I just watched a documentary called Sea Rex 3D about primitive sea reptiles. At one point they show a wonderful sequence of two massive Liopleurodons going through an elaborate courting ritual. But after watching it I suddenly wondered just how biologists could know anything at all about the mating rites of prehistoric creatures.
The documentary is extremely well-researched and many prominent marine biologists make appearances in it so I’m assuming the director didn’t just make this stuff up. But I still don’t see how anyone could know how these animals behaved.
Lisren carefully to the script of the narrator of the feature. The cable channels like Discovery and NatGeo are notorious for making up everything from whole cloth, such as aliens and crytids, and every sentence of the script contains a cop-out, like “Could it be that. . .?”, or "Some scientists believe that . . . ". In fact, as far as I know, it wold be impossible to even know (or guess) the color of long-extinct organisms.
But they might just feel confident in extrapolating things like courtshp rituals based on the behavior of their modern descendants.
Lots of speculation, some of it based on fragmentary evidence - for example it is possible, I believe, to identify the remnants of pigmentation molecules in fossils, so knowing what kind of markings an animal had is probably marginally better than in-the-dark guessing about its behaviour.
Having said that though, one only need look at the mating rituals of living birds to realise that we would never guess them even if we were given the fresh corpses. We’d look at crests of coloured feathers and figure out that they were there for some reason (and that reason is often related to reproduction), but exactly how the animal uses them is going to involve a lot of guesswork, if you haven’t seen it firsthand.
Most vertebrates have some kind of courtship ritual, so it’s not a stretch to guess that Liopleurodon did as well. But since it has no close surviving relatives, it can only be a guess as to what form they took.
In some cases, extinct animals have elaborate sound-making structures, or highly developed frills or crests. In such cases it’s pretty likely those were used in courtship, especially if they differ between the sexes.
Animals become extinct for many reasons, but mating rituals that don’t “work good” is one of the less likely.
I’ve posted this link here before, take a look at it for an idea how real the science in these documentaries is. (Unlike many places, be sure to read the comments.) (Bonus articles here and here.) You need to look any and all pop-sci “documentaries” very, very skeptically–they aren’t about teaching science, they are about selling commercials to advertisers. Documentaries about real paleontology (which would be mostly limited to the physical descriptions of bones and of their chemical properties) wouldn’t get a big enough audience.
Mating rituals don’t just pop up fully-formed in a single generation. If they did, and they were no good, they could result in the extinction of the species.
But they don’t - they develop gradually as the result of competition over the course of many generations. Thus, there is no reason for bad mating rituals to ever come into existence in the first place.
Here is what I see happening repeatedly in different cable channel “documentaries”:
Step 1: The scientist is contacted and asked if they want to give their expertise in a documentary. The producer(s) go on about how they want to inform the public about the subject and scientist agrees to do it.
Step 2: The scientist comes down to the studio and is filmed giving factual information about the subject.
Step 3: The scientist’s footage is chopped up into little bits and they either use only a partial quote and/or use a quote out of context to make it seem like the scientist is supporting something completely BS, often the complete opposite of the point that the scientist is actually trying to make.
Step 4: The scientist blogs about how crappy the documentary is, refuting it point-by-point, and swears to never do one of those stupid shows again.
One of the “walking with Dinosaurs” episodes (“ALLOSAUR”) kind of impressed me (relative to peers).
It came on a separate disc. After the faux documentary, they had interviews with scientists ( I know, 'cuz they wore white coats) in which they recapitulated scenes with discussions about how they knew this, why they had a pretty good idea about that, and how the other part was speculation based on whatever.
I think they could have admitted to speculation more frequently than they did, but of the topics they did cover, I thought they did pretty well.