Akrabou Formation
{{Short description|Geological formation in Morocco}}
{{Infobox rockunit|name=Akrabou Formation|image=File:Gr10 lrg.jpg|image_caption=Fish of the Akrabou Formation|type=Geological formation|age=latest Cenomanian to ?middle Turonian
~{{fossil range|93.9|90}}|period=Turonian|prilithology=Limestone|underlies=|region=Er Rachidia|country=Morocco, Algeria|coordinates={{coord|30.5|N|4.8|W|region:MA|display=inline,title}}|paleocoordinates={{coord|17.8|N|4.8|W|display=inline}}|subunits=Agoult, Goulmima, others|extent=central and eastern Morocco north and south of the Pre-African Trough|map={{Location map+ | Morocco
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{{ Location map~ | Morocco
| lat_deg = 32.50
| lon_deg = -4.50
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}}|overlies=Kem Kem Group|year_ts=2004|namedby=El Mostafa Ettachfini, Bernard Andreu}}The Akrabou Formation is a Late Cretaceous (latest Cenomanian to early/mid Turonian)-aged geological formation and Konservat-Lagerstätte in Morocco.{{Cite journal |last1=Ettachfini |first1=El Mostafa |last2=Andreu |first2=Bernard |date=2004-04-01 |title=Le Cénomanien et le Turonien de la Plate-forme Préafricaine du Maroc |url=https://linkinghub.elsevier.com/retrieve/pii/S0195667104000229 |journal=Cretaceous Research |volume=25 |issue=2 |pages=277–302 |doi=10.1016/j.cretres.2004.01.001 |bibcode=2004CrRes..25..277E |issn=0195-6671|url-access=subscription }} It overlies the slightly older freshwater deposits of the Kem Kem Group, which it was once thought to be a part of. It was deposited over following the Kem Kem ecosystem's submergence by the Tethys Ocean during a marine transgression from the Cenomanian-Turonian boundary event, as part of a wider deposition of carbonate platforms across the region from the event.{{cite journal |last1=Ibrahim |first1=N. |author-link=Nizar Ibrahim |last2=Sereno |first2=P.C. |author-link2=Paul Sereno |last3=Varricchio |first3=D.J. |last4=Martill |first4=D.M. |last5=Dutheil |first5=D.B. |last6=Unwin |first6=D.M. |last7=Baidder |first7=L. |last8=Larsson |first8=H.C.E. |last9=Zouhri |first9=S. |last10=Kaoukaya |first10=A. |year=2020 |title=Geology and paleontology of the Upper Cretaceous Kem Kem Group of eastern Morocco |journal=ZooKeys |issue=928 |pages=1–216 |bibcode=2020ZooK..928....1I |doi=10.3897/zookeys.928.47517 |pmc=7188693 |pmid=32362741 |doi-access=free}}{{Cite journal |last1=Cavin |first1=L. |last2=Tong |first2=H. |last3=Boudad |first3=L. |last4=Meister |first4=C. |last5=Piuz |first5=A. |last6=Tabouelle |first6=J. |last7=Aarab |first7=M. |last8=Amiot |first8=R. |last9=Buffetaut |first9=E. |last10=Dyke |first10=G. |last11=Hua |first11=S. |last12=Le Loeuff |first12=J. |date=2010-07-01 |title=Vertebrate assemblages from the early Late Cretaceous of southeastern Morocco: An overview |url=https://linkinghub.elsevier.com/retrieve/pii/S1464343X09002404 |journal=Journal of African Earth Sciences |volume=57 |issue=5 |pages=391–412 |doi=10.1016/j.jafrearsci.2009.12.007 |bibcode=2010JAfES..57..391C |issn=1464-343X|url-access=subscription }}{{Cite journal |last1=Ibrahim |first1=Nizar |last2=Sereno |first2=Paul C. |last3=Varricchio |first3=David J. |last4=Martill |first4=David M. |last5=Dutheil |first5=Didier B. |last6=Unwin |first6=David M. |last7=Baidder |first7=Lahssen |last8=Larsson |first8=Hans C.E. |last9=Zouhri |first9=Samir |last10=Kaoukaya |first10=Abdelhadi |date=2020-04-21 |title=Geology and paleontology of the Upper Cretaceous Kem Kem Group of eastern Morocco |journal=ZooKeys |issue=928 |pages=1–216 |doi=10.3897/zookeys.928.47517 |doi-access=free |issn=1313-2989 |pmc=7188693 |pmid=32362741|bibcode=2020ZooK..928....1I }}
Localities
The Akrabou Formation has outcrops across the Anti-Atlas, but it has two especially prominent localities: Agoult and Goulmima (also known as Asfla). The Agoult locality is also commonly referred to as Gara Sbaa due to it outcropping at the hill of the same name, but this name is also used for the underlying freshwater-based deposit of the Kem Kem Group at the same locality, which may lead to nomenclatural confusion.{{Cite book |last1=Murray |first1=Allison M. |title=Mesozoic Fishes 5 – Global Diversity and Evolution |last2=Wilson |first2=Mark V. H. |last3=Gibb |first3=Stacey |last4=Chatterton |first4=Brian D. E. |date=2013 |publisher=Verlag Dr. Friedrich Pfeil |isbn=978-3-89937-159-8 |pages=525–548 |chapter=Additions to the Late Cretaceous (Cenomanian/Turonian) actinopterygian fauna from the Agoult locality, Akrabou Formation, Morocco, and comments on the palaeoenvironment}} Both localities are considered lagerstätten due to their excellently preserved fossils, but they differ in time period, paleoenvironment, and preservation of fossils.
The Agoult locality is the older of the two and appears to have been deposited around the time of the Cenomanian-Turonian boundary event, dating it to latest Cenomanian or earliest Turonian. It is a plattenkalk that contains excellently preserved two-dimensional fossils of fish, land plants, marine and terrestrial invertebrates, and some terrestrial reptiles. The presence of a significant terrestrial component indicates it was deposited in a shallow marine environment close to shore, although the deposits record the gradual deepening of the habitat as the sea level rose.
In contrast, the Goulmima locality is younger, dating to the early or mid Turonian, and appears to have been deposited in an offshore environment on the continental shelf. Fossils from this locality, which include fish and marine reptiles, are found in concretions and have a unique three-dimensional preservation akin to that of the older Santana Formation in Brazil.
In addition, several other localities are also known, some of which cross the border into Algeria, which have a rich fauna of ammonites and nautiloids.{{Cite journal |last1=Meister |first1=Christian |last2=Piuz |first2=André |last3=Cavin |first3=Lionel |last4=Boudad |first4=Larbi |last5=Bacchia |first5=Flavio |last6=Ettachfini |first6=El M. |last7=Benyoucef |first7=M. |date=2017 |title=Late Cretaceous (Cenomanian-Turonian) ammonites from southern Morocco and south western Algeria |url=https://link.springer.com/10.1007/s12517-016-2714-1 |journal=Arabian Journal of Geosciences |language=en |volume=10 |issue=1 |doi=10.1007/s12517-016-2714-1 |bibcode=2017ArJG...10....1M |issn=1866-7511|url-access=subscription }}
Paleoenvironment
In the basal Agoult horizons of the formation, a number of plant remains are known, which are similar to those found in southern Europe at the same time, suggesting floristic exchanges between northern Africa and southern Europe. Based on these, the paleoclimate of the ecosystem, at least earlier during its deposition, is suggested to have been a mildly dry subtropical climate akin to that of the modern western Canary Islands.{{Cite journal |last1=Martill |first1=David M. |last2=Ibrahim |first2=Nizar |last3=Brito |first3=Paulo M. |last4=Baider |first4=Lahssen |last5=Zhouri |first5=Samir |last6=Loveridge |first6=Robert |last7=Naish |first7=Darren |last8=Hing |first8=Richard |date=2011-08-01 |title=A new Plattenkalk Konservat Lagerstätte in the Upper Cretaceous of Gara Sbaa, south-eastern Morocco |url=https://www.sciencedirect.com/science/article/abs/pii/S0195667111000164 |journal=Cretaceous Research |volume=32 |issue=4 |pages=433–446 |doi=10.1016/j.cretres.2011.01.005 |bibcode=2011CrRes..32..433M |issn=0195-6671|url-access=subscription }}
Paleobiota
{{Paleobiota-key-compact}}Most fish are documented in a species list from Amalfitano et al (2020) & Cooper et al (2023):{{Cite journal |last1=Amalfitano |first1=Jacopo |last2=Giusberti |first2=Luca |last3=Fornaciari |first3=Eliana |last4=Carnevale |first4=Giorgio |date=2020-04-03 |title=UPPER CENOMANIAN FISHES FROM THE BONARELLI LEVEL (OAE2) OF NORTHEASTERN ITALY |url=https://riviste.unimi.it/index.php/RIPS/article/view/13224 |journal=Rivista Italiana di Paleontologia e Stratigrafia |language=en |volume=126 |issue=2 |doi=10.13130/2039-4942/13224 |issn=2039-4942}}
= Vertebrates =
== Cartilaginous fish ==
== Bony fish ==
== Reptiles ==
= Mollusks =
Based on Kennedy et al (2008) & Meister et al (2017):{{Cite journal |last1=Kennedy |first1=W. |last2=Gale |first2=A. |last3=Ward |first3=D. |last4=Underwood |first4=C. |date=2008 |title=Early Turonian ammonites from Goulmima, southern Morocco |url=https://ora.ox.ac.uk/objects/uuid:05a70004-d013-46ec-80ad-744f4d7fb638 |journal=Bulletin de l'Institut Royal des Sciences Naturelles de Belgique, Sciences de la Terre |language=English |volume=78 |issn=0374-6291}}
| class="wikitable" style="margin:auto;width:100%;"
!Genus !Species !Locality !Material !Notes !Image |
| Angulithes
|A. mermeti |Douira, Goulmima & Tazzougert | rowspan="16" |Shells | |
| rowspan="2" |Choffaticeras
|C. segne | rowspan="2" |Goulmima | rowspan="2" |A pseudotissotid ammonite. | |
| C. sinaiticum
| |
| Eutrephoceras
|E. sp. |Douira & Taouz |A nautilid nautiloid. |
| rowspan="2" |Fagesia
|F. peroni | rowspan="2" |Goulmima | rowspan="2" |A vasoceratid ammonite. | rowspan="2" |frameless |
| F. cf. tevesthensis |
| rowspan="2" |Hoplitoides
|H. mirabilis | rowspan="2" |Goulmima | rowspan="2" |A hoplitid ammonite. | |
| H. gr. wortmanni
| |
| Mammites
|M. nodosoides |Goulmima |An acanthoceratid ammonite. |
| Nannovascoceras
|N. intermedium |Goulmima |A vasoceratid ammonite. | |
| Neolobites
|N. vibrayeanus |Agoult, Tazzougert, Taouz, Tizi Momrad |An engonoceratid ammonite. | |
| rowspan="2" |Neoptychites
|N. cephalotus |Goulmima | rowspan="2" |A vasoceratid ammonite. | |
| N. aff. hottingeri
|Goulmima | |
| Romaniceras (Yubariceras)
|R. (Y.) reymenti |Goulmima |An acanthoceratid ammonite. | |
| Thomasites
|T. rollandi |Goulmima |A vasoceratid ammonite. | |
| Wrightoceras
|W. munieri |Goulmima |A pseudotissotid ammonite. | |
= Arthropods =
= Plants =
Based primarily on Krassilov & Bacchia (2013):
| class="wikitable" style="margin:auto;width:100%;"
!Genus !Species !Locality !Material !Notes !Image |
| style="background:#D1FFCF;" |Abietites
|style="background:#D1FFCF;" |A. (Tritaenia) cf. linkii |style="background:#D1FFCF;" rowspan="10" |Agoult |style="background:#D1FFCF;" |Needles |style="background:#D1FFCF;" |A conifer. |style="background:#D1FFCF;" | |
| style="background:#D1FFCF;" |Barykovia
|style="background:#D1FFCF;" |B. cf. tschuckotika |style="background:#D1FFCF;" |Leaf |style="background:#D1FFCF;" |A potentially fagalean angiosperm. |style="background:#D1FFCF;" | |
| style="background:#D1FFCF;" |Cocculophyllum
|style="background:#D1FFCF;" |C. cf. fucinerve |style="background:#D1FFCF;" |Leaf |style="background:#D1FFCF;" |A climbing angiosperm. |style="background:#D1FFCF;" | |
| style="background:#D1FFCF;" |Coniopteris
|style="background:#D1FFCF;" |C. cf. Dicksonia mamiyai |style="background:#D1FFCF;" |Leaflet. |style="background:#D1FFCF;" |A fern. |style="background:#D1FFCF;" |File:Dictyophyllum and Coniopteris (cropped).jpg |
| style="background:#D1FFCF;" |Dryophyllum
|style="background:#D1FFCF;" |D. cf. subcretaceum |style="background:#D1FFCF;" |Leaf |style="background:#D1FFCF;" |A potentially fagalean angiosperm. |style="background:#D1FFCF;" | |
| style="background:#D1FFCF;" |Frenelopsis
|style="background:#D1FFCF;" |F. cf. teixeirae |style="background:#D1FFCF;" |Shoot |style="background:#D1FFCF;" |A cheirolepidiacean conifer. |style="background:#D1FFCF;" |File:Frenelopsis cf. Ramosissima - Paja Formation, Colombia.jpg |
| style="background:#D1FFCF;" |Garasbahia
|style="background:#D1FFCF;" |G. flexuosa |style="background:#D1FFCF;" |Branching shoot with leaves. |style="background:#D1FFCF;" |A cabombacean angiosperm. |style="background:#D1FFCF;" | |
| style="background:#D1FFCF;" |Pseudotorellia
|style="background:#D1FFCF;" |P. cf. ensiformis |style="background:#D1FFCF;" |Leaf |style="background:#D1FFCF;" |A ginkgoalean. |style="background:#D1FFCF;" | |
| style="background:#D1FFCF;" |Sulcatocladus
|style="background:#D1FFCF;" |S. cf. robustus |style="background:#D1FFCF;" |Shoot |style="background:#D1FFCF;" |A conifer. |style="background:#D1FFCF;" | |
| style="background:#D1FFCF;" |Welwitschiophyllum
|style="background:#D1FFCF;" |W. sp. |style="background:#D1FFCF;" |Leaf |style="background:#D1FFCF;" |A possible welsitschialean.{{Cite journal |last1=Roberts |first1=Emily A. |last2=Martill |first2=David M. |last3=Loveridge |first3=Robert F. |date=2020-02-01 |title=Phytogeographical implications of the probable occurrence of the gnetalean plant Welwitschiophyllum in the Late Cretaceous (Cenomanian) of Africa |url=https://linkinghub.elsevier.com/retrieve/pii/S0016787819301208 |journal=Proceedings of the Geologists' Association |volume=131 |issue=1 |pages=1–7 |doi=10.1016/j.pgeola.2019.10.002 |bibcode=2020PrGA..131....1R |issn=0016-7878|url-access=subscription }} |style="background:#D1FFCF;" | |
