P-T: Infrasound Warfare and the Terror Plumes

(I shrunk the title. Now it sounds like the Permian Mass Extinction Event abbreviation)

So, here you go guys, you have two paleo-turtorials for one. YAAAAAAAAAAAAAAAAAAAY

Okay, first off: Infrasound. Most large bodied animals can produce it, from alligators to elephants. A while back, there was this conversation on the Saurian Discord on dinosaur ultrasound. Basically, a cassowary can rattle your body with its guttural calls thanks to infrasound. Scale that up to the size of a T.rex, and it could damage your organs. Scale that up to the size of a large sauropod, and you may be dead.

Now, why would large theropods like T.rex even need such powerful shockwaves of infrasound? Well, one might say maybe it could act as a stun gun against prey, but of course, that is a horrible strategy. Imagine your just standing there in the middle of no where when all of a sudden, someone behind you is running out you and screaming. You would immediately run as fast as you can away from them (or maybe not, IDK). What I think is that T.rex and other large theropods used their infrasound on each other in territorial disputes. This is seen in one modern apex predator: the tiger.

www.newscientist.com/article/d…

It was once thought that tigers used the infrasound part of their roars to stun their prey. However, new research has shown that tigers actually use these powerful shockwaves on each other during disputes for territory. While large theropods don't have a larynx, they were capable of infrasound if their modern descendants and their crocodilian cousins are any indication. Like any modern land predator, T.rex and other large theropods probably wanted to avoid confrontation as much as possible, so maybe when they did come into contact, they try to intimidate each other using powerful infrasound shockwaves. 

As for sauropods, they probably used infrasound like elephants, were they communicate over long range with other herds.

Secondly: Terror Birds. We all know the awesomeness that is the family Phorusrhacidae. These hyper-carnivorous birds were the top predator of South America for almost 60 million years. They have heads the size of horses that could be used as deadly bludgeons, massive claws that can be used to kick and stomp prey, and to top it all off, they probably swam or island hopped here into North America before the formation of the Panama Land Bridge. However, they may have been much more extravagant than we think.

Every depiction of a terror bird I've ever seen show them to have tiny stumps of a wing, or have them be covered in small pennaceous feathers, but if modern birds have taught us anything, terror birds were probably more extravagant than that. 

i.huffpost.com/gen/2824166/thu…

Here we have a skeletal diagram of Llallawavis, a newely described terror bird that is beautifully complete. As you can see from the skeletal, the arms of Llallavis are particularly long, comparable to that of a modern rhea today. This suggests that the wings were probably not stumps even in the largest of terror birds. Another thing I might want to add is the evolution of terror birds. Terror Birds along with their cousins, the seriamids, evolved from birds with the ability to fly in the Southern Hemisphere in the Late Cretaceous (we have bones of a seriamid like bird from the Late Cretaceous on an island in Antarctica). With 60 million years of evolution where they remained totally flightless, it may stand to reason that terror birds may have lost their aerodynamic feathers which eventually became just downy feathers like in modern ratites. This is well seen in Jonagold's restoration of Kelenken, the tallest of the terror birds.

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However, maybe instead of the pennaceous wing feathers seen here, large terror birds had large, fluffy feathers sprouting out of their arm, like those of ostriches and rheas. Perhaps terror birds were a lot more extravagant than we thought, with the males using their feathered plumes to impress the females during courtship, or maybe they were used to help steer the terror bird when hunting for prey. This is something that most likely varies among all terror bird species. For example, cassowaries and ostriches are both ratites, yet cassowaries have small arms that don't support an extravagant plume like in ostriches. So while these massive plumes may not apply for all terror birds, its interesting to think about what they looked like in life. 

Well, I hope you like this new edition of Paleo-Turtorials. WWK episode coming soon and maybe the long awaited second edition of the Bears vs. Cats series.