Evolution: air-filled bones strong but lightweight (Introduction)

by David Turell , Saturday, March 18, 2023, 15:17 (403 days ago) @ David Turell

Helped dinosaurs to reach giant size:

https://www.sciencealert.com/this-adaptation-allowed-dinosaurs-to-not-only-survive-but-...

"It's sometimes difficult to imagine how the planet we call home, with its megalopolis cities and serene farmlands, was once dominated by dinosaurs as big as buses and five-story buildings.

"But recent research has helped deepen our understanding of why dinosaurs prevailed: the answer may lie in their special bones, structured like Aero chocolate.

"Brazilian paleontologist Tito Aureliano found that hollow bones filled with little air sacs were so important to dinosaur survival, they evolved independently several times in different lineages.

"According to the study, aerated bones evolved in three separate lineages: pterosaurs, technically flying reptiles, and two dinosaur lineages, theropods (ranging from the crow-sized Microraptor to the huge Tyrannosaurus rex) and sauropodomorphs (long-necked herbivores including Brachiosaurus).

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"The variant the Brazilian team studied was aerated vertebrae bones, which would have enhanced the dinosaurs' strength and reduced their body weight.

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"The study found no common ancestor had this trait. All three groups must have developed air sacs independently, and each time in slightly different ways. (my bold)

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"Echoes of this dinosaur legacy lie in many animals alive today. It is not only long-dead animals which found this type of adaptation useful. Many bird species living today rely on hollow bones to fly.

"Others animals use the air sacs to buttress and strengthen their large bones and skulls, without weighing them down.

"An excellent example of this is the elephant skull. Inside elephant skulls are large air sacs which allow the animal to move its massive head and heavy tusks without straining the neck muscles.

"The human brain is also protected by two layers of hard, compact, bone (inner and outer tables) which sandwich a layer of softer, spongey, and aerated bone in between, known as the diploe. This allows our skulls to be light, but strong and able to absorb shocks to cranium."

Comment: note my bold, no precursors!!! This gives us another design gap along with the Cambrian, etc.