Round Three: Changmiania vs Bisticeratops
Changmiania liaoningensis
Artwork by @i-draws-dinosaurs, written by @zygodactylus
Name Meaning: Eternal Sleeper from Liaoning
Time: 125.755 million years ago (Barremian stage of the Early Cretaceous)
Location: Lujiatun Beds, Yixian Formation, Liaoning, China
Changmiania is a gorgeously preserved ornithopod known from the earliest time of the famed Yixian Formation, adding it to the ranks of amazing fossils known from this unique preservational environment. The multiple specimens of this species are found in sleeping poses, curled up on the ground with their legs and arms tucked up against them. This indicates they had been buried alive, possibly inside their own burrows. Given the depositional environment of Yixian is a sort of prehistoric Pompeii, with many dinosaurs covered very quickly in ash and dust from an exploding volcano, this makes a certain degree of sense - perhaps the two little dinosaurs had scurried into their burrow to escape the oncoming tragedy (sorry if I just made you sad), or had been asleep and unaware of the oncoming danger. At only one meter long and less than half a meter tall, Changmiania would have been easily missed in its environment, hiding among the dense vegetation from potential predators. With robust leg bones, it would have been a fast runner, able to move efficiently through the crowded undergrowth. It had a weirdly short neck for ornithischians, and that combined with its short forearms and hands indicates it was fossorial - ie, a digging animal, hence its burrow home and final resting place. Given they were found together, they were probably social creatures as well, living in small family groups. The Yixian was a dense temperate forest, filled with freshwater lakes and a great diversity of plantlife. Conifers, ferns, cycads, horsetails, and early flowering plants filled the environment and indicated a humid, possibly rainforest environment. Periodic wildfires, noxious lake gasses, and volcanic eruptions all lead to regular moments of rapid burial and amazing preservation in this environment - essentially giving us snapshots of how it changed over the course of many millions of years. In the Lujiatun bed specifically, Changmiania was neighbors with Euhelopus, Jeholosaurus, Liaoceratops, Psittacosaurus, Liaoningornis, Daliansaurus, Graciliraptor, Mei, Sinovenator, Sinusonasus, Dilong, Hexing, Incisivosaurus, Shenzhousaurus, and outside of dinosaurs mammals such as Acristatherium, Gobiconodon, Juchilestes, Maotherium, Meemannodon, and Repenomamus (yes, THAT Repenomamus), and the toad Liaobatrachus.
Bisticeratops froeseorum
Artwork by sauriazoicillus, written by @zygodactylus
Name Meaning: Froese’s Dééł Náázíní Horned Face
Time: 74 million years ago (Campanian stage of the Late Cretaceous)
Location: Farmington Member, Kirtland Formation, New Mexico, United States
Bisticeratops is an early Chasmosaurine, known from a partial skull found in the Kirtland Formation. Yet another of a largely growing number of Chasmosaurine taxa from the Campanian of North America, it appeared to resemble Pentaceratops, but was more closely related to later ceratopsians known from the Kirtland formation, as well as one unnamed taxon from the Almond Formation in Wyoming. Interestingly, Bisticeratops shows signs of bite marks from tyrannosaurids, which apparently had begun to heal prior to death. However, we do not know which tyrannosaurid may have left these marks - while the Kirtland Formation is a well studied environment, the Farmington Member has never yielded dinosaurian fossils before now, taking place earlier than the more famous De-Na-Zin of the formation. Like other iterations, the Kirtland was a coastal plain along the western interior seaway, preserving a muddy and sandy environment that would have been filled with a variety of subtropical plants. It is presumable that other dinosaurs lived here besides Bisticeratops and a tyrannosaurid - hadrosaurs, ankylosaurs, pachycephalosaurs, ornithomimosaurs, and dromaeosaurs would all have been possible members of this ecosystem based on the following and preceding ones from this formation.
Changmiania or Bisticeratops?
Changmiania
Bisticeratops
