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Stop Ruining It!
(lemmy.ml)
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this post was submitted on 28 Jul 2023
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How do we know anything about their visual acuity or sense of smell?
It's amazing how much you can infer from the shape and size of the various features of a bone.
For eyesight, simple physics: bigger is better. That's why we build huge telescopes, they collect more light and have better angular resolution than small ones, and the same goes for eyes. In addition, birds in general have very good eyesight and dinos are very closely related to birds. For T. rex, they also have narrow snouts allowing for excellent binocular vision.
Smell is similar—big nasal cavities allow for big olfactory organs, meaning a lot of receptors that can bind with airborne molecules.
That really is amazing. But why did we previously think that the T-Rex's eyesight was terrible, then (as seen in the first Jurassic Park movie)?
The JP movie (and book, too) took a lot of artistic license. Which is understandable; if the T. rex was depicted as having realistic senses, it would have been a quite short movie with a grizzly ending. And realistic velociraptors wouldn't have been as intimidating—they's been small and quite dumb.
What I really wish is that they'd done the vocalisations of T. rex more realistic—the high pitched screaming was not right. Imagine if the first sign of the rex wasn't ripples in the water glass but the barely perceptible sub-20 Hz vocalisations from the distance that grow loud and nauseating as it gets close. Granted, not many sound systems could reproduce it—mine can and it's glorious.
Just curious, since most postpone can only hear from 20-20k Hz or something and since most sound systems don't go lower, what kind of media to you listen to that actually go that low? Why would anyone record it if only you and a few other audiophiles can reproduce it?
Our hearing has no hard limit in low frequencies--sensitivity falls off at the extreme, but it doesn't mean you can't hear sounds below 20Hz. That 20 Hz limit is often quoted simply because the tests that were done in the past didn't measure lower. In reality, most people can hear 15 Hz and lower, just the threshold of hearing goes up. That's ignoring tactile effects of these frequencies, which adds a whole new dimension of sensing ULF.
Many movies have a crapton of LFE below 20Hz (for example Blackhawk Down has a scene with single-digit ULF effects), though you generally get it only on blu-ray or DVD releases, streaming services tend to have a neutered sound mix. Today's subwoofer tech has advanced to a point that even commercially available subwoofers can do 20 Hz and lower; bespoke sealed cab systems with 8 or more 18" or 21" drivers and a dozen kW of amplification can do single digits at 120+ dB in-room. Head over to avsforum.com for discussion and home cinema system show-offs :)
Why would anyone put these frequencies on a record? Well, sound designers and mixers tend to have very good sound systems, both at work and at home, and are generally very passionate about their work. Same thing as guitarists are very picky about their instruments and pedals, while the average concertgoer or radio listener couldn't make out any difference between a 500€ and a 10000€ guitar, never mind different pickups and overdrive pedals.
We can infer a lot from the size and position of its eye sockets. The eyes were position so as to be forward facing, not side facing like an herbivores.
This article has a really good pocture in it showing you a direct view of the eye sockets from the snout. Its cheekbones and nostrils are designed so that it's visual field easily would clear them, giving it binocular vision like ours. The study that article discusses used fossils to model what dinosaur faces would have looked like, then examined their visual field. The trex had around a 55 degree binocular range, which is larger than many predatory birds that we know to have excellent vision over long distances. It's eyes were also gigantic, allowing for a lot of light to get in.
As for sense of smell, I don't know how we know about it; I think we assume it did because it's nostrils were also huge, and because most animals today have good senses of smell, meaning it's a good adaptation to have and likely would be present on the largest land predator to ever exist.
It seems like a lot of guesswork based on a small amount of evidence.
Because of being extremrly large and nonflying I don't see why a trex would gain an advantage by being able to a see a mouse from kilometers away like a modern bird if prey. Between that the millions of years of evolution between them, I wonder if their eyes were less developed in some way.
Given that we have a lot of evidence that trex would swim to islands in the middle of north America to hunt (there was an inland sea here 66 million years ago), I think them having very good long distance vision actually makes a lot of sense. If they were hunting across flat crasslands and looking for food on islands across stretches of water then it would make a lot of sense that they need such good vision.
They don't need to see a mouse from kilometers away, they need to see if that big Grey blob on the Shor of the island 2km across a strait is a washed up icthyosaur, or a triceratops, or just a rock.