover. A good example is the Sideroxylon grandiflorum of Mauritius, often called the Dodo Tree. It is theorized that the extremely thick and hard endocarp needs to be abraded in the gizzard of the now extinct Dodo before germination. There are now only 13 of these trees left, all estimated to have sprouted as the last dodos died out.

However, if monkeys, birds and other smaller fauna are still going at spiny palms for the fruit (before the ripe stuff drops to the ground), these spines are still necessary to prevent looting of undeveloped seeds. Furthermore, I am curious how many palms with spiny leaves are understory dwellers and susceptible to browsing by still living herbivores?

anyway, ramble ramble ramble, post....