The Dinosaurs They are a-Changin’

The dinosaurs I met as a kid aren’t around anymore. I don’t mean to say that all the classic dinosaurs I saw in the late 1980s were sunk, synonymized or otherwise driven into a second extinction. “Brontosaurus” is the only major example of that (although Torosaurus and Anatotitan may soon follow). No, what I mean is that the tail-dragging, drab, stupid dinosaurs I was first introduced to have all been replaced by agile, brightly-colored, complex animals that were amazingly bird-like.

Our image of what a dinosaur is, and what dinosaur biology was like, has been changing ever since naturalists began scientifically describing creatures such as Megalosaurus and Iguanodon in the early 19th century. Dinosaurs have transformed from 100-foot-long lizards to bizarre creatures with a reptilian gloss, and only by the 1870s, when paleontologists started finding partial skeletons, did we start to get a picture of how unique dinosaurs were. Dinosaurs were re-envisioned as dynamic, bird-like animals by naturalists such as Edward Drinker Cope and Thomas Henry Huxley, only to have their hot-blooded dinosaurs replaced by sluggish swamp-dwellers that fully deserved the extinction that wiped them out. Thankfully, the “Dinosaur Renaissance” of the late 20th century sparked a dinosaur makeover and an interest in dinosaur paleobiology—dinosaurs were transformed into perplexing creatures that lived fast and died young, and the realization that birds are living dinosaurs gave paleontologists a new pool of information to investigate the details of dinosaur lives.

And now we’re in what paleontologist Thomas Holtz has called the “Dinosaur Enlightenment.” While the Dinosaur Renaissance was mostly an image change that raised a slew of questions about dinosaur biology, the Dinosaur Enlightenment is employing new techniques and ideas to approach long-standing questions about dinosaur biology. We’re finally starting to understand how dinosaurs grew up, how they might have mated and even what colors some dinosaurs were. But even the most basic aspects of dinosaur biology are open to revision—for example, paleontologists are trying to find ever-more-accurate and precise ways to estimate how heavy dinosaurs actually were.

Still, a complete and comprehensive perspective of dinosaur natural history remains far beyond our present knowledge. The more we discover, the stranger dinosaurs become. Our general picture of dinosaurs is more accurate than what has come before, but the details will undoubtedly continue to shift, especially as new discoveries are made and speculative ideas are tested. As paleontologist Paul Barrett recently wrote at the Guardian:

We are still in the dark when it comes to some aspects of dinosaur life: how exactly did they die out? Why did some of them prosper while others were short-lived? What were the functions of bizarre features, like Spinosaurus’s “sail”. And which factors led to their runaway evolutionary success? For now, there are still plenty of things we know nothing about – and scientists shouldn’t be afraid to say so.

Dinosaur mysteries will continue to pile up. In another Guardian editorial, paleontologist Dave Hone points out that dinosaurs were far more diverse and disparate than we often appreciate. Everyone knows Tyrannosaurus, Triceratops, Allosaurus, Diplodocus and other classic creatures found during the bone rush of the late 19th and early 20th centuries. These animals are dinosaurian royalty, the most famous of all, but they are only a tiny sampling of the vast array of forms dinosaurs evolved into. In fact, as Hone points out, paleontologists are naming new dinosaurs at an exceedingly rapid pace, and each new discovery adds a little bit more to our understanding of how weird and varied dinosaurs were. Hone writes:

The sheer number of species recovered may itself be notable, but the diversity of forms encompassed in that is probably also under-appreciated. Dinosaurs are famous not just for the huge sizes reached by many, but also their weird and wonderful body types. Animals like Diplodocus, Spinosaurus or Triceratops might seem odd, but there are other dinosaurs out there that stand out just as much compared with their relatives or are simply odd in their own right.

The feathery, ant-eating alvarezsaurs, and the pot-bellied, long-clawed herbivores called therizinosaurs are just two of several dinosaur lineages that paleontologists have only recently recognized, and these puzzling creatures have presented scientists with new, confounding questions about how such creatures lived and what pressures shaped their evolution. The more we learn, the more wonderful and mysterious dinosaurs become.

Riley Black | | READ MORE

Riley Black is a freelance science writer specializing in evolution, paleontology and natural history who blogs regularly for Scientific American.