In the annals of science fiction, humans and non-avian dinosaurs have been brought together in a variety of ways. Genetic engineering experiments and time travel are probably the most common these days, but I have always had a soft spot for tales of “lost worlds.” What could be more fantastic than dinosaurs that somehow escaped extinction and persisted in some isolated spot for 65 million years? My childhood self really wanted someone to find a living Tyrannosaurus, Apatosaurus, or Triceratops in some remote locale, and that wish was fed by reports that one elusive dinosaur was hiding in Africa.

First thing first—living dinosaurs certainly do exist. We know them as birds, and a combination of fossil discoveries and laboratory research has confirmed the evolutionary connection between birds and feather-covered maniraptoran dinosaurs. But from time to time, people have proposed that non-avian dinosaurs may also still be hanging around.

The most famous of the supposed living dinosaurs I heard about was Mokele-mbembe. This unknown creature—often restored as a swamp-dwelling, tail-dragging sauropod akin to old restorations of “Brontosaurus“—is said to inhabit the dense jungle in what is now Cameroon and the Democratic Republic of the Congo. At least, that’s the way I was introduced to the legendary animal in the late 1980s. A blurry photograph of a lump in a lake and an ambiguous sound recording made by Herman Regusters during a 1981 expedition to find the animal were cited as possible evidence that a semi-aquatic sauropod was swimming around Lake Tele, and the feature film Baby: Secret of the Lost Legend fleshed out the hypothetical dinosaurs. Tall tales and legends of Mokele-mbembe had been circulating for decades before, and sensationalist basic cable television programs still fund expeditions to try and find the animal from time to time.

Is there any good evidence that a sauropod still wades through the muck of African swamps? Sadly, no. I would be thrilled if a living, non-avian dinosaur really did turn up somewhere, but such a fantastic find would have to be backed up by equally fantastic evidence. Despite the fact that multiple expeditions have been sent to the Democratic Republic of the Congo over many years, there is no solid evidence that Mokele-mbembe is a dinosaur or even a real, unknown species of animal. I seriously doubt anyone will ever find any evidence of such a creature at all, and part of the reason why related to a paper published by University of Queensland zoologists Diana Fisher and Simon Blomberg last year.

The major message of Fisher and Blomberg’s study was positive: Some modern mammal species thought to be extinct may still survive in small, hard-to-find pockets of their former ranges. But the researchers also noted that the effort put into finding supposedly extinct species makes a difference as to whether we should expect to find those animals. The researchers found that species that still survived were often found after three to six searches, but if more than eleven searches were made with no results—as is the case for the Tasmanian tiger and Yangtze river dolphin—then the species is probably actually extinct. Since so many searches have been made for Mokele-mbembe with no solid results, I don’t think that there’s actually any large, hidden species there to find.

There is a flipside to that argument, although it also doesn’t bode well for the rumored dinosaur. Many of the searches for Mokele-mbembe have been made by self-described explorers who have little to no relevant field experience in tracking and studying wildlife. Some of these folks are even religious fundamentalists who are striving to somehow undermine evolutionary theory. Their credibility is highly suspect, but you would think that at least one group would have blundered into the animal by now. After all, there has to be a population of animals which would be leaving tracks, scat and occasionally bodies. The evidence for huge creatures living in the swamp should be readily apparent, and the best the many dinosaur hunters can come up with are tall tales and misshapen globs of plaster that look nothing like the tracks the casts are claimed to be.

But the most obvious problem is that there’s no trace of sauropods in the fossil record—at all—in the 65 million years since the end-Cretaceous extinction. Nothing. The last of these dinosaurs died out long ago, and there is not even a scintilla of evidence that sauropods survived past the close of the Mesozoic. If sauropods survived at all we would expect to find some indication of their existence in the fossil record. These were not small animals or creatures that were hidden away in the deep sea. Given the number of terrestrial fossil deposits and they way they have been sampled, Cenozoic sauropods would have turned up by now if they had survived.

There are plenty of other problems with the idea that there’s a sauropod trundling around in the swamps of the Congo Basin. One of the most ridiculous aspects of Mokele-mbembe stories is that the supposed dinosaurs resemble what the searchers expected sauropod dinosaurs to look and act like based on inaccurate restorations. The hypothetical dinosaurs act just like their counterparts in old Charles R. Knight and Zdeněk Burian paintings. Actual, living sauropods would have looked markedly different from those old restorations, and according to recent research, sauropods would have been really lousy swimmers due to the considerable volume of air-filled spaces in their bodies. A sauropod would not be able to act like a crocodile and hide underwater as Mokele-mbembe supposedly does. The weakness of the “Mokele-mbembe as sauropod” hypothesis is underscored by the fact that the supposed anatomy and behavior of the animal is clearly based on outdated images of dinosaurs. As Darren Naish pointed out in his brilliant April Fool’s Day post on Mokele-mbembe from this year, the idea that the animal was an old-school, tail dragging sauropod grates against everything we have learned about sauropods during the past three decades.

Paleontologist Don Prothero also took a few good whacks of Mokele-mbembe in a recent Monster Talk episode. Not surprisingly, Prothero points out that many of the reports about the animal are extremely inconsistent. A number of supposed sightings don’t refer to anything dinosaur-like at all, and even those that do are inconsistent and ambiguous. On top of that, Prothero and the show’s hosts bring up the fact that fanatics in search of Mokele-mbembe can easily misconstrue what local people might be saying about the animal because of a lack of shared cultural background and other translation problems. While visiting explorers often use the term “Mokele-mbembe” to refer to a supposed dinosaur or similar animal, the word can also refer to something that is not real or has no physical manifestation. If film crews and self-described explorers keep passing through and spending money in the region, it’s not surprising that people will tell the monster hunters what they want to hear.

The take-home lesson is this: If you want to find sauropods, sign up to volunteer on a professional fossil excavation with well-trained scientists.