245 million years ago, Chinese scientists dinocephalosaurus fossils found in dinocephalosaurus fetus
"Dinosaur found a pregnancy? Dinosaurs did not hatch dinosaur eggs, there are also viviparous? ”
"Fear of head Dragon, not a dinosaur! ”
The afternoon of February 14, 2017, Liu June surging again News (www.thepaper.CN) highlighted.
A few hours later, on February 15, 2017, one of his research papers in international journals nature newsletter (Nature Communications) officially published online. The paper will publish a surprising fossils-a has a long neck, giant dragon, its belly wrapped around a small dinocephalosaurus.
Pregnant dinocephalosaurus restoration plan. This pictures are provided by Liu June.
"Is the ingestion of a similar, also gave birth to a fetus? ”
Six years ago, when Liu June when he was a doctoral candidate at the University of Hong Kong, he is also thinking about all these possible. Whether it be cannibalism, or give birth, any hypothesis is confirmed, will be unusual finds.
Liu June has now graduated from the University of Hong Kong, finished his postdoctoral research at Sydney University, Hefei University of technology associate professor, College of resources and environmental engineering current.
The fossils were found in 9 years ago, in 2008. At that time, the Organization field researcher at the Chengdu Institute of geology and mineral resources Zhang Qiyue and his team found that national geological park in luoping County of luoping in Qujing, Yunnan province collected. But wrap fossils in limestone, only to see a little, want to study would have to be careful off the fossils come out.
Dinocephalosaurus fossil excavation site.
Dinocephalosaurus lived in the ocean, it does not have gills, then will float to the surface for air. Liu Jun said that the Chengdu Institute of geology and mineral resources in the laboratory to complete the overall repair of fossils, he was very excited. He found that the fossil belly-wrapped small trunk pointing to the mother of the whole front of the dinocephalosaurus, dinocephalosaurus long necks to ambush eaten Hunt, if the undigested prey, usually reserved in dinocephalosaurus head back inside the body cavity. In addition, maternal dinocephalosaurus fossils in the form of complete package "protect" small-headed dragon to be fossils overlap.
Liu June, researchers also found that dinocephalosaurus fetal bones have grown into, and the fossils were not detected in and around calcium in egg composition and long necks, dinocephalosaurus is difficult to survive the Ocean Shore nests hatch.
Growing number of clues, researchers increasingly sure dinocephalosaurus in viviparous reproduction.
The fossils of 245 million years ago, "the results demonstrate for the first time give birth to in the presence of Dragon-type animal in the early. This discovery enables us to learn from Dragon animal reproduction at the beginning before the Jurassic thrust into the Triassic, crossed 50 million years ahead ", said Liu June.
The dinocephalosaurus fossils found; enlarged part of the embryonic skeleton; scale is 10 cm.
Talk about fear of differences between dragons and dinosaurs, in short, dinocephalosaurus more original than the dinosaurs.
Liu June explained that dinocephalosaurus occurred earlier, it lives in the middle of the Triassic, and present evidence, dinosaurs during the late Triassic. Dinocephalosaurus is the original dragons, dinosaurs were Dragons at the beginning, which together constitute the long part of the fauna.
The paper said world about one-third of the Dragon early amniotic eggs animals are animals, bird was, of course, and account for the majority.
Dragon animal contains the extant crocodiles, birds, as well as the extinct reptiles such as dinosaurs and pterosaurs, at present there are about more than 10,000 living species. But at the beginning of the Dragon-type animal in the group, to having this kind of reproductive method has never been found, was previously known, is oviparous (lay their eggs).
People such as Liu June results show that dinocephalosaurus is viviparous. It subverted the people awareness.
As dinocephalosaurus is viviparous, what about dinosaurs?
Liu Jun said, has not yet found any evidence that dinosaurs have the possibility of viviparous.
What about birds, why are eggs, egg-laying and viviparous had not occurred?
There is a variety of assumptions, such as birds flying, lack of birth required for physiological structure, lack of natural selection pressures, but studies have been inconclusive, also needs further research to explore the mechanism.
The paper one reviewer commented, "it's a very important discovery, reshaping our understanding of the evolution of reptile reproduction and make circles current research focus on what factors limit the birth at the beginning of the Dragon appears in the animal moved to explore long animal, natural selection at the beginning of the birth and evolution of the role of".
In addition, the study by simulation of biological lineage found dinocephalosaurus gender determined by the genes of future generations. Dinocephalosaurus is most closely related to the living taxa, including turtles and crocodiles, the offspring's sex is determined by the ambient temperature. This difference also amaze researchers.
Liu Jun, who believes that birth and the sex of the offspring gene mechanism, the combination of the two, makes dinocephalosaurus animals such as Sea King.
Beginning of the paper, titled Dragon reptiles of the viviparous (Live birth in an archosauromorph reptile), Liu Jun for the first authors and corresponding author of the paper, four other researchers from Montana State University, University of Bristol, University of Sydney and the University of Queensland.
(Editors: xiaowugang UN845)
2017-02-15 02:32:55
Surging news
中国科学家在2.45亿年前恐头龙化石中发现恐头龙胎儿
“发现了一头怀孕的恐龙？恐龙不是孵恐龙蛋吗，也有胎生的？”
“是恐头龙，不是恐龙！”
2017年2月14日下午，刘俊这样一再向澎湃新闻（www.thepaper.cn）强调。
数小时后，2017年2月15日零时，他的一篇研究论文将在国际学术期刊《自然·通讯》（Nature Communications）上正式在线发表。这篇论文将公布一个令人惊讶的化石——一头拥有超长脖子、体型巨大的恐头龙，它的腹中包裹着一只小恐头龙。
怀孕恐头龙的复原图。 本文图片均由刘俊提供。
“是吞食了一个同类，还是孕育了一个胎儿？”
六年前，当刘俊还是香港大学的博士研究生时，他也在思考这种种可能。无论是同类相食，抑或是胎生，任何一种假说被证实，都将是不同寻常的发现。
现在刘俊已经从香港大学毕业，在悉尼大学做完了博士后研究，到合肥工业大学资源与环境工程学院现任副教授。
这一化石发现于9年前，2008年。当时，成都地质矿产研究所张启跃研究员及其团队组织野外发掘，在云南省曲靖市罗平县的罗平国家地质公园采集到的。但化石包裹在石灰岩中，只能看到一点点，想研究就得小心将化石剥离出来。
恐头龙化石发掘现场。
恐头龙生活在海洋中，它没有腮，过一会儿就要浮上海面换气。刘俊说，在成都地质矿产研究所的实验室完成该化石的整体修理后，他非常激动。他发现，化石腹部包裹的小恐头龙的躯干整体指向母体的前方，但恐头龙通过长脖子以伏击方式吞食捕猎，如果是未消化的猎物，一般其头部都朝后存留在恐头龙体腔内。此外，母体恐头龙化石以完全包裹的形式“保护”着小恐头龙，不可能是化石重叠。
刘俊等研究人员还发现，恐头龙胎儿的骨骼已经长成，且该化石中及周边均未检测到钙质的蛋壳成分，而且脖子如此长，又生存在海洋中的恐头龙难以上岸筑巢孵化。
逐渐增多的线索，让研究人员愈发肯定，恐头龙以胎生的方式生殖。
这一化石距今2.45亿年，“研究结果首次证实了胎生在初龙型动物中的存在。这一发现使得我们对初龙型动物生殖方式的了解从侏罗纪前推到了三叠纪，往前跨越了5千万年”，刘俊说。
本研究发现的恐头龙化石；放大的部分为胚胎骨骼；比例尺为10厘米。
谈起恐头龙与恐龙的区别，简而言之，恐头龙比恐龙更原始。
刘俊解释说，恐头龙出现得更早，它生活在三叠纪中期，而目前已有的证据显示，恐龙出现在三叠纪晚期。恐头龙属于原龙，恐龙属于初龙，二者共同构成了初龙型动物类群的一部分。
该论文称，现在全世界大约三分之一的羊膜卵动物都是初龙型动物，鸟类当然是，而且占了大部分。
初龙型动物包含现存的鳄鱼、鸟类，以及已经绝灭的恐龙和翼龙等爬行动物，目前约有超过一万种现生种类。但是在初龙型动物这一类群中，胎生这种生殖方式从未被发现过，此前发现的，都是卵生（下蛋）。
刘俊等人的研究结果却显示，恐头龙是胎生的。这颠覆了人们此前的认知。
既然恐头龙是胎生的，那么恐龙呢？
刘俊表示，目前尚未发现任何证据显示恐龙有胎生的可能性。
那么鸟类呢，为什么都是下蛋、卵生，而没有出现过胎生？
此前学术界存在多种假设，比如鸟类要飞翔，缺乏胎生所需要的生理结构，缺乏相应的自然选择压力等，但相关研究还没有定论，还需要更进一步研究工作去探寻其机理。
该论文一位评审人评论称，“这一非常重要的发现，重塑了我们对爬行动物生殖方式演化的理解，并将使学界目前的研究重心从对什么因素限制了胎生在初龙型动物中的出现，转移到探讨自然选择在初龙型动物演化出胎生中所扮演的角色”。
此外，该研究通过对生物谱系的模拟，发现恐头龙后代的性别由基因决定。但与恐头龙关系最为密切的现生类群，包括龟类以及鳄鱼，其后代的性别都是由外界环境温度决定。这一差别也令研究人员惊讶。
刘俊等人认为，胎生和后代的性别基因决定机制，这两者的结合，使得恐头龙等动物得以成为海洋中的霸主。
该论文标题为《初龙型爬行动物的胎生》（Live birth in an archosauromorph reptile），刘俊为该论文的第一作者和通讯作者，其他四位研究者分别来自于美国蒙大拿州立大学、英国布里斯托尔大学、澳大利亚悉尼大学以及昆士兰大学。
(责任编辑：肖武岗 UN845)
2017-02-15 02:32:55
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