Jinyunpelta: Beast of the Week

This week we will be checking out a newly discovered dinosaur that gives us interesting insight on the evolution of the armored ankylosaurids.  Check out Jinyunpelta sinensis!

Jinyunpelta was a plant-eating dinosaur that lived in what is now China during the Cretaceous period, between 106 and 96 million years ago.  The genus name translates to "Jinyun Shield" in reference to the part of China its bones were unearthed in.  Jinyunpelta was a member of the ankylosaurid family, charcterized by having bony armor  and a bony tail club.  More famous members of this family are the later Euoplocephalus and Ankylosaurus.

Life reconstruction of Jinyunpelta in watercolors by Christopher DiPiazza

Jinyunpelta is currently the oldest example of an ankylosaur that had a tail club.  That being said, its tail club is actually just as developed as much later members of its family.  The club, itself, was somewhat hexagonal when viewed from above, and widens towards the tip.  The tail vertebrae just behind the club are stiffened by bony rods, which would have added extra support in life.   The fact that Jinunpelta's club is so advanced tells us that ankylosaurs evolved tail clubs much earlier than the the time of Jinyunpelta.  So far no intermediate, smaller, less fortified tail club has ever been found on an older dinosaur.  The purpose of the tail club, as is the case with all ankylosaurids, is somewhat of a mystery.  However, it would have made for an effective weapon, by swinging it against the legs of predatory dinosaurs, or possibly even at the heads or flanks of members of the same species if they practiced any sort of intraspecies combat for dominance.

Jinyunpelta's tail club.  Image from Zheng's 2018 paper.

Jinyunpelta's skull was discovered, luckily.  Like all ankylosaurids, it had a flat beak, which was a bit more narrow than the beaks of known later ankylosaurids, but wider than the beaks of earlier armored dinosaurs.  The back of Jinyunpelta's mouth housed small teeth ideal for shredding plants.  Jinyunpelta would have had bony armor on the top of its head, and short horns over each eye, and growing from its cheek bones. (called jugals)

Jinyunpelta's skull.  Image from Zheng's 2018 paper.

Jintunpelta is an important scientific discovery because it proves that heavily armored, club-tailed ankylosaurs developed much earlier in history than previously thought.  This not only gives us answers, but also brings up more questions.  What were the environmental pressures causing these features to pop up at that time?  Maybe one day we'll find out.

References

Wenjie Zheng; Xingsheng Jin; Yoichi Azuma; Qiongying Wang; Kazunori Miyata; Xing Xu (2018). "The most basal ankylosaurine dinosaur from the Albian–Cenomanian of China, with implications for the evolution of the tail club". Scientific Reports. 8: Article number 3711.