Akrabou Formation

The Akrabou Formation is a Late Cretaceous (latest Cenomanian to early/mid Turonian)-aged geological formation and Konservat-Lagerstätte in Morocco.^[1] 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.^[2][3][4]

Akrabou Formation
Stratigraphic range: latest Cenomanian to ?middle Turonian ~93.9–90 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Sub-units	Agoult, Goulmima, others
Overlies	Kem Kem Group
Lithology
Primary	Limestone
Location
Coordinates	30.5°N 4.8°W / 30.5; -4.8
Approximate paleocoordinates	17.8°N 4.8°W / 17.8; -4.8
Region	Er Rachidia
Country	Morocco,  Algeria
Extent	central and eastern Morocco north and south of the Pre-African Trough
Type section
Named by	El Mostafa Ettachfini, Bernard Andreu
Year defined	2004
Akrabou Formation (Morocco)

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.^[5][6] 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.^[7]

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.^[7][8]

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.^[9]

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.^[6][7]

Paleobiota

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Most fish are documented in a species list from Amalfitano et al (2020) & Cooper et al (2023):^[10]

Vertebrates

Cartilaginous fish

Genus	Species	Locality	Material	Notes	Image
Asflapristis	A. cristadentis	Goulmima	Incomplete three-dimensional skeletons, isolated teeth	A ptychotrygonid sawskate.[11]
Cretomanta	C. sp.	Goulmima	Isolated teeth	A chondrichthyan of uncertain affinties, possibly an aquilolamnid.[8]
Haimirichia	H. amonensis	Agoult	Partial skeleton	A haimirichiid mackerel shark.[8]
Ptychodus	P. maghrebianus	Goulmima	Dental battery, isolated teeth	A ptychodontid shark.[12]
Ptychotrygon	P. rostrispatula	Goulmima	Incomplete skeletons	A ptychotrygonid sawskate.[8]
?Rhinobatos	?R. sp.	Goulmima	Incomplete cranium	A presumed guitarfish.[8]
Squalicorax	S. sp.	Goulmima	Teeth	A crow shark.[8]
Tingitanius	T. tenuimandibulus	Goulmima	Three-dimensionally preserved incomplete skeleton of a young individual	The oldest known platyrhinid ray.[13]

Bony fish

Genus	Species	Locality	Material	Notes	Image
Acanthomorpha indet.		Agoult	Complete specimen	A poorly-preserved acanthomorph of uncertain affinities.[14]
Agoultichthys	A. chattertoni	Agoult	Complete specimen	A macrosemiid.[15]	Agoultichthys chattertoni Murray & Wilson, 2008
Agoultpycnodus	A. aldrovandii	Agoult	Complete specimen	A pycnodont.[16]
Amioidea gen. et sp. nov. 1		Agoult		Undescribed amiiforms in their own family.[5][17]
Amioidea gen. et sp. nov. 2
Anomoeodus	A. sp. "A"	Goulmima	Isolated jaw bones.	A pycnodont.
	A. sp. "B"
Armigatus	A. oligodentatus	Agoult	Complete specimens	An armigatid clupeomorph.[18]
Belonostomus	B. sp.	Agoult	Complete specimen	An aspidorhynchid.
Araripichthys	A. corythophorus	Goulmima	Incomplete specimens with associated skull remains	An araripichthyiform.
cf. Chanoidei indet.		Agoult	Complete specimen	A potential chanid.[5]
Cladocyclus	C. sp.	Agoult		An ichthyodectid.[7]
cf. Dercetis	cf D. sp.	Agoult	Complete specimens	A dercetid aulopiform.[5]
Enchodus	E. sp.	Goulmima	Incomplete specimens, isolated crania & teeth,	An enchodontid aulopiform.
Errachidia	E. pentaspinosa	Agoult	Complete specimen	A pharmacichthyid lamprimorph.[14]	Errachidia pentaspinosa Murray & Wilson, 2014
Goulmimichthys	G. arambourgi	Goulmima	Complete specimen.	A pachyrhizodontid crossognathiform.
Grandemarinus	G. gherisiensis	Goulmima	3 specimens known, one complete.	A gar.[8]
Ghrisichthys	G. bardacki	Goulmima	Isolated cranium	An ichthyodectid.[19]
Homalopagus	H. multispinosus	Agoult	Complete specimen	A pharmacichthyid lamprimorph.[14]	Homalopagus multispinosus Murray & Wilson, 2014
Ichthyodectes	I. sp.	Goulmima	Complete specimen, isolated crania	An ichthyodectid.
Kradimus	K. asflaensis	Goulmima	Complete specimen.	A pachyrhizodontid crossognathiform.[20]
Lusitanichthys	L. africanus	Agoult	Complete specimen	A clupavid otophysan.[21]	Lusitanichthys africanus Cavin, 1999
Maghrebichthys	M. nelsoni	Agoult	Complete specimen	A pycnosteroidid beardfish.[14]	Magrebichthys nelsoni Murray & Wilson, 2014
Neomesturus	N. asflaensis	Goulmima	Isolated jaw bones.	A pycnodont.[22]
Nursallia	N. fenestrata	Goulmima		A pycnodont[23]
Osmeroides	O. rheris	Goulmima	Isolated crania	An osmeroidid albuliform.
Paranursallia	P. cavini	Goulmima	Isolated jaw bones.	A pycnodont.[22]
Pleuropholis	P. danielae	Agoult	Complete specimen	The last known pleuropholid.[24]
Polazzodus	P. sp.	Goulmima	Isolated jaw bones.	A pycnodont.[22]
Rhynchodercetis	R. sp.	Agoult	Complete specimens.	A dercetid aulopiform.[7]	Rhynchodercetis sp.
Saurorhamphus	S. sp.	Agoult	Complete specimens.	A eurypholid aulopiform.[7]
Sorbinichthys	S. africanus	Agoult	Complete specimen.	A sorbinichthyid clupeomorph.	Sorbinichthys africanus Murray & Wilson, 2011
Teleostei indet.		Agoult	Complete specimen	An indeterminate teleost.[5]
Thorectichthys	T. marocensis	Agoult	Complete specimens.	A paraclupeid clupeomorph.	Thorectichthys marocensis Murray & Wilson, 2013
	T. rhadinus				Thorectichthys rhadinus Murray & Wilson, 2013

Reptiles

Genus	Species	Locality	Material	Notes	Image
Brachauchenius	B. lucasi	Goulmima	Partial mandible	A pliosaur, the first record of this species outside North America.[25]
Libonectes	L. morgani (=L. atlasense)	Goulmima	Articulated skull and post-cranial skeleton.	An elasmosaurid plesiosaur, the first record of this species outside North America.[26]
Manemergus	M. anguirostris	Goulmima	Partially complete skeleton	A polycotylid plesiosaur.
Protostegidae indet.		Goulmima	Carapace, skull	Indeterminate protostegid turtles.[3]
Tethysaurus	T. nopcsai	Goulmima	Hundreds of specimens of different age classes, some nearly complete[27]	A tethysaurine mosasaur.
Thililua	T. longicollis	Goulmima	Complete skull, lower jaw, and articulated vertebrae	A polycotylid plesiosaur.
Polycotylidae indet.		Goulmima	Skull with mandible	An indeterminate polycotylid plesiosaur.[26]
Squamata indet.		Agoult	Complete specimen	A small indeterminate terrestrial lizard, specimen now lost.[7]

Mollusks

Based on Kennedy et al (2008) & Meister et al (2017):^[28][9]

Genus	Species	Locality	Material	Notes	Image
Angulithes	A. mermeti	Douira, Goulmima & Tazzougert	Shells	A hercoglossid nautiloid.
Choffaticeras	C. segne	Goulmima		A pseudotissotid ammonite.
	C. sinaiticum
Eutrephoceras	E. sp.	Douira & Taouz		A nautilid nautiloid.
Fagesia	F. peroni	Goulmima		A vasoceratid ammonite.
	F. cf. tevesthensis
Hoplitoides	H. mirabilis	Goulmima		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.
Neoptychites	N. cephalotus	Goulmima		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

Partially based on Garassino, Angeli & Pasini (2014):^[29]

Genus	Species	Locality	Material	Notes
Afroapseudes	A. cretacicus	Agoult		A tanaidacean crustacean.[30]	Afroapseudes cretacicus Pasini, Vega & Garassino 2022
Amazighopsis	A. cretacea			An astacidean crustacean.[31]
Corazzatocarcinus	C. cf. hadjoulae			A necrocarcinid crab.
Cretagalathea	C. exigua			A munidid squat lobster.
Cretapenaeus	C. berberus			A penaeid prawn.	Cretapenaeus berberus Garassino, Pasini & Dutheil, 2006
Galathea	G. sahariana			A galatheid squat lobster.	Galathea sahariana Garassino, De Angeli & Pasini, 2008
?Glyphea	G. garaasbaensis			A glypheid crustacean.	Glyphea garasbaaensis Garassino, De Angeli & Pasini, 2008
Mesolimulus	M. tafraoutensis		Two complete specimens	A horseshoe crab.[32]
?Isoptera indet.			Complete specimen	A potential termite.[33]
Marocarcinus	M. pasinii			A marocarcinid crab.
Muelleristhes	M. africanus		Complete specimen	A porcelain crab.[29]
Palinuridae indet.			Complete specimen	A spiny lobster.[34]
Phagophytichnus	P. ekowskii		Trace fossil	Feeding traces on a leaf.[33]
Polyphaga indet.			Complete specimen	A polyphagan beetle.[33]
Telamonocarcinus	T. cf. gambalatus			A dorippid crab.
Troponoma	T. constricta		Trace fossil	Trail made by a leafminer.[6]
Unusuropode	U. castroi		Complete specimen	A sphaeromatid isopod, first record of this species outside Brazil.[35]	Unusuropode castroi Duarte & Santos, 1962

Plants

Based primarily on Krassilov & Bacchia (2013):^[6]

Genus	Species	Locality	Material	Notes	Image
Abietites[6]	A. (Tritaenia) cf. linkii	Agoult	Needles	A conifer.
Barykovia[6]	B. cf. tschuckotika		Leaf	A potentially fagalean angiosperm.
Cocculophyllum[6]	C. cf. fucinerve		Leaf	A climbing angiosperm.
Coniopteris[6]	C. cf. Dicksonia mamiyai		Leaflet.	A fern.
Dryophyllum[6]	D. cf. subcretaceum		Leaf	A potentially fagalean angiosperm.
Frenelopsis[6]	F. cf. teixeirae		Shoot	A cheirolepidiacean conifer.
Garasbahia[6]	G. flexuosa		Branching shoot with leaves.	A cabombacean angiosperm.
Pseudotorellia[6]	P. cf. ensiformis		Leaf	A ginkgoalean.
Sulcatocladus[6]	S. cf. robustus		Shoot	A conifer.
Welwitschiophyllum[6][36]	W. sp.		Leaf	A possible welsitschialean.[36]