SocraticGadfly: Are a number of American trees range-limited today by no gomphotheres?

January 09, 2023

Are a number of American trees range-limited today by no gomphotheres?

First, what is a gomphothere? Per the link, an extinct, largely Northern Hemisphere family of animals related to elephants.

Second, are they the reason some trees aren't well spread today? Blogging friend Tales of Whoa says yes, but, outside the avocado, whose large seed side says it would have needed a big animal to shit it out, not so fast. (And, he doesn't link to an outside source for these claims.)

Take the Osage orange, aka hedge apple, aka bois d'arc baseball. Wiki explicitly calls it a just so story to claim this is an archaic evolutionary adaptation. It notes that squirrels eat the seeds and deer eat the whole fruit today. Indeed, while out at Hagerman NWR New Year's Eve, I saw several that had been eaten by either deer or wild hogs, as shown at left.

Also, speaking from Tex-ass, the range of the bois d'arc almost exactly maps onto that of the cedar elm and nobody's ever said their range is limited because of an extinct family of elephantine animals.

Or, the honey locust. Like with mesquites, livestock eat the bean pods, which I knew without the Wiki link. Wildlife today eat them too. AFAIK, neither the pod sheaths nor the beans themselves are tougher than common mesquite, and certainly not tougher than screwbean mesquite.

Papaya? Southern end of most gomphotheres' range. May have been dependent on giant sloths spreading them, but, that wasn't Tales' claim.

Pawpaw? Spread by mammoths and mastodons, not gomphotheres, it appears.

Persimmon? Eaten by many small-sized mammals today.

As an avid birder, respectfully, he should also know that thorns and spines that might deter large animals, whether mammals or larger birds, don't deter small ones.

Finally, the relict bigtooth maples in Big Bend and Guadalupe Mountains national parks in Tex-ass' trans-Pecos show that species of flora can become geographically confined for reasons that have nothing to do with the extinction of species, genera or families of fauna. (In their case, it's the altitude of sky island mountains mixed with climate change.)

I debated about tagging him, but eventually subtweeted instead.


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