When I travel to an unfamiliar country to report a story, I seldom know in advance about the personalities of the people I need to work with: Will they be helpful or in a hurry, plainspoken or obscure? But the moment I met the paleontologist Junchang Lü a few years ago in northeastern China, I knew I had lucked out.

We were in a nondescript office building in a provincial city, and Junchang—bone thin, in hiking shoes and a red windbreaker over a polar fleece, his thick black hair kept close-cropped, a matter of indifference—greeted me with a big, easy grin. He led me down the hall to what appeared at first to be a broom closet.  But when the door swung open, the room lit up like a treasure chest with astonishing slab fossils on every shelf, all over the floor, and propped against the walls.  Some of them were type specimens of species he had already introduced to the world, others were new species he hadn’t yet gotten around to describing. He posed for a photograph beside one of them, a huge pterosaur named Zhenyuanopterus. The pterosaur’s long, thin head was turned away, but it seemed to be reaching the opposite forelimb back as if to tickle the scientist who had named it. It was a fitting image for the way Junchang lived—both whimsical and up to his eyeteeth in work. For the next two days, he took time out of his frantic schedule to show me around the fossil wonders of Liaoning Province.

So I was stunned, along with fossil lovers worldwide, to learn that Junchang Lü, a professor at the Chinese Academy of Geological Sciences in Beijing, had died on October 8, age 53. The night before, he was pushing students to complete their manuscripts for publication and talking with fellow fossil-hunter Xu Xing about a joint project, according to an email from Hokkaido University Museum paleontologist Yoshi Kobayashi, Junchang’s “academic brother, from their years together as doctoral students at Southern Methodist University in Dallas. “His wife heard Junchang eating and closing windows around midnight. On the next morning, she found Junchang cold. It was a sudden death. Probably heart attack, they said. It is so like Junchang that he talked about manuscripts until the last minute he was gone.”

Junchang Lü made his reputation in part for his numerous discoveries of new pterosaurs. Since parting ways in 2001, he and Xiaolin Wang of Beijing’s Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) had repeatedly one-upped each other in one of the most productive paleontological rivalries of our time, describing a combined total of more than 50 new species, roughly a quarter of all pterosaurs now known.

Among Junchang’s most celebrated finds, he and his co-authors described Darwinopterus modularis—named for Darwin of course, but also for “a remarkable modular combination” of traits from two separate pterosaur groups, suggesting that tightly-linked characteristics could pass down by a process of “modular evolution.” One Darwinopterus specimen, dubbed “Mrs. T” (for Mrs. Pterosaur), came with an egg apparently pushed out on death and another still in her oviduct. It was the first certain evidence of gender in any pterosaur.

On hearing of Junchang’s death, University of Leicester paleontologist David M. Unwin, a co-author on Darwinopterus and many other discoveries, remarked, "I can hear his voice in my head chiding me for having not finished some manuscript or another, or for writing something he didn't agree with. I hope it never goes away."

Junchang Lü was also a leading authority on the dinosaurs called oviraptorosaurs (“egg-thief lizards”).  In an email, University of Alberta paleontologist Philip J. Currie recalled field research with him in Canada, China, and Mongolia. The two described the uncharacteristically tiny oviraptorosaur Yulong mini together, and Junchang was also “instrumental is having Baby Louie (the cover story of a National Geographic article in 1996) repatriated to China, so that we could finish our description of this specimen.”

This embryo squeezed out of a gigantic 18-inch-long egg was first discovered during the early-1990s Wild West period in Chinese paleontology. Amateur fossil hunters quickly sold it into the international trade and it would have remained there, undescribed in science. Instead, Baby Louie now belongs to the Henan Geological Museum in Zhengzhou, near the site of its discovery, and it is properly named Beibeilong sinensis, the embryo of one of the largest oviraptorids known.

“Junchang was the lynchpin that connected so many of China's fossil collectors and small regional museums to the international academic community,” said University of Edinburgh paleontologist Stephen Brusatte, also by email. “There are dozens of new dinosaur and pterosaur species that the world would have never known about without him. Every time I saw him, he got out his computer and showed me photos of the newest fossils he was working on, always with a big smirk on his face.”

On Twitter, Brusatte recalled Junchang gleefully inducing him to eat rodent-tail stir fry, boiled bull testicles, and mule penis during visits to China. But he also recalled being “led down a narrow hallway, into a side room where a big slab of rock perched dangerously on a much-too-small table. I was speechless. Before us was a skeleton of a dinosaur, its chocolate-brown bones standing out from the drab limestone surrounding it. And all around the bones were feathers. The arms even had full-on wings. We figured out that it was a new species of dinosaur, a close cousin of Velociraptor. We called it Zhenyuanlong”—meaning the Fluffy Poodle from Hell, he notes—“and it is by far the most gorgeous fossil I've ever had the privilege of studying, and that was all because of Junchang. He is one of the most important dinosaur researchers of the past half century, and he should be remembered as a scientific titan.”