{{Short description|Geological formation in Egypt}} {{Infobox rockunit | name = Dakhla Formation | image = | caption = | type = Geological formation | age = Maastrichtian-Danian <br/> ~{{fossil range|71|63}} | period = Cretaceous | prilithology = Shale<ref name=":0" /> | otherlithology = Marl, Phosphorite | namedfor = | namedby = | region = | country = Egypt | coordinates = | unitof = | subunits = * Ammonite Hill Member<ref name=":2" /> * Baris Oyster Mudstone Member<ref name=":5" /> * Beida Shale Member<ref>{{Cite web |title=UPPER DAKHLA FORMATION ( BEIDA SHALE MEMBER) AT G. DUWI, RED SEA, EGYPT: MINERALOGICAL AND GEOCHEMICAL ASPECTS {{!}} Faculty of Science |url=https://www.aun.edu.eg/science/upper-dakhla-formation-beida-shale-member-g-duwi-red-sea-egypt-mineralogical-and-geochemical |access-date=2022-11-23 |website=www.aun.edu.eg}}</ref> * Kharga Shale Member<ref name=":5" /> | underlies = Tarawan Formation<ref name=":0" /> | overlies = Duwi Formation<ref name=":0" /> | thickness = 230 meters<ref name=":0" /> | extent = | area = | map = | map_caption = }}
The '''Dakhla Formation''', also called the '''Dakhla Shale''',<ref name=":8">{{Cite journal |last1=El-Kheir |first1=Gebely A. Abu |last2=Shaker |first2=Ahmed A. |last3=Street |first3=Hallie P. |last4=Longrich |first4=Nicholas R. |last5=Strougo |first5=Amin |last6=Asan |first6=Anhar |last7=AbdelGawad |first7=Mohamed |date=9 November 2023 |title=A Prognathodontin Mosasaur from the Maastrichtian of the Dakhla Oasis, Western Desert, Egypt |journal=Fossil Studies |language=en |volume=1 |issue=1 |pages=60–75 |doi=10.3390/fossils1010007 |doi-access=free |issn=2813-6284}}</ref> is a Maastrichtian-Danian geologic formation in the Western Desert, Egypt.<ref name=":0">{{Cite journal |last1=Anan |first1=Tarek I. |last2=Abd El-Wahed |first2=Ahmed G. |date=2017-12-15 |title=The Maastrichtian-Danian Dakhla Formation, Eastern Desert, Egypt: Utilization in manufacturing lightweight aggregates |url=https://www.sciencedirect.com/science/article/pii/S0169131717303782 |journal=Applied Clay Science |language=en |volume=150 |pages=10–15 |doi=10.1016/j.clay.2017.08.027 |bibcode=2017ApCS..150...10A |issn=0169-1317|url-access=subscription }}</ref><ref>{{Cite journal |last1=Tantawy |first1=A. A. |last2=Keller |first2=G. |last3=Adatte |first3=T. |last4=Stinnesbeck |first4=W. |last5=Kassab |first5=A. |last6=Schulte |first6=P. |date=2001-12-01 |title=Maastrichtian to Paleocene depositional environment of the Dakhla Formation, Western Desert, Egypt: sedimentology, mineralogy, and integrated micro- and macrofossil biostratigraphies |url=https://www.sciencedirect.com/science/article/pii/S0195667101902915 |journal=Cretaceous Research |volume=22 |issue=6 |pages=795–827 |doi=10.1006/cres.2001.0291 |bibcode=2001CrRes..22..795T |issn=0195-6671|url-access=subscription }}</ref> Dinosaur remains are among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus.<ref name="dinosaurdistribution">Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517–607.</ref>
==Fossil content== {{Paleobiota-key-compact}}
===Reptiles=== ====Dinosaurs==== {| class="wikitable" align="center" |- ! colspan="6" align="center" | '''Dinosaurs reported from the Dakhla Formation''' |- ! Genus !! Species !! Presence !'''Material'''!! Notes !! Images |- | Sauropoda | | Ammonite Hill Member<ref name=":7">{{Cite journal |last1=Rauhut |first1=Oliver W M |last2=Werner |first2=Christa |date=January 1997 |title=First record of a Maastrichtian sauropod dinosaur from Egypt |url=https://www.researchgate.net/publication/235907515 |journal=Palaeontolgia Africana |volume=34 |pages=63–67}}</ref> |A left femur (Vb-646).<ref name=":7" /> | Most similar to femurs of ''Brachiosaurus'' or ''Saltasaurus''.<ref name=":7" /> | |- |}
====Turtles==== {| class="wikitable" align="center" |- ! colspan="6" align="center" | '''Turtles reported from the Dakhla Formation''' |- ! Genus !! Species !! Presence !'''Material'''!! Notes !! Images |- |rowspan=2|''Arenila'' |''A. krebsi'' |Ammonite Hill Member<ref name=":4" /> |Partial skull.<ref name=":4" /> |A bothremydid turtle. | |- |?Cf. ''A. krebsi'' |Ammonite Hill Member<ref name=":4" /> |Partial dorsal shell & right pelvis.<ref name=":4" /> |A bothremydid turtle. | |- |Bothremydidae |Undetermined large forms |Ammonite Hill Member<ref name=":4">{{Cite journal |last1=de Lapparent |first1=France |last2=Werner |first2=Christa |date=April 1998 |title=New Late Cretaceous turtles from the Western Desert, Egypt |url=https://www.researchgate.net/publication/240435581 |journal=Annales de Paléontologie |volume=84 |issue=2 |pages=131–214|doi=10.1016/S0753-3969(98)80005-0 |bibcode=1998AnPal..84..131D }}</ref> |Nuchal bone, left pleuron & partial plastron of one individual.<ref name=":4" /> |A large bothremydid turtle, with a shell length of 70 to 80 centimeters.<ref name=":4" /> | |- |''Gigantochelys''
|''G. aegyptiacus''<ref name="Gigantochelys">{{Cite journal |last1=Mousa |first1=Mohamed K. |last2=Tantawy |first2=Abdel Aziz A. |last3=Abu El-Kheir |first3=Gebely A. |date=February 2026 |title=First known gigantic dermochelyid turtle (Pan-Chelonioidea) from the Upper Cretaceous deposits of Dakhla Oasis, Western Desert, Egypt. |journal=Cretaceous Research |language=en |article-number=106357 |issue=in press |doi=10.1016/j.cretres.2026.106357}}</ref> |Beris Member<ref name="Gigantochelys" /> |Pelvic girdle<ref name="Gigantochelys" /> |A large dermochelyid turtle | |- | Panchelonioidea |Gen. et. sp. indet. | Ammonite Hill Member<ref name=":3">{{Cite journal |last1=Abu El-Kheir |first1=G. A.-M. |last2=AbdelGawad |first2=M. K. |last3=Kassab |first3=W. G. |date=2021 |title=First known gigantic sea turtle from the Maastrichtian deposits in Egypt |url=https://www.app.pan.pl/article/item/app008492020.html |journal=Acta Palaeontologica Polonica |volume=66 |issue=2 |pages=349–355}}</ref> |Humerus (NVP010).<ref name=":3" /> | A giant marine turtle. | |- |rowspan=2|''Taphrosphys'' |''T.'' cf. ''sulcatus'' |Ammonite Hill Member<ref name=":4" /> |Anterior part of dorsal shell & partial dorsal shell with partial anterior plastral lobe.<ref name=":4" /> |A bothremydid turtle. | |- |Cf. ''T.'' sp. |Ammonite Hill Member<ref name=":4" /> |Left first pleural.<ref name=":4" /> |A bothremydid turtle. | |- |?Aff. ''Tasbacka'' |?Aff. ''T.'' sp. |Ammonite Hill Member<ref name=":4" /> |Left humerus.<ref name=":4" /> |A chelonioid sea turtle. |center|150 px |- |''Zolhafah'' |''Z. bella'' |Ammonite Hill Member<ref name=":4" /> |Skull.<ref name=":4" /> |A bothremydid turtle. | |- |}
====Mosasaurs==== {| class="wikitable" align="center" |- ! colspan="6" align="center" | '''Mosasaurs reported from the Dakhla Formation''' |- ! Genus !! Species !! Presence !'''Material'''!! Notes !! Images |- |''Globidens'' |''G. phosphaticus'' |Beris Oyster Mudstone Member<ref name=":5">{{Cite journal |last1=AbdelGawad |first1=Mohamed K. |last2=Abu El-Kheir |first2=Gebely A. |last3=Kassab |first3=Walid G. |date=September 2021 |title=The youngest records of mosasaurid reptiles from the Upper Cretaceous of the South-Western Desert in Egypt |url=https://www.researchgate.net/publication/354793174 |journal=Proceedings of the Geologists' Association |volume=132 |issue=5 |pages=556–562 |doi=10.1016/j.pgeola.2021.07.004 |bibcode=2021PrGA..132..556A |issn=0016-7878}}</ref> |A single tooth crown (CUNV0011).<ref name=":5" /> |A mosasaurine. |center|150 px |- |''Halisaurus'' |''H. hebae'' |Beris Oyster Mudstone Member<ref>{{Cite journal |last1=Shaker |first1=A. A. |last2=Longrich |first2=N. R. |last3=Strougo |first3=A. |last4=Asan |first4=A. |last5=Bardet |first5=N. |last6=Mousa |first6=M. K. |last7=Tantawy |first7=A. A. |last8=Abu El-Kheir |first8=G. A. |year=2023 |title=A new species of ''Halisaurus'' (Mosasauridae: Halisaurinae) from the lower Maastrichtian (Upper Cretaceous) of the Western Desert, Egypt |journal=Cretaceous Research |volume=154 |at=105719 |doi=10.1016/j.cretres.2023.105719}}</ref> | |A halisaurine | |- |Mosasaurinae |Indeterminate |Beris Oyster Mudstone Member<ref name=":5" /> |A fragmentary small dentary with a single tooth (CUNV0012).<ref name=":5" /> |A mosasaurine. | |- |''Prognathodon'' |''P''. sp. |"Lower part" |Two tooth crowns, three cervical, nine dorsal, three caudal vertebrae, and ribs, found in association (NVP025).<ref name=":8" /> |Most similar to ''P. overtoni'', possibly a member of that species | |}
===Fish=== {| class="wikitable" align="center" |- ! colspan="6" align="center" | '''Fish reported from the Dakhla Formation''' |- ! Genus !! Species !! Presence !'''Material'''!! Notes !! Images |- |''Anomoeodus'' |''A. aegypticus'' |Lower Beris Member<ref name=":6">{{Cite journal |last1=Capasso |first1=Luigi |last2=Abu El-kheir |first2=Gebely Abdelmaksoud |last3=Mousa |first3=Mohamed Kamel |last4=Tantawy |first4=Abdel Aziz |date=December 2021 |title=ANOMOEODUS AEGYPTICUS N. SP. (PISCES, †PYCNODONTIFORMES) FROM THE LATE CRETACEOUS OF THE DAKHLA FORMATION, WESTERN DESERT, EGYPT |url=https://www.researchgate.net/publication/357930651 |journal=Thalassia Salentina |issue=43 |pages=89–104}}</ref> |A single specimen (NVP023).<ref name=":6" /> |A pycnodont. | |- | ''Diastemapycnodus'' |''D. tavernensis'' | Beris Member<ref name=":1">{{Cite journal |last1=Abu El-Kheir |last2=Tantawy |last3=Mousa |last4=Wahba |last5=Capasso |date=2022-12-02 |title=Diastemapycnodus tavernensis gen. et sp. nov. (Actinopterygii, †Pycnodontiformes) from the marine Maastrichtian (Late Cretaceous) of the Dakhla Formation, Western Desert, Egypt |url=https://www.ingentaconnect.com/content/tandf/ghbi/2022/00000034/00000012/art00007 |journal=Historical Biology: A Journal of Paleobiology |volume=34 |issue=12 |pages=2324–2331 |doi=10.1080/08912963.2021.2014482|bibcode=2022HBio...34.2324A |s2cid=245051336 |url-access=subscription }}</ref> |"A single vomer with partial dentition".<ref name=":1" /> | A pycnodont. | |- | ''Sclerorhynchus'' | ''S.'' cf. ''leptodon''<ref name=Greenfield>{{cite journal|author=Greenfield, T.|year=2025|title=No evidence for a giant, late-surviving ''Onchopristis'': Comment on Capasso et al. (2024)|journal=Journal of African Earth Sciences|volume=223|at=105541|doi=10.1016/j.jafrearsci.2025.105541}}</ref> | Beris Member | Four fragmentary rostral denticles originally attributed to ''Onchopristis'' sp.<ref name=Capasso2024/> |A sawskate. |- | cf. ''Otodus'' | cf. ''O. obliquus''{{cn|date=October 2025}} | | Fragmentary teeth and possible vertebra founds. | A otodontid. | |- | Sclerorhynchoidei | Indeterminate<ref name=Greenfield/> | Beris Member | An exceptionally large, {{convert|1.46|m|ft}} long rostrum originally attributed to ''Onchopristis'' sp.<ref name=Capasso2024>{{Cite journal|last1=Capasso |first1=L. |last2=Abdel Aziz |first2=S. |last3=Tantawy |first3=A. A. |last4=Mousa |first4=M. K. |last5=Wahba |first5=D. G. A. |last6=Abu El-Kheir |first6=G. A. |year=2024 |title=The first described ''Onchopristis'' Stromer, 1917, (Elasmobranchii: †Onchopristidae) from the Marine Maastrichtian of Dakhla Formation, Western Desert, Egypt |journal=Journal of African Earth Sciences |at=105415 |doi=10.1016/j.jafrearsci.2024.105415 }}</ref> |A sawskate. | |- | ''Wadiichthys'' | ''W. anbaawyi'' | Beris Member<ref>{{Cite journal|last1=Abu El-Kheir |first1=G. A. |last2=Marzouk |first2=A. |last3=Capasso |first3=L. |last4=Zahran |first4=E. |last5=Kasem |first5=A. M. |last6=Kamel |first6=A. |last7=Mousa |first7=M. K. |last8=Elbsebeshi |first8=A. |year=2026 |title=A new saurodontid fish from the Late Cretaceous of the Western Desert, Egypt |journal=Acta Palaeontologica Polonica |volume=71 |issue=1 |pages=85–94 |doi=10.4202/app.01277.2025 |doi-access=free }}</ref> | | A saurodontid Ichthyodectiform | |}
===Invertebrates=== ====Bivalves==== {| class="wikitable" align="center" |- ! colspan="6" align="center" | '''Bivalves reported from the Dakhla Formation''' |- ! Genus !! Species !! Presence !'''Material'''!! Notes !! Images |- |style="background:#FEF6E4;" |''Apectoichnus'' |style="background:#FEF6E4;" |''A. longissimus'' |style="background:#FEF6E4;" |Ammonite Hill Member<ref name=":2">{{Cite journal |last1=El Hedeny |first1=M. |last2=Kassab |first2=W. |last3=Rashwan |first3=M. |last4=Abu El-Kheir |first4=G. |last5=AbdelGawad |first5=M. |date=2020-07-01 |title=Bivalve borings in Maastrichtian fossil''Nypa''fruits: Dakhla Formation, Bir Abu Minqar, South Western Desert, Egypt |url=https://www.researchgate.net/publication/339002137 |journal=Ichnos |volume=28 |issue=1 |pages=24–33 |doi=10.1080/10420940.2020.1784158 |s2cid=225527064 |issn=1042-0940}}</ref> |style="background:#FEF6E4;" |Borings in ''Nypa'' fruits.<ref name=":2" /> |style="background:#FEF6E4;" |Bivalve borings. |style="background:#FEF6E4;" | |- |style="background:#FEF6E4;" |''Teredolites'' |style="background:#FEF6E4;" |''T. clavatus'' |style="background:#FEF6E4;" |Ammonite Hill Member<ref name=":2" /> |style="background:#FEF6E4;" |32 moderately preserved borings (TBT02-33) & two badly preserved specimens (TBT44-45) in ''Nypa'' fruits.<ref name=":2" /> |style="background:#FEF6E4;" |Bivalve borings. |style="background:#FEF6E4;" | |- |}
===Plants=== {| class="wikitable" align="center" |- ! colspan="6" align="center" | '''Plants reported from the Dakhla Formation''' |- ! Genus !! Species !! Presence !'''Material'''!! Notes !! Images |-style="background:#D1FFCF;" |rowspan=2|''Nypa'' |''N. burtinii'' | |Fruits & seed casts.<ref>{{Cite journal |last1=El-Soughier |first1=Maher I. |last2=Mehrotra |first2=R.C. |last3=Zhou |first3=Zhi-Yan |last4=Shi |first4=Gong-Le |date=January 2011 |title=Nypa fruits and seeds from the Maastrichtian–Danian sediments of Bir Abu Minqar, South Western Desert, Egypt |url=https://www.researchgate.net/publication/251707921 |journal=Palaeoworld |volume=20 |issue=1 |pages=75–83 |doi=10.1016/j.palwor.2010.09.016 |issn=1871-174X}}</ref> |A mangrove palm | |- style="background:#D1FFCF;" |''N.'' sp. |Ammonite Hill Member<ref name=":2" /> |Fruits with bivalve borings.<ref name=":2" /> |A mangrove palm. | |- |}
== See also == {{Portal|Geology|Paleontology|Dinosaurs}} * List of dinosaur-bearing rock formations ** List of stratigraphic units with indeterminate dinosaur fossils
== References == {{Reflist}}
=== Bibliography === * Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. {{ISBN|0-520-24209-2}}.
Category:Geologic formations of Egypt Category:Upper Cretaceous Series of Africa Category:Maastrichtian Stage Category:Shale formations Category:Phosphorite formations Category:Long stubs with short prose
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