以中國科學(xué)院古脊椎動物與古人類研究所研究員鄧濤為首的研究小組在《美國科學(xué)院院刊》(PNAS)上發(fā)表論文,,對在西藏阿里地區(qū)札達(dá)盆地上新世地層中發(fā)現(xiàn)的三趾馬骨架化石進(jìn)行運動功能分析,,從而虛擬再現(xiàn)了其生態(tài)環(huán)境,,并據(jù)此推測出青藏高原在460萬年前的上新世中期的古海拔高度,。4月23日,,PNAS的網(wǎng)絡(luò)版(Early Edition)披露了這一最新研究成果,。
關(guān)于青藏高原的隆升歷史和過程,,尤其是不同地質(zhì)時期的古高度,,長久以來都存在激烈爭論,。鄧濤等人通過對札達(dá)三趾馬骨架化石的研究,證明它是一種生活于高山草原上善于奔跑的三趾馬,。這樣的開闊環(huán)境在札達(dá)盆地所處的陡峭青藏高原南緣應(yīng)位于林線之上,,根據(jù)與現(xiàn)代植被垂直帶譜的對比并經(jīng)古氣溫校正,札達(dá)盆地當(dāng)時的海拔高度約為4000米,,由此證明西藏南部至少在上新世中期已經(jīng)達(dá)到現(xiàn)在的高度,。
在青藏高原發(fā)現(xiàn)的三趾馬化石曾經(jīng)為研究高原的隆升歷史提供了堅實的證據(jù),,其中就包括在札達(dá)發(fā)現(xiàn)并被命名為札達(dá)三趾馬的頭骨和下頜骨。新的三趾馬骨架化石的牙齒特征指示其屬于札達(dá)三趾馬,,古地磁測年結(jié)果顯示其埋藏的地層形成于460萬年前,。由于骨骼化石的形態(tài)和附著痕跡能夠反映肌肉和韌帶的狀態(tài),所以可以據(jù)此分析絕滅動物在其生活時的運動方式,。札達(dá)三趾馬的骨架保存了全部肢骨,、骨盆和部分脊椎,因此提供了重建其運動功能的機(jī)會,。
札達(dá)三趾馬生活的460萬年前對全球來說正處于上新世中期的溫暖氣候中,,溫度比現(xiàn)代高約2.5℃。按照100米0.6℃的氣溫直減率,,則札達(dá)馬生活時期札達(dá)地區(qū)的林線高度應(yīng)位于海拔4000米處,。札達(dá)三趾馬骨架化石的發(fā)現(xiàn)地點海拔接近4000米,也就是說,,札達(dá)盆地至少在上新世中期就已經(jīng)達(dá)到其現(xiàn)在的海拔高度,。(生物谷:Bioon.com)
doi:10.1073/pnas.1201052109
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Locomotive implication of a Pliocene three-toed horse skeleton from Tibet and its paleo-altimetry significance
Tao Deng, Qiang Li, Zhijie Jack Tseng, Gary T. Takeuchi, Yang Wang, Guangpu Xie, Shiqi Wang, Sukuan Hou, and Xiaoming Wang
Three benchtop high-throughput sequencing instruments are now available. The 454 GS Junior (Roche), MiSeq (Illumina) and Ion Torrent PGM (Life Technologies) are laser-printer sized and offer modest set-up and running costs. Each instrument can generate data required for a draft bacterial genome sequence in days, making them attractive for identifying and characterizing pathogens in the clinical setting. We compared the performance of these instruments by sequencing an isolate of Escherichia coli O104:H4, which caused an outbreak of food poisoning in Germany in 2011. The MiSeq had the highest throughput per run (1.6 Gb/run, 60 Mb/h) and lowest error rates. The 454 GS Junior generated the longest reads (up to 600 bases) and most contiguous assemblies but had the lowest throughput (70 Mb/run, 9 Mb/h). Run in 100-bp mode, the Ion Torrent PGM had the highest throughput (80–100 Mb/h). Unlike the MiSeq, the Ion Torrent PGM and 454 GS Junior both produced homopolymer-associated indel errors (1.5 and 0.38 errors per 100 bases, respectively).