Big and scary they may have been, but dinosaurs were by no means lumbering brutes. The more we learn about them, the more we see just how misguided our early assumptions were.
Here are the seven biggest ways our understanding of dinos has changed...
1. Tyrannosaurus rex
In 1902, in the desolate badlands of Hell Creek, Montana, the palaeontologist Barnum Brown spotted a jumble of enormous bones. They were from a muscular animal that stood several metres tall and walked on its hind legs.
The skull and jaws had the snarly grin of a fierce predator.
Brown shipped the bones back to New York, where they were displayed at the American Museum of Natural History in 1905. Crowds were aghast. The monster – a dinosaur christened Tyrannosaurus rex – was described by the New York Times as “the most formidable fighting animal of which there is any record whatever.”
In the 120 years since Brown’s discovery, dozens of T. rex skeletons have been found in the 66-million-year-old Cretaceous rocks of North America. Scientists still regard T. rex as one of the largest and strongest carnivores in Earth history.
But the ‘Tyrant Lizard King’ was no mere brute. It had a large brain and keen senses of smell and hearing, as revealed by CAT scans of fossil skulls. What made T. rex so special was that it had brawn and brains… and its body probably sported at least some wispy feathers.
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2. Iguanodon
Some say Mary Ann Mantell discovered the first evidence of Iguanodon (some giant petrified teeth). Others believe it was her doctor husband, Gideon.
Regardless, when Gideon presented the fossils, found in Sussex, to the Royal Society of London in 1822, the crowd was dumbfounded and assumed the teeth must belong to some as yet undiscovered huge fish, or possibly a rhinoceros.
What they didn’t, couldn’t, know is that the teeth came from a dinosaur – because the term ‘dinosaur’ wasn’t coined until 1842.
Soon, however, it became clear the teeth were reptilian and resembled scaled-up versions of iguana teeth. Hence, Mantell named the animal they belonged to Iguanodon.
The first artistic renderings of Iguanodon showed it in a lizard-like pose, grasping a branch between its hands and feet, and with a big horn on its nose.
Later discoveries of complete skeletons revealed that Iguanodon was a ground-living giant that walked confidently on its hind limbs and sometimes on its forelimbs and had spikes on its hands, which it probably used for self-defence.
3. Dryptosaurus
Of the more than 2,000 known species of dinosaurs today, Dryptosaurus is an obscure one; not a household name like Tyrannosaurus, Brontosaurus or Triceratops. But it wasn’t always so.
In the late 1800s, Dryptosaurus was one of the most famous extinct species of all. When its bones were discovered in a New Jersey marl pit (where a type of clay rich in carbonate was mined) in 1866, they were the first well-preserved carnivorous dinosaur skeleton known from North America.
Initially christened Laelaps – or ‘Hurricane’, after the inescapable hunting dog of Greek mythology – the predator’s name was later changed to Dryptosaurus (‘tearing lizard’) due to a taxonomic bookkeeping error.
A shame, as ‘Laelaps’ encapsulates the speed, ferocity and tenacity of this 67-million-year-old T. rex cousin.
When the great palaeoartist Charles Knight painted Dryptosaurus in watercolour for the American Museum of Natural History in 1897, his evocative scene of two playful, ‘leaping Laelaps’ was the first widely produced piece of art showing dinosaurs as active, dynamic animals.
Old views were changing, however, and over the next century, dinosaurs would be reimagined as lively, vibrant, energetic bird-like animals, not the plodding overgrown lizards envisioned by Gideon Mantell and the first generation of dinosaur hunters.
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4. Elasmosaurus
At the same 1824 meeting where the first scientific name for a dinosaur was bestowed on Megalosaurus, naturalists also described the skeleton of another type of distantly related extinct reptile: a plesiosaur.
It had a very unusual body: small head, long neck, squat belly, and all four hands and feet modified into paddle-shaped flippers. One scientist quipped that it resembled “a sea serpent run through a turtle.”
Plesiosaurs were so wacky that they continued to confound palaeontologists for decades.
When the Philadelphia scientist Edward Drinker Cope was sent several crates of bones discovered on the Kansas frontier, in the Midwest US, in the late 1860s, he could tell they belonged to a plesiosaur, which he called Elasmosaurus.
Its vertebral column was remarkable; sticking out of one end of the body was a long, sinuous series of vertebrae, while a shorter, stubbier set of bones projected from the other.
Marsh thought the head attached to the end of the stubby bones, while the long sequence was a slithery, snake-like tail.
He got it backwards, though, which is why we now believe Elasmosaurus had one of the longest necks of any animal that ever lived.
5. Stegosaurus
Everyone knows the Stegosaurus profile today: long body, low shoulders and a row of big vertical plates on its back – each big enough to dwarf a coffee table.
But when Stegosaurus bones were first found in the Jurassic-aged rocks (circa 150 million years old) of North America in the 1870s, palaeontologists had never seen anything like them.
The prickly Yale professor, Othniel Charles Marsh thought they were from some strange, new aquatic species, a turtle, perhaps, with the plates lying flat on its back as a protective carapace.
This inspired the name: Stegosaurus, the ‘roofed lizard.’
Later, after more complete skeletons were discovered, Marsh realised that the plates stood erect, but it still wasn’t enough to explain their purpose.
Scientists continue to debate this today. It’s likely that they were display structures to attract mates and intimidate rivals, but they may also have been for thermoregulation.
6. Ichthyosaurs
Mary Anning was one of the greatest fossil hunters of all time. The daughter of a cabinetmaker in the seaside town of Lyme Regis, on England’s southwest coast, young Mary collected fossils in the Jurassic-aged rocks near her home, which she sold to support the family’s meagre income.
In 1811, her brother Joseph found a skull with a big eye socket and long, pointed jaws studded with many tiny, sharp teeth.
The next year, 12-year-old Mary found part of the skeleton of the same animal. More fossils soon followed, and they were odd: the hands and feet were flippers, the body was streamlined, and the tail was fluked.
What was it? A fish? A crocodile? Something else? The palaeontologists Henry De la Beche and William Conybeare argued that it was a new type of extinct water-living reptile, which they called an ichthyosaur (‘fish lizard’).
When Mary found herself destitute in 1830, De la Beche developed a generous plan: he would sell prints of a painting to his friends and give Mary the proceeds.
He titled the painting Duria Antiquior. It showed a grinning ichthyosaur with its jaws clamped around the neck of a plesiosaur, pterosaurs flying overhead.
Today this is recognised as the first visual representation of a scene of ancient life based on fossils. It was the first piece of palaeoart.
7. Pterosaurs
In 1784, the Italian naturalist Cosimo Collini – once Voltaire’s secretary – held in his hands a most unusual object.
It was a petrified skeleton of delicate bones in a block of limestone, with toothy jaws agape, a little body and, most peculiar of all, a stretched finger on each hand.
At the time, Biblical views of Earth history still reigned supreme. The concepts of evolution and extinction were not yet widely accepted. But this creature was so drastically different from anything currently alive.
Some naturalists at the time argued that it still lived somewhere, maybe in the open ocean, where it used its long finger as a paddle. The eminent French anatomist George Cuvier knew otherwise, though.
Cuvier, one of the first people to articulate the idea of extinction to the public, recognised the long finger as the supporting architecture of a wing. This was a flying animal, which he called a ‘ptero-dactyle’, meaning ‘wing finger’.
Today we recognise pterodactyls, or pterosaurs as they’re formally known, as lightweight reptiles that glided and flew on wings made of skin anchored to the stretched finger.
They weren’t dinosaurs, but close cousins. And they were the first animals with bones to ever evolve powered flight.
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