Charonosaurus jiayinensis: Lambeosaurines in the Maastrichtian.
Size: 32.8 feet (10 meters).
Time Period: The Maastrichtian Stage of the Late Cretaceous.
Locale: The Yuliangze Formation of China.
Name: The generic name honors Charon, the Ancient Greek ferryman of the dead. The specific name honors Jiayin village, which lies east of the Yuliangze Formation.
Parasaurolophus is one of the most famous hadrosaurs known by the public. Its crest makes it unique and bizarre in appearance. Still, there’s a good deal of anachronism in the public portrayal at times. I remember an episode of The Magic School Bus when Parasaurolophus was portrayed as a contemporary of Triceratops, Tyrannosaurus, and Troodon. This is false, as Parasaurolophus was actually from the Campanian Stage of the Late Cretaceous, while the other dinosaurs that I mentioned lived during the Maastrichtian Stage. Indeed, all North American relatives of Parasaurolophus, called the lambeosaurines, were gone by the time the dinosaurs went extinct. They had been replaced by hadrosaurs like Edmontosaurus. But was it the case elsewhere?
Charonosaurus was the closest relative of Parasaurolophus known to science, and the only hadrosaur quite like it. The partial skull of Charonosaurus indicates that it probably possessed the same tube-shaped crest as its relative. The difference between these two creatures is fairly simple. One: Charonosaurus was a good deal larger than Parasaurolophus, sharing this trait with the rather distantly related Shantungosaurus and paralleling the gigantism observable in Late Cretaceous Mexican hadrosaurs like Velafrons and Magnapaulia (see my post on Velafrons). Two: Charonosaurus lived during the Maastrichtian Stage of the Late Cretaceous, later in time than Parasaurolophus. In a time when lambeosaurines were basically gone from North America, what was it doing in Asia?
Well, it’s really not that complicated. It’s probably true that the faunal assemblages of Mongolia/China and Canada/USA/Mexico were different during the Late Cretaceous. For example, therizinosaurs were present in Asia during the Late Cretaceous, but not in North America. Maybe we haven’t found any yet, but after about 90 million years ago (with Nothronychus), they are absent in the fossil record. In Asia, ceratopsids were largely absent (see my post on Sinoceratops). Otherwise, the fauna were largely similar, a fact ensured by faunal interchanges.
It’s possible that the climate conditions of the Maastrichtian were different from Asia to North America. This would entail that certain groups thrived where others were very rare. In addition to the animals that I mentioned before, sauropods were far more common in Southwest America than in Asia. In addition, yes, lambeosaurines survived into the Maastrichtian, while the saurolophines replaced them in North America. Though saurolophines were actually present in Mongolia during the Late Cretaceous in the form of Saurolophus itself, the lambeosaurines were still very common and successful (e.g. Amurosaurus, Olorotitan, Barsiboldia). The differences between the Maastrichtian fauna of continents that were joined at the time are quite intriguing, and I believe that more research involving this faunal interchange should be done. Like I’ve said before, some research should also be done on the gigantism of hadrosaurs in China and Mexico, which parallel one another uniquely.
Charonosaurus is interesting because it very closely resembles the similar Parasaurolophus, despite having lived in a different time and area. The differences between faunas with so many shared components are surely due to environmental factors, and are unique in the Maastrichtian world. Sometimes, the division of the continents is just as interesting as their rejoining.