When we talk about the universe expanding, we generally are assuming that the fundamental constants which control the strength of gravity, electromagnetism, the strong nuclear force (etc.) are unchanged. Yes, there are some current theories which postulate that the constants may have changed since the Big Bang, but those theories aren’t meant to address the fundamentals of Hubble expansion.
Therefore, tightly bound objects (like nuclei, atoms, molecules, and solids/liquids) would not have expanded. Their sizes [bond lengths] are unchanged. Very large, less tightly bound objects, like galaxies and local galactic clusters will have been large enogh to experience some expansion as the universe expanded, but their properties would also change (i.e. they would assume the shapes and behaviors of less dense galaxies, because they would interact more weakly internally on average) When we get to extremely large features, like galactic sheets and voids, there is very little long-diastance interaction between objects to begin with (try measuring or calculating the pull of even a nearby star, much less galaxy)
On scales larger than a solar scale (e.g. a gaseous cloud condenssing into a star and planet) the higher density of the early universe meant conditions were very different, so astronomical structures evolved differently (also, the amounts of various elements were different, before stellar fusion from early generations of stars produced heavy elements beyond hydrogen and a trace of helium)
The expansion in the mere hundred million or so since the dinosaurs hasn’t been enough time to really do all that much expansion. Also, Hubble’s constant (which can be used to estimate the rate of expansion) has decreased, as the average velocity of various astronomic objects is decreased from their initial Big Bang values, due to mutual gravitation. (As the “rubber band” between galaxies got stretched, the galaxies losewed down)
The time since the era of the dinosaurs was about 2/3-3/4 of 1% of the time since the Big Bang, but the net expansion since then was even less. In the late 20th century, Hubbles “constant” was estimated as 50-100 km/sec per megaparsec. (the best current esitmate seems to be 72 +/-8 ). Since a megaparsec is 3x10^19 km, you can see that the expansion is very slow indeed, even over very large distances [This is a crude impression, complicated by the fact that we can only observe very distant objects where they were, and as they were, hundreds of millions of years ago. – on year per light year of distance)
