Literal-minded as I am, when I first read your post, I assumed you were presenting this theory as a serious proposal of what
The Land Before Time was intended to be. It only later occurred to me that you might have intended it as more of a playful "what if?" idea for the purpose of getting people thinking and provoking discussion, much like the content of the “
Wild Mass Guessing” pages on TV Tropes. Am I correct in assuming that this is the case?
Just to be clear, I don't have a problem with people sharing WMG-type theories. (The way I see it, even proposing an idea that no one else buys into can be beneficial if it prompts people to evaluate and defend their established views and think outside the box.) Just to offer some constructive criticism, though, you might want to make it clear from the get-go when presenting a concept like this one that it is
not about the creator-intended nature of the series in question, but more of a hypothetical alternative interpretation for your own headcanon. Otherwise you'll have a lot of people taking one look at your post (or even just the title, which, with all due respect, makes things even more confusing because it implies that your theory is that the LBT dinosaurs are mammals, not lizards), and either deciding that your theory (which they assume to be an "out-of-universe" explanation) is either too off-the-wall to be worth their time, or, after seeing someone like jansenov debunk all the points of the argument as they would apply to an "out-of-universe" theory, assume that the case is closed and that there is nothing more they can add. In either case, the reader may well avoid partaking in the discussion altogether. My point is that you're not asking, "Do you think maybe this is what LBT's creators really had in mind for their series?"; you're asking, "Do you think this reimagined version of the LBT universe I developed for my headcanon sounds feasible?", and I think it's important that the people who read your theory know that from the start.
I actually started writing a fairly long and elaborate response to your post last night, but it got too late (i.e., the sun started to come up
), and I had to stop. By the time I was able to get back to writing the last 10% of my response, you had posted your follow-up and more or less confirmed my suspicions about this being an idea for your own headcanon, and much of what I had already written was rendered more or less irrelevant, as I had written them while I was still entertaining the possibility that your theory applied to the filmmakers' intentions for LBT. I hope this isn't inappropriate, but I decided to include most of this material anyway. Some of it might still be applicable, and at the very least, it provides insight into my initial reaction to this topic, which I think helps illustrate my point about why it helps to establish the context of a proposed theory right from the get-go.
Case in point, my original opening paragraph:
Unfortunately to say, I’m fairly certain that just about anyone on this forum who were to read this topic would have more or less the same conclusion: none of this argument holds water. The opening narration of pretty much every LBT movie explicitly establishes the setting as long before the time of humans, and the characters as dinosaurs.
First of all, the various species shown in the series never lived together in real life, neither geographically nor temporally.
The Mesozoic Melting Pot is one of the oldest and most ubiquitous tropes in portrayals of the prehistoric world. Most writers and filmmakers creating a story about prehistoric animals just can’t bear to limit themselves to the biodiversity that existed at just one time and place in the Mesozoic. (Truthfully I can’t really blame them; when presented with the full gamut of extraordinary creatures spread out across the fossil record like delicacies on a banquet table, it’s hard to pick just one plate and focus exclusively on it.) In almost all cases, they’ll find a way to showcase prehistoric animals from multiple periods, sometimes via a loophole (making their work an anthology, as in
Walking With Dinosaurs, or bringing their cast of creatures to the present day, as in
Jurassic Park), but more often by deciding, “To Hell with geochronological boundaries!” and mixing all their chosen prehistoric stars together in an anachronism stew.
For example, the length of time separating Stegosaurus from Triceratops is actually longer than the length of time separating Triceratops from modern humans. So showing a Stegosaurus with a Triceratops is even more inaccurate than showing a human with a Triceratops.
That statement about the time disparities is technically true (I've heard a very similar version of that quote multiple times before), but I feel inclined to point out that while
Stegosaurus and
Triceratops were separated by more geological time than
Triceratops and humans, they were
not separated by an extinction event that wiped out all known land animals larger than 25 pounds. So I would argue that depicting
Stegosaurus surviving into the late Cretaceous would still be more plausible than depicting
Triceratops surviving to the present day.
They are also anatomically inaccurate. For example, the tyrannosaurs are shown standing with their tail resting on the ground, like a kangaroo. This posture is now known to be inaccurate.
The original
Land Before Time was made in the 1980s, when the paleontological epiphanies of the “Dinosaur Renaissance” were still struggling to work their way into mainstream educational media (and let’s face it: even a quarter century on, there’s still a disturbing prevalence of kangaroo-shaped tyrannosaurs and hadrosaurs, naked raptors with pronated “bunny hands”, elephant-footed sauropods, and leathery-skinned skeletal pterosaurs in pop culture depictions of dinosaurs.) Don Bluth’s designs were also clearly inspired by the paintings of classical paleoartists such as
Charles R. Knight, Zdeněk Burian
Zdeněk Burian, and
Rudolph F. Zallinger; magnificent, high-quality works well deserving of their pedestals in the paleoart hall of fame, but decades behind contemporary paleontological knowledge even then. So it should come as no surprise that the dinosaurs in LBT do not stand up to our current understanding of what dinosaurs looked like in life. (It does deserve applause, in my book, however, for being pretty much the only dinosaur movie
ever to put fur on its pterosaursónamely Petrie with his neck ruff and the chirpy little black-and-white flyers that line up to meet Littlefoot at his birthósomething not even many educational films manage to get right.)
It has been said that global warming might make reptiles larger and more dominant. My theory is that, in the world of TLBT, global warming causes most of the mammals, including humans, to become extinct. After humans become extinct, the lizards take over as the dominant group of animals on Earth. Millions of years later, they evolve to look like dinosaurs. They also evolve the ability to communicate, like humans.
It’s not impossible that someday an extinction event will wipe out or severely impact mammals while giving reptiles the chance to flourish, but it’s probably not going to be anthropogenic global warming, if that’s what you’re talking about. While warm conditions are certainly very favorable to reptiles, they are not necessarily adverse to mammals. There are plenty of mammals living in hot climates, including tropical rainforests and deserts, ranging from rodents and bats to bears and ungulates. In fact, most of the major groups of placental mammals alive originated before or during the Eocene period, 10 million years after the Cretaceous extinction, when the global temperature suddenly and rapidly climbed as high or possibly higher than it was during the Mesozoic. Clearly mammals are adaptable enough that even if humans do not survive the inevitable mass extinction we are unwittingly instrumenting, it will probably not be the end for all mammals. I’m not sure what sort of environmental catastrophe could wipe out mammals while sparing the reptiles, and for the purposes of your theory (assuming you establish it as the “official” backstory for your version of the LBT universe), I would suggest you do some brainstorming until you settle on a more complex scenario for the disappearance of mammals. Or, just don’t specify what wiped them out. When in doubt, leave the details ambiguous.
It is certainly true that the lineage leading to lizards and the lineage leading to dinosaurs split from each other a considerably long time ago. However, that doesn't mean they couldn't evolve to be similar. For example, there was an animal called the thylacine that used to live in Australia until it became extinct in the 1930s. It looked amazingly similar to a wolf. In fact, anatomy students often have a difficult time telling the difference between the skull of a wolf and the skull of a thylacine. However, it is a marsupial, while the wolf is a placental mammal. The lineage leading to marsupials and the lineage leading to placentals split from each other at least 161 million years ago, but the wolf and the thylacine still look remarkably similar to each other. Given enough time, I don't see why a species of lizard couldn't evolve to look like a particular species of dinosaur.
It's not overly far-fetched that a lineage of lizards could evolve convergently with dinosaurs, resulting in certain forms that bear a close resemblance to actual dinosaurs. Ironically,
T. rex and other large theropods were arguably incidental mimics of certain members of much older group of reptiles from the Triassic period, the pseudosuchians. More closely related to crocodiles than to dinosaurs (though they were still archosaurs), this group included a number of large predatory species such as
Poposaurus,
Postosuchus, and
Arizonasaurus (which gets bonus points for resembling
Dimetrodon[among the apex top predators of their respective ecosystems, but are now suspected by paleontologists to have been bipedal. Much like your thylacine example, the skulls of these reptiles were so theropod-like that virtually any layperson shown a picture of one would almost surely identify it as a T. rex. There were other Triassic pseudosuchians, too, that bore striking similarities to some of the dinosaurs that succeeded them: the beaked Shuvosaurus[/U] was actually thought to be an unusally ancient ornithomimosaur until a more complete specimen of a close relative, Effigia, was discovered (they look even more like Limusaurus, a bizarre toothless ceratosaur from the late Jurassic of China). And some might argue that the aetosaurs (including Desmatosuchus and Typothorax), low-slung armored herbivores, looked a bit like clubless-tailed ankylosaurs such as Nodosaurus and Gastonia (though I, and I’m pretty sure most paleontologists as wellówould be more apt to compare them to a cross between a crocodile and an armadillo).
Even with all these real-life examples of convergent evolution between dinosaurs and other reptiles, one aspect of the theory that seems unlikely to me is that these hypothetical future lizards would evolve to inadvertently replicate the exact diversity of dinosaurs seen in The Land Before Time (along with pterosaur-mimics, plesiosaur-mimics, and repetitions of the various other non-dinosaur species that appear in LBT) while at the same time not producing any forms that look noticeably unlike anything seen in the series. To put it another way, while a thylacine could be conceivably mistaken for a wolf (disregarding the more subtle aspects of its physiology that define it as a distinctly different animal), many of the species that shared its environment, such as wombats, platypuses, and pademelons, have no such evolutionary doppelg‰ngers in other parts of the world. A future Earth inhabited by squamate-descended dinosaur facsimiles would surely contain many other, much less familiar-looking organisms, a red flag to the fact that this is not the Mesozoic era, not even a melting pot version.
The variables involved in evolution are virtually infinite, and in order to really closely resemble the original dinosaurs (or even LBT’s versions of them), lizards would have to stumble upon many of the same evolutionary adaptations that the dinosaurs developed, or at least equivalent adaptations that served the same functions and allowed for similar evolutionary flexibility. For example, dinosaurs were able to walk with their hindlimbs permanently upright because the head of the femur fit into a sideways-facing hip socket, whereas pseudosuchians like Postosuchus had “pillar-erect” hindlimbs, with a shelf of bone at the top of the hip and a downward-facing hip socket (see diagram). The dinosaurian hip socket was also backed by cartilage rather than bone, which may have allowed the legs to move more smoothly. It’s not clear whether this adaptation has anything to do with the fact that dinosaurs survived the extinction event at the end of the Triassic while most pseudosuchians apart from crocodylomorphs became extinct.
One could also argue that lizards would never evolve to closely resemble the LBT dinosaurs, because the bodies of the dinosaurs in the series are biologically unfeasible, and so it would be unlikely for any species to adapt them. For example, the kangaroo-like upright posture of the bipedal dinosaurs in LBT is inaccurate because it is simply nonsensical: the function of the long, heavy tail in dinosaurs was to counterbalance the body (reptile tails also contain muscles that attach to the femur and provide extra leg power); in fact, the vertebrae and tendons in most dinosaur tails were arranged in such a way that the tail wouldn't droop, with most of the flexibility being in the horizontal plane. Allowing the tail to droop all the way to the ground and weigh the back half of the body down, with the head and neck held so high up that the animal would be required to practically perform a headstand every time it needed to take a drink or pick up a piece of food on the ground, seems positively biologically illogical. Kangaroos have the excuse that they use their tail as a fifth limb (literally; studies have found that, when walking on all fours, a kangaroo's tail contributes more mechanical work than the rest of its limbs combined), and as a prop when they rear back and kick with their hind legs. The LBT dinosaurs are never shown doing this, and I’m not sure it would even be biomechanically feasible for such large animals. To say nothing of why a large terrestrial animal would forgo a perfectly good counterbalancing appendage in favor of subjecting itself to perpetual caudal rugburn.
Admittedly, there are a couple of caveats with this issue. Firstly, if I know one thing about natural selection, it’s that it’s more than capable of generating adaptations so bizarre, complex, ungainly, or impractical in appearance to human eyes, that if we didn’t know they existed, not even the most creative human mind could have ever conceived them, let alone the evolutionary processes that led to them. (Seriously, could you imagine a creature that eats its way out of an egg; grows to 2,000 times its birth weight in less than two weeks; casts off the entire exterior of its body to become a featureless, leaflike pod; which later splits open, birthing a bloated creature that immediately redistributes its bodily fluids to inflate a set of wings so it can fly to the other side of a continent to sleep; if you had never heard of butterflies?) Maybe there is a biologically feasible evolutionary path that would lead to an enormous, upright-walking, droopy-tailed reptilian biped; I just can’t think of one. Secondly, I’ve noticed that, compared to the sequels, the bipedal dinosaurs in the original LBT are a lot better at keeping their spines in a realistic horizontal posture while walking, and both the bipeds and quadrupeds spend a lot more time with their tails held high off the ground (probably due to Bluth and co., making a stronger effort to maintain an element of realism in their dinosaurs than the makers of the sequels). So if you envisioned all the characters in your version of the LBT universe as being more like the dinosaurs in the first movie, you might be able to bypass the issue of improbably-kangaroo-shaped dinosaurs at least.
In any event, your scenario is a big fat honking heck of a lot more likely than the agonizingly ubiquitous clichÈ in science fiction of the evolutionary processes on different planets independently churning out species that look more or less identical to humans 
(made even worse when said humanoid species are depicted as being able to interbreed with one another 
), or the idea that a humanoid species could “seed” a planet with genetic material destined to eventually replicate the body plan of its progenitor (as seen in the movie Prometheus). If you could see yourself creating a story or headcanon involving aliens with little or no qualms about scientific adherence, then your idea for dinosaur-mimicking future lizards is hardly worth fussing over.
Incidentally, a British paleontologist named Darren Naish has already imagined a speculative alternate Cenozoic in which lizards and snakes became the dominant large animals following the Cretaceous extinction: the Squamozoic era.
Global warming may or may not pressure lizards to develop in such a way. Mammals rapidly evolved during the Paleogene thermal maximum while lizards remained small animals, for example. There must be other factors involved.
Actually, it’s been recently discovered that that there
were large lizards living alongside mammals during the Paleocene and Eocene epochs. The impressively named
Barbaturex morrisoni (“[Jim] Morrison’s Bearded King”), from the Eocene of Myanmar, was at least three feet (1 meter) long not counting the tail, with an estimated mean body weight of almost 60 pounds (26.7 kilograms), ranking it among the larger animals in its habitat; which included a diverse assortment of primates, ungulates, and carnivorous mammals. This was a large reptile that clearly did quite well for itself despite being surrounded by potential mammalian competitors, casting doubt on the conventional wisdom that large herbivorous reptiles cannot evolve alongside herbivorous mammals because mammals supposedly always outcompete reptiles attempting to share the same niche.
[/i]
And an increase in lizard intelligence is likely, since their fellow amniotes, the mammals and dinosaurs, also show an increase in brain size and complexity over time. However, lizards and crocodiles have not developed their brains nearly as fast as the above two until now, so they may take more time to get to their level.
This is going a bit off-topic, but there is a bastion of zoological dogma that desperately needs to be demolished, and that’s that reptiles are primitive, unsophisticated creatures possessed of limited intellect and with minimal capacity for social behavior. In the last several years, however, it is becoming increasingly apparent that this is absolute bunk. Far from simpleminded submarine bear-traps, crocodilians are now recognized as perceptive, flexible hunters that learn the favorite watering locations and even the habits of their prey, from migrating fish to humans washing at the riverbank. Moreover, American alligators and Indian mugger crocodiles have recently been discovered to lurk beneath heron and egret rookeries with sticks (a much-sought-after resource for the nesting birds) balanced across their snouts, enticing the birds within striking range.
Reptiles have been found to have problem-solving skills, too. An experiment with a red-footed tortoise given eight chances to collect eight treats, one at each end of an eight-spoked radial-arm maze (i.e., collect every treat without taking the same path twice), found that the tortoise used objects visible beyond the maze as landmarks to keep track of its progress, and when those were obscured, modified its behavior, systematically entering each arm of the maze adjacent to the one before it in turn (a strategy that not even all mammals are apparently able to replicate). Another experiment found that tortoises can learn to solve a problem they can’t figure out by themselves if they watch another tortoise complete the same task (in this case, taking a long detour around a wire fence separating them from a piece of fruit); in other words, they are capable of social learning.
On the subject of social behavior, shingleback skinks, while solitary for most of the year, have been found to form monogamous pair bonds, seeking out the same mate year after year for as long as two decades. Some pythons actively incubate their eggs by first raising their own body temperature through sunbathing and then coiling around the clutch. Mother caimans “adopt” the offspring of other females, which congregate in a single massive crËche guarded by a single female, who guards them against predators and leads them to new sources of water if the pool dries up. (The sheer number of hatchlings increases the odds that the “babysitting” mother’s own offspring will not be taken by predators, while the other adult females are free to disperse, allowing for less competition between them.)
Many reptiles have even been recorded engaging in play behavior in captivity, such as the case of a Nile softshell turtle that formed a habit of engaging in self-mutilation behavior (a common response to lack of enrichment among animals in captivity), which decreased after it was provided with toys such as basketballs and hoops of hose, which it would manipulate with its mouth in various ways or push around its enclosure. There was also a well-studied Komodo dragon who not only played with shovels, blankets, boxes, and other objects placed in her enclosure, but play tug-of-war with her keepers, pull hendkerchiefs and notebooks from their pockets, and yanking or nipping off their shoelaces (all while distinctly not treating the objects in question as food).
As more and more of these behaviors come to light, the more likely it appears that the traditional view of reptiles as unintelligent and asocial was based more on limited research and flawed lab studies biased towards mammalian behavior and living conditions than actual evidence. That prejudiced mindset subsequently became so deeply ingrained in scientific doctrine that reptiles were largely ignored in further studies of animal intelligence and social behavior, and herpetologists were trained to believe that such behavior in reptiles didn’t exist, so they seldom if ever thought to watch for it. Now that researchers are starting to give reptiles their due, it is becoming increasingly apparent that big-brained birds and mammals are not as special as we once thought they were.
Sources:
http://www.nytimes.com/2013/11/19/science/...ean-stupid.htmlhttp://www.newscientist.com/article/mg2122...the-uptake.htmlhttp://blogs.scientificamerican.com/tetrap...ocs-and-gators/http://scienceblogs.com/tetrapodzoology/20...me-out-to-play/Life in Cold Blood by David Attenborough (documentary; HIGHLY recommended)
Holy bleeping bleepity bleep…I may have a new contender for the longest post I’ve ever written. :blink: Well, I hope it at least benefits the discussion to some extent, and that I did not unintentionally come off as offensive or condescending at any point. :unsure:
