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Chinese scientists find 11 embryos in 244-million-year-old ichthyosaur Mixosaurus fossil, giving clue to reproduction of ancient marine reptile_我的网站

一 |     北京时间8月22日，据名记Shams报道，六届NBA全明星德罗赞已经同意与丹佛掘金签下一份1年390万美元的合同。    

    Photo: Screenshot from peerj.com
Chinese scientists studying a 244-million-year-old ichthyosaur Mixosaurus fossil from Southwest China’s Guizhou Province found at least 11 embryos inside the specimen. The discovery sets a new record for the highest number of embryos found in ichthyosaur lineages and reveals that high reproductive capacity in ichthyosaurs emerged earlier than previously believed, chinanews.com reported on Wednesday. 
Ichthyosaur was among the most successful Mesozoic marine reptiles, and its reproductive strategy was considered crucial to their adaptation to ocean environments. Its reproductive ability before extinction has long intrigued paleontologists.
A joint research team from the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences (CAS), and the Zhejiang Museum of Natural History, has published the study on the ichthyosaur paleontology in the international journal PeerJ. 
According to Wang Wei, the paper’s corresponding author and an associate professor at the institute, embryo-preserving ichthyosaur fossils have been found across 11 genera from the Early Triassic to the Early Cretaceous. 
However, for ichthyosaur groups that diverged in the Early Triassic, embryo-bearing fossils known to scientists remain scarce, and knowledge about the number of offspring they carried is especially limited. Previous discoveries of pregnant specimens, such as Chaohusaurus and Mixosaurus, contained no more than three embryos, suggesting limited early reproductive capacity among early ichthyosaurs.
According to Gu Shengxiao, the paper’s first author and a researcher at the Zhejiang Museum of Natural History, the study examined an almost complete adult Mixosaurus panxianensis fossil from Guizhou’s Middle Triassic strata, dating back about 244 million years. The specimen measures 112 centimeters long, including a skull length of 22 centimeters, with only the tail tip missing. 
The researchers identified 11 fetal ichthyosaur skeletons with skulls inside the adult specimen’s abdomen, confirming they were embryos rather than cannibalized prey based on their position and morphology. There are also fossil pieces outside the belly of the adult, which could belong to the 11 or represent other embryos. 
All embryos in the Mixosaurus panxianensis fossil were at a similar late developmental stage, suggesting the mother died shortly before giving birth, according to the researchers.
The Mixosaurus panxianensis fossil containing at least 11 embryos sets a record for Triassic ichthyosaurs and all known ichthyosaur species. The researchers believe this indicates that Mixosaurus may have adopted a reproductive strategy of producing large numbers of offspring in a single birth. This exceptionally high reproductive capacity may have provided them with a survival advantage. 
Among Triassic ichthyosaurs and all known ichthyosaur groups, Mixosaurus is the genus with the largest number of fossil specimens and is also one of the most widely distributed ichthyosaurs. 
The researchers said the multi-embryo Mixosaurus panxianensis fossil may represent an extreme case, but it confirms the species’ ability to produce large numbers of offspring, potentially contributing to its dominance among contemporaneous marine reptiles. 
The study offers the first fossil evidence of high fertility in Triassic ichthyosaurs. Future research will examine other embryo-bearing Triassic ichthyosaurs to determine whether a multiple-offspring reproductive strategy was common in early ichthyosaur evolution and what factors drove this trait, Wang said. 
Global Times
。         德罗赞本月刚满37岁。

二 | 国王队为缩减薪资开支，将他那份部分保障合同裁掉，他在7月成为自由球员。这位六届全明星、三次最佳阵容成员，在决定加盟掘金之前，据称收到过多支球队的招募意向。         名记海恩斯表示，尼古拉・约基奇、阿隆・戈登以及贾马尔・穆雷都参与了招募德罗赞加盟掘金的工作。消息人士向海恩斯透露，总得分排在NBA历史第16位的德罗赞十分渴望为一支争冠强队效力。         尽管德罗赞已经不在巅峰水准，而且他向来不是一名优秀的防守球员，但这份新合同下他依旧可以提供很大价值。由于掘金已经超出第二土豪线，德罗赞这份合同是老将底薪。         作为2009年选秀大会的9号秀，德罗赞职业生涯出勤表现十分稳定，NBA17个赛季里，每个赛季常规赛出场数都不少于60场；过去五个赛季，他每一年的出场数都至少达到74场。         掘金本周早些时候将佩顿・沃特森送往克利夫兰，这笔交易是一笔涉及五支球队的先签后换操作的一部分。作为回报，掘金得到骑士2031年无保护首轮签，以及来自国王转交的2032年次轮签。

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