Scientists name ancient crocodile species found in rock that built the Great Sphinx

The croc family tree may be getting a new branch. Analyzing fossilized remains discovered in the same bedrock that built the Great Sphinx, paleontologists newly identified a crocodilian species that once roamed a shallow sea in what’s now Egypt about 45 million years ago.

The Mokattam Formation in northern Egypt is a thick layer of limestone that has preserved prehistoric marine fossils, including fish, sharks and early whales. That same limestone outcrop also provided much of the raw material ancient Egyptians used to build some of their most famous monuments, including the Great Sphinx and the pyramids at Giza.

Now, scientists have identified the extinct crocodile species that lived millions of years before the Egyptians built the structures . Not only do the crocodile specimens share the same geologic foundation as the iconic landmarks, but one of the key fossils, a nearly complete skull, bears a striking resemblance to the Sphinx : The skull, first unearthed in the 1920s, is missing the tip of its snout similar to the Sphinx statue, which famously lost its nose. This coincidental trait inspired researchers to name the new genus Herugavialis after Heru, or Horus, the Egyptian god associated with the construction of the mythical creature.

Jaime Bran Sarmiento

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The species discovery adds to scientists’ understanding of the diversity and history of gharials, a group of crocodilians with a complicated evolutionary history, according to the authors of a study published Tuesday in the journal Royal Society Open Science .

“Herugavialis cairensis is one of the six species of gharials that we see in the Mediterranean across a 43 million year period, from 66-23 million years ago. Of course, there could be even more species that we just don’t know about yet,” said co-lead study author Paul Burke, a vertebrate paleontologist and postdoctoral researcher at the Swedish Museum of Natural History in Stockholm.

Only two gharial species exist today — found in the Indian subcontinent and Southeast Asia — but the lineage’s fossil record spans the globe, with specimens uncovered in places including the United Kingdom, Sweden, Italy, Egypt and Japan, Burke said in an email.

Gharials, or gavials, are characterized by their long, slender snouts. The two living species include the critically endangered Indian gharial , Gavialis gangeticus, and the endangered false gharial, Tomistoma schlegelii. The false gharial gets its moniker from its resemblance to the Indian gharial, despite being a different species.

Arun Sankar/AFP/Getty Images

The fossils analyzed in the new study, including the skull and five other specimens, were initially classified in 1927 as the previously named extinct species Tomistoma cairense based on their resemblance to the living false gharial. However, after performing evolutionary analyses to assess the relationships of extinct and living crocodilians, and computed tomography or CT scanning to peer inside the skull, the study authors found that the remains did not belong to the genus Tomistoma.

“It was already known and recognised as something distinct, but more detailed work was needed to resolve exactly what it represented,” said co-lead study author Philip Mannion, a professor of paleobiology at the University College London.

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Instead, the crocodilian’s features represent a new genus, Herugavialis. Burke, who was reconstructing fossil gharials for his doctoral project, noted the subtle differences between the unidentified species and the false gharial, and started to work on an up-to-date description in December 2023.

Herugavialis had razor-sharp, pointed teeth “which, alongside their long, thin snout would have been adapted to capture fish,” Burke said in an email. “The Mokattam Formation, where Herugavialis was recovered from, preserves several species of bony and cartilaginous fish fossils, which Herugavialis likely fed on.”

The semiaquatic predator’s eyes would have also protruded from the skull, similar to the Indian gharial, because the eye sockets were raised like a telescope, Burke added.

The Herugavialis skull may have not been discovered within the Great Sphinx itself, but the statue and the pyramids are known to be troves for both ancient Egyptian and prehistoric finds. Scientists have previously discovered hundreds of thousands of smaller fossilized organisms, such as bivalves and foraminifera — tiny creatures that lived in Egypt’s past marine ecosystem — embedded within the grand monuments.

“It’s probable that larger fossils are also present within the walls of these monuments and I think it’s very likely that other fossils will continue to be found in this formation, especially of animals that like shallow marine environments,” Mannion said in an email, adding that prehistoric turtles could be a potential example.

The vast fossil collection unearthed from the Mokkattam Formation reveal the rich ecosystem and the wide diversity of species that once lived in prehistoric Egypt, he said. Identifying Herugavialis from a nearly centuries-old fossil find also highlights the importance of reevaluating museum collections.

“There are other fossils in similar situations, but often this is just about time and resources, both for researchers and curators, rather than that no-one is aware of their existence,” Mannion said.

Cris Bouroncle/AFP/Getty Images

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Reclassifying the crocodile species “helps paint a better picture of what large predators were like in the region,” said Alex Hastings, the Fitzpatrick Chair of Paleontology at the Science Museum of Minnesota in Saint Paul, who was not involved with the study.

“This expands the known variety of forms of these amazing long-snouted crocodylians across the Mediterranean in ancient times and gives us better understanding for how that would have influenced ecosystems during the greenhouse environment of the Eocene ,” Hastings said in an email, referring to the period from about 56 million to 34 million years ago when global temperatures were much warmer than today.

Herugavialis, like many other species, had initially been assigned to a living genus even though the croc was alive a long time ago, he noted. “Studies like this provide crucial data that allows us to realize the real diversity and evolutionary background of these creatures rather than lumping them into living systems.”

Taylor Nicioli is a freelance journalist based in New York.

鳄鱼家族的族谱可能要添新成员了。古生物学家分析了在建造狮身人面像的同一基岩中发现的化石遗骸，新发现了一种鳄鱼物种，它大约在4500万年前曾漫游于如今埃及的浅海中。

埃及北部的莫卡塔姆组是一层厚厚的石灰岩，保存着史前海洋生物化石，包括鱼类、鲨鱼和早期鲸鱼。这层石灰岩露头也为古埃及人建造一些最著名的古迹提供了大量原材料，例如吉萨大狮身人面像和金字塔。

如今，科学家们已经确认了生活在埃及人建造这些建筑之前数百万年的已灭绝鳄鱼物种。这些鳄鱼化石不仅与这些标志性建筑拥有相同的地质基础，而且其中一件关键化石——一个近乎完整的头骨——与狮身人面像有着惊人的相似之处：这个头骨最早于20世纪20年代出土，它的吻部尖端缺失，这与狮身人面像缺失鼻子的情况如出一辙。这一巧合启发研究人员将新属命名为赫鲁加维亚利斯（Herugavialis），以纪念与建造狮身人面像相关的埃及神祇荷鲁斯（Heru/Horus）。

海梅·布兰·萨米恩托

新发现的化石揭示，史前海牛曾被鳄鱼和鲨鱼捕食。

根据周二发表在《皇家学会开放科学》杂志上的一项研究的作者称，这一物种的发现增进了科学家对恒河鳄多样性和历史的了解，恒河鳄是一类进化史复杂的鳄鱼。

“在距今6600万至2300万年的4300万年间，我们在地中海地区发现了六种恒河鳄，其中就包括开罗恒河鳄（Herugavialis cairensis）。当然，可能还有更多我们尚未发现的物种，”该研究的共同第一作者、斯德哥尔摩瑞典自然历史博物馆的脊椎动物古生物学家兼博士后研究员保罗·伯克（Paul Burke）说道。

伯克在一封电子邮件中表示，目前仅存两种恒河鳄——分别分布在印度次大陆和东南亚——但该物种的化石记录遍布全球，在英国、瑞典、意大利、埃及和日本等地都发现了标本。

恒河鳄（或称长吻鳄）的特征是其细长的吻部。现存的两个物种分别是极度濒危的印度恒河鳄（Gavialis gangeticus）和濒危的假恒河鳄（Tomistoma schlegelii）。假恒河鳄因其外形与印度恒河鳄相似而得名，尽管它们并非同一物种。

Arun Sankar/AFP/Getty Images

这项新研究分析的化石，包括头骨和其他五个标本，最初于1927年被归类为已灭绝的物种——卡伊鳄（Tomistoma cairense），原因是它们与现存的假长吻鳄（Metistoma sigral）外形相似。然而，在进行进化分析以评估已灭绝和现存鳄鱼的亲缘关系，并利用计算机断层扫描（CT）观察头骨内部结构后，研究人员发现这些遗骸并不属于卡伊鳄属（Tomistoma）。

“它早已被人们所知并认可为一种独特的事物，但还需要更详细的研究来确定它究竟代表什么，”该研究的共同主要作者、伦敦大学学院古生物学教授菲利普·曼尼恩说。

古代蛋壳为从树上捕猎的鳄鱼提供了新的线索

相反，这种鳄鱼的特征代表了一个新属，即赫鲁加维亚利斯属（Herugavialis）。伯克当时正在为他的博士项目重建化石恒河鳄，他注意到了这种未鉴定物种和假恒河鳄之间的细微差别，并于2023年12月开始着手撰写最新的描述。

伯克在一封电子邮件中写道，赫鲁加维亚利斯鱼拥有锋利无比的尖牙，“加上它们细长的吻部，非常适合捕食鱼类”。“赫鲁加维亚利斯鱼化石发现于莫卡塔姆组地层，该地层保存着多种硬骨鱼和软骨鱼化石，赫鲁加维亚利斯鱼很可能以这些鱼类为食。”

伯克补充说，这种半水生捕食者的眼睛也会像印度长吻鳄一样从头骨中突出，因为它们的眼窝像望远镜一样凸起。

虽然赫鲁加维利斯头骨并非在大狮身人面像内部发现，但众所周知，这座雕像和金字塔都是古埃及和史前文物的宝库。科学家们此前已在这些宏伟的建筑中发现了数十万个小型生物化石，例如双壳类和有孔虫——这些微小的生物曾生活在埃及古代的海洋生态系统中。

曼尼恩在一封电子邮件中表示：“这些古迹的墙壁内可能还存在更大的化石，我认为很可能还会继续在这个地层中发现其他化石，特别是喜欢浅海环境的动物的化石。”他还补充说，史前海龟可能就是一个潜在的例子。

他表示，从莫卡塔姆组地层出土的大量化石揭示了史前埃及曾经拥有的丰富生态系统和广泛的物种多样性。从一块近数百年前的化石中鉴定出赫鲁加维利斯属（Herugavialis）物种，也凸显了重新评估博物馆藏品的重要性。

“还有其他化石也处于类似的境地，但这通常只是时间和资源的问题，无论是对研究人员还是保管员来说，而不是因为没有人知道它们的存在，”曼尼恩说。

克里斯·布隆克/法新社/盖蒂图片社

科学家提供证据支持狮身人面像起源的可能说法。

明尼苏达州圣保罗市科学博物馆的菲茨帕特里克古生物学主席亚历克斯·黑斯廷斯（Alex Hastings）表示，重新对鳄鱼物种进行分类“有助于更好地了解该地区大型掠食者的样子”，他并未参与这项研究。

“这扩展了人们对古代地中海地区这些神奇的长吻鳄的已知形态的了解，并让我们更好地了解它们在始新世温室环境下对生态系统的影响，”黑斯廷斯在一封电子邮件中说，他指的是大约 5600 万年前到 3400 万年前的时期，当时全球气温比现在高得多。

他指出，像许多其他物种一样，赫鲁加维亚利斯鳄最初被归入一个现存的属，尽管这种鳄鱼生活在很久以前。“像这样的研究提供了关键数据，使我们能够认识到这些生物的真实多样性和进化背景，而不是将它们简单地归入现存的分类系统中。”

泰勒·尼乔利是一位居住在纽约的自由撰稿人。