恐龍父母是怎么知道他們的孩子什么時(shí)候發(fā)燒的?

恐龍父母是怎么知道他們的孩子什么時(shí)候發(fā)燒的?

From the time that dinosaur fossils were first discovered, these creatures have fascinated scientists and laypeople alike. In the academic world, their remains provide important clues into the prehistoric world; in popular culture, dinosaurs have inspired blockbuster hits, such as Jurassic Park and King Kong.

從恐龍化石被發(fā)現(xiàn)開(kāi)始，這些生物就吸引了科學(xué)家和普通人。在學(xué)術(shù)界，他們的遺骸為我們了解史前世界提供了重要的線索;在流行文化中，恐龍激發(fā)了無(wú)數(shù)電影大片的靈感，如《侏羅紀(jì)公園》和《金剛》。

Now, a research team headed by Professor Hagit Affek at the Hebrew University of Jerusalem's Institute of Earth Sciences has unlocked a mystery that has stymied researchers for decades: How did dinosaurs regulate their body temperatures? Were they warm-blooded or cold-blooded?

現(xiàn)在，由耶路撒冷希伯來(lái)大學(xué)地球科學(xué)研究所的Hagit Affek教授領(lǐng)導(dǎo)的一個(gè)研究小組，揭開(kāi)了一個(gè)困擾研究人員數(shù)十年的謎團(tuán)：恐龍是如何調(diào)節(jié)體溫的?他們是溫血?jiǎng)游镞€是冷血?jiǎng)游?

Affek's study, published today in Science Advances, relies on a novel method to measure historical temperatures. Called clumped isotope geochemistry, this method analyzes chemical bonds among heavy isotopes in calcium carbonate minerals—the main ingredient in egg shells. This allows scientists to calculate both the temperature at which the minerals formed and the body temperature of the mother that laid the egg.

今天發(fā)表在《科學(xué)進(jìn)展》雜志上的Affek的研究，依靠一種測(cè)量歷史溫度的新方法。這種方法被稱(chēng)為塊狀同位素地球化學(xué)，它分析了蛋殼主要成分碳酸鈣礦物中的重同位素之間的化學(xué)鍵。這使得科學(xué)家可以計(jì)算出礦物質(zhì)形成的溫度和產(chǎn)蛋母親的體溫。

Affek and her team applied this method to fossilized eggs from three distinct dinosaur species along the evolutionary path from reptile to bird and found that their body temperature ranged from 35-40 degrees Celsius. However, this bit of information still did not answer the question as to whether dinosaurs were endothermic or exothermic, meaning, did they generate their own body heat or get warm from the sun and their environment?

Affek和她的團(tuán)隊(duì)，將這種方法應(yīng)用于從爬行動(dòng)物到鳥(niǎo)類(lèi)的三種不同的恐龍蛋化石，發(fā)現(xiàn)它們的體溫在35-40攝氏度之間。然而，這些信息仍然沒(méi)有回答恐龍是吸熱還是放熱的問(wèn)題，也就是說(shuō)，它們是自己產(chǎn)生熱量，還是從太陽(yáng)和它們的環(huán)境中獲得熱量?

The global climate during the dinosaur era was significantly warmer than it is today. For this reason, measuring only the body temperatures of dinosaurs who lived near the equator wouldn't tell us whether they were endo- or exothermic because their body temperature may simply have been a cold-blooded response to the hot climates they lived in, shared Affek.

“恐龍時(shí)代的全球氣候比現(xiàn)在暖和得多。因此，僅僅測(cè)量生活在赤道附近的恐龍的體溫，并不能告訴我們它們是吸熱還是放熱的，因?yàn)樗鼈兊捏w溫，可能只是對(duì)它們生活的炎熱氣候的一種冷血反應(yīng)。”

To address this issue, her team focused on dinosaurs that lived in high latitudes like Alberta, Canada—far enough north to ensure that their warm body temperatures were the result of an internal, metabolic warming process rather than merely reflecting the climate around them.

為了解決這個(gè)問(wèn)題，她的團(tuán)隊(duì)把重點(diǎn)放在了生活在像加拿大阿爾伯塔這樣高緯度地區(qū)的恐龍身上，因?yàn)槟抢锏木暥茸銐蚋?，可以確保它們溫暖的體溫是內(nèi)部新陳代謝變暖過(guò)程的結(jié)果，而不是僅僅反映了它們周?chē)臍夂颉?/p>

To verify their hypothesis, Affek and her team needed to determine the environmental temperature in Alberta back when dinosaurs lived. They accomplished this by applying their isotope method to mollusk shells that lived in Alberta alongside the dinosaurs. Since mollusks are cold-blooded creatures, they reflect the ambient climate of the time. The mollusks' body temperature measured 26°C and showed that the dinosaurs living in Alberta were endothermic; otherwise, they could not have maintained a body temperature of 35-40°C.

為了驗(yàn)證假說(shuō)，Affek和她的團(tuán)隊(duì)需要確定阿爾伯塔省恐龍生活時(shí)期的環(huán)境溫度。他們將同位素法應(yīng)用于與恐龍生活在一起的亞伯達(dá)省的軟體動(dòng)物殼上，從而實(shí)現(xiàn)了這一目標(biāo)。由于軟體動(dòng)物是冷血?jiǎng)游铮鼈兎从沉水?dāng)時(shí)的環(huán)境氣候。這些軟體動(dòng)物的體溫為26℃，這表明生活在阿爾伯塔省的恐龍是吸熱的;否則，他們就無(wú)法保持35-40℃的體溫。

As dinosaurs evolved, they moved from lizard-like (cold-blooded) characteristics to avian (warm-blooded) ones. "We believe that this transformation happened very early on in dinosaurs' evolution since the Mayasaura eggs—a lizard-like dinosaur species that we tested—were already able to self-regulate their body temperature, just like their warm-blooded, bird-like cousins, the Torrdons," explained Affek.

隨著恐龍的進(jìn)化，它們從類(lèi)蜥蜴(冷血?jiǎng)游?特征轉(zhuǎn)變?yōu)轭?lèi)鳥(niǎo)類(lèi)(溫血?jiǎng)游?特征。“我們相信這種轉(zhuǎn)變?cè)诳铸堖M(jìn)化的早期就發(fā)生了，因?yàn)镸ayasaura蛋——一種我們測(cè)試過(guò)的類(lèi)似蜥蜴的恐龍物種——已經(jīng)能夠自我調(diào)節(jié)它們的體溫，就像它們的溫血表親，鳥(niǎo)類(lèi)一樣。”Affek解釋道。

The fact that both of these species, located at opposite ends of the dinosaur evolutionary tree, had body temperatures higher than those of their environment means that both had the ability to warm themselves.

這兩個(gè)物種都位于恐龍進(jìn)化樹(shù)的兩端，它們的體溫都高于周?chē)h(huán)境的溫度，這意味著它們都有保暖的能力。