Sure it is worth considering. I suppose this really might deserve it's own thread. But where is the evidence for such an anomaly. As Tommy said I think is has to due with available elements in the rich atmosphere at the time. The trees were also huge also. But when scientists try to explain if or why or how an animal is supposed to operate they sometimes get it wrong. The bumblebee wasn't supposed to be able to fly, but it does.
But we've seen (at least hypothesized) strange differences in the past. The expansion of space and time at unbelievable rates. So fast that we had to invent explantions like "inflatons" that are the backbone of inflationary theory. The variable speed of light (VSL)is a theory that may explain the horizon problem in the big bang.
Either way I hane never seen a coherent theory of variable gravity even though there might be one. If there is, I'd like to read it. Send your links if you have them. Certainly we like to think we know it all. But I'm just guessing that we don't. Ahhh, the vanity.
I still maintain that we know so little about gravity....and nature! We humans so often say that something in the nature is not possible only to have nature promptly prove us wrong.
