巨齒鯊的幼崽比成年人類還要大

巨齒鯊的幼崽比成年人類還要大

Research came out last year that revealed the mighty megalodon was indeed the ocean giant we believed it to be. At around 16 meters (52 feet) long with fins as long as an adult human’s body, they dwarfed other fish in the sea when they were alive. Now, a new study published in the journal Historical Biology has claimed that these ocean giants’ progeny were also giants in their own way, making their first few tail swishes in the open ocean at a size already larger than most adult humans.

去年的一項(xiàng)研究揭示了巨大的巨齒鯊確實(shí)是我們所相信的海洋巨人。它們身長(zhǎng)約16米(52英尺)，魚鰭和成年人身體一樣長(zhǎng)，使它們?cè)谑罆r(shí)在海里的其他魚類相形見絀?，F(xiàn)在，發(fā)表在《歷史生物學(xué)》雜志上的一項(xiàng)新研究聲稱，這些海洋巨人的后代也以自己的方式成為巨人，它們?cè)诠Ｉ献畛醯膸状挝舶蛿[動(dòng)的大小已經(jīng)超過了大多數(shù)成年人類。

Rachael Funnel

The study was investigating the growth pattern and life expectancy of megalodon, Otodus megalodon, to shed light on their reproductive biology. "As one of the largest carnivores that ever existed on Earth, deciphering such growth parameters of O. megalodon is critical to understand the role large carnivores play in the context of the evolution of marine ecosystems,” wrote paleobiologist at DePaul University in Chicago and lead author of the study Dr Kenshu Shimada in a statement.

這項(xiàng)研究正在調(diào)查巨齒鯊的生長(zhǎng)模式和預(yù)期壽命，以闡明它們的生殖生物學(xué)。“作為地球上曾經(jīng)存在過的最大的食肉動(dòng)物之一，破解巨齒鯊的生長(zhǎng)參數(shù)對(duì)于理解大型食肉動(dòng)物在海洋生態(tài)系統(tǒng)進(jìn)化過程中所扮演的角色至關(guān)重要。”芝加哥德保羅大學(xué)的古生物學(xué)家，該研究的第一作者Kenshu Shimada博士在一份聲明中寫道。

Using computed tomography (CT) scanning technology, Shimada and colleagues were able to look at 'growth bands' in megalodon vertebral specimens, housed in the Royal Belgian Institute of Natural Sciences in Brussels. These bands are similar to tree rings, with each ring representing another year in the fishes’ lifetime. The results revealed the vertebra of a shark estimated to be nine meters long had 46 bands, meaning it was 46 years old when it died.

使用計(jì)算機(jī)斷層掃描技術(shù)，Shimada和同事能夠觀察巨齒鯊脊椎標(biāo)本中的“生長(zhǎng)帶”，這些標(biāo)本保存在布魯塞爾的比利時(shí)皇家自然科學(xué)研究所。這些年輪類似于樹木的年輪，每個(gè)年輪代表魚類生命中的另一年。結(jié)果顯示，這條鯊魚的脊椎骨估計(jì)有9米長(zhǎng)，有46條帶子，這意味著它死的時(shí)候46歲。

The vertebra of the extinct megatooth shark have growth rings like a tree, making it easier to estimate their age at death. DePaul University/Kenshu Shimada

This information could be used to back-calculate the shark's body size at birth, which told the researchers that it was a wee bonny megalodon measuring around 2 meters (6.6 feet) when it came into the world. They posit that this suggests Megalodon gave live birth and that these fish were capable of snacking on their siblings while waiting to be born. The sinister practice is known as oophagy or intrauterine cannibalism, and is seen in all extant lamniform sharks, says that study. A famous tale among shark biologists describes the moment a scientist was dissecting a dead female tiger shark who was bitten by a cannibalistic embryo that had survived inside the oviduct. If the findings are correct, it could mean that megalodon babies were the largest ever baby sharks.

這些信息可以用來反向計(jì)算鯊魚出生時(shí)的體型，這告訴研究人員，這是一條瘦小的巨齒鯊，剛來到這個(gè)世界時(shí)，身長(zhǎng)約2米(6.6英尺)。他們推測(cè)，這表明巨齒鯊是活產(chǎn)的，而這些魚能夠在等待出生的時(shí)候吃掉它們的兄弟姐妹。該研究稱，這種邪惡的行為被稱為食卵癖或子宮內(nèi)同類相食，在所有現(xiàn)存的羊膜狀鯊魚中都可以看到。鯊魚生物學(xué)家們流傳著一個(gè)著名的故事:一位科學(xué)家解剖了一只雌性虎鯊的尸體，這只虎鯊被一個(gè)存活在輸卵管內(nèi)的同類相食的胚胎咬傷。如果這些發(fā)現(xiàn)是正確的，這可能意味著巨齒鯊寶寶是有史以來最大的小鯊魚。

Megalodon is a popular species among shark fans, regularly featuring in sci-fi movies such as The Meg. While the fossil record of these apex predators is rich, we still don’t know very much about their biology. This is a common problem in cartilaginous fish, who rarely leave much to be found in the fossil record other than teeth. This is why the discovery of their gigantic vertebrae represents such an exciting opportunity academically speaking, as scientists work to close the gap in our knowledge of these fearsome hunters.

巨齒鯊在鯊魚迷中很受歡迎，經(jīng)常出現(xiàn)在《巨齒鯊》等科幻電影中。雖然這些頂端食肉動(dòng)物的化石記錄很豐富，但我們?nèi)匀徊惶私馑鼈兊纳飳W(xué)。這在軟骨魚類中是一個(gè)常見的問題，除了牙齒以外，在化石記錄中，軟骨魚類很少留下其他東西。這就是為什么發(fā)現(xiàn)它們巨大的脊椎骨在學(xué)術(shù)上代表著如此令人興奮的機(jī)會(huì)，因?yàn)榭茖W(xué)家們正在努力縮小我們對(duì)這些可怕的獵人的了解。