When thinking of paleontology and the study of fossilized remains, we typically envision a white, petrified skeleton lying in some desert badland, exposed by wind and rain. However,recent discoveries have put an ever-increasing focus on the preservation of non-skeletal fossil remains- that is to say, the preservation of soft tissues that have remarkably survived the test of time, sometimes hundreds of millions of years. Published in PNAS in October, an international team of scientists led by Drs.Jingmai O'Connor and ZHOU Zhonghe at the Institute of Vertebrate Paleontology and Paleoanthropology(IVPP), Chinese Academy of Sciences (CAS) have identified probable lung tissue in an exceptionally wellpreserved specimen of Archaeorhynchus spathula, a very basal member of the Ornithuromorpha (that is the clade that includes all modern birds nested within), that was part of the Jehol Biota and lived approximately 125-120 million years ago.

我国城市化建设速度，呈现出日益上升的趋势，在经济不断发展，人们生活水平不断提高的新时期，我国电力企业为了适应时代发展的要求，其施工技术与施工机械，也在逐步的变革中，电力自动化在电力工程中的运用，使电力工程的工作效率得到了很大的提高。但是，受到种种因素的制约，电力自动化系统，在运行时，还存在一些问题。这些问题对我国电力系统的整体质量产生了不同程度影响，因此，国家有关部门应该高度重视起来，在电力工程实现电力自动化的过程中，不断的加大工程监管力度和施工人员的技术水平，使得我国的电力工程自动化进程可以不断的加快。我国居民也会因此得到实惠，工业以及各项社会事业的建业也会因此得到更好的发展。

Lung tissue being previously though impossible to preserve, scientists have long struggled to understand the evolution of modern avian respiration within the Dinosauria using skeletal indicators such as the morphology of the rib cage - especially that of boney processes that project off the ribs, called uncinate processes (which are primitively unfused to the ribs in Archaeorhynchus), as well as indicators of skeletal pneumaticity such as pneumatopores that indicate a bone has been invaded by pneumatic air sacs that aid in respiration in living birds, as well as reduce the weight of the skeleton for flight (indication of which are absent in Archaeorhynchus except for the cervical air sacs plesiomorphic to most dinosaurs). Scientists are interested in avian respiration because it is extremely specialized compared to that of other reptiles* and more efficient than that of mammals. Compared to mammal lungs, birds not only can inhale greater amounts of air but they can also extract more oxygen with every breath.This is probably one factor that has made birds the most successful clade of amniotes alive today and makes possible incredible physical feats, such as geese that fl y over the Himalayan Mountains during migration.

Exceptionally well-preserved soft tissues are identified in a fossilized early bird that lived approximately 125-120 Million years ago,named the Archaeorhynchus spathula. The soft tissues might include remains from lungs of the bird. (Image by WANG Min)

This unlikely specimen of Archaeorhynchus, the fifth to be described but the first to preserve significant soft tissue, preserves what we identify as lung tissue based on anatomical position and microstructure, as revealed through scanning electron microscopy (SEM).The preserved microstructure revealed the network of air and blood capillaries forming the functional tissue of the lung and indicated that this tissue was extremely subdivided, as it is in bird lungs today. This extreme subdivision increases surface area and helps to facilitate birds' ability to meet the high oxygen demands of powered flight - the most physically demanding form of locomotion. Although preservation of lung tissue, which- if you have ever dissected or slaughtered a chicken -you will have noticed appears thin and delicate, seems unlikely or even impossible, in fact, this is not the first documented occurrence of preserved lung tissue in the fossil record (though it is the first to be informative).Lung tissue was reported in Nature (https://www.nature.com/articles/nature14905) in a mammal a few million years older than this specimen of Archaeorhynchus and has also been documented in a few amphibians from the Cenozoic (the oldest being 40 million years old).Although very thin, the tissue that forms the avian lung contains type IV collagen, which is a strong connective tissue that may have facilitated preservation of this soft tissue. This discovery indicates that specializations of the lung tissue date back at least 125 million years and predate skeletal specializations that have previously been studied as indicators of advanced respiratory function.

The authors of the study include WANG Xiaoli(Linyi University), Jingmai O'Connor (IVPP), John Maina (University of Johannesburg), PAN Yanhong(Nanjing University), WANG Min (IVPP), WANG Yan(Linyi University), ZHENG Xiaoting (Linyi University)and ZHOU Zhonghe (IVPP).

This research was supported by the National Natural Science Foundation of China (NSFC), CAS,National Science Foundation of South Africa, and the Strategic Priority Research Program of the CAS.

在对口支援中加快缩小区域差距。很多东中部省份都把中小学多媒体教室建设、优质教育资源共享作为援建重要内容，在一定程度上缩小了区域、城乡之间的“数字差距”。

Microscopic structure of the fossilized soft tissues in the specimen,in comparison with those of an existant bird. (Image by WANG Min)