Dinosauria

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**Dinosaurs**, a superorder of reptilian lizards one of the most successful groups of animals (in terms of longevity) that have ever lived, evolved into many diverse sizes and shapes, with many equally diverse modes of living. The term "Dinosauria" was invented by *Sir Richard Owen* in 1842 to describe these "fearfully great reptiles," specifically *Megalosaurus*, *Iguanodon*, and *Hylaeosaurus*, the only three dinosaurs known at the time. The creatures that we normally think of as dinosaurs lived during the **Mesozoic era**, from the early *Triassic* period (about 252 million years ago) until the end of the *Cretaceous* (about 66 million years ago). But we now know that they actually live on today as the **Birds**.

## Dinosaur Myths

### Everything Big And Dead is a Dinosaur

All too often, books written (or movies made) for a popular audience include animals such as **Mammoths**, **Mastodons**, **Pterosaurs**, **Plesiosaurs**, **Ichthyosaurs**, and the sail-backed *Dimetrodon*. *Dinosaurs* are a specific subgroup of the **Archosaurs**, a group that also includes Crocodiles, Pterosaurs, and birds. Although **pterosaurs** are close relations, they are not true **dinosaurs**. Even more distantly related to **Dinosaurs** are the *marine reptiles*, which include the pliosaurs, mosasaurs and ichthyosaurs. *Mammoths* and mastodons are **mammals** and did not appear until many millions of years after the close of the Cretaceous period. *Dimetrodon* is neither a reptile or a mammal, but a basal synapsid, an early relative of the ancestors of mammals.

### All Dinosaurs Lived at The Same Time

Different **dinosaurs** lived at different times. Despite the portrayals in movies like *King Kong* and *Jurassic Park*, no *Stegosaurus* ever saw a Tyrannosaurus, because *Tyrannosaurus* didn't appear on the scene until 80 or so million years following the extinction of stegosaurs. The same goes for *Apatosaurus* ("Brontosaurus") — it's bones were already well-fossilized by the time *T. rex* came along.

### Dinosaurs Are Extinct

Technically. Based on features of the skeleton, most people studying dinosaurs consider birds to be *dinosaurs*. This shocking realization makes even the smallest hummingbird a legitimate **dinosaur**. So rather than refer to "Dinosaurs" and birds as discrete, separate groups, it is best to refer to the traditional, extinct animals as "non-avian dinosaurs" and birds as/or "avian dinosaurs." It is incorrect to say that dinosaurs are extinct, because they have left living descendants in the form of cockatoos, cassowaries, and their pals — just like modern vertebrates are still vertebrates even though their **Cambrian** ancestors are long extinct.

### Dinosaurs Went Extinct Because They Weren't "Fit" Enough

This is an example of the circular reasoning that plagues students of Darwinian evolution. There's no objective measure by which one creature can be considered "more fit" than another; it all depends on the environment in which it lives. The fact is that, up to the cusp of the **K-T Extinction Event**, *Dinosaurs* fit extremely well into their ecosystem, with herbivorous dinosaurs dining on lush vegetation and carnivorous dinosaurs dining at leisure on these fattened, slow-witted gourmands. In the blasted landscape left by the meteor impact, small, furry mammals suddenly became "more fit" because of the drastically changed circumstances (and drastically reduced amounts of food).

However, **Dinosaur**,**Pterosaur**, and marine reptile populations were declining by the close of the cretaceous. Studies indicate that volcanic activity around 70 to 60 million years ago was dramatic, filling the air with toxic gases and populants, and Dinosaurs and their cousins were unlucky enough to be get more exposure to it than the flying Birds and mammals. Because numbers were low, the non-avian dinosaurs eventually went extinct during the K-T extinction.

## Dinosaur Records

### Largest

The biggest **Dinosaur** we currently know about is the *Argentinosaurus*. **Paleontologists** estimate it weighed about a staggering 90-100 tons and measured approximately 115-130 feet long (making it much longer than the modern Blue Whale)... Many **paleontologists** have claimed they found a larger dinosaur species, which has been proven false time and time again.

### Smallest

The *Microraptor* may be the smallest dinosaur ever. It was only about one and a half feet in length, about the size of a pigeon.

### Largest Predator

The really big **Dinosaurs** were all herbivores, but the biggest one that ate meat was the was the truly-massive, 50-foot long, 10 ton *Spinosaurus* of mid-Cretaceous North Africa, an estimated 110-90 million years ago. In comparison, the Tyrannosaurus measured only 40 feet in length with a mass of 8-9 tons in the upper range.

### Smartest

We don't really know for sure how smart **Dinosaurs** were, but the best guess is that they weren't very smart. However, the smartest was likely the Troodon. According to *Troodons* cerebrum-to-brain-volume-ratio, it was highly intelligent for your average dino, having about the same IQ of an ostrich. It is thought that the T-Rex was pretty smart for a dinosaur as well (it's brain was twice the size of other meat-eating dino, most notably the Giganotosaurus, whose brain was the size and shape of a banana).

### Dumbest

All dino fans probably know that *Stegosaurus* was definitely the dumbest **dinosaur.** In fact, it had one of not the smallest brain-to-body ratio of any animal of ever exist (some even go as far as to say that it's brain was the size of a peanut, which was likely correct).

### Fastest

The 30-foot two ton Allosaurus of western USA had an agile build, and scientists believe for it's massive size it was extremely fast, at a staggering 35 mph. However, the much punier but swiffer *Ornithomimus* was even quicker than the so-called "Velociraptors" in Jurassic World/Park, at a whopping 40-50 mph.

## All Shapes And Sizes

**Dinosaurs**, in general, were very large. Some dinosaurs are thought to have been 40 feet tall or more, over is twice as tall as the tallest Giraffe specimen ever on record. There were also some smaller **Dinosaurs** that were just a foot or so tall. There were a wide variety of dinosaurs from giant lumbering plant eaters (such as Sauropods) that walked on four legs to huge, fast and deadly meat eaters (such as Theropods) that were capable of walking and running on their two hind legs.