This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: During the Late Cretaceous period, parts of Egypt were covered in water. A new study, published in the journal Cretaceous Research, describes new evidence that this tropical sea was home to a diverse community of sharks.
The study adds five new species to the region's history, found in what the authors refer to as a "shark graveyard." The Cretaceous period was marked by warmer temperatures and high sea levels due to a strong greenhouse effect. What is now Egypt's Western Desert once lay beneath a warm tropical sea sometime between 145–66 million years ago. The Abu-Tartur Plateau, in the southern part of this desert, holds one of the largest phosphate reserves in Egypt.
The phosphate found there is the result of ancient marine conditions during the Late Cretaceous, when organic-rich sediments accumulated and transformed into thick phosphorite beds over time. Fossils from the Duwi Formation, which stretches across Egypt and includes the Abu-Tartur Plateau, had already indicated a rich marine ecosystem with fish, sea turtles and marine reptiles. The team involved in the new study had also previously discovered several fossilized teeth from two types of lamniform sharks, also known as mackerel sharks.
The team decided to take a deeper dive into Egypt's long-lost ocean and search for additional shark species. This led to a surface collection of 14 more fossil shark teeth from a phosphate bed in the Abu-Tartur mine area. The new teeth ranged from needle-like to triangular and serrated, and their coloration varied from dark brown to yellow.
The researchers identified the teeth by comparing their shapes and features with published records and museum specimens. Of the 14 teeth, the team identified at least five additional extinct lamniform shark species, bringing the total number of shark species to seven for the Abu-Tartur region. Two of these species, Serratolamna serrata and Squalicorax bassanii, had never been reported in Egypt before.
Another, Scapanorhynchus raphiodon—an ancient relative of today's goblin shark—had never been reported anywhere in Africa before. This may also be the youngest known appearance of this species in the fossil record. However, the apparent record-breaking age of Scapanorhynchus raphiodon still needs confirmation from more specimens and future taxonomic work.
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