and
ischium Its remains were found in a
bonebed in the middle
Maastrichtian-age
Yuliangze Formation, dated to 69 million years ago. This bonebed is otherwise dominated by fossils of the
lambeosaurine hadrosaurid (hollow-crested duckbill)
Sahaliyania.
Wulagasaurus was named by
Pascal Godefroit and colleagues in 2008. Only partial remains are known at this time. It is one of several hadrosaurids from the
Amur River region named since 2000. The
type and only species to date is
W. dongi, named in honor of Chinese paleontologist
Dong Zhiming.
Wulagasaurus is
based on GMH W184, a partial
dentary (toothbearing bone of the lower jaw). Godefroit and colleagues assigned additional remains from the bonebed to their new genus, including three
braincases, a
cheekbone, two
maxillae (the toothbearing bone of the upper jaw), another dentary, two
shoulder blades, two
sternal elements, two
upper arm bones, and an
ischium. It can be
distinguished from other hadrosaurids by its slender dentary and the unique form of its upper arm, which had distinctive articulations and placements for muscle attachments. Godefroit and colleagues performed a
phylogenetic analysis that suggests
Wulagasaurus was the most
basal saurolophine known (which would result in a long ghost lineage), and interpreted this as evidence that saurolophines and hadrosaurids in general originated in Asia, which has been supported by other finds since. ==Description==