The latest fossil discoveries and paleontological research continue to revise our view of the world’s most famous dinosaur, Tyrannosaurus rex. An updated depiction of the extinct giant is now on display in a New York City exhibit that’s bound to ruffle some feathers.
From the opening room of the American Museum of Natural History’s display, where a model of a fluffy, bird-like juvenile takes the stage, to the final interactive video wall of a full-motion, earth-shaking dinosaur, the exhibit is peppered with new insights — and more than a few nagging mysteries. (There are also plenty of creepy moments, such as an undulating silhouette of a full-grown T. rex with hair-like feathers.)
The centrepiece of “T. rex: The Ultimate Predator” is a full-scale, full-colour model into which the curators poured all the latest research. Fans of T. rex will note that the adult dinosaur (which generally only lived to into its late 20’s) looks more svelte in this incarnation and has slightly raised rear haunches.
“But I think the feathers on the adult would still be considered contentious,” said Mark Norell, curator of the T. rex exhibit and chair of the museum’s paleontology department, pointing to the model during an interview.
Tufts of feathers adorn the T. rex’s head and run down its spine. It’s widely accepted that many dinosaurs had feathers and bird-like features. Indeed, Norell was part of the team that discovered the first fossilized remains of a feathered tyrannosaur (Dilong paradoxus) in China in 2004. However, putting plumage on the adult T. rex is still considered by some to be an inferential leap.
“No one has found a fossil feather on a T. rex, but we’ve found more relatives of T. rex with feathers, so we can infer it,” explained Norell.
Much of the evidentiary record has expanded in recent years, offering new insights into the king of carnivores. “Ten years ago we only had seven or eight skeletons—today we have 40 pretty decent skeletons,” said Norell.
And researchers have been applying increasingly refined techniques to investigate the fossil record, often combining several disciplines. For example, paleontologists now know that the T. rex had a literally bone-crushing bite force of nearly 3,629kg, thanks to biomechanical modelling of its head and chemical analysis of its fossilized faeces (called coprolites).
“We know some of what it ate because of the poop; 50 per cent of it was bone,” explained Jasmina Wiemann, a molecular paleobiologist and doctoral student who contributed to the exhibition. Thanks to x-ray fluorescence and microprobe analysis, we know T. rex chewed up and swallowed the bones of its victims.
“It’s was a head killer,” said Gregory Erickson, a paleobiologist at Florida State University who consulted on the exhibition. “That is, it used its head to kill.” From the force of its bite to its regenerating gigantic sharp pointy teeth—and the digested evidence — Erickson says we can infer something about its predatory practice: It probably didn’t use its notoriously tiny forearms for much.
“I think they are vestigial, just remnants,” he said. While the arms with sharp claws could have been used to dissect its prey, the evidence suggests it wasn’t necessary.
Using 3D scanning and 3D modelling, researchers have also concluded that T. rex was smarter than your average tyrannosaur. It had a larger brain than previously thought, with a more pronounced olfactory area and large eyes, indicating that it had an acute sense of smell and sharp vision. (So much for hiding from the dinosaur by standing still.)
Also along the skull of the giant dinosaur are several pronounced bumps. Some researchers have suggested the protuberances are an indication of additional armour or horn-like growths. But the exhibition team eschewed adding horns to their models. Walking around the display for the adult T. rex, Norell explained that the scientists looked at related animals with similar micostructures. It turned out the nodes on the dinosaur were more like those on lizards and crocodiles, which don’t have horns.
So what about that sound-of-thunder T. rex roar: Is that bogus, too?
The dinosaur’s throat structure and surrounding soft cartilage are not things that got preserved in the fossil record, according to Erickson, the paleobiologist: “Sounds don’t fossilize.” However, from what they can determine from T. rex’s overall cranial structure, it probably didn’t have a Jurassic Park lion-like roar, but it also didn’t chirp like a bird. Best guess is something akin to a crocodile’s bellow.
Perhaps the biggest mystery still surrounding T. rex (and other dinosaurs) is what colours they sported. Was the great predator a bronze behemoth or a magenta monster?
Microbiologist Wiemann said a lot of exciting progress has been made in the area of colour thanks to chemical analysis. She was able to dissolve small pieces of T. rex bone, for example, to isolate some soft tissue cells. Looking for molecular signatures has revealed that some pigments are more stable over time and therefore easier to test for. That’s how scientists have been able to determine that some dinosaur eggs were coloured, and it’s how researchers discovered a banding pattern in the feathers of other dinosaurs (a feature on display in the new exhibit).
In a virtual-reality part of the exhibit involving HTC’s Vive headsets, T. rex’s eggs are depicted as being green, but because no one has found a T. rex nest yet, no one knows for certain whether the big beast’s eggs were patterned like a bird’s or ivory like a crocodile’s. To find out, we’ll have to await the discovery of a T. rex nest.
“As for fossilized skin, the big issue with it is it’s likely coloured by melanin—and keratin,” said Wiemann, “and keratin can range from purple to orange to red.” The trick is knowing how well it is preserved (or is degraded) over thousands of years in order to judge what colour a T. rex might have been 70 million years ago. Until we know those rates, we can’t say with any precision whether the scale-like skin of T. rex was orange or brown.
“But in 10 years,” said Wiemann, “the instruments like mass spectrometers will be more sensitive and less expensive, so we’ll be able to learn more.”
“T.rex: The Ultimate Predator” opens to the public on Monday, March 11, 2019. If you can’t get to New York City to see it, the organisers say plans are already underway to have it tour to other cities once its run is finished at the American Museum of Natural History.