SCIENCE AND CULTURE

Dinosaur art evolves with new discoveries inpaleontologyAmy McDermott, Science Writer

Under soft museum lights, the massive skeleton of aTyrannosaurus rex is easy to imagine fleshed out andalive, scimitar teeth glimmering. What did it look likein life? How did its face contort under theMontana sunsome 66 million years ago? What color and texturewas its body? Was it gauntly wrapped in scales, fluffywith feathers, or a mix of both?

Increasingly, paleontologists can offer answers tothese questions, thanks to evidence of dinosaur softtissues discovered in the last 30 years. Translating thosediscoveries into works that satisfy the public’s imaginationis the purview of paleoartists, the scientific illustratorswho reconstruct prehistory in paintings, drawings, andsculptures in exhibit halls, books, magazines, and films.

Those creations necessarily require some artisticlicense, says freelancer Gabriel Ugueto, who’s basedin Miami, FL. As new discoveries offer artists a bettersense of what their subjects looked like, the findingsalso constrain their creativity, he says, by leaving fewerdetails to the imagination.

Even so, he and other artists welcome new discov-eries, as the field strives for accuracy. The challengenow is sifting through all this new information, includingcharacteristics that are still up for debate, such as theextent of T. rex’s feathers, to conjure new visions of theprehistoric world.

Paleoartists often have a general science back-ground or formal artistic training, although career

Among the earliest examples of paleoart, this 1830 watercolor painting, called Duria Antiquior or “A more ancientDorset,” imagines England’s South Coast populated by ichthyosaurs, plesiosaurs, and pterosaurs. Image credit:Wikimedia Commons/Sir Henry Thomas De la Beche.

Published under the PNAS license.

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paths vary. “There is no one way that people get intopaleoart,” says Mark Witton, a paleoartist and paleon-tologist at the University of Portsmouth in the UnitedKingdom, who recently wrote a paleoart handbook(1). Regardless of their backgrounds, professionalpaleoartists share a dedication to credibility and typi-cally consult with paleontologists, or reference scien-tific articles and specimen photos, to ensure scientificaccuracy—or at least defensibility if an animal’s exactappearance remains open for debate.

Today’s paleoart interpretations are informed byan unprecedented level of detail related to dinosaurskin, scales, fat, and feathers, thanks to hundreds ofnew fossil discoveries since the 1990s, Ugueto says. A2017 study, for example, described the well-preservedremains of a plesiosaur, discovered in a quarry in north-eastern Mexico. Plesiosaurs were marine reptiles withrounded bodies, short tails, and four flippers (2). Somehad crocodile-like heads and long necks. This particularfossil lies on its back—a nearly complete skeleton sur-rounded by skin and thick, fatty, subdermal tissue,which looks like dark smudging surrounding the fos-silized bones. It’s among very few records of plesio-saur soft tissue ever found.

Responding to the discovery, Ugueto now drawshis plesiosaurs with a layer of insulating fat, similar tothat of modern marine mammals. Although the generalpublic knows plesiosaurs from drawings reminiscent ofthe Loch Ness Monster, Ugueto says his thicker-neckedand heavier-bodied depictions are well-received.“When you show people an animal that looks like ananimal, there’s a natural reaction of ‘oh, yes, this makessense,’” he says.

Plesiosaurs aren’t the only prehistoric creaturesdepicted without much fat. Most dinosaurs, and evenprehistoric mammals, are “shrink-wrapped,” Uguetosays—the colloquial term for paleoart that squeezesthe bones and muscles under a gaunt layer of skin.Shrink-wrapping is the conservative approach to imag-ining an entire animal based on fossil bones ratherthan speculating about soft tissue as well, says NewMexico-based freelance paleoartist Matt Celeskey;Ugueto believes that shrink-wrapping caught on sim-ply because artists and paleontologists have been sofocused on the form suggested by bones.

In any case, an artistic movement in the last decadeis pushing back, arguing that modern animals looknothing like their skeletons. If paleoartists drew extantspecies based on their bones alone, “they’d be verygrotesque, hyper-muscled things with all their teeth

exposed,” says Celeskey. Take roosters, for example.Illustrating them from their skeletons, he says, wouldoverlook their crests, their wattles, the extent of spurson their legs, and the iridescence of their feathers.

Menagerie of MethodsArtists gain fresh eyes on the past by studying newlyunearthed fossils and by adopting new methods torevisit the fossils resting in museum drawers. Considerthe famous dinosaur Archaeopteryx, a distant cousinof modern birds. Paleontologists found the firsttwo putative Archaeopteryx fossils in Germany’sSolnhofen limestone quarry around 1861. One was asingle fossilized feather, and the other a skeleton withclearly preserved impressions of feathers surroundingit. Researchers wouldn’t know the color of that plum-age until 2012, when they analyzed the isolated fos-silized wing feather, stored at the Museum of NaturalHistory in Berlin, Germany, using a scanning electronmicroscope. They found the tiny, rod-shaped im-pressions and three-dimensional structures of mela-nosomes, organelles containing the pigment melaninwithin the feather’s fibers. Based on the rod-shape andother characteristics of the melanosomes comparedwith those of modern birds, the authors concludedthat the feather would have been black (3).

Another feathered dinosaur, unveiled in a studypublished in 2018, was iridescent (4), with arrays of flatand wide melanosomes stacked on top of each otherin the feathers around its head and neck. Today’s hum-mingbirds have the most similarly shaped arrays in theiriridescent feathers, says study coauthor Julia Clarke, apaleontologist at the University of Texas at Austin.

Hence, artist renderings of the species, calledCaihong juji, appropriately depict a shimmering headand neck. Artists wouldn’t have the freedom to skip theiridescence on this animal. However, whether thosefeathers had a reddish, bluish, or greenish sheen is stillup for artistic interpretation. The hue comes from thespacing of melanosome arrays in the feather, which wasnot preserved. “What tonalities that shiny color wouldhave,” Clarke says, “is artistic license.”

Terrible LizardsAs paleontologists unearth new evidence, artists adapt.Artists’ willingness to change with the field reflects amarriage of art and science over the last two centuries.

In her 2017 book Paleoart: Visions of the PrehistoricPast, New York-based journalist Zoë Lescaze tellsthe story of the first work of paleoart—a watercolor

Fossil evidence of plesiosaur fat published in 2017 suggests a chunkier vision of those marine reptiles than previouslythought. Image credit: Gabriel Ugueto.

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painting of a prehistoric scene of England’s southerncoast populated by species known from local fossils,including marine and flying reptiles, and painted byEnglish clergyman and geologist Sir Henry Thomas Dela Beche, circa 1830 (5). “What’s charming about thatimage,” Lescaze says, “is he wasn’t setting out to launcha genre. He wasmore or less trying to help a friend.”Dela Beche was raising money for Mary Anning, a prolificself-taught paleontologist, who discovered the firstplesiosaur among other species, but received littlecredit for her discoveries because of her gender andclass, according to Lescaze. To raise funds, De la Becheimagined his watercolor scene of the English coast fullof species Anning had discovered. That painting“proved hugely influential,” Lescaze says, “and sparkedan interest among researchers in having their discov-eries reanimated in this way.”

The movement spread through Europe and acrossthe Atlantic to the United States, infiltrating mu-seums by the late 1800s. De la Beche and other earlypaleoartists strove for scientific accuracy. But therewas just less evidence back then. New data about colorand form gleaned from soft tissues, as well as detailsabout animal movement based on bone stress tests,are “leaving less room for the artist’s imagination,”Lescaze says. Her book closes in the 1990s, when thefield’s aesthetic shifted away from fine art influences

like impressionism, toward more realistic, almostphotograph-like scientific illustrations.

A Great DebateNew data may limit artistic freedom, but they also opennew possibilities. Take T. rex, for example: Two lines ofpotentially conflicting evidence hint at its appearance.

Fossils discovered in the last 20 years show thatearly relatives of T. rex had feathers “nose to tail,” sayspaleontologist David Hone at Queen Mary Universityof London, England (6). Artists responded by illus-trating Tyrannosaurus with a feathery coat. But then,three years ago, paleontologists found several smallscraps of skin from across T. rex’s body, with apparentscales instead of feathers (7).

Some artists had “an emotional response as wellas a rational one,” says Witton. For years, paleoartistshad depicted T. rex with feathers, and Witton suspectsthat some people preferred that established style.Because the 2017 study only found a few small scalyskin patches, it didn’t conclusively prove whetherT. rex was entirely scaly or had some feathers, soartists still have some room for personal preferenceand interpretation.

Paleoartist Julius Csotonyi, based in British Columbia,Canada, faced the dilemma to depict T. rex with orwithout feathers recently, when the US Postal Serviceapproached him to illustrate the “Nation’s T. rex,”housed at the Smithsonian’s National Museum ofNatural History in Washington, DC, in a set of foreverstamps released in August 2019. Csotonyi consultedwith paleontologists and decided to take amiddle path,illustrating a downy hatchling Tyrannosaurus, a juvenilewith some feathers on its back, and an adult with scalesand without feathers. He believes that there's insuffi-cient data to determine whether T. rex had feathers ornot, and he disagrees with some in the paleoart com-munity who have taken a strong stance either way.

New evidence challenges artists to relearn theanatomy of animals they’re already accustomed toreconstructing in a certain way, Witton says. Suddenlyknowing the placement of feathers or color can bejarring.

But Witton doesn’t believe that the new discover-ies constrain paleoart. He says they feel more like newadditions to his collection of knowledge, keeping himon his toes as he tries to stay current. At the core ofpaleoart “is a desire to recreate some sort of ancienttruth,” Witton says. “So it’s a nice feeling when newdata come along and you learn a little more, evenabout something familiar to you.”

Updating illustrations of a familiar species can feellike seeing an old friend who’s suddenly wearingglasses, he adds. It can be disconcerting. And yet,knowing what dinosaurs really looked like “is the endgoal” Witton emphasizes. “This is what we should bemoving toward.”

1 M. P. Witton, The Palaeoartist’s Handbook: Recreating Prehistoric Animals in Art (The Crowood Press, Marlborough, UK, 2018).2 E. Frey et al., A new polycotylid plesiosaur with extensive soft tissue preservation from the early Late Cretaceous of northeast Mexico.Bol. Soc. Geol. Mex. 69, 87–134 (2017).

Created by paleoartist Mark Witton, this never-before-released image of afeathered cousin of the T. rex called Yutyrannus is an homage to legendarypaleoartist Charles Knight. Because ancient cousins of Tyrannosaurus hadfeathers, some paleontologists and artists argue that T. rex would have had themas well. Image credit: Mark Witton.

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3 R. M. Carney, J. Vinther, M. D. Shawkey, L. D’Alba, J. Ackermann, New evidence on the colour and nature of the isolatedArchaeopteryx feather. Nat. Commun. 3, 637 (2012).

4 D. Hu et al., A bony-crested Jurassic dinosaur with evidence of iridescent plumage highlights complexity in early paravian evolution.Nat. Commun. 9, 217 (2018).

5 Z. Lescaze, Paleoart: Visions of the Prehistoric Past (Taschen, Cologne, 2017).6 X. Xu et al., Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids. Nature 431, 680–684 (2004).7 P. R. Bell et al., Tyrannosauroid integument reveals conflicting patterns of gigantism and feather evolution. Biol. Lett. 13,20170092 (2017).

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