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Compared to the 19th century, now there is a huge amount of accumulated data about the history of the Earth, which is internally consistent and consistent with any scientific experiments that we are doing in the present.
While we know only a small part of what happened millions of years ago, many of the things that we know are much more certain than what we know about things that happen in the present, but which are hidden from us, so we do not have enough information about them.
From time to time some suppositions about the past have to be changed in the light of new evidence, but to falsify a thing supported by such a huge amount of diverse evidence, like the fact that 70 million years ago there were living dinosaurs, that would require an incredible amount of new evidence.
You do not have such evidence, so your comment is not useful. You could comment that anything you hear in this world should be doubted, including the past existence of dinosaurs, which is very true, but that does not mean that everything is equally doubtful. Some things have a great uncertainty, while other things have an overwhelming probability to be true.
Governments frequently make great efforts to alter the presentation of the human history in ways that are beneficial for them, e.g. to convince their people that they were the good guys in a war, while the opponents were the bad guys, so there are serious reasons to doubt the official histories supported in many countries, but what happened more than a few thousand years ago has too little political importance, so there are no conspiracies to alter the conclusions of paleontology. At most, some bad researchers may try to publish false data, if that can be useful for their careers, but that is usually discovered sooner or later, and it can never influence facts so fundamental like the existence of dinosaurs.
The real reason for which is of course that … Dinosaurs are Too Big to Fail. :)
Discovery of a couple large aquatic lizards preceded the invention of the dinosaurs by a few decades. Most notably among these, we find mosasaurus, ichthyosaurus, and plesiosaurus, which looks dubious and which Cuvier thought was a hoax.
I read the German Wiki article on mosasaurus, and even though the creature looks straightforward by comparison, and I find no reason to doubt its existence in a configuration roughly similar to what's presented today, the science isn't settled at all in the matter, and there's considerable questioning and shuffling about of the various specimens and the corresponding taxonomy, which is because the evidence is scarce and sketchy, by the very nature of the fossil record.
Far greater and deeper questions arise when we turn to the dinosaurs. Fundamental things like their posture (wrt to their tail) have been "corrected" in the past decades, and it looks like a couple decades from now they'll actually have feathers to be more in line with how they've been inserted into the evolutionary graph as the ancestors of birds. Other things such as the unlikely (and unviable) anatomy of many of the most famous dinosaurs don't look like they can ever be fixed.
With all the bona fide and even sympathy for such phantastic paleontological scenarios, I simply do not understand how this situation can be a base for any kind of "certainty". Curiosity and fascination, okay, I get it – but certainty?
I asked Chatty for the best book on the history of the discovery (or invention) of the dinosaurs in the first half of the 19th century†, and it came up with The Dawn of Dinosaurs by John R. Horner, published in 2005. The title struck me as odd (I would have preferred Dawn of the Dinosaurs), and it appears the book doesn't exist, Chatty had made it up.
But that turned my attention to Jack Horner, a very important figure in paleontology (at least in the USA), who has discovered various T-rex skeletons and dinosaur eggs and whatnot, and so I watched a couple minutes of a lecture he gave in 2001, which left a peculiar impression (I mean his personality), and then I read his Wiki page and was not disappointed to find my impressions totally confirmed by the article …
https://www.wikipedia.org/wiki/Jack_Horner_(paleontologist)
Can't fault him for liking young girls, that's human nature, and he had the money to be a customer of Jeffrey Epstein; but isn't it curious how he didn't allow dyslexia from stopping him to rise to the top of the field? And what does it say about a field (at least in the USA) if such characters somehow manage to rise to the top? Could it be there is a (well-funded) system that facilitates their ascent? Because they have just what it takes to fulfil the role?
That, of course, should not reflect negatively on whatever paleo findings were made on the lands of your grandparents.
† Chatty next suggested The Dinosaur Hunters by Deborah Cadbury (Terrible Lizard for the US edition), which I found on AA and which seems to do a proper dive into history as is essential to find the truth of the matter.