Dinosaur Fun Facts #4

Thanks to decades of movies, comic books and less-than-accurate TV documentaries, many people continue to hold mistaken notions about Dinosaurs. Here are some things you thought you knew about dinosaurs that aren’t actually true.

Plant-eating dinosaurs ate grass
Only a very few plant-eating dinosaurs would have had the pleasure of a meal of grass. The earliest fossil evidence for grass is only 66 million years old – so we know this plant only appeared right at the end of the Mesozoic Era, the ‘Age of the Dinosaurs’. 

Large sauropods had 2 brains, one in their hip
Not true, although it makes good sense considering the distance from head to tail in some of these massive plant-eating dinosaurs. However, scientists did discover that some had enlarged nerve clusters at the base of their spine that helped pass on messages from the brain. 

Dinosaurs were the first reptiles to rule the earth
The first reptiles evolved from their amphibian forebears during the late Carboniferous period, over 300 million years ago, while the first true dinosaurs didn’t appear until well into the Triassic period (about 230 million years ago). In between, the Earth was dominated by various families of prehistoric reptiles, including therapsids, pelycosaurs and archosaurs (the last of which included the ancestors of pterosaurs, crocodiles and dinosaurs).

Even when dinosaurs first appeared they were not the dominate type of reptile – they were simply another group of small reptiles in a world full of reptiles. By the end of the Triassic they dominated life on land and would for another 140 million years, till the close of the Mesozoic. Their rise was due to a combination of chance, superiority and physical features. A ‘well-timed’ extinction event early in the Late Triassic wiped out most of their competition, clearing the way for dinosaurs. We are not sure why they then thrived. Perhaps they were better adapted to the arid, dry conditions than other animals were or their more efficient, upright way of running gave them an advantage.

Dinosaurs were incinerated by the end-Mesozoic meteor impact
About 66 million years ago, a meteor or comet about 10 kilometres wide smashed into Mexico’s Yucatan Peninsula. It created fire storms and tsunamis, and raised a cloud of dust and ash that spread around the world, blotting out the sun and causing plants to die. The popular perception is that dinosaurs (along with pterosaurs and marine reptiles and 70 per cent of all life forms) were killed within hours by this explosion, but in fact, it may have taken tens of thousands of years for the last non-avian dinosaurs to die out. The fossil record is only so accurate!

Not all scientists believe this impact caused the mass extinction event. The fossil record shows many families of dinosaurs were already in decline at the end of the Cretaceous period. These scientists blame climate change or massive volcanic eruptions that turned Earth in to a hostile place to live. Most scientists, however, believe that the extinction event was the result of a combination of these deadly causes.

Mammals only evolved after dinosaurs died out
Tiny primitive mammals appeared in the Late Triassic about 225 million years ago. They lived in the shadow of the dinosaurs for the next 150 million years, mainly occupying ecological niches as small, nocturnal animals. They were also relatively small, with some weighing as little as 2 grams but others growing to the size of badgers. The end-Mesozoic extinction 66 million years ago, which included the demise of the non-avian dinosaurs, left a mass of niches for larger mammals to evolve and fill. Most of the types of mammals we know today evolved after this time