科学与数学nationalgeographic.com
发现一亿一千万年前带皮肤和软组织的恐龙
110M-year-old dinosaur discovered with skin and soft tissue
2017 — 2020，它一次次回到首页
黑点是上首页（≥ 50 分）的那次投稿，空心点是没冲上去的投稿，点越大分数越高。
导读
国家地理对一具约 1.1 亿年前的结节龙化石的报道：它出土于加拿大阿尔伯塔的矿区，保存异常完好，连鳞片的皮肤印痕和软组织轮廓都留存下来。化石制备人员花了五年多、7000 多小时才将其从岩块中一点点剥离出来。
为什么经久不衰：它展示了恐龙化石保存的惊人极限，也记录了化石制备这一极少被了解的漫长工艺，多年后重读依然震撼。
HN 评论精选
作者补充技术细节：皮肤化石极薄、DNA 不可能留存、年代测定可靠
我是这篇报道的记者。保存鳞片轮廓的富有机质薄膜（也就是石化皮肤）只有几毫米厚，所以制备人员必须极其缓慢地操作才能顺着薄膜剥离。另外，DNA 在 13.1°C 下的半衰期约为 521 年，即使按最极端的低温模型，也绝不可能存活 1.1 亿年。该遗址的年代测定很可靠：化石出自 Clearwater 组 Wabiskaw 段，其下油砂经放射性测年为 1.12±0.53 亿年。
michaelgreshko查看英文原文
Hey, I'm the journalist who wrote the story. A few things: - The organic-rich film preserving the outlines of scales (so, yes, fossilized skin) is only a few millimeters thick. So Mitchell had to prepare the fossil extremely slowly in order to follow the film through the matrix. - The half-life of DNA is ~521 years at 13.1°C, as found in this 2012 paper: http://rspb.royalsocietypublishing.org/content/279/1748/4724 The team's model predicts higher half-lifes at truly freezing temperatures, but even at the extreme end, there's no way DNA would survive 110 million years. - The dating on the site is well constrained to ~110 million years old. The fossil was found in the Wabiskaw Member of the Clearwater Formation, a well-dated rock formation in Alberta. The underlying oil sands have been radiometrically dated to 112±5.3 million years old. (http://science.sciencemag.org/content/308/5726/1293)
感叹化石制备工作耗时之长、之艰难
过去五年里超过 7000 个小时，Mitchell 缓慢剥离化石的皮肤和骨骼，过程就像从混凝土里取出压缩的滑石粉，'几乎每一毫米都要争取'。真没想到要花这么久。
blakesterz查看英文原文
"For more than 7,000 hours over the past five years, Mitchell has slowly exposed the fossil’s skin and bone. The painstaking process is like freeing compressed talcum powder from concrete. “You almost have to fight for every millimeter,” he says." Wow! I had no idea this took so long.
回顾 2005 年霸王龙软组织发现，追问后续研究进展
2005 年研究人员曾在霸王龙化石中发现软组织——保留原有柔韧性和弹性的中空血管，是在切割化石准备运输时意外发现的，当时令人难以置信。但此后围绕这具标本做了哪些研究？科学界当时很兴奋，我却记不起有什么重大成果。
mrb查看英文原文
Back in 2005, researchers found soft tissues in a T-rex fossil (hollow blood vessels retaining their original flexibility, elasticity, and resilience): http://www.rpgroup.caltech.edu/~natsirt/stuff/Schweitzer%20Science%202005.pdf IIRC they were cutting the large fossil to transport it, and it is while cutting it that they unexpectedly stumbled upon these soft tissues inside. This discovery was so mind-boggling at the time. What research has been conducted on this specific 2005 T-rex specimen? The scientific community seemed ecstatic after finding it, but I do not remember any significant discovery made from the tissue.
亲历者推荐：实物观感震撼，值得专程前往
我亲眼见过这具化石，几乎每年去博物馆都会驻足惊叹约 30 分钟。与远古世界的联系感非常真切，可以离得很近，博物馆也不拥挤。如果你有机会去加拿大 Drumheller 一带，尤其是这座博物馆，一定要去。
cknoxrun查看英文原文
I've seen this in person, and almost every year I visit the museum and have the same reaction. I stand there in wonder looking at it for about 30 minutes. The connection to the past world feels absolutely visceral. You can get very close to it, and it is never too busy around the museum as it is so large. If you ever get a chance to visit this part of Canada (Drumheller), and particularly this museum, you should go for it.
历次讨论
同类还值得读
如果月球只有 1 像素：一个极其精确的太阳系模型（2014）
If the moon were only 1 pixel: A tediously accurate solar system model (2014)
一个网页版太阳系模型，以“如果月亮只有 1 像素”的真实比例呈现：你必须一路横向滚动，才能体会行星之间空旷到何等程度。
科学与数学上首页 7 次 · 2014–2025joshworth.com编辑精选沉浸式线性代数（2016）
Immersive Linear Algebra (2016)
《Immersive Linear Algebra》是一本完全免费、开放在线的线性代数“超文本教科书”，其最大特色是大量可交互的图形：读者可以直接拖动、操作图中的向量、矩阵和变换…
科学与数学上首页 5 次 · 2015–2024immersivemath.com编辑精选如何将贝果切成两个相连的半环（2009）
How to Slice a Bagel into Two Linked Halves (2009)
数学家 George Hart 的经典教程，演示如何用一刀把贝果切成两个相互扣住的环，并附上切割步骤与数学原理。
科学与数学上首页 5 次 · 2009–2022georgehart.com“犹太问题”：一组用于歧视的数学题
Jewish problems
一篇 arXiv 论文，整理并讨论苏联时期犹太学生在申请大学数学系时被问到的特殊数学难题：这些题往往有简单解法却极难想到，被用作面试中拒绝犹太考生的手段。
科学与数学上首页 5 次 · 2011–2021arxiv.org你的身体并非为长久而造：人类死亡率数据的一课
Your body wasn’t built to last: a lesson from human mortality rates
文章从人类死亡率随年龄变化的统计规律出发，解释身体并非为长久使用而设计：年轻时死亡风险较低，之后随年龄近似指数上升，像复杂系统在不断累积损伤。
科学与数学上首页 5 次 · 2009–2018gravityandlevity.wordpress.com