Stegosaurus: The giant herbivore with a deadly tail

Maybe the most iconic genus of dinosaurs ever excavated, the Stegosaurus was a herbivorous titan, capable of consuming huge quantities of low-level foliage while protecting itself from predators with its vast armoured frame and potentially lethal spiked tail.

The first example of Stegosaurus – from which its family name, Stegosauridae, derived – was unearthed in 1877 and since then four confirmed species of the dinosaur have been officially identified. Each species demonstrates a similar structure and feature set, with each animal epitomising a large quadruped, sporting a series of diamond-shaped plates along its back. These large creatures were over eight metres (26 feet) long and were heavily built at over 3,000 kilograms (6,614 pounds).

Stegosaurus size
How big was the stegosaurus?

Interestingly, it’s these plates that palaeontologists and academics know the least about, with a variety of arrangements, structures and uses suggested. When first unearthed it was speculated that they were used as a form of armoured defence against carnivorous predators. However, their positioning along the back and apparent bluntness has led to this theory being largely dismissed today. Instead, academics suggest that the plates were used as a decorative feature – perhaps in mating displays or to ward off Stegosaurus rivals in territory disputes.

The field of palaeobiology reveals almost everything else about this genus. Studying fossilised evidence it is clear that due to Stegosaurus’s very small and narrow skull, they had a tiny brain and so were not very intelligent – something seemingly confirmed by their primitive and mundane feeding habits. The low level of the animal’s neck, short but bulky forelegs and raised pelvis/elongated hind legs indicate that Stegosaurus spent much of its daily routine consuming large quantities of low-lying foliage (such as ferns, cycads and conifers). This is confirmed by the shape and formation of its teeth and a low bite force.

Upon closer inspection of the dinosaur’s legs it is also clear that it could not move very quickly. This is apparent as the discrepancy in size between the front and hind legs is so great that, if the creature ran at over eight kilometres (five miles) per hour, its longer back legs would cross over the forelegs leading it to fall.

Despite these shortcomings, Stegosaurus wasn’t totally defenceless, as it boasted a flexible, armour-plated and spiked tail. Taking Stegosaurus stenops as an example, the dinosaur had four dermal tail spikes of approximately 75 centimetres (29.5 inches) in length each, which extended out from the tail slightly off the horizontal plane. These spikes enabled the Stegosaurus to whip its tail and puncture the flesh of any attackers.

Top 5 Facts

1) Plate debate

The arrangement of the Stegosaurus’s plates has been a major controversy in the palaeontology sphere. Academics have suggested four possible configurations.

2) Hip to be brainy

On finding a large canal in the hip region of the spine, some have argued it could have been the place of a secondary ‘brain’ structure, responsible for controlling rear reflexes.

3) Prosperous dino

Evidence implies Stegosaurus was a very successful species, with fossilised remains widely distributed geographically and temporally across the entire Late Jurassic period.

5) Four footed

When the first Stegosaurus remains were unearthed in 1877, it was believed to be a bipedal creature. But as new specimens emerged, it was reclassified as a quadruped.

6) Species

There are four confirmed species: S armatus, S stenops, S sulcatus and S longispinus. There are also four unconfirmed species from incomplete specimens.

For more amazing dinosaur facts, pick up the Issue 73 of How It Works magazine. Order it in print, download the digital version or subscribe today to ensure you never miss an issue!
How It Works cover issue 73