Yandusaurus (/"yan-du-SORE-us"/; "Yandu lizard" ) is a genus of herbivorous basal neornithischian dinosaur from the Bathonian age of the Middle Jurassic period (approximately 168 to 162 million years ago). Its fossils were discovered within the Lower Shaximiao Formation of Sichuan Province, China. Chinese paleontologist He Xinlu described the genus in 1979.

Description and Classification

Yandusaurus belongs to the Ornithischia clade, a diverse group of herbivorous dinosaurs characterized by their distinctive bird-like pelvic structure. While small compared to later ornithischians, it reached an estimated length of 3 to 4 meters (10 to 13 feet). Yandusaurus was a bipedal dinosaur with a relatively long neck, small head, and a long tail. It had strong hind legs and shorter forelimbs with five-fingered hands.

Distinguishing Features

One of the most notable features of Yandusaurus is its unique dentition. Its teeth show a peculiar pattern of parallel vertical ridges, prompting some researchers to compare them to the fingers of Buddha statues. The purpose of these ridges is not fully understood, but they likely played a role in processing tough plant material.

Paleoenvironment and Diet

During the Middle Jurassic, the Sichuan province of China was a lush environment with diverse flora. As an herbivore, Yandusaurus would have browsed on a variety of vegetation, including ferns, cycads, and primitive conifers. It likely shared its habitat with other ornithischians like Agilisaurus, as well as sauropods and theropods.

Significance and Ongoing Research

Yandusaurus is a significant representative of the early radiation of ornithischian dinosaurs. Its anatomy helps paleontologists understand the evolutionary changes leading to the more diverse and specialized ornithischian groups that flourished later in the Mesozoic Era. Continued research on Yandusaurus can offer insights into the biomechanics, diet, and social behaviors of these early plant-eaters.

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