Pressurized gas can act like a liquid. And at sea level, thick atmosphere would certainly be pressurized. smaller lungs aren't relevant to the issue that comes

Pressurized gas can act like a liquid. And at sea level, thick atmosphere would certainly be pressurized. smaller lungs aren't relevant to the issue that comes up regarding extremely large dinosaurs. Because it's not an issue of lung capacity, or oxygen supply per liter of blood. We're not talking about animals that are comparable to modern day elephants. Have you seen the size comparisons of dreadnoughtus to blue whales? They are enormous. The physics start to come into question. Just the sheer weight of skin and muscle hanging on bone. Even if the bones are hallow and even if the muscle is somehow more efficient due to increased oxygen in the blood. Like a whale plopped on dry land, they'd collapse under their own weight standing up. Much less, hunting, mating, and fighting. furthermore the thick atmosphere theory helps solve another tricky mystery which is the, Mesozoic Paleoclimate Paradox During the Mesozoic era a remarkably homogeneous flora of tropical and temperate plant species covered the Earth. Plants such as ferns, laurels, palm trees, and Magnolia that could not withstand freezing, thrived at 70 degrees north and south latitude. Many of the same plants that existed near the equator were also thriving at the Polar Regions of the Earth. For decades paleoclimatologists have tried to explain the Mesozoic paleoclimate paradox. If they matched the vegetation of the lower and middle latitudes then their climate models were too cold at the higher latitudes. If they matched the warm temperatures of the Polar Regions then their models projected an unrealistic hot sauna for the rest of the planet that again conflicts with the geological evidence. The reason their climate software models fail to match the Mesozoic climate is because perhaps the paleoclimatologists make the incorrect assumption that the Mesozoic atmosphere was the same thickness as the present. As stated earlier, the variation of temperatures around a planet whether it is day or night or according to latitude, is a function of the thickness of a planet’s atmosphere. Planets or moons with no atmosphere will have the most extreme difference in temperatures, planets such as the present day Earth and Mars that have relatively thin atmosphere will still have these differenced in temperatures but much less extreme, while extreme thick atmosphere planets such as Venus and the Mesozoic Earth show almost no temperature difference at all according to latitude.