Complex question. For one I am not sure about how strong this trend is, as I’ve never seen representative figures for this. I’d agree it is more likely it is left-wing than right-wing, but there are probably fields of interest that are considerably more left-wing, on average, than paleontology.
As for possible reasons, there is quite a lot of empirical evidence that cognitive ability, the tendency to think scientifically and political views are all strongly linked.
There is a strong inverse correlation between intelligence and religiosity, see for example:
Lynn, R., Harvey, J. and Nyborg, H. 2009. Average intelligence predicts atheism rates across 137 nations. Intelligence 37 (1): 11–15.
Nyborg, H. 2009. The intelligence–religiosity nexus: A representative study of white adolescent Americans. Intelligence 37 (1): 81–93.
There is also evidence that higher intelligence tends to predict more socially liberal, "leftist" or "woke" views, E.g.:
Solon, I.S. 2015. Scholarly elites orient left, irrespective of academic affiliation. Intelligence 51: 119–130.
Hodson, G. and Busseri, M.A. 2012. Bright Minds and Dark Attitudes. Psychological Science 23 (2).
Dhont, K. and Hodson, G. 2014. Does Lower Cognitive Ability Predict Greater Prejudice? Current Directions in Psychological Science 23 (6).
Now I can of course only speculate as to the causality underlying these correlations, but it doesn’t take much of a leap in imagination to come up with an explanation for why more intelligent people are less religious and less bigoted than less intelligent ones; it harder to develop or hang onto viewpoints that cannot be rationally justified when you’re more intelligent, be they religious (religions after all having basically been invented as a way to explain phenomena that cannot be explained rationally) or socially conservative (nobody has yet been able to offer a rational justification for racism or homophobia).
Interestingly enough, there doesn’t seem to be the same correlation of higher intelligence with economically left-wing views, or at least not as clearly:
Carl, N. 2014. Verbal intelligence is correlated with socially and economically liberal beliefs. Intelligence 44: 142–148.
I speculate again, but it seems quite plausible that since individuals with higher intelligence are also, on average, more wealthy, they may tend to oppose wealth-redistribution out of self-interest (although that hypothesis admittedly has some holes, such as that obviously the three people who own more than the entire lower half of the US population wouldn’t be enough to cause this correlation all on their own). Of course intelligence doesn’t automatically mean being more selfless or "morally upstanding", so it makes sense why more intelligent people may be more averse to causing harm to others (e.g. through racism, homophobia, science denial) when there is no profit in it, but will happily do so (e.g. opposing wealth redistribution) when it does.
So as for how this related to "this interest", this interest being paleontology, or more broadly natural sciences;
Science is obviously heavily skewed towards irreligion relative to the base population (even in a religiously fundamentalist country like the US):
Simpson, A. and Rios, K. 2019. Is science for atheists? Perceived threat to religious cultural authority explains U.S. Christians’ distrust in secularized science. Public Understanding of Science 28 (7).
The causative link here is rather obvious, as religion has many central tenets that are inherently science-denialist (not to mention that religious communities tend to indoctrinate their members against science, fearing, understandably, that science is a fundamental threat to their existence). Of course you can explain them away and just believe in the parts of your religion that you want to believe in, and I’m not saying that there is anything wrong with that at all (quite the opposite), but ignoring some parts of your religion’s teaching because they are obviously wrong will naturally set a precedent to make you more likely to question the others as well, possibly leading to rejection of religion as a whole among people with a scientific mindset.
People in the natural sciences also obviously tend to have above-average intelligence. See e.g. the statistics by field of study here:
international-iq-test.com/en/I trust there is no need to explain why more intelligent people tend to do better at, and are more interested in science than less intelligent people. Being good at science obviously requires a certain level of intelligence, and doing stuff that one isn’t good at just isn’t as much fun, by and large.
So both of these factors, being related to each other and to more socially liberal views, would make us expect that people with an interest in science, such as paleontology, will probably also be more socially liberal, i.e. "left-wing" in one sense of the word, or "woke" if you prefer. For what it’s worth, the above matches my personal observations; I do not know a single person in science who holds views that one could describe as "socially conservative" across the board, though I know several who are fairly hypocritical and ignore the values they claim to subscribe to as soon as it’s in their interest, and also quite a number of very economically liberal (i.e. right-wing) people.