#jinzhousaurus

By José Carlos Cortés

Etymology: Reptile from Jinzhou

First Described By: Wang & Xu, 2001

Classification: Dinosauromorpha, Dinosauriformes, Dracohors, Dinosauria, Ornithischia, Genasauria, Neornithischia, Cerapoda, Ornithopoda, Iguanodontia, Dryomorpha, Ankylopollexia, Styracosterna, Hadrosauriformes, Hadrosauroidea

Status: Extinct

Time and Place: Jinzhousaurus lived about 124.4 million years ago, in the Aptian of the Early Cretaceous 

Jinzhousaurus is known from the Dawangzhangzi Beds of the Yixian Formation 

Physical Description: Jinzhousaurus was a Hadrosauroid, a type of dinosaur closely related to the duck-billed dinosaurs (Hadrosaurids) of the late Cretaceous - and a member of the group from which they evolved. This group experimented a lot with how they chewed and acquired food, mainly in order to deal with the rapidly changing environment of the Cretaceous Period. As the late Cretaceous turned into a very humid landscape, however, most of these forms died out, giving way to the Hadrosaurids to take over with their specialized-for-mushy-plant-food mouths. Jinzhousaurus was a fairly medium-sized dinosaur, reaching about 7 meters in length with a skull a half a meter long. It had very large nose holes and a wide back of the skull, with a small crest. It probably would have moved back and forth between walking on two legs versus four. It had three toes on each foot and five fingers on each hand, though only the first three fingers had claws - so it wasn’t really evolving the hoof-like front limbs seen in the Hadrosaurids proper. Its snout wasn’t a duckbill, but more like that of Iguanodon, with a rounded bulky beak - but different enough that it probably had a different feeding strategy than its cousin. Its back was stiffened extensively, making it rigid for balance and the tail mainly inflexible.

Diet: Jinzhousaurus primarily ate plants at the medium-browsing level - so mainly coniferous trees and the like.

Behavior: Jinzhousaurus probably didn’t live in groups but, rather, was mainly solitary. It would have spent most of its time wandering through its environment, grazing on plants alone, and remaining vigilant for danger. It also probably would have taken care of its young, though little else is known about its behavior. 

By Scott Reid

Ecosystem: Jinzhousaurus lived in the Yixian Formation, a highly diverse ecosystem showcasing the variety and evolution of birdie dinosaurs at the beginning of the Cretaceous period. This was a diverse coniferous forest in a temperate, seasonal climate. Very humid, it’s likely that Jinzhousaurus would have seen snow on a regular basis. There were notable dry seasons as well, leading to more tough vegetation for Jinzhousaurus to chew on. There were many flowering plants there too, along with ferns, horsetails, ginkgoes, cycads, seed ferns, and so many others - all good food for Jinzhousaurus. This was also a dense freshwater lake environment, with abundant minerals due to volcanic eruptions - leading to periodic environmental turnover.

Jinzhousaurus lived alongside many other kinds of dinosaurs, as this was an exceptionally diverse community. Here there was the ankylosaurid Liaoningosaurus, another ornithopod called Bolong, and an unnamed titanosaur in terms of other herbivores. There were many kinds of small fluffy dinosaurs - the Compsognathid Sinosauropteryx; the raptors Zhenyuanlong, Changyuraptor, Sinornithosaurus, and Tianyuraptor; the Troodontid Jianianhualong; the protobirds Jeholornis, Confuciusornis, and Zhongornis; the Anchiornithid Yixianosaurus; the Opposite Birds Dalingheornis and Shanweiniao; and the early nearly-true-birds Archaeorhynchus, Eogranivora, Yanornis, Hongshanornis, and Longicrusavis. Non-dinosaurs were of course also present - many types of fish, amphibians, and lizards; mammals such as Akidolestes, Sinobaatar, Sinodelphys, Chaoyangodens, and the famous Eomaia; Choristoderes like Hyphalosaurus and Monjurosuchus; and pterosaurs like Cathayopterus and Ningchengopterus. Essentially, a beautiful snapshot of the Early Cretaceous.

Other: Jinzhousaurus is sort of a mix between earlier ornithopods and the later hadrosaurs, so its classification was difficult to place for a while. But now it seems to be a basal member of the group that lead to the Hadrosaurids, rather than more close to Iguanodon proper.

~ By Meig Dickson

Sources under the Cut 

By José Carlos Cortés on @ryuukibart

PLEASE support us on Patreon! We really do need all of your support to keep this blog running - any amount helps!

Name: Jinzhousaurus yangi

Name Meaning: Jinzhou Reptle

First Described: 2001

Described By: Wang & Xu

Classification: Dinosauria, Ornithischia, Genasauria, Neornithischia, Cerapoda, Ornithopoda, Iguanodontia, Dryomorpha, Ankylopollexia, Styracosterna, Hadrosauriformes, Hadrosauroidea

Jinzhousaurus is another Hadrosauroid, found from the Dakangpu member of the Yixian Formation in Liaoning, China. It dates back to the Hauterivian to Barremian ages of the Early Cretaceous, about 135 to 144 million years ago. It is known from a fairly complete skeleton, about 7 meters in length and with a half a meter long skull. Originally found to be an indeterminant ornithopod, it has been since found in subsequent analyses to be a Hadrosauroid. It had some similarities to Iguanodon, such as in the shape of its snout and skull, though some parts of its jaw were different. This may indicate that it had a modified feeding strategy than Iguanodon. It was also very similar to Probactrosaurus, though less similar to Hadrosaurids than it was. It is the first large sized Ornithischian known from its ecosystem, and there are no Sauropods in its locality, indicating that it had a major role as a large sized herbivore. Furthermore, there were no large sized predators in the ecosystem, which might either be an aspect of bias or due to no large predators being present to feed on Jinzhousaurus, potentially due to flora turnover. It lived alongside such dinosaurs as Liaoningosaurus, Archaeorhynchus, Confuciusornis, Dalingheornis, Hongshanornis, Longicrusavis, Shanweiniao, Zhongornis, Sinornithosaurus, Tianyuraptor, Sinosauropteryx, and Yixianosaurus. 

Sources:

Barrett, P. M., R. J. Butler, W. Xiao-Lin, X. Xing. 2009. Cranial anatomy of the Iguanodontoid Ornithopod Jinzhousaurus yangi from the Lower Cretaceous Yixian Formation of China. Acta Paleontologica Polonica 54(1): 35-48.

McDonald, A. T., D. G. Wolfe, J. I. Kirkland. 2010. A new basal hadrosauroid (Dinosauria: Ornithopoda) from the Turonian of New Mexico. Journal of Vertebrate Paleontology 30(3): 799-812. 

Wang, X., & X. Xu. 2001. A new iguanodontid (Jinzhousaurus yangi gen. et sp. nov.) from the Yixian Formation of western Liaoning, China. Chinese Science Bulletin 46(19): 1669-1672. 

Zhou, Z. 2006. Evolutionary radiation of the Jehol Biota: chronological and ecological perspectives. Geological Journal 41: 377-393.