‘Mona Lisas’ of the Mesozoic to take center stage in renewed Peabody

The fossilized bones of Poposaurus, an early crocodilian species that once roamed modern day Utah, spent more than 200 million years embedded in rock before Yale paleontologists began excavating them in 2003. For the past 15 years, researchers from across the globe have studied the ancient remains — by far the most complete specimen of its kind — behind the scenes at Yale’s Peabody Museum of Natural History. But Poposaurus’ time in the limelight is coming. 

When the Peabody reopens following a top-to-bottom renovation, the mauve-hued skeleton will stand in the museum’s dinosaur hall, joining old favorites like Brontosaurus and Stegosaurus. About 14 feet long, Poposaurus will enlighten visitors about life in the Late Triassic Period, when crocodilians and dinosaurs vied for dominance. 

The two-legged predator was a crocodilian champion in this evolutionary contest. Ultimately, the dinosaurs overwhelmed their crocodilian competitors and flourished, evolving into birds. The refurbished Peabody will tell this and many other stories about the development of life using these extraordinary fossils and lifelike models of prehistoric beasts. 

Poposaurus won’t be the only new resident of the museum’s fossil-rich first floor. The bipedal predator will be joined by a smaller, four-legged, and even more complete crocodilian specimen, nicknamed “Popo Buddy,” that was discovered in the same hillside of Utah’s Grand Staircase-Escalante National Monument. 

There’s more: A lifelike, full-scale model of Gastornis, a towering, flightless bird that roamed after the Cretaceous–Paleogene mass extinction, which killed off the giant dinosaur species about 66 million years ago, will underscore the fact that one group of dinosaurs still walk (and fly) among us as modern birds — an area of research where Yale scientists continue to make groundbreaking discoveries.

And like the hall’s other exhibits, the model will highlight the prominent role Yale scientists have played in illuminating the history of life on Earth. 

The COVID-19 pandemic temporarily delayed the Peabody’s renovation, but work on the project has resumed and the museum aims to reopen in about three years. 

“Given all that has gone on during this year, we feel incredibly fortunate that this project is moving forward and that we are under construction,” said Peabody Director David Skelly, the Frank R. Oastler Professor of Ecology. “The design of the renovated and expanded museum is fantastic and we are excited to be able to share completely renewed exhibitions with everyone in a couple of years.”

The renovations to the Peabody — which houses more than 13 million objects representing about 4 billion years of geological, biological, and human history — were made possible by a $160 million gift from Edward P. Bass ’68 B.S. in 2018. The project will increase the museum’s exhibit footprint by 50% and create new spaces for research and teaching with Peabody collections. 

Last fall, Peabody staff began clearing collection objects from storage rooms in the museum’s basement to prepare the building for construction. In February, the fossil skeletons in the museum’s Great Hall and Hall of Mammals were dismantled. Nine of the specimens, including Brontosaurus and Stegosaurus, were shipped to Research Casting International (RCI), an Ontario-based company that specializes in preparing and preserving fossil mounts, to be cleaned, mended, and adjusted into dynamic poses that reflect the latest science. (When the fossils return to New Haven, keep an eye on the tails. They will be elevated to show that Brontosaurus and Stegosaurus were lively animals, not the plodding brutes often depicted in textbooks and popular culture.) And exhibits on the museum’s second floor, including the mineral specimens in David Friend Hall, are being dismantled. Construction on the museum’s building is scheduled to begin next year.

In the meantime, Peabody staff members are busy planning new and innovative ways to inform and fascinate visitors once the museum reopens. 

That’s where Poposaurus and Gastornis come in.

Discoveries of a lifetime

Before Yale researchers discovered the Poposaurus specimen, most of what was known about this distant relative of the crocodile was drawn from fossil fragments. Over three years, beginning in 2003, paleontologists excavated a nearly complete skeleton of a Poposaurus juvenile. Some pieces of teeth and bone from the tip of the upper jaw were all that remained of the animal’s skull, but its body was largely intact. 

“Popo Buddy” was discovered underneath its larger counterpart. The specimen, which is awaiting a scientific name and description, resembles a greyhound with a long, reptilian tail, said Bhart-Anjan Bhullar ’05 B.S., assistant professor of geology and geophysics and an assistant curator at the Peabody.

The two fossils provide unique insight into members of the crocodile lineage during that early part of the Age of Reptiles, Bhullar said. 

“Either of these specimens would have been the discovery of a lifetime,” he said. “They are unique in the way that a Renaissance masterpiece like the ‘Mona Lisa’ is unique. They provide enormous contributions to the body of human knowledge about the history of life.” 

Living crocodiles and birds belong to the same clade, or evolutionary group, called Archosauria, which means “ruling reptiles.” While the Mesozoic Era is widely known as the Age of Dinosaurs, it didn’t necessarily begin that way. Crocodilians and dinosaurs competed with each other over tens of millions of years during the Triassic Period. 

Poposaurus, a land-living predator that walked upright, might signal a point where crocodiles had the upper hand in this evolutionary contest, Bhullar said.

“It was bigger than most contemporaneous dinosaurs. Crocodiles hadn’t gone into the water yet. Poposaurus was a predator that ran on two legs. It was impinging on dinosaur territory,” Bhullar said. “We didn’t know that until we discovered the specimen.” 

RCI will construct the Poposaurus skeleton using some of the original fossil bones as well as 3-D models of others that are too delicate for display or needed for research purposes. Peabody staff members are creating the reproductions, which will be sent to RCI next year, said Chris Norris, the Peabody’s director of public programs.

The skeleton will have a more barrel-shaped body set lower to the ground than the dinosaurs displayed alongside it, Bhullar explained. “Visitors will notice that, compared to Poposaurus, the dinosaur specimens have narrow wedge-shaped bodies, like birds,” he said. 

Poposaurus also has simpler arms than dinosaurs, whose forelimbs were evolving into intricate wing-like structures, Bhullar noted.

“Popo Buddy” will be partially encased in a replica of its field jacket — the plaster covering used to protect a fossil as it is transported to a lab or museum for study — Norris said.  

Both specimens will be displayed underneath “The Age of Reptiles,” Rudolph F. Zallinger’s iconic 1947 mural in the Great Hall, which depicts 32 dinosaur species spanning 362 million years. “Popo buddy” will be housed inside a glass case in front of Poposaurus.  

They will be displayed in a continuum of exhibits that chart the evolutionary development of vertebrate life in the Mesozoic Era, particularly the development of dinosaurs into modern birds, explained Kailen Rogers, the Peabody’s assistant director of exhibitions.  

“The display moves from land-dwelling animals to the development of winged flight,” Rogers said. “We’ll take visitors through that and other story arcs using fossils.”  

A big, menacing bird

The dinosaurs ultimately prevailed in their evolutionary contest with crocodiles. Today, there are more species of birds, which are living dinosaurs, than any other species of land vertebrate. (Crocodilians thrived, but through stolid persistence, not the flamboyant diversification of the bird line, Bhullar noted. Although represented by far few living species than birds, today’s crocodilians often sit atop the food chain, occasionally even in places where people live.)

A fully feathered, 7-foot-tall scale model of Gastornis, an extinct bird species, will provide museum guests with a striking reminder that dinosaurs’ evolutionary empire persisted after an asteroid impact wiped out most of their species.

The model, which is being fabricated at Minnesota-based Blue Rhino Studio, will greet visitors as they exit the Great Hall and enter what was formerly the Hall of Mammals. (The name will change to better reflect the biological diversity of the Cenozoic Era, Norris said.) The project is funded by a gift from Keith and Elizabeth Parker Crow. Keith Crow ’83 B.S., a partner at the law firm of Kirkland & Ellis in Chicago, explained that he became interested in natural history after his son developed a fascination with dinosaurs.

“We wanted to direct our gift to Yale toward something that we’re really passionate about and dinosaurs have become a passion,” he said. “We think the Gastornis model will be a very fun and educational exhibit that will enhance people’s experiences at the Peabody. This big, menacing bird will help kids imagine about what the animal was like and inspire them to become interested in science.”

The studio’s artists are consulting with Yale scientists on fleshing out and feathering the big bird, drawing on information from modern fowl, such as chickens and ducks, which are Gastornis’s closest living relatives. 

Another model Blue Rhino is creating for the museum will depict Anchiornis, a winged dinosaur from the Jurassic Period that was the subject of a seminal Yale discovery. Using insights on pigmentation drawn from a fossilized squid’s ink sac in the Peabody’s collection, Yale researchers identified the color patterns in Anchiornis’s feathers, which were a combination of black, white, gray, and reddish brown. It was the first time anyone identified the color patterns of a dinosaur’s plumage.  

The model will be displayed underneath the mural and paired with a squid fossil featuring a clearly visible ink-sac fossil, which enabled the discovery, Rogers said.

That ancient ink sac demonstrates the enduring utility of the museum’s fossil collection, said Bhullar.

“Good fossil specimens, like the Peabody’s, are the gift that keeps on giving,” he said. “They become relevant again with every new generation of scientists and research techniques. Yale researchers are gaining enormous insights about aspects of the lives of these animals with specimens in the museum’s collections.”