Friday, May 07, 2021
Brilliant experiment, brilliant description
Paleontologists at Yale are using casts of the inner ears of dinosaurs to infer the lifestyle of the dinos.
Because we've been making such casts of modern skulls for a long time, we know how the configuration of the vestibular system correlates with motion patterns of living animals.
Default mammals, with spine and head horizontal, have very little resonance. The larynx is immediately followed by the mouth, which is typically open on both sides. There's no cavity or tube or column after the larynx.
Humans, with spine and head vertical, are built like a pipe organ or train whistle. The pharynx is a closed Helmholtz resonator above the larynx, with the mouth branching off and providing another closed resonator.
Birds are bugles. The mouthpiece or reed is at the bottom of a long resonator with muscular control. The beak is open on both sides like a cat, but the beak isn't needed as a resonator.
Resonators phase-lock the song into discrete notes.
The cochlear inferences are mixing fox-type and bird-type dinos together, which misses an important part of the signaling and coding ability. Bird-like discrete notes make language possible. Fox-like howling is a signal, but doesn't allow for detailed coding by discrete symbols.
The form of the vestibular system is a window into understanding bodies in motion. One vestibular cluster corresponded with "sophisticated" fliers, species with a high level of aerial maneuverability. This included birds of prey and many songbirds. Another cluster centered around "simple" fliers like modern fowl, which fly in quick, straight bursts, and soaring seabirds and vultures. Most significantly, the inner ears of birdlike dinosaurs called troodontids, pterosaurs, Hesperornis, and the "dino-bird" Archaeopteryx fall within this cluster.In other words, dinobirds were chickens. We also know how the configuration of the cochlea correlates with frequency range of living animals.
Bhullar said the data suggest that the cochlear shape's transformation in ancestral reptiles coincided with the development of high-pitched location, danger, and hatching calls in juveniles. It implies that adults used their new inner ear feature to parent their young, the researchers said. "All archosaurs sing to each other and have very complex vocal repertoires," Bhullar said. "We can reasonably infer that the common ancestors of crocodiles and birds also sang. But what we didn't know was when that occurred in the evolutionary line leading to them. We've discovered a transitional cochlea in the stem archosaur Euparkeria, suggesting that archosaur ancestors began to sing when they were swift little predators a bit like reptilian foxes."An important distinction on the production side might complicate these inferences about the reception side. The configuration of the vocal tract determines the style of singing.
Default mammals, with spine and head horizontal, have very little resonance. The larynx is immediately followed by the mouth, which is typically open on both sides. There's no cavity or tube or column after the larynx.
Humans, with spine and head vertical, are built like a pipe organ or train whistle. The pharynx is a closed Helmholtz resonator above the larynx, with the mouth branching off and providing another closed resonator.
Birds are bugles. The mouthpiece or reed is at the bottom of a long resonator with muscular control. The beak is open on both sides like a cat, but the beak isn't needed as a resonator.
Resonators phase-lock the song into discrete notes.
The cochlear inferences are mixing fox-type and bird-type dinos together, which misses an important part of the signaling and coding ability. Bird-like discrete notes make language possible. Fox-like howling is a signal, but doesn't allow for detailed coding by discrete symbols.Labels: Grand Blueprint, Language update
¶ 4:51 AM
