| Akrabou Formation | |
| Type: | Geological formation |
| Age: | latest Cenomanian to ?middle Turonian ~ |
| Period: | Turonian |
| Prilithology: | Limestone |
| Region: | Er Rachidia |
| Country: |  Morocco,  Algeria |
| Coordinates: | 30.5°N -4.8°W |
| Paleocoordinates: | 17.8°N -4.8°W |
| Subunits: | Agoult, Goulmima, others |
| Extent: | central and eastern Morocco north and south of the Pre-African Trough |
| 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.[1] It overlies the slightly older freshwater deposits of the Kem Kem Group, which it was once thought to be apart 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]
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] 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.[6]
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.[7]
Most fish are documented in a species list from Amalfitano et al (2020) & Cooper et al (2023):[8]
| Genus | Species | Locality | Material | Notes | Image | |
|---|---|---|---|---|---|---|
| Asflapristis | A. cristadentis | Goulmima | Incomplete three-dimensional skeletons, isolated teeth | A ptychotrygonid sawskate.[9] | ||
| Cretomanta | C. sp. | Goulmima | Isolated teeth | A chondrichthyan of uncertain affinties, possibly an aquilolamnid.[10] | ||
| Haimirichia | H. amonensis | Agoult | Partial skeleton | A haimirichiid mackerel shark. | ||
| Ptychodus | P. maghrebianus | Goulmima | Dental battery, isolated teeth | A ptychodontid shark.[11] | ||
| Ptychotrygon | P. rostrispatula | Goulmima | Incomplete skeletons | A ptychotrygonid sawskate. | ||
| ?Rhinobatos | ?R. sp. | Goulmima | Incomplete cranium | A presumed guitarfish. | ||
| Squalicorax | S. sp. | Goulmima | Teeth | A crow shark. | ||
| Tingitanius | T. tenuimandibulus | Goulmima | Three-dimensionally preserved incomplete skeleton of a young individual | The oldest known platyrhinid ray.[12] |
| Genus | Species | Locality | Material | Notes | Image |
|---|---|---|---|---|---|
| Acanthomorpha indet. | Agoult | Complete specimen | A poorly-preserved acanthomorph of uncertain affinities.[13] | ||
| Agoultichthys | A. chattertoni | Agoult | Complete specimen | A macrosemiid.[14] | |
| Agoultpycnodus | A. aldrovandii | Agoult | Complete specimen | A pycnodont.[15] | |
| Amioidea gen. et sp. nov. 1 | Agoult | Undescribed amiiforms in their own family.[16] | |||
| 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.[17] | |
| 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. | ||
| Cladocyclus | C. sp. | Agoult | An ichthyodectid. | ||
| cf. Dercetis | cf D. sp. | Agoult | Complete specimens | A dercetid aulopiform. | |
| Enchodus | E. sp. | Goulmima | Incomplete specimens, isolated crania & teeth, | An enchodontid aulopiform. | |
| Errachidia | E. pentaspinosa | Agoult | Complete specimen | A pharmacichthyid lamprimorph. | |
| Goulmimichthys | G. arambourgi | Goulmima | Complete specimen. | A pachyrhizodontid crossognathiform. | |
| Grandemarinus | G. gherisiensis | Goulmima | 3 specimens known, one complete. | A gar. | |
| Ghrisichthys | G. bardacki | Goulmima | Isolated cranium | An ichthyodectid.[18] | |
| Homalopagus | H. multispinosus | Agoult | Complete specimen | A pharmacichthyid lamprimorph. | |
| Ichthyodectes | I. sp. | Goulmima | Complete specimen, isolated crania | An ichthyodectid. | |
| Lusitanichthys | L. africanus | Agoult | Complete specimen | A clupavid otophysan.[19] | |
| Kradimus | K. asflaensis | Goulmima | Complete specimen. | A pachyrhizodontid crossognathiform.[20] | |
| Maghrebichthys | M. nelsoni | Agoult | Complete specimen | A pycnosteroidid beardfish. | |
| Neomesturus | N. asflaensis | Goulmima | Isolated jaw bones. | A pycnodont.[21] | |
| Osmeroides | O. rheris | Goulmima | Isolated crania | An osmeroidid albuliform. | |
| Paranursallia | P. cavini | Goulmima | Isolated jaw bones. | A pycnodont. | |
| Pleuropholis | P. danielae | Agoult | Complete specimen | The last known pleuropholid.[22] | |
| Polazzodus | P. sp. | Goulmima | Isolated jaw bones. | A pycnodont. | |
| Rhynchodercetis | R. sp. | Agoult | Complete specimens. | A dercetid aulopiform. | |
| Saurorhamphus | S. sp. | Agoult | Complete specimens. | A eurypholid aulopiform. | |
| Sorbinichthys | S. africanus | Agoult | Complete specimen. | A sorbinichthyid clupeomorph. | |
| Teleostei indet. | Agoult | Complete specimen | An indeterminate teleost. | ||
| Thorectichthys | T. marocensis | Agoult | Complete specimens. | A paraclupeid clupeomorph. | |
| T. rhadinus |
| Genus | Species | Locality | Material | Notes | Image | |
|---|---|---|---|---|---|---|
| Brachauchenius | B. lucasi | Goulmima | Partial mandible | A pliosaur, the first record of this species outside North America.[23] | ||
| Libonectes | L. morgani (=L. atlasense) | Goulmima | Articulated skull and post-cranial skeleton. | An elasmosaurid plesiosaur, the first record of this species outside North America.[24] | ||
| Manemergus | M. angirostris | Goulmima | Partially complete skeleton | A polycotylid plesiosaur. | ||
| Protostegidae indet. | Goulmima | Carapace, skull | Indeterminate protostegid turtles. | |||
| Tethysaurus | T. nopcsai | Goulmima | Hundreds of specimens of different age classes, some nearly complete[25] | 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. | |||
| Squamata indet. | Agoult | Complete specimen | A small indeterminate terrestrial lizard, specimen now lost. |
Based on Kennedy et al (2008) & Meister et al (2017):[26]
| 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. |
Partially based on Garassino, Angeli & Pasini (2014):[27]
| Genus | Species | Locality | Material | Notes | Image |
|---|---|---|---|---|---|
| Afroapseudes | A. cretacicus | Agoult | A tanaidacean crustacean.[28] | ||
| Amazighopsis | A. cretacea | An astacidean crustacean.[29] | |||
| Corazzatocarcinus | C. cf. hadjoulae | A necrocarcinid crab. | |||
| Cretagalathea | C. exigua | A munidid squat lobster. | |||
| Cretapenaeus | C. berberus | A penaeid prawn. | |||
| Galathea | G. sahariana | A galatheid squat lobster. | |||
| ?Glyphea | G. garaasbaensis | A glypheid crustacean. | |||
| Mesolimulus | M. tafraoutensis | Two complete specimens | A horseshoe crab.[30] | ||
| ?Isoptera indet. | Complete specimen | A potential termite.[31] | |||
| Marocarcinus | M. pasinii | A marocarcinid crab. | |||
| Muelleristhes | M. africanus | Complete specimen | A porcelain crab. | ||
| Palinuridae indet. | Complete specimen | A spiny lobster.[32] | |||
| Phagophytichnus | P. ekowskii | Trace fossil | Feeding traces on a leaf. | ||
| Polyphaga indet. | Complete specimen | A polyphagan beetle. | |||
| Telamonocarcinus | T. cf. gambalatus | A dorippid crab. | |||
| Troponoma | T. constricta | Trace fossil | Trail made by a leafminer.[33] | ||
| Unusuropode | U. castroi | Complete specimen | A sphaeromatid isopod, first record of this species outside Brazil.[34] |
Based primarily on Krassilov & Bacchia (2013):
| Genus | Species | Locality | Material | Notes | Image |
|---|---|---|---|---|---|
| Abietites | A. (Tritaenia) cf. linkii | Agoult | Needles | A conifer. | |
| Barykovia | B. cf. tschuckotika | Leaf | A potentially fagalean angiosperm. | ||
| Cocculophyllum | C. cf. fucinerve | Leaf | A climbing angiosperm. | ||
| Coniopteris | C. cf. Dicksonia mamiyai | Leaflet. | A fern. | ||
| Dryophyllum | D. cf. subcretaceum | Leaf | A potentially fagalean angiosperm. | ||
| Frenelopsis | F. cf. teixeirae | Shoot | A cheirolepidiacean conifer. | ||
| Garasbahia | G. flexuosa | Branching shoot with leaves. | A cabombacean angiosperm. | ||
| Pseudotorellia | P. cf. ensiformis | Leaf | A ginkgoalean. | ||
| Sulcatocladus | S. cf. robustus | Shoot | A conifer. | ||
| Welwitschiophyllum | W. sp. | Leaf | A possible welsitschialean.[35] |