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| Khargachelys caironensis AbdelGawad, Pérez-García, Hirayama, Mohesn, Tantawy & El-Kheir, 2023 |
Abstract
The Quseir Formation is an Upper Cretaceous (Campanian) deposit in the Kharga oasis of the Southwestern Desert (Egypt). This formation comprises a clastic sequence of bioturbated mudstone and sandstone intercalations, including rare scattered and fragmented vertebrate remains such as shark teeth, dinosaur remains, and turtle plates. These deposits indicate a supratidal marsh environment. A complete shell of a turtle discovered from the Quseir Formation, at the Kharga oasis, is attributed here to Bothremydini (Pleurodira, Bothremydidae), and determined as a new taxon: Khargachelys caironensis gen. et sp. nov. This form represents the only Bothremydini member currently identified in the Campanian record not only of Egypt but also of North Africa. Therefore, it helps fill the missing evolutionary gap from the Late Cretaceous pleurodires in Egypt and in North Africa.
Keywords: Campanian; Quseir Formation; Kharga; Bothremydini; Khargachelys caironensis gen. et sp. nov
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| NVP005, the shell of the bothremydid turtle Khargachelys caironensis gen. et sp. nov., from the Campanian age of Kharga Oasis, South Western Desert, Egypt, in dorsal (A,A’) and ventral (B,B’) views. |
Systematic Paleontology
Testudines Batsch, 1788
Pleurodira Cope, 1864
Pelomedusoides Cope, 1868
Bothremydidae Baur, 1891
Bothremydini Gaffney, Tong and Meylan, 2006
Khargachelys caironensis gen. et sp. nov
Holotype: NVP005, complete carapace and plastron.
Type locality and horizon: Qarn Gennah (Kharga oasis); Quseir Formation; Campanian age.
Diagnosis: Member of Bothemydini that differs from the other representatives of this clade by the following character combination: long shell close to 60 cm in length; oval-shaped carapace, reaching its widest point at the fifth peripherals; narrow and shallow nuchal emargination; seven neurals; almost as long and wide as the first pair of peripherals; first vertebral scute being the widest of the vertebral series; second to the fourth vertebrals noticeably longer than wide; first pair of marginals overlapping half the lateral nuchal margins; anterior margin of the plastron reaching the anterior carapace edge; anterior plastral lobe wider than the posterior one; twice as wide as long entoplastron; entoplastron width equivalent to almost half the anterior plastral lobe width; extragulars overlapping the entoplastron; humero-pectoral sulcus located behind the epiplastra, showing a relatively long distance between them; pectoral scutes overlapping the anterior region of the mesoplastra.
Description: The carapace is almost complete but partially broken (Figure 2). The damaged and crushed parts are due to the pressure from the overlying sediments. The carapace is estimated to be about 580 mm long and 430 mm wide. The height of the carapace cannot ...
Etymology: “Kharga” honors Kharga Oasis, where the specimen was collected; “chelys” is Greek for, turtle; “caironensis” honors Cairo, the capital city of Egypt, and honors Cairo University.
Conclusions:
The described turtle shell here, from the Quseir Formation of Kharga Oasis, in the South Western Desert (Egypt), represents the first record of Bothremydidae (Pleurodira) from the Campanian age in Egypt and in Africa. The Campanian deposits in the Kharga area indicate a supratidal marsh environment, concordant with the occurrence of such aquatic turtles. The specimen is attributed to a new genus and species of Bothremydini, Khargachelys caironensis gen. et sp. nov. This specimen brings new data to the poorly known diversity of turtles from the Late Cretaceous of Egypt.
The restricted brackish water environments and the gradual shallow shelf together with fossils such as freshwater gastropods and palynofloras, support indications of the ability of Bothremydidae to reside in different environments, such as freshwater and coastlines. The diversity of the paleoenvironments of the Bothremydidae enabled them to reach a wide distribution in both the northern and southern continents during the Late Cretaceous, along the coastlines of the Atlantic Ocean, breaking the barriers of the vicariance pattern of evolution.
Mohamed AbdelGawad, Adán Pérez-García, Ren Hirayama, Sara Mohesn, Abdel-Aziz Tantawy and Gebely Abu El-Kheir. 2023. The First Side-Necked Turtle (Pleurodira, Bothremydidae) from the Campanian (Late Cretaceous) of Egypt. Diversity. 15(2); 284. DOI: 10.3390/d15020284
(This article belongs to the Special Issue Fossil Reptiles and Associated Faunal Record)
