This comment seems to be generating downvotes, but I find the questions fascinating. It is a stretch to say the fossil record rules out any evolutionary changes to anacondas. However, if anacondas represent another form of so-called "living fossils" [0], it is interesting to think about what makes them resistant to the change that seems to occur as a matter of course in many other organisms?

0. https://en.wikipedia.org/wiki/Living_fossil

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chiefalchemist 4 days ago | parent [-]

It was my comment. Thanks, cause I see plenty of NH treads that go completely off topic and there are too few down votes for that.

In any case, 12M years a long time for a species to survive, let alone survive “as is”. It makes me think of the creature in Alien and how it evolved into deadly perfection. But these creatures aren’t fictional.

p.s. Aren’t octopuses another species of little to no change? But they’re weird anyway so it’s not a surprise?

	▲	adolph 3 days ago \| parent [-]
		Octopuses are all soft tissue (except for their "beak"), so it would be very hard to determine from the fossil record how much change has occurred. Perhaps as a result, they are not mentioned in the "living fossil" article above. An additional complication is that some cephalopods have a relatively unique ability to change gene expression in response to environmental factors [0]. As a result, even if one were to see physiological change or change in ecological niche, it might not be as a result of speciation. Hopefuly soon techniques of analyzing ancient DNA [1] will be more broadly used to understand the stories of long surviving species. 0. https://www.nsf.gov/news/masters-acclimation-octopuses-adjus... 1. https://en.wikipedia.org/wiki/Ancient_DNA