People are familiar with modern turtles, but the evolution of turtles remains one of the biggest mysteries in paleontology. The turtle has a unique body form of tetrapods (four-leg vertebrates,or vertebrates except fishes, such as lizards/crocodiles,birds, and mammals). It has a shell composed of carapace and plastron, and most of the skeleton,including the vertebrae, ribs and some limb girdles is fused with the shell inside. It is the only extant reptile without temporal fenestrae (openings behind the orbits on the skull), and like birds, it has a toothless beak.

How turtles acquired these unusual characters from their evolution has long baffling paleontologists. On the other hand, their phylogenetic position has also long puzzled researchers: is the turtle a lineage derived from a separate reptile group called Anapsid, which has no fenestra on the skull behind the orbit either, or one that shares with other reptiles such as lizards, crocodiles and dinosaurs (including birds) a common ancestor called Diapsid? This common ancestor has double fenestrae behind its orbits, but the openings in turtles could have closed in their evolution, therefore no post-orbit opening is visible on an extant turtle skull.

同理，如果基层工作也免除了那无事忙的“五怕”，有点抵制“痕迹主义”的自由，少点瞎折腾，我们的中国梦是不是也能早点实现？

A reconstruction of Eorhynchochelys, a “turtle before turtles” without a shell, together with its ambient environment. Strikingly, it has a primitive beak with teeth and enclosed temporal fenestrae - openings behind the orbits of its skull. (Image by courtesy of IVPP)

The skull of the Eorhynchochelys sinensis shows a primitive beak with teeth and enclosed temporal. (Upper: Structure in the specimen; Bottom: Reconstruction of the skull. Images by courtesy of LI Chun's group)

The specimen of Eorhynchochelys sinensis. (Image by courtesy of LI Chun's group)

For quite a long time, the oldest and most primitive turtle documented was Proganochelys, dated back around 200 million years. However, it already had the same body structure as turtles today. It had a complete shell and a beak. Therefore, the question has become how turtles evolved before Proganochelys. Unfortunately, no such fossil record was discovered until 2008.

In the year 2008, a turtle specimen named Odontochelys, meaning “turtle with teeth and semishell,” dated back about 220 million years was found from Guanling of Guizhou. This work was led by LI Chun of the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences (CAS). For the first time, people saw a creature one step earlier in the evolution of turtles.

主从模式是最标准、最简单的双机热备，即是目前通常所说的Active／Standby方式。它使用两台服务器，一台作为主服务器（Active），运行应用系统来提供服务；另一台作为备机，安装完全一样的应用系统，但处于待机状态（Standby）。当Active服务器出现故障的时候，通过软件诊测（一般是通过心跳诊断）将Standby机器激活，保证应用在短时间内完全恢复正常使用。

Later in 2015, another primitive turtle,Pappochelys, dating back about 240 million years,was discovered in Germany. Although very scattered,scientists from German and US gave a reconstruction of this primitive turtle: it did not have a shell, but did have small openings - temporal fenestrae on the skull.

目前，中国已成为非专利产品制造大国，部分农药产品供过于求，大量产品用于出口。业界需要从常规产品的简单仿制升级为高端绿色产品的创制研发；农药零增长计划使业界在关注农药产品质量时，除了有效成分、含量、杀虫灭菌的效果外，还要延伸到农药产品使用后对自然环境、作物及使用者的影响；新修订的《农药管理条例》农药生产许可由过去的工信、质监等部门转变为省级农业部门发放生产许可证，这也对规范农药企业日常生产经营行为、提升行业质量管理水平提出了新要求。

Again, on Aug 23, 2018, the same research team led by LI Chun published in Nature a new early turtle from Guizhou. It was discovered from the marine Triassic of Guanling, shedding new light on the earliest evolution of turtles. Dating back about 228 million years, this fossil represents the oldest turtle ever discovered with a toothless beak, and thus named as Eorhynchochelys, meaning “the first turtle with a beak.” The fossil turtle is more than 2 meters long, with a short trunk and enclosed temporal fenestrae, but no shell on its back and abdomen. Although the beak was developed, there are teeth on the posterior part of the jaws. “It showed not only primitive, but also derived and transitional features, indicating a complexity in the early stage of turtle's evolution. The evolutionary position of Eorhynchochelys is between Odontochelys and Pappochelys, filling another missing link in turtle's natural history,” said LI Chun, leader of the work.

“Its skeleton suggests the turtle might have lived an amphibious life near the estuary, and had a habit of digging holes,” LI said.

“With the discovery of recent early turtles, more and more evidence suggests that turtles evolved gradually. I think our new discovery supports Darwin's theory that biological evolution went on step by step, and gave us the idea that what a turtle before turtles looks like.”

Reviewers of Nature commented that the finding was extremely important as it closed a major gap in the evolution of the turtle, and indicated the development was more complex than previously assumed.