Fishy discovery raises hopes Hong Kong's first dinosaur could be found
An undergraduate university student and a dinosaur expert have found Hong Kong’s first fossilized animal with a spine that dates back to the time of the dinosaurs. It’s the back half of a tiny, 147-million-year-old fish, but it could point to more fossil discoveries, possibly even Hong Kong’s first dinosaur.
The entire fish is only about 4cm, roughly the length of two HK $5 coins put together, but it’s a famous and well-studied species. Its living relatives include the freshwater butterfly fish and the endangered Asian Arowana, which is sometimes called the “dragonfish” and kept because they are believed to bring good luck.
But, although this fish, Paralycoptera, has been found in other parts of China, as far north as Jilin and as far south as Fujian, it has never been found this far south before. Edison Tse Tsz-Kei, the undergraduate who led the identification of the specimen, says this extends the range of the fish by some 700km.
“This is an astonishing distance, for a fish anyway,” Tse says.
Tse and his co-author and supervisor, Michael Pittman, a research assistant professor who specializes in dinosaurs, sent the fossil to a Chinese fossil fish expert at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing to check their findings and clarify the finer details of the fish’s anatomy. Before this fossil was found, the earliest record of its type was from the Early Cretaceous period. But, this one dates back to the Late Jurassic, so that means it was actually around for about 40 million years earlier than what scientists previously thought. Thus, we can conclude that it’s a 147-million-year-old fish.
That’s an important finding for fish researchers, but the implications go beyond that, as Tse explains.
“This is the first vertebrate fossil found in Hong Kong from the Jurassic age. Of course, the other vertebrates from that time that everyone knows are the dinosaurs, so we might find some in Hong Kong. For people like us, it’s exciting just to imagine that.”
The fish fossil comes from Lai Chi Chong in the northeastern corner of Hong Kong, north of Sai Kung. Around 147 million years ago, that area used to have active volcanoes and freshwater lakes, and we can find fossils preserved in the rocks that represent layers of mud, silt and volcanic ash on lake beds, says Michael Pittman, head of the Vertebrate Palaeontology Laboratory at the University of Hong Kong and the second author of the journal article published in the peer-reviewed open access journal PeerJ on March 26.
Pittman says the potential for finding other vertebrate fossils in Hong Kong that date back to the time of the dinosaurs is encouraging. That’s because Chinese sediments similar in age and type to the ones in Lai Chi Chong preserve some of the world’s best fossils.
For example, famous fossil beds in Liaoning, one of which has been called “one of Earth’s most celebrated fossil beds,” have produced many significant fossils, such as ones of feathered dinosaurs in July 2014.
Modern birds are the only living dinosaurs, and Pittman is doing ongoing research on the finer details of how birds evolved from their closes dinosaur relatives.
“We could find a feathered dinosaur [in Hong Kong] which for me, would be a very exciting prospect because it could be a high impact finding,” Pittman says.
He adds that Hong Kong is far away from places like Liaoning, so any dinosaur found here is likely to be a new species.
To explain why this kind of rock is so good for preserving fossils, Pittman says we should imagine the images on old, 20-year-old TV screens. They look grainy because the pixels are large. Similarly, if a type of rock is made up of big rock particles, like in a sandstone, then the fossils inside are typically only preserved as bones. However, what we have in Lai Chi Chong are mudrocks, which have finer particles, analogous to smaller pixels on the newer TVs.
“Mudrocks with volcanic ash are like high resolution TV [screens], so that’s why when you see these [feathered dinosaur fossils from Liaoning] you can see feathers… some of them preserve the contents of their stomach…you can see their skin very well,” Pittman explains.
However, it’s not as simple as just exploring the rest of Lai Chi Chong to see what other fossils lie beneath the surface. Pittman says it’s very rare for an animal to fossilize because it has to die, get buried, and remain intact for millions of years. That’s why palaeontologists dig quarries to increase the chance of finding a fossil.
For example, Pittman does field work in the Gobi desert in northern China every year over the summer, and he says he surveys an area about the size of Hong Kong to try to find a few dinosaur fossils.
“You wander around for weeks and weeks and hope to find one,” he says.
He shows me the skull of a dinosaur he found there. It’s a relative of Velociraptor, the small but fast predators with retractable claws that play a major role in the movie Jurassic Park. He says he wandered the desert for two weeks before he found that with his friend.
Pittman can’t just dig fossil quarries in Hong Kong, because parts of Lai Chi Chong belong to the Hong Kong Global Geopark of China, so no one is allowed to dig there. He says he understands the need to preserve the environment for the benefit of visitors and future generations.
They’ll also look through museum collections in Hong Kong. In fact, this fish fossil belongs to the collections at the Stephen Hui Geological Museum at the University of Hong Kong. Pittman asked Tse to survey the museum’s Hong Kong fossil collection, which is where Tse found the specimen. Tse has since graduated from HKU and is doing geological work for the government, but he plans to help Pittman with his future dinosaur research.