# A revised ammonoid biostratigraphy for the Aptian of NW Africa: Essaouira-Agadir Basin, Morocco

Tim L. Luber, Luc G. Bulot, Jonathan Redfern, Camille Frau, Angel Arantegui, Moussa Masrour

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Tim L. Luber, Luc G. Bulot, Jonathan Redfern, Camille Frau, Angel Arantegui, et al. A revised ammonoid biostratigraphy for the Aptian of NW Africa: Essaouira-Agadir Basin, Morocco. Cretaceous Research, 2017, 79, pp.12-34. 10.1016/j.cretres.2017.06.020. hal-01765607

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# A revised ammonoid biostratigraphy for the Aptian of NW Africa

**DOI:**

10.1016/j.cretres.2017.06.020

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**Citation for published version (APA):**

Luber, T. L., Bulot, L. G., Redfern, J., Frau, C., Arantegui Gonzalez, A., & Masrour, M. (2017). A revised ammonoid biostratigraphy for the Aptian of NW Africa: Essaouira-Agadir Basin, Morocco. *Cretaceous Research, 79*, 12-34.
https://doi.org/10.1016/j.cretres.2017.06.020

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A revised ammonoid biostratigraphy for the Aptian of NW Africa: Essaouira-Agadir Basin, Morocco

Tim L. Luber, Luc G. Bulot, Jonathan Redfern, Camille Frau, Angel Arantegui, Moussa Masrour

<figure><img src="image_4.png" /></figure>

PII: S0195-6671(17)30186-6

DOI: 10.1016/j.cretres.2017.06.020

Reference: YCRES 3649

To appear in: *Cretaceous Research*

Received Date: 19 April 2017

Revised Date: 28 June 2017

Accepted Date: 29 June 2017

Please cite this article as: Luber, T.L., Bulot, L.G., Redfern, J., Frau, C., Arantegui, A., Masrour, M.,
A revised ammonoid biostratigraphy for the Aptian of NW Africa: Essaouira-Agadir Basin, Morocco,
*Cretaceous Research* (2017), doi: 10.1016/j.cretres.2017.06.020.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1 A revised ammonoid biostratigraphy for the Aptian of NW Africa: Essaouira-Agadir Basin,

2 Morocco.

3

4 Tim L. Luber¹, Luc G. Bulot², ¹, Jonathan Redfern¹, Camille Frau³, Angel Arantegui¹, Moussa Masrour⁴

5

6 ¹University of Manchester, School of Earth and Environmental Sciences, North Africa Research

7 Group, M13 9PL, Manchester, UK

8 ²Aix Marseille Université, CNRS, IRD, Coll France, CEREGE, Aix-en-Provence, Site Saint-Charles - case

9 67 - 3, place Victor Hugo - 13331 Marseille cedex 3, France

10 ³Groupement d'Intérêt Paléontologique, Science et Exposition, 60 bd Georges Richard, 83000

11 Toulon, France

12 ⁴Université Ibn Zohr, Faculté des Sciences, Département de Géologie, Laboratoire de Géologie

13 Appliquée et Géo-Environnement (LAGAGE), B.P 8106 Cité Dakhla, Agadir, Morocco

14
15 Abstract

16

17 A revised ammonoid biostratigraphy is presented for the Aptian of NW Africa, Essaouira-Agadir Basin

18 (EAB), Morocco, based on detailed analysis of 5 key sections. A number of bio-events are

19 documented and 26 genus and 43 species fully documented, forming the largest published Aptian

20 ammonite collection made from NW Africa. The section at Tiskatine is documented as the type

21 section, and 8 zones and subzones are defined, of which 5 are new. This work allows correlation of

22 the Aptian of the **EAB** to the Standard Mediterranean Ammonite Scale (**SMAS**).

23 Two main hiatuses are identified at the scale of the basin scale: a major one that includes most of

24 the lower Aptian and the base of the upper Aptian and a second one encompass the top of the

25 upper Aptian and the base of the lower Albian. The ammonite fauna displays a clear Tethyan

26 palaeobiogeographic character affected by a fairly high degree of endemism at the genus and

27 species level. The new genus and species *Elsaella tiskatinensis* is introduced.

28

29 Keywords: Ammonite, Biostratigraphy, Aptian, Essaouira-Agadir Basin, Morocco
1. Introduction

31

Aptian to lowermost Albian ammonite biostratigraphy across the northwest African Atlantic margin remains poorly documented compared to counterparts of the Mediterranean Tethys; such as in Spain (Moreno Bedmar et al., 2008, 2009, 2010, 2012a, 2014), France (Delanoy, 1995a; Cecca et al., 1999; Ropolo et al., 1999; Kennedy et al., 2000; Ropolo et al., 2000a-c; Dauphin, 2002; Dutour, 2005; Ropolo et al. 2006; Ropolo et al., 2008a-b; Frau et al., 2015), Tunisia (Lehmann et al., 2009; Chihaoui et al., 2010; Latil, 2011), and Iran (Raisossadat, 2004, 2006; Bulot in Vincent et al., 2010; Seyed-Emami and Wilmsen, 2016); or on the opposite side of the Central Atlantic Margin (CAM), e.g. Mexico (Barragán-Manzo and Méndez-Franco, 2005; Moreno Bedmar et al., 2012b, 2013, 2015, Barragán et al., 2016).

The Aptian Stage contains some globally significant events, recording a time of high sea-level during the mid-Cretaceous greenhouse period (Larson and Erba, 1999; Leckie et al., 2002). It also records some of the most wide-spread and best studied oceanic anoxic events (Schlager and Jenkyns, 1976; Scholle and Arthur, 1980; Arthur et al., 1990; Bralower et. al, 1994; Weissert et al., 1998; Föllmi et al., 2006; Föllmi, 2012).

In this study we present a new high-resolution dataset from NW Morocco, discussed within a broader regional/global context and with special reference to the standard ammonite zonal scheme of the Mediterranean Tethys (Reboulet et al., 2011, 2014). In Morocco, the Aptian successions of the west-central part of the Essaouira-Agadir Basin (EAB) is part of one of the most complete and best-constrained successions of the Lower Cretaceous in NW Africa. The Aptian succession is characterized by ammonite-rich, shallow-marine (Bouzergoun Formation) to shelf deposits (Tamzergout and Oued Tidzi formations), that crop out in a corridor along the Moroccan coast between the cities of Agadir and Essaouira (Fig. 1). The aim of the present contribution is to improve the biostratigraphic frame of the Aptian and lowermost Albian of the EAB based on the detailed analysis of the bed by bed distribution of ammonoids at five key sections (Fig. 1).
Our results document the specific character of the ammonoid fauna of the **EAB** and discuss its similarities and differences with equivalent ammonite faunas of Mediterranean-Caucasian Subrealm of the Tethyan Realm. The results of this study develop a strong reference framework for the Aptian to earliest Albian for the northwest African Atlantic margin (figure 12).

## 2. Regional Setting and Stratigraphy

Lower Cretaceous strata crops out over an area 100 km wide and 150 km long, adjacent to the Moroccan Atlantic coast; the only continuous succession of Mesozoic fill of the Central Atlantic Margin (CAM) (Fig. 1). Following Permo-Triassic rifting that separated Africa and North America (Le Roy and Piqué, 2001), extensive Jurassic carbonate platforms developed all along the NW Africa (Jansa and Wiedmann, 1982). Later deposition shared this inherited regional physiography, but also record distinct sub-basins with variable subsidence, evolving throughout the Early Cretaceous (Rey et al., 1988; Davison, 2005; Wenke et al., 2011).

During this time, the **EAB**, the focus of this study, was limited to the north by the Meseta and the Jebilet, to the south by the Souss Basin and to the east by the Massif Ancien de Marrakech. The general physiography formed a large gulf-like embayment opening out to the west into the Atlantic Ocean (Behrens et al., 1978). Present day exposure of the Mesozoic basin fill and adjacent basement terrains reflects the Cretaceous to Cenozoic inversion and uplift linked to the Atlantic/Alpine orogeny (Laville et al., 2004) and associated salt tectonics (Tari and Jabour, 2013).

This study focuses on the outcrops in the west-central part of the **EAB**, located between the prominent Cretaceous Essaouira and Chichaoua escarpment to the north and the broad Cap Ghir anticline to the south (Fig. 1). Strata are mainly flat lying, only exhibiting folding with steep flanks close to fault zones and associated with salt diapirs (Hafid et al., 2000, 2006). The maximum thickness of the entire Cretaceous post-rift succession is estimated to be 1300 m (Behrens et al., 1982) (Zem Zem section). The Lower Cretaceous reaches approximately 800 m in thickness but
varies dramatically, thinning toward salt diapirs, suggesting Cretaceous syn-sedimentary activity
(Hafid et al., 2000; Le Roy and Pique, 2001; Zühlke et al., 2004).

The Early Cretaceous represents a time of major change from the predominately carbonate-dominated system in the Middle- to Late Jurassic to a mixed carbonate-siliciclastic or purely siliciclastic systems in the Cretaceous, following drowning of the Jurassic carbonate platform.

Cretaceous deposits in the **EAB** are dominated by shelfal mudstone successions with discrete intervals of coarse clastic sediment delivery in the late Valanginian, late early Hauterivian and late Barremian to earliest Aptian (Ambroggi, 1963; Behrens et al., 1978).

During the Aptian the paleogeography of the **EAB** was dominated by an open marine shelf.

Arid climatic conditions are indicated by low nannofossil productivity (Herrle, 2002; Peyernes et al., 2013) and clay mineral composition (Daoudi and Deconinck, 1994). The **EAB** is thought to have been located away from the main upwelling zone, which existed during Aptian and early Albian times around the Mazagan Plateau to the north (Herrle, 2002). A cooling climatic trend has been recognized from the late Aptian – early Albian, evidenced by southward migration of high-latitude/boreal nannofossil into mid- and low-latitudes (Jeremiah, 1996, 2001; Herrle and Mutterlose, 2003; Rueckenheim et al., 2006). This trend was also observed in the **EAB** by Peyernes et al. (2013).

Overall the Aptian to Albian transition is a time of global eustatic sea-level rise (Hardenbol et al., 1998; Haq, 2014). In the **EAB** shallow-marine conditions were widespread during the early Aptian, with a transgression recognised in the late Aptian, the establishment of outer shelf conditions, and reoccurrence of the Atlas Gulf (Behrens et al., 1978).

Most of the formation names for the Lower Cretaceous were introduced by Duffaud et al. (1966), later revised by Rey et al. (1986a and b, 1988). The reference sections are mainly located along an E-W trending transect in the northern part of the **EAB** (Essaouira to Imi'n'Tanoute). There are no stratigraphic units at group level defined in the **EAB**. Previous sedimentological and stratigraphic work on the Lower Cretaceous in the areas was carried out by Ambroggi (1963),
Duffaud et al. (1966), Wiedmann et al. (1978, 1982), Adams et al. (1980), Behrens et al. (1982) and Rey et al. (1986a and b, 1988). More recent studies have mainly focused on the ammonite biostratigraphy of the Berriasian to Hauterivian interval (Ettachfini, 1991, 2004; Wippich, 2001, 2003) and the integrated stratigraphy of the Barremian/Aptian interval (Witam et al., 1993; Witam, 1998; Nouidar and Chellai, 2001, 2002; Company et al., 2008; Peyernes et al., 2013).

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## 2.1 Barremian to Albian lithostratigraphic framework

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The first attempt to subdivide the lithostratigraphic succession of the **EAB** was made by Duffaud et al. (1966). For the Barremian to Albian interval, those authors introduced five lithostratigraphic units: the "Calcaires lumachéliques de Taboulaourt", the "Grès et marnes rouges du Bou Zergoun", the "Marno-calcaires de Tamzergout", the "Grès marneux du Lemgo" and the "Marnes de l'Oued Tidsi". This synoptic lithostratigraphic chart was introduced without formal description, a definition of boundaries or designation of reference sections.

Subsequent works by Rey et al. (1986a and b, 1988), Andreu (1989), Witam et al. (1993) and Witam (1998) led to refining the litho- and biostratigraphic framework of the **EAB**, but little attention was paid to the formal description and definition of the formations. Despite Witam's (1998) attempt to propose reference sections for the lithostratigraphic units introduced by Duffaud et al. (1966), a unified lithostratigraphic nomenclature for the **EAB** is still lacking. This drastically limits the value of the lithostratigraphic units for the correlation of the Barremian to Albian strata and also reflects the limited published work on regional stratigraphic relationships. Revising the lithostratigraphic framework of the **EAB** is beyond the scope of the present contribution and in this study we have utilised the existing scheme of Duffaud et al. (1966) that best applies to our observations in the west-central part of the basin (Fig. 2).

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### 2.1.1 *Bouzergoun Formation*
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The Bouzergoun Fm., composed of sandstones and red mudstones, was introduced by Duffaud et al. (1966). Rey et al. (1986a, 1988), describes them as margino-littoral deposits made of sands, varicoloured clays, dolomites and bioclastic-rich limestones with large cross-stratification; and topped by a major disconformity.

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There is no agreement in the literature about the age of the Bouzergoun Fm. Rey et al. (1986a) proposed a late Barremian age, based on the occurrence of early Barremian ammonites in the underlying Taboulouart Fm. and early Aptian ammonites in the overlying Tamzergout Fm. This was amended by Nouidar and Chellaï (2001) who assigned the upper part of the Bouzergoun Fm. (red beds) to the lower Aptian, based on the occurrence of *Salpingoporella? dinarica* Radoičić.

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However, it is unclear if the occurrence is derived from new data obtained by the authors or from a misinterpretation of Canérot et al. (1986), who never reported these dasyclad algae from the **EAB**. In any case, the occurrence of *Salpingoporella? dinarica* does not allow discrimination between the Barremian and Aptian stages.

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Analysis of outcrops for this new study identify the Bouzergoun Fm. as being composed of a thick succession of shelfal muds with minor sandstones at the base, truncated by coarsening and thickening-upward shallow-marine and deltaic sand-rich deposits and fluvial deposits. In places, erosional channel and valley features are in-filled by coarse clastic material and greenish to red-coloured mudstones with interbedded sandstones. The uppermost part of the formation is made of sandstones, sandy limestones and mudstone interbeds bearing marine fauna and often oyster-rich beds to the top (Fig. 2). The unit reaches a maximum thickness of 84 metres at Assaka.

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Ammonites collected from Assaka identify a condensed horizon that marks the boundary between the Taboulouart and the Bouzergoun formations, of early late Barremian age (early to middle part of the *Gerhardtia sartousiana* Zone) (see also discussion in Company et al., 2008). In most sections studied the occurrence of *Procheloniceras dechauxi* (Kilan and Reboul, 1915) firmly establish an earliest Aptian age (see discussion below) for the uppermost beds of the Bouzergoun
160 Fm. (see discussion below). At Tiskatine, the top of the formation is marked by two beds of siltstones that contain a rich early late Aptian ammonite fauna (lower part of the *Colombiceras tobleri* Zone) (see discussion below). This indicates that the top of the Bouzergoun Fm. is diachronous and ranges in age from earliest to early late Aptian (base of the *Deshayesites forbesi* to lower part of the *Colombiceras tobleri* zones).

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166 2.1.2 *Tamzergout Fm.*

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168 The Tamzergout Fm. was defined by Duffaud et al. (1966) as a succession of marls and limestones. The vertical and lateral extension of this unit has been variously interpreted by subsequent authors (see discussion in Witam, 1998, p. 153-154).

171 The formation is mainly made up of fossiliferous alternating blue-grey marls and grey limestones that correspond to shallow-marine to shelfal deposits (Fig. 2). Rey et al. (1986a) restricted its age to the early Aptian (= Bedoulian in regional French stratigraphy) and limited its occurrence to the west and central part of the **EAB**. Rey et al. (1986a) also introduced the Tadhart Fm. of late Aptian age (= Gargasian in regional French stratigraphy), sitting between the Tamzergout and subsequent Oued Tidzi Fm. In this study we propose a different age range for the Tamzergout Formation (see below), from the early to latest Aptian. We therefore consider the Tadhart Fm. a time-equivalent unit for parts of the upper Tamzergout Fm. that is restricted to the eastern and more proximal parts of the basin. In the western and central part of the basin it cannot be discriminated from the Tamzergout Fm. In the studied area, the top of the Tamzergout Fm. is marked by a regional unconformity that was previously reported from Agadir (discontinuity **D4** of Peybernes et al. 2013). The formation reaches a maximum thickness of 33 metres at Tiskatine.

183 In most sections studied, the lower part of the formation contains the base of the *Deshayesites forbesi* Zone (lowermost Aptian). *Procheloniceras dechauxi* is abundant, but first appears in the underlying Bouzergoun Fm. At Tiskatine, the first limestone bed of the Tamzergout
186 Fm. is marked by the First Occurrence (FO) of "Epicheloniceras" marocanus (Roch, 1930) that indicates the base of the upper part of the *Colombiceras tobleri* Zone (see discussion below). The assigned ages further highlight the diachronicity of the top Bouzergoun and base Tamzergout Formation. The upper part of the formation is usually rich in small pyritic ammonites that indicate a latest Aptian age (*Elsaella tiskatinensis* Zone, see definition and discussion below).

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192 **2.1.4 Lemgo Formation**

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194 The Lemgo Fm. was introduced by Duffaud et al. (1966) and subsequently reinterpreted by
195 Rey et al. (1986b) to include a complex of green marls, yellow sandy marls and sandy dolomites at
196 the top. It is named after the Jbel Lemgo ridge, to the east of Imi'n'Tanoute.

197 Based on our field observations and microfacies analysis in the Mramer section, the Lemgo
198 Fm. is composed of argillaceous sandstones and bioclastic-rich sandy limestones. Regional
199 correlations suggest that the Lemgo Fm. represents the proximal equivalent of the upper
200 Tamzergout Formation and is not present in the western central part of the basin (see discussion
201 below).

202 Rey et al. (1988) assigned the formation to the uppermost Aptian (= Clansayesian in regional
203 French stratigraphy) based on the occurrence of ammonite assemblages that characterized the
204 *Nolaniceras nolani* and *Hypacanthoplites jacobi* zones. Material collected in this study of what is
205 exposed of the Lemgo Fm. at the Mramer section indicates a latest Aptian to earliest Albian age
206 (*Acanthohoplites ashiltaensis* to *Mellegueiceras chihaouiae* zones, see discussion below).

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208 **2.1.4 Oued Tidzi Formation**

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210 Described by Duffaud et al. (1966) as marls, it was redefined by Rey et al. (1988) as a
211 complex of green marls bearing small pyritic ammonites, intercalated with marly limestones and
212 sandy dolomites.

213 The unit is easily recognized in the west-central part of the **EAB** where it reaches a maximum
214 thickness of 340 m and forms extensive recessive slopes in the landscape. Our field observations and
215 microfacies analysis, focused on the lower part of this formation, show a clear change from blue
216 marls and limestones of the Tamzergout Fm. to a complex of green marls with minor bioclastic-rich
217 sandstone interbeds (Fig. 2). The early Albian age of the basal sandstones is established by the
218 occurrence of the diagnostic ammonite genus *Douvilleiceras*.

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220 **2.2 Previous Work on Aptian biostratigraphy**

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222 Pioneering work reporting and describing ammonites in the **EAB** was undertaken by Kilian
223 and Gentil (1906), Roch (1930) and Ambroggi (1963). The work of Ambroggi (1963) has to be
224 highlighted, as it established the first regional biostratigraphic framework for the Lower Cretaceous.
225 The ammonite biostratigraphy of the Berriasian - Barremian interval was subsequently refined by
226 Ettachfini (1991, 2004), Wippich (2001, 2003) and Company et al. (2008). Yet, despite the good
227 accessibility of sections and abundance of ammonites, no recent studies have focused on the
228 detailed ammonite palaeontology and biostratigraphy of the Aptian – Albian interval.

229 Following the work of Roch (1930) and Ambroggi (1963), extensive faunal lists of Aptian and
230 Albian ammonites were published by Bergner et al. (1982), Rey et al. (1986a and b, 1988), Witam et
231 al. (1993) and Witam (1998). Unfortunately, the precise stratigraphic position of the material within
232 the formations was not documented and only a very limited number of specimens were illustrated in
233 the literature. As a consequence, the available previously published data sets do not fulfil the
234 standards of modern biostratigraphic studies and it is difficult to reinterpret them in the light of our
235 own results.
Most recently a detailed biostratigraphic framework based on bed by bed collections from a transect along the Agadir segment of the **EAB** was published by Peyernes et al. (2013). A fairly high degree of endemism was suggested by the introduction of many new species and genus names that are unfortunately not formally described or illustrated. The authors chose not to introduce new biostratigraphic units, but pointed out the necessity for a local ammonite zonal scheme. The published zonation is an attempt to apply the upper lower Aptian to lower Albian ammonite zonal scheme of northern Tethys (Reboulet et al., 2011) to the **EAB**. This interval is described as being strongly affected by condensation and temporal hiatuses. According to these authors, the co-occurrence of *Cheloniceras* sp. and *Deshayesites* sp. indicates an early Aptian age for the base of the Tamzergout Fm. (tentatively assigned the *Deshayesites deshayesi* Zone). Condensation and merging of unconformities across the lower/upper Aptian boundary is supported by the mixing of *Dufrenoyia furcata* and *Epicheloniceras martini* zones assemblages. The upper Aptian *Epicheloniceras martini*, *Parahoplites melchioris*, *Acanthohoplites nolani* and *Hypacanthoplites jacobi*, zones are identified on the basis of characteristic ammonites assemblages, even so it is highlighted that the extension of the *P. melchioris* Zone is uncertain, as the index fossil is absent and indicative taxa are scarce. The lower Albian *Leymeriella tardefurcata* Zone and *Douvilleiceras mammillatum* Superzone are recognized throughout most of the basin even though the index species are absent. It should be noted that a bed by bed distribution of ammonites is only documented in the Addar section and the authors do not provide photographic plates to substantiate the ammonite systematics used in their contribution.

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### 3. Studied Sections

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The present publication is focused on five Aptian-Albian sections (Fig. 1). Locations were chosen to reinvestigate previously studied sections for reference and further to add new sections for better spatial constraints and coverage of the western, central and the northern part of the basin.

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**3.1. Tiskatine** (Fig. 3) - Lat.: 30.821463° Long.: -9.702555° (Tiskatine 1) and Lat.: 30.810477° Long.: -9.739966° (Tiskatine 2).

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The lower part of the succession (beds **TK 159 to 206**, Fig. 3) is best exposed 6.5 Km to the east of the village of Assaka (Tiskatine 1), northwest of Adrar (mountain) Tiskatine. The upper beds (**TK 206 to 249**) are better exposed 3 Km to the east of Assaka (Tiskatine 2). The two sections were correlated using the marker bed **TK 206**. Section Tiskatine 1 starts in the river bed south of the road from Assaka to Tazzougart and continues to the north. At Tiskatine 2 the beds crop out on both sides of the road. Tiskatine 1 was previously studied by Roch (1930) and Ambroggi (1963).

3.1 m of the upper part of the Bouzergoun Fm. are exposed at Tiskatine. The first bed (**TK 157**) is a well-consolidated oyster-rich, ammonite-barren, sandy limestone topped by an iron-rich crust. It is followed by yellow sandstones interbedded with yellow to green mudrock partings (beds **TK 158-162**). The sandstones are fine-grained and show low angle cross-bedding and laterally extensive undulating surfaces. They are often topped by iron-enriched crusts, yielding phosphatic, glauconitic pebbles and fossils. The fossil content comprises ammonites, belemnites, echinoids, gastropods, and rare solitary coral fragments. The top surface of bed **TK 161** is marked by a belemnite accumulation that suggests transport and winnowing by currents (type 4 condensation accumulates of Doyle and Macdonald, 1993). The deposits represent a deepening-upward shallow marine succession. Wave-influenced shoreface sedimentation dominates at the base (bed **TK 157**) with a subsequent transition into lower shoreface to offshore sedimentation (bed **TK 158-162**). The contact with the overlying Tamzergout Fm. is marked by well-developed marls in bed **TK 163**. The contact is abrupt and marks the change to shelfal conditions below storm wave base.
The alternating blue-grey marls and grey limestones of the Tamzergout Formation develop from bed **TK 163** to bed **TK 247**. The marls are laminated, forming decimetre to metre thick beds. Limestones are 10 to 20 centimetres thick and appear massive. Contact between alternating beds are mostly sharp and planar. In the middle part of the succession some limestones beds have detrital component (**TK 180, 182, 192** and **194**) and two prominent fine-grained sandstone beds (**TK 184** and **TK 186**) are recognised. The sandstones are topped by ferruginous crusts. From bed **TK 197** to bed **TK 246** the succession is characterized by a fairly monotonous alternation of marls and limestones. **TK 206** is a prominent extremely fossiliferous marker bed, with a well-developed iron-crust on the top. Above, the marls are rich in pyritic nodules and ammonites, and some minor detrital input was observed toward the top of the Tamzergout Fm. that ends at a distinct glauconitic horizon (bed **TK 247**) rich in phosphate nodules. The total thickness of the Tamzergout Fm. is 33.15 metres. Sedimentation of the Tamzergout Fm. is mainly through suspension fall out. Sandstone beds **TK 184** and **TK 186** are interpreted as gravity flow deposits.

The base of the Oued Tidzi Fm. is marked by a fossil-rich sandstone bed **TK 248** that contains reworked phosphatic pebbles and glauconitic fossils (including ammonites). It is capped by a well-developed iron crust directly overlain by distinctive green to yellow marls of the Oued Tidzi Fm. Bed **TK 248** is interpreted as a shelf gravity flow.

Ammonite abundance and diversity vary throughout the succession. This discontinuous palaeontological record may partially reflect collection failure, despite an intensive search of the barren intervals. Based on our present knowledge, the following sequence of bio-events is recognised as regionally significant following comparison with the other sections studied:

- Bio-event 1: sudden mass occurrence of *Procheloniceras* in bed **TK 159**, followed by the first observed occurrence of *Deshayesites* in bed **TK 160**;

- Bio-event 2: peak of diversity in bed **TK 161a** dominated by *Colombiceras* and *Epicheloniceras*;
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- Bio-event 3: first apparition datum of the endemic species "Epicheloniceras" *marocanus* at the top of bed **TK 162**, followed by its acme in bed **TK 166**;

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- Bio-event 4: lowest occurrence of *Acanthohoplites* in bed **TK 184**;

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- Bio-event 5: peak of abundance of *Pseudoaustraliceras* in beds **TK 192** and **TK 194**;

317

- Bio-event 6: sudden mass occurrence of *Elsaella* gen. nov. in bed **TK 206**;

318

- Bio-event 7: radiation of the Acanthohoplitidae (*Nodosohoplites*, *Protacanthoplites* and *"Hypacanthoplites"*) from bed **TK 206** to bed **TK 221**;

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- Bio-event 8: lowest occurrence of *Douvilleiceras* in bed **TK 248**.

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Tiskatine is the only studied section where the complete succession of events was recognized and documented. It has, therefore, been selected as the reference section for the ammonite biostratigraphy of the west central part of the **EAB**.

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326

**3.2. Tamanar** (Fig. 4) - Lat.: 31.057403° Long.: -9.601503°

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328

This outcrop is 10 Km northeast of Tamanar and the section is also known as Ida Ou Shak named after the nearby village. It can be reached via an unmade track that leaves National road 1 approximately 8 Km north of Tamanar. This section has not been previously described in literature.

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331

Fine-grained laminated sandstones with interbedded calcareous mudstones make up the lower 8 metres (beds **TM 49 to 58**) of the studied section and comprise the uppermost part of the Bouzergoun Fm. Oysters and other large bivalves are abundant throughout. The lower part of the logged section is affected by soft sediment deformation. The first occurrence of ammonites is recognised on top of the slumped interval. The deposits of the Bouzergoun Fm. here are interpreted as lower shoreface to offshore shelf transition.

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334

335

336

337

The base of the Tamzergout formation is marked by the change to limestones and interbedded marls, both containing abundant open-marine fauna (e.g. ammonites and belemnites).

338
339 The formation encompasses beds **TM 59** to **TM 80**. Compared to the interval exposed at Tiskatine, 340 the limestones here have a stronger siliciclastic detrital component. The succession is fairly 341 monotonous, but a few beds have notable features. From bottom to top, these are: 342

343 - Bed **TM 69** contains very abundant ammonites (dominantly *Procheloniceras dechauxi*) 344 associated with a high ferruginous content;

345 - Bed **TM 70a** is a slumped complex marked the only occurrence of upper lower Aptian 346 ammonites (*Cheloniceras*) identified in this study;

347 - Bed **TM 71** contains a phosphatic, glauconitic and ferruginous fossil assemblage rich in 348 ammonites, belemnites, bivalves, and brachiopods.

349 - Bed **TM 73** contains belemnites and bivalves and is marked by a well-developed and 350 prominent iron crust.

351 - Bed **TM 76** is rich in ammonites and marks an increase in diversity of the ammonite fauna

352 - Bed **TM 80** yields abundant pyritic ammonites.

353
354 The sandstone of bed 81 is interpreted to define the base of the Oued Tidzi Formation, displaying a similar depositional environment to Tiskatine.

355
356 The Tamzergout Formation has a total thickness of 19.20 metres. At this location it is 357 interpreted to be mixed shelfal pelagic marls, with changes in siliciclastic sediment influx transported 358 by wave and current supported gravity flows, forming the sandy limestones.

359
360 Compared to the succession of bio-events recognized at Tiskatine, several points should be outlined:

361
362 - Bio-event 1 is marked by a less sudden appearance of *Procheloniceras* in bed TM 55;

363
364 - Bio-event 2 is not well expressed due to poor outcrop conditions but merely lies at the top of bed TM 71;
365

- Bio-event 3 is marked by the spot occurrence of "*Epicheloniceras*" *marocanus* in bed TM 72;

366

- Bio-event 4 and 5 are not recorded;

367

- Bio-event 6 and 7 are identified in beds TM 76 to TM 80 with a slightly different expression due to condensation combine with temporal hiatus.

368

369

370

**3.3. Zem Zem (Fig 5) - Lat.: 31.241846° Long.: -9.372052°**

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372

Located about 17 Km to the south-southeast of Meskala, this outcrop can be reached via an unmade road leaving the main road between Bizdad and Ait Daoud, approximately 2 Km south-southeast of Bizdad. Nearby sections have been studied by Roch (1930), Butt (1982), Rey et al. (1986a, 1988) and Witam (1998).

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374

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376

The Bouzergoun Fm. reaches a thickness of 12 metres at Zem Zem (up to bed **ZZ 60**). The upper part is composed of sandy rudstones, sandstones and minor wackestones with marls interbedded. Fauna is dominated by brachiopods, oysters, ammonites and echinoderms, pointing towards open-marine conditions. Horizon **ZZ 59** is a prominent ferruginous surface just below the topmost bed of the formation, containing abundant fossils with phosphatic preservation. Deposition overall took place in a shoreface to carbonate-rich subtidal environment with higher energy index, on a shallow shelf.

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378

379

380

381

382

383

The Tamzergout Fm. is interpreted to extend from bed **ZZ 61** to **ZZ 68** and is dominated by marls with two prominent limestone beds (**ZZ 61** and **ZZ 65**) and a sandstone bed topped by an iron crust (**ZZ 67**). The thickness of the Tamzergout Fm. is approximately 20 metres, and the presence of laterally extensive marls with limestone interbeds containing open marine fauna and reduced siliciclastic input suggests a low-energy shelf environment, similar to that at Tiskatine.

384

385

386

387

388

The base of the Oued Tidzi Fm. is defined as a prominent sandstone horizon, and continues to the top of the measured section, with a minimum thickness of 10 metres.

389
At Zem Zem, the palaeontological record shows that bio-event 1 (mass occurrence of *Procheloniceras*) is well expressed and almost directly overlain by the sudden appearance of *Elsaella* gen. nov., followed by the radiation of the Acanthohoplitidae (bio-events 6 and 7). Bio-event 2 is suspected in the condensed horizon at the top of the Bouzergoun Fm. (spot occurrence of *Epicheloniceras* with reworked *Deshayesites* at the top of bed ZZ 60). Bio-events 3, 4 and 5 are not recorded and outline the existence of a major temporal hiatus at the base of the Tamzergout Fm.

**3.4. Oued Tlit (Fig. 6) - Lat.: 31.194306° Long.: -9.665616°**

The section is located 4 Km southeast of Smimou, on the northern flank of the Djebel Amsittene anticline, north of the road between Smimou and Imi'n'Tlit. This locality has previously been studied by Roch (1930), Rey et al. (1986a, 1988) and Witam (1998).

The top of the Bouzergoun Formation comprises the lowermost 2.10 metres. It is composed of fine to medium-grained non-amalgamated sandstones interbedded with mudstones. The sandstones exhibit hummocky cross-stratification and are often affected by in-situ soft-sediment deformation. The upper part is formed by a very prominent set of oyster rudstones. The depositional environment is interpreted as shoreface to subtidal.

Ammonites occur immediately above the set of oyster rudstones and the remaining 11.70 m are interpreted to as part of the Tamzergout Formation. It comprises alternating marls and micritic limestones. A well-expressed hardground surface marked by iron crust and glauconite, associated with belemnite accumulation and phosphatic ammonites, occurs at the top of bed OT 11. The upper part of the Tamzergout Fm. has not been investigated in this study.

The succession of bio-event 1 (sudden appearance of *Procheloniceras*) and bio-event 2 (peak abundance of *Epicheloniceras* and *Colombiceras*) are recognized in the lower part of the Tamzergout Fm. Our findings also question the identification of the *Dufrenoyia* and *Epicheloniceras* illustrated by Witam (1998) from this section (see discussion below).
416

417

**3.5. Mramer** (Fig. 7) - Lat.: 31.657033° Long.: -9.164205° (Mramer 1) and Lat.: 31.666118° Long.: -9.153251° (Mramer 2).

419

420

Mramer represents the northernmost section studied in the **EAB**. It is located approximately 60 Km to the ENE of Essaouira and 12 Km NE of Tafetachte. The Mramer section is a composite section, both locations cropping out in a river bed. Mramer 1 is located about 1.5 Km to the northeast of the market in Mramer and location Mramer 2 is at the base of a steep slope south of the market. This outcrop was mentioned by Roch (1930) but not reported in detail.

421

422

423

424

425

The upper 3.50 metres of the Bouzergoun Fm. are exposed at this locality. Strata are dominated by sandstones and siltstones. The fauna is rich in oyster fragments, and further includes scarce ammonites; towards the top echinoderm fragments are common. The medium to fine-grained sandstones exhibit in-situ soft sediment deformation structures and common bioturbation, they are dominated by low-angle cross lamination, interpreted to have been deposited under shoreface conditions.

426

427

428

429

430

431

The following interval (beds **MR 9a to 9f**) comprises part of the Tamzergout Fm., here composed of sandy limestones and marls interbedded. The limestones contain belemnites, bivalves, and echinoderms and exhibit prominent iron crusts at the tops. The exposed part of the Tamzergout Fm. records a return to shelfal, open water, and lower-energy depositional environments. This interval is capped by a zone of poor exposure that is 17.5m thick and likely composed of limestones and interbedded marls with increasing abundance of ammonites.

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433

434

435

436

437

It is overlain by the Lemgo Fm., the proximal equivalent to the upper Tamzergout Fm. The base of the Lemgo Fm. is not exposed in the study area. It is composed of yellow argillaceous sandstones and sandy limestones obtaining a minimum thickness of 4.50 metres. Fossil-rich sandy limestones at the base (beds **MR 9x to 9z**) are laterally continuous. Beds **MR 10** to **MR 17** comprise very fine to fine-grained sandstones interbedded with floatstones. Sandstones exhibit large-scale,

438

439

440

441
higher energy dune bed forms and often rework the interbedded limestones. Limestones have well-developed iron crusts and are rich in fossils containing brachiopods, ammonites, gastropods, and belemnites. These fossils often occur in phosphatic and glauconitic preservation, pointing to a reoccurrence of anoxia.

This mixed siliciclastic-carbonate succession is interpreted to represent shelfal carbonates being reworked by sandstones deposited during intermittent, wave-influenced sedimentation. Abundance of ammonites and cosmopolitan taxa imply an open-marine connection but reoccurrence of anoxia and absence of indicative, open-marine fauna is pointing towards a periodic development of restricted environment. Overall, this represents a shallowing-up succession with a higher energy index than other time-equivalent sections studied in the sections of the central and western part of the basin. The Lemgo Fm. is overlain by marls and minor sandy limestones of the Oued Tidzi Fm. that starts at bed MR 20 and marks the return into lower-energy shelfal sedimentation.

At Mramer, the Lemgo Fm. records the local expression of bio-events 6 to 8. The ammonite succession is characterized by the radiation of the Acanthohoplitidae from bed MR 10m to MR 15, followed the lowest occurrence of *Douvilleiceras* in bed MR18. Noteworthy is the occurrence of a well preserved and abundant fauna of *Mellegueiceras*, a genus that was so far only known from Central Tunisia (Latil, 2011).

## 4. Systematic Palaeontology

More than 1000 ammonite specimens were collected during two field sessions in 2015 and 2016. To our knowledge, the material collected represents the largest bed by bed collection made from the Bouzergoun and Tamzergout formations of the central and northern part of the EAB. The preservation of the material is variable and includes internal calcareous, phosphatic and pyritic
moulds. Abundance varies considerably throughout the studied sections and high diversity is
observed in specific horizons, some of which can be correlated at the scale of the **EAB**.

As already outlined in the faunal lists given by our predecessors (Roch, 1930; Ambroggi,
1963; Rey et al., 1986a), the ammonite assemblages are largely dominated by the Douvilleiceratidae
Parona and Bonarelli, 1897 and Acanthohoplitidae Stoyanow, 1949. The Deshayesitidae Stoyanow,
1949, Desmoceratidae Zittel, 1895 and Ancyloceratidae Gill, 1871 are minor elements of the faunas.
Aconeceratidae Spath, 1923, Phylloceratidae Zittel, 1884 and Tetragonitidae Hyatt, 1900 are even
rarer.

Despite an extensive list of published work, the systematics of the Aptian Ammonoidea is
still at a very preliminary stage due to the lack of modern taxonomic revision taking in consideration
intraspecific variation and sexual dimorphism. This is especially true for the Douvilleiceratidae and
Acanthohoplitidae, for which a plethora of typological species was introduced over the years (see
lists in Klein and Bogdanova, 2013). Moreover, there is hardly any agreement among authors
regarding the limits and content of *Colombiceras* Spath, 1923, *Acanthohoplites* Sinzow, 1908;
*Protacanthoplites* Tovbina, 1970; *Nolaniceras* Casey, 1961; *Hypacanthoplites* Spath, 1923;
*Procheloniceras* Spath, 1923; *Diadochoceras* Hyatt, 1900; *Nodosohoplites* Egoian, 1965 and
*Epicheloniceras* Casey, 1954.

Finally, a large number of species are based on material that was collected from condensed
beds. This is the case for many key taxa from South-eastern France (Seunes, 1887; Jacob, 1905) and
Switzerland (Jacob and Tobler, 1906); and the great majority of the late Aptian faunas from western
Caucasus (Egoian, 1965, 1969), northern Caucasus (Sinzow, 1906, 1913; Nikchitch, 1915), Dagestan
(Anthula, 1900; Kazansky, 1914), Georgia (Kvantaliani, 1971, 1972), Turkmenistan (Glazunova, 1953;
Tovbina, 1968, 1970, 1982) and Mangyschlak (Sinzow, 1908; Glazunova, 1953). Although the recent
contribution of Bogdanova and Mikhailova (2016) clarifies the biostratigraphic distribution of the
early late Aptian ammonites of the northern Caucasus and Transcaspia to some extent, the precise
range of the latest Aptian faunas remain poorly understood.
The palaeontological study of the Aptian ammonite faunas from the **EAB** deserve extensive
taxonomic descriptions that are beyond the scope of the present paper. Selected elements of the
fauna that are crucial for the definition of the biostratigraphic scheme are illustrated (Figs. 8 to 11)
and their taxonomic assignments are briefly discussed. In most cases, the identifications are based
on direct comparison with the originals or plaster casts of the type material from SE France (Seunes,
1887; Jacob, 1905; Kilian and Reboul, 1915), Switzerland (Jacob and Tobler, 1906), Dagestan
(Anthula, 1900) and Mexico (Burckhardt, 1925; Humphrey, 1949). A deliberate choice has been
made to reduce synonymies to a limited number of key specimens. Emphasis has been taken on
material from Morocco previously illustrated in the literature. Unless otherwise mentioned the
suprageneric classification retained herein follows the nomenclature of Wright et al. (1996).

503

Order Ammonoidea Zittel, 1884

Suborder Ancyloceratina Wiedmann, 1966

Superfamily Douvilleiceratoidea Parona and Bonarelli, 1897

Family Douvilleiceratidae Parona and Bonarelli, 1897

508

Comment. For the reasons exposed by Bulot in Vincent et al. (2010, p. 184), Cheloniceratinae Spath,
1923 is herein considered as a junior subjective synonym of the subfamily Douvilleiceratinae.

511

Subfamily Douvilleiceratinae Parona and Bonarelli, 1897

Genus *Procheloniceras* Spath, 1923

514

Type species. *Ammonites stobieckii* d'Orbigny, 1850, p. 113.

516

*Procheloniceras dechauxi* (Kilian and Reboul, 1915)

Figure 8.7–12
519

520

Holotype. *Douvilleiceras Martinii* var. *Dechauxi* Kilian and Reboul, 1915, p. 56, pl. 1, fig. 7, 7b, pl. 7, fig. 2. The specimen is housed in the Université de Grenoble collections (catalogue number UJF-ID.1084).

523

524

*Remarks.* The genus *Procheloniceras* was reported on various occasions from the Tamzergout Fm. of the **EAB**. According to Roch (1930), *Procheloniceras pachystephanum* (Uhlig, 1883) is the most common species with *P. albrechtiaustriae* (Uhlig, 1883). Additionally, *P. stobieckii* (d'Orbigny, 1850) was reported by Rey et al. (1986a, 1988). None of the specimens quoted by those authors were illustrated. The well-preserved and abundant material collected at Tamanar and Zem Zem questions those identifications. Even though a full revision of the genus is needed, the recent contributions of Delanoy (1995, 1998) and Delanoy et al. (2008) has helped to clarify the systematics of *Procheloniceras*. Our material differs from *P. pachystephanum* and *P. albrechtiaustriae* by its smaller umbilicus, more depressed whorl section, and rigid and regular ornamentation. Most Moroccan specimens (Fig 8.7–10) match the holotype of *Procheloniceras dechauxi* well. The variability of the populations includes a slender morphology (Fig. 8.11–12) that superficially matches the lectotype of *P. stobieckii* illustrated by Conte (1981) and Ropolo et al. (2008a).

525

526

527

528

529

530

531

532

533

534

535

536

537

Genus *Epicheloniceras* Casey, 1954

538

539

*Type species.* *Douvilleiceras Tschernyschewi* Sinzow, 1906, by original designation.

540

541

*Epicheloniceras gr. subbuxtorfi – paucinodum* (Burckhardt, 1925)

542

Figure 9.1–8.

543

544

v 1930. *Douvilleiceras buxtorfi* Jacob and Tobler; Roch, p. 381, pl. 19, fig. 1a–d.
v 1930. *Douvilleiceras aequicostatum* Burckhardt; Roch, p. 381, pl. 20, fig. 1a-b.

1998. *Cheloniceras (Epicheloniceras) gr. martinioides* Casey; Witam, p. 356, pl. 7, fig. 2-6.

547

Remarks. *Epicheloniceras* is a fairly common element of the late Aptian ammonite faunas of the **EAB**.

It is noteworthy that the large population from Tiskatine (bed **TK 161A**) can easily be distinguished

from the *Epicheloniceras* of the *martini* (d'Orbigny, 1841) and *buxtorfi* (Jacob and Tobler, 1906)

groups by the early loss of the ventral tubercles, simplified ornamentation and highly distinctive

subrounded whorl section. The various morphotypes show close similarities with *Epicheloniceras*

*paucinodum* (Burckhardt, 1925), *E. subbuxtorfi* (Burckhardt, 1925) and *E. aequicostatum*

(Burckhardt, 1925). This affinity with the Mexican taxa was already recognised by Roch (1930, p.

381).

556

*"Epicheloniceras" marocanus* (Roch, 1930)

Figure 9.25-28.

559

v 1930. *Parahoplites (?) marocanus* Roch, p. 378, pl. 16, fig. 5-6.

561

Lectotype. *Parahoplites (?) marocanus* Roch, 1930, pl. 16, fig. 5 (UJF-ID.1601), herein designated.

563

Type locality. Tiskatine (= Djebel Tissakatine in Roch, 1930).

565

Description. Small-sized planulate ammonites (Dmax ≤ 50mm) with a moderately evolute coiling.

Earliest ontogeny unknown. On the adult whorl, the whorl section is depressed, sub-rounded and

becomes progressively compressed, sub-rectangular and is higher than it is wide. The venter is

moderately flattened and becomes rounded near the aperture. The umbilical wall is rounded and
tends to become steep in the adult. The suture line is unknown. Two ornamental stages on the adult whorl:

(i) alternation of tuberculate primary and one to two atuberculate secondary ribs. Small rounded tubercles occur on the upper part of the flank and divide into two branches. All ribs cross the venter but the adoral branches bear small thickenings on the ventrolateral margin;

(ii) abrupt change toward spaced, simple ribs with rare secondaries. Ribs are slightly flexuous or straight with a marked apertural bending on the upper part of the flank. All ribs cross the venter forming an elevated proverse bending.

Remarks. This micromorphic species is provisionally assigned to *Epicheloniceras*. Derivation from an *Epicheloniceras* stock is based on the similarity of its early ontogenetic stages with the juveniles of the *Epicheloniceras* of the *waageni* (Anthula, 1900) – *tschernyschewi* (Sinzow, 1906) group that occur in underlying level (see Fig. 9.29-32).

Family Deshayesitidoidea Stoyanow, 1949

Family Deshayesitidae Stoyanow, 1949

Genus *Deshayesites* Kazansky, 1914

Type species. Ammonites *Deshayesi* d'Orbigny, 1841, by original designation.

*Deshayesites* aff. *euglyphus* Casey, 1964 in Delanoy (1995)

Figure 8.1–6.

Microconchs
595 v 1995. *Deshayesites* aff. *euglyphus* Casey, Delanoy, p. 77, pl. 1, fig. 4, pl. 4, fig. 4.

596 v 1998. *Deshayesites* aff. *euglyphus* Casey, Delanoy, pl. 6, fig. 2, pl. 24, fig. 2 (= Delanoy, 1995, pl. 1

597 ,fig. 4, pl. 4, fig. 4).

598 1998. *Deshayesites* aff. *luppovi* Bogdanova, Witam, p. 357, pl. 8, fig. 2.

599

600 Macroconchs

601

602 v 1995. *Deshayesites* aff. *evolvens* Luppov, Delanoy, p. 77, pl. 3, fig. 1.

603

604 *Remarks*. The Moroccan material includes both microconchs and macroconchs. The microconch
605 forms show an intermediate morphology between *Deshayesites luppovi* Bogdanova, 1983 and the
606 coarser morphotypes of the *D. forbesi* Casey, 1961 group such as *D. euglyphus* Casey, 1964. They
607 match well the specimens illustrated by Delanoy (1995) as *D. aff. euglyphus*. The larger macroconchs
608 compares with specimens from South East France that were most often misidentified as
609 *Deshayesites consobrinus* (d'Orbigny, 1841) (Ropolo et al., 2000a, p. 162-163, fig. 3.2 and 4; Ropolo
610 et al.,2006, pl. 6, fig. 6). The Moroccan specimens are left in open nomenclature and their species
611 assignment will be addressed in a forthcoming contribution once the ongoing revision of the
612 material from South-eastern France is completed.

613

614 Superfamily Acanthohoplitoidea Stoyanow, 1949

615

616 *Remark*. Our ongoing revision of the Acanthohoplitidae supports the view that it has no phyletic link
617 with the Parahoplitidae, even so both families derivate iteratively from the Douvilleiceratidae.

618

619 Family Acanthohoplitidae Stoyanow, 1949

620 Genus *Colombiceras* Spath, 1923
621

622 *Type species*. *Ammonites crassicostatus* d'Orbigny, 1841, by original designation.

623

624 *Colombiceras tobleri* (Jacob and Tobler, 1906)

625 Fig. 9.9-12

626

627 v 1930. *Parahoplites teffryanus* Karsten in Anthula; Roch, p. 377, pl. 16, fig. 7.

628 ? 1998. *Colombiceras* aff. *tobleri* Jacob and Tobler; Witam, p. 362, pl. 10, fig. 5.

629

630 *Remarks*. Among the material from Morocco two morphologies can be distinguished. The most
631 common is a compressed and finely ribbed morphotype with rectangular section and tabulate
632 venter (Fig. 9.9–10). It somewhat bears a similarity to *Colombiceras crassicostatum* (d'Orbigny, 1841)
633 and *Gargasiceras gargasense* (d'Orbigny, 1841) but the early ontogeny differs by having a distinct
634 ribbing pattern where all the ribs appears single or by pairs on the umbilical margin and cross the
635 venter without weakening. The other morphotype is a coarsely ribbed form that shows a rounded
636 rectangular whorl section higher than wide, and a widely spaced alternation of primary and
637 intercalatory ribs. It closely matches the lectotype of *Colombiceras discoidale* (Sinzow, 1908, pl. 5,
638 fig. 17–18) at similar growth stages. In our opinion the slender and coarse morphotypes are
639 conspecific and are linked by intermediate forms such as the specimen illustrated on Figure 9.9–11.

640 Since the examination of a large number of specimens from South-eastern France has convinced us
641 that *Colombiceras discoidale* represent a compressed morphotype of *C. tobleri*, the Moroccan
642 specimens are considered to fall within the range of variation of the later species. It should be noted
643 that the lectotype of *C. tobleri* notably differs from our material by its rounded section throughout
644 ontogeny.

645

646 *Genus Acanthohoplites* Sinzow, 1908
647

648

*Type species. Parahoplites aschiltaensis* Anthula, 1900, by subsequent designation (Roman, 1938).

649

650

*Remarks*. Re-examination of Anthula's type material leaves no doubt that the lectotype designated by Dimitrova (1967, p. 185) is the microconch of the large specimen illustrated by Anthula (1900, pl. 10, fig. 4, pl. 11, fig. 1). Our material includes a series of individuals that match the macroconch well.

653

Even though the large specimen illustrated on Figure 11.1-2 does not show the characteristic juvenile ornamental stage of *A. aschiltaensis*, complete material from other sections support its specific identification. The very large adult body chambers, which are characterized by a rigid adult ornamentation, and were collected from bed **MR 10t and 11** at Mramer, are left in open nomenclature.

658

659

Genus *Protacanthoplites* Tovbina, 1970

660

661

*Type species. Parahoplites abichi* Anthula, 1900, by original designation.

662

663

*Remarks*. The genus has been variously interpreted since its introduction by Tovbina (1970) and some authors suggest that it could be a junior subjective synonym of *Acanthohoplites* (Wright et al., 1996, Bogdanova and Mikhailova, 2016). Comparison of the lectotypes of *A. aschiltaensis* and *P. abichi* shows that the two species are fairly close but the material at our disposal does not allow yet a definitive conclusion regarding synonymy. For the time being, we maintain the genus *Protacanthoplites* to accommodate the Moroccan specimens, that occur above the last occurrence *Acanthohoplites aschiltaensis*, and closely match *P. abichi* (Fig. 9.17–20), *P. bergeroni* (Seunes, 1987) and "*Protacanthoplites*" aff. *multinodosus* Tovbina, 1982 (Fig. 9.13–16).

664

665

666

667

668

669

670

671

672

Genus *Diadochoceras* Hyatt, 1900
673

674 *Type species*. *Ammonites nodosocostatum* d'Orbigny, 1841, by original designation.

675

676 *Remarks*. Specimens of *Diadochoceras* from the type locality of *D. nodosocostatum* are fairly numerous in the French historical collections (Obata, 1975), but our understanding of the genus is largely handicapped by the condensed character of faunas and the absence of a proper revision of the type species that is based on a single poorly preserved juvenile specimen (neotype designed by Guerin-Franiatte in Gauthier et al., 2006). Examination of the topotype material strongly suggest that the large number of new taxa introduced by Glazunova (1953), Mikhailova (1963), Egoian (1965, 1969) and Kvantaliani (1971, 1972) merely represent sexual dimorphism and intraspecific variation.
677
678
679
680
681
682
683 This high variability is reflected by the Moroccan specimens and assignment to a *Diadochoceras nodosocostatum* group was preferred to identification of specific typologic taxa (Fig. 9.21-22).
684

685

686 *Genus Nodosohoplites* Egoian, 1965

687

688 *Type species*. *Nodosohoplites subplanatus* Egoian, 1965, by original designation.

689

690 *Remarks*. As pointed out by Klein and Bogdanova (2013), there is no agreement in the literature about the validity and content of *Nodosohoplites*. Wright et al. (1996) consider that the genus is a junior subjective synonym of *Diadochoceras*. Szives et al. (2007) suggest that some of the specimens that were placed in *Nodosohoplites* by Egoian (1965) are sexual dimorphs of *Diadochoceras*. Our material shows that the planulate forms with a reduced trituberculate ornamental stage similar to *Nodosohoplites subplanatus* and *N. multispinatus* (Anthula, 1900) appear at a slightly younger stratigraphical level than the first occurrence of *Diadochoceras* of the *nodosocostatum* group.
691
692
693
694
695
696
697 Pending a global revision of *Diadochoceras* and *Nodosohoplites* based on abundant and stratigraphically well-documented populations we prefer to keep the two genera separate.
698
699

700 Genus *Elsaella* gen. nov.

701

702 *Derivation of name*. Dedicated to Elsa Schnebelen-Bulot for her participation to our field investigations in Morocco and continuous support to one of us (L.G.B.) during the preparation of this work.

705

706 *Type species*. *Elsaella tiskatinensis* sp. nov., by monotypy.

707

708 *Diagnosis*. Small-sized (D ≤ 45–50 mm), planulate ammonite with a moderately evolute coiling. Sub-rounded whorl section in the juvenile becomes sub-rectangular as growth increases. Venter is rounded throughout ontogeny. Umbilical wall is low to moderately steep at the adult stage. Two ornamental stage (i) irregular alternation of simple or bifurcate primary ribs and simple secondaries (D ≤ 15 mm); (ii) Uniform and dense ribs originate by pairs or bundles from periumbilical bullae. Bullae strengthen as growth increases and the ribs are more spaced on the outer part of the body chamber. All ribs cross the venter without interruption and slightly bend forward. Aperture is simple. Acanthohoplitid suture line.

716

717 *Discussion*. The genus *Immunitoceras* (type species: *I. immunitum* Stoyanow, 1949) compares superficially to *Elsaella*. The original description and the re-examination of the holotype leave no doubt that the primary ribs are bituberculated at the younger stages and do not compare with the equivalent ontogenetic stages of *Elsaella*. The only other acanthohoplid genus that can be compared with *Elsaella* gen. nov. is *Nolaniceras*. Differences between the type species of the two genera are discussed below.

723

724 *Elsaella tiskatinensis* sp. nov.
725 Fig. 10.1-16.

726

727 1998. *Nolaniceras nolani* Seunes, Witam, p. 361, pl. 9, fig. 7a-b, pl. 10, fig. 1-2 (sol).

728 1998. *Nolaniceras nolani* var. *planulata* Egoian, Witam, p. 361, pl. 10, fig. 3a-b (sol).

729

730 *Holotype*. (MANCH) LL.16123, (Fig. 10.1-2).

731 *Paratypes*. (MANCH) LL.16124 – LL.16131, (Fig. 10.3-16).

732 *Type locality*. Tiskatine, Essaouira-Agadir Basin, Morocco.

733

734 *Type strata*. Bed **TK206**, *Elsaella tiskatinensis* Zone (see definition below), upper Aptian.

735

736 *Diagnosis*. As for the genus.

737

738 *Discussion*. *Elsaella tiskatinensis* sp. nov. has been misidentified as *Nolaniceras nolani* in the
739 Moroccan literature (Rey et al. 1986a, 1988, Witam 1998, Peybernes et al. 2013). In a recent
740 revision, Bulot et al. (2014) have shown that *Nolaniceras nolani* differs from all other uppermost
741 Aptian Acanthohoplitidae by its highly distinctive low and convex umbilical wall and most unusual
742 ornamental style. Compared to *Elsaella tiskatinensis* sp. nov., *Nolaniceras nolani* can be
743 distinguished by its compressed suboval whorl section throughout ontogeny, the absence of
744 umbilical bullae and attenuation of the ribbing on the venter.

745

746 *Remarks*. The late upper Aptian Moroccan faunas also includes a coarser and larger forms of *Elsaella*
747 that compare with *Acanthoceras bigoti* Seunes (1887) and *Acanthoceras migneni* Seunes (1887).

748 These two species have been diversely interpreted in the literature and remain poorly understood
749 since it seems that the originals from the Mignen collection are lost. The coarser forms of *Elsaella*
750 that dominates the assemblages at Mramer and Zem Zem are provisionally referred as *Elsaella* sp. 1
and sp. 2. More work is needed to determine if these forms represent ecological morphotypes of *E. tiskatinensis* or new taxa.

753

*Geographical and stratigraphical distribution.* Since *E. tiskatinensis* is a very common ammonite in the lower part of the late upper Aptian of the **EAB**, it is selected herein as the index species of the *E. tiskatinensis* Zone. Outside Morocco, and despite an extensive survey of the literature, none of the specimens previously referred to *Nolaniceras nolani* in the literature can be assigned with certainty to our new species.

759

Genus *Hypacanthoplites* Spath, 1923

761

*Type species.* *Acanthoceras Milletianum* Var. *plesiotypica* Fritel, 1906, by original designation.

763

*Remarks.* Problems with the systematics of the genus *Hypacanthoplites* have been addressed at length by Bulot (2010). The genus was reported on many occasions in the Moroccan literature (Rey et al. 1986a, 1988, Witam 1998, Peyernes et al. 2013). Our new collection shows that hypacanthoplid-like ammonites occur at two different levels in the **EAB**.

The older fauna is preserved as small pyritic internal moulds that occur above the *Elsaella* beds at Tiskatine, Tamanar, and Zem Zem. Those forms are provisionally placed in "*Hypacanthoplites*" and left in open nomenclature as sp. 1, sp. 2 and sp. 3. They all show a very clear tabulate venter associated with a weakening of the ribs on the siphonal line. Even though there is a reinforcement of the ribs on both sides on the ventral shoulder; this feature is not as marked as in true *Hypacanthoplites*. The ornamental style of the very finely ribbed "*Hypacanthoplites*" sp. 1 (Fig. 11.15-25) suggests evolution from *Elsaella tiskatinensis*. To the difference "*Hypacanthoplites*" sp. 3 (Fig. 11.3-11) shows a very distinct bituberculate ontogenetic stage that somehow recalls the
776 ornamentation of *Hypacanthoplites tuberculatus* Egoian, 1969 and *H. microtuberculatus* Egoian, 1969.
777

778 Higher up in the succession, a collection of specimens that match the type material of
779 *Mellegueiceras chihaouiae* Latil, 2011 and "*Hypacanthoplites*" paucicostatus Breistroffer in
780 Dubourdieu, 1953 was made. This fauna will be described in a separate paper and its early Albian
781 age is established by the co-occurrence of the genus *Douvilleiceras*. It should be noted that the
782 fragments identified by Witam (1998, pl. 9, fig. 4-6) as *Hypacanthoplites* gr. *jacobi* (Collet, 1907) are
783 merely misidentified "*Hypacanthoplites*" paucicostatus.

784

785 **5. Ammonite biostratigraphy and correlation to the Standard Mediterranean Ammonite Scale**
786 **(SMAS)**

787

788 As shown by the systematic notes, the ammonite faunas from the **EAB** have a distinct
789 character that is most certainly linked to the palaeogeography of the basin. Although the successive
790 assemblages are clearly of Tethyan affinity, none of the index species of the Standard Mediterranean
791 Ammonite Scale (**SMAS**) of Reboulet et al. (2011, 2014) were found in the course of our study. As a
792 consequence, we have chosen to introduce a regional biostratigraphic scale based on the main bio-
793 events recognized at the basin scale (Fig. 12). When possible correlations with the **SMAS** are
794 proposed, the precision of these correlations is handicapped by the fact, that for the upper part of
795 Aptian Stage, the biostratigraphic subdivision of the **SMAS** is largely based on assemblage zones and
796 subzones originally defined in the former Soviet Union (Bogdanova and Tovbina, 1995) for which
797 detailed successions are still poorly documented.

798

799 Lower Aptian – *Procheloniceras dechauxi* Zone, new this paper

800

801 *Index species.* *Procheloniceras dechauxi* (Kilian and Reboul, 1915)
802 *Reference section*. Tiskatine – bed **TK 159** to **TK 160b**.

803

804 *Definition*. The base of the zone is defined by the first occurrence of the index–species that largely

805 dominates the assemblage in all studied sections. The diversity is low but some beds are rich in

806 *Deshayesites* aff. *euglyphus* Casey in Delanoy (1995). It should be noted that *P. dechauxi* and *D. aff.*

807 *euglyphus* are most often mutually exclusive. *Audouliceras* sp. ind., *Pseudohaploceras* cf. *matheroni*

808 (d'Orbigny, 1841) and *Melchiorites melchioris* (Tietze, 1872) are minor elements of the fauna.

809

810 *Correlations*. Correlation with the **SMAS** is based on the occurrence of *P. dechauxi* and *D. aff.*

811 *euglyphus*. These two taxa are known to occur in the lower part of the *Deshayesites forbesi* Zone in

812 South East France (Delanoy, 1995, 1998; Pictet, 2012).

813

814 Upper Aptian – *Colombiceras tobleri* Zone, Eristavi (1960) emended.

815

816 *Index species*. *Colombiceras tobleri* (Jacob and Tobler, 1906)

817 *Reference section*. Tiskatine – bed **TK 161a** to **TK 183c**.

818

819 *Definition*. Since its first introduction, the *Colombiceras tobleri* Zone was variously interpreted in the

820 literature (see discussion in Bogdanova and Mikhailova, 2016). As herein understood, the zone is

821 defined by the first occurrence of its index–species. Two subzones can be distinguished in the **EAB**.

822

823 *Colombiceras tobleri* Subzone, new, this paper

824

825 *Index species*. As for the zone.

826 *Reference section*. Tiskatine – bed **TK 161a** to **TK 163**.

827
828 *Definition*. The base of the subzone is defined by the first occurrence of the index-species. The

829 diversity of the fauna is fairly high. Together with the index species, the various *Epicheloniceras* of

830 the *subbuxtorfi* – *paucinodum* group are the most common elements of the faunal assemblage.

831 Desmoceratids are unusually common compared to the rest of the succession. *Pseudohaploceras*

832 *angladei* Dutour, 2005 non (Sayn, 1891), *Zuercherella zuercheri* (Jacob and Tobler, 1906),

833 *Melchiorites* aff. *emerici* (Raspail, 1831) and *Caseyella* sp. ind. were identified. The heteromorph taxa

834 "*Ammonitoceras* lahuseni (Sinzow, 1906) and ? *Pseudoaustraliceras* sp. are minor elements of the

835 fauna. A single phylloceratid tentatively assigned to *Phylloceras* sp. was collected.

836

837 "*Epicheloniceras* marocanus Subzone, new, this paper

838

839 *Index species*. "*Epicheloniceras* marocanus (Roch, 1930)

840 *Reference section*. Tiskatine – bed **TK 164** to **TK 183c**.

841

842 *Definition*. The base of the subzone is defined by the first occurrence of the index-species. The

843 diversity of the fauna is very low. The lower part of the subzone is marked the acme of

844 "*Epicheloniceras* marocanus and its upper part correspond to a barren interval. The last occurrence

845 of *C. tobleri* is to be noted at the base of the subzone. In the barren interval, spot occurrence of

846 *Epicheloniceras* of the *waageni* (Anthula, 1900) – *tschernyschewi* (Sinzow, 1906) group was

847 identified.

848

849 *Correlations*. Because of the highly endemic character of the fauna, a precise correlation with the

850 **SMAS** is hard to establish. A provisional correlation between the base of the *C. tobleri* Zone of

851 Morocco and the base of the *E. gracile* Subzone (*E. martini* Zone) can be proposed on the basis of

852 the evolution of the genus *Colombiceras* in SE France (Bulot in Dauphin 2002), Caucasus and

853 Transcaspia (Bogdanova and Mikhailova, 2016). Due to the somehow “primitive” character of the
854 Moroccan *C. tobleri* a slightly older position in the *E. martini* Zone cannot be excluded. Ongoing

855 study of the large collection of *Epicheloniceras* should allow more precise correlation in the future.

856

857 Upper Aptian – *Acanthohoplites aschiltaensis* Zone, Mordvilko (1960) emended.

858

859 *Index species*. *Acanthohoplites aschiltaensis* (Anthula, 1900). First

860 *Reference section*. Tiskatine – bed **TK 184** to **TK 205**.

861

862 *Definition*. Since its introduction, the *Acanthohoplites aschiltaensis* Zone has had a number of

863 interpretations in the literature (see discussion in Bogdanova and Mikhailova, 2016). As herein

864 understood the zone is defined by the first occurrence of the index-species. The diversity is very low

865 but a distinctive horizon rich in *Pseudoaustraliceras* of the *ramososeptatum* (Anthula, 1900) group

866 (Fig. 9.23 – 24) was identified in the middle part of the zone. The geographical extension of this bio-

867 event at the scale of the basin remains unknown. In the marginal areas of the **EAB**, the occurrence of

868 large *Epicheloniceras* that do not match any species of the literature is also to be noted. The precise

869 range and affinities of those specimens are still to be documented.

870

871 *Correlations*. The precise range of *A. aschiltaensis* has never been precisely calibrated with the **SMAS**

872 zones. Data from South-eastern France suggests that the lowest occurrence of the *Acanthohoplites*

873 of the *aschiltaensis* group occurs in the uppermost part of the *E. martini* Zone close to its boundary

874 with the *P. melchioris* Zone (Bulot in Dauphin, 2002; Frau and Bulot, unpublished data). According to

875 Russian literature, *A. aschiltaensis* is a common element of the *P. melchioris* Zone (Bogdanova and

876 Mikhailova, 2016, with references).

877

878 Upper Aptian – *Elsaella tiskatinensis* Zone, new this paper

879
880 *Index species*. *Elsaella tiskatinensis* gen. nov. sp. nov.

881 *Reference section*. Tiskatine – bed **TK 206** to **TK 247**.

882

883 *Definition*. The zone is defined by the first occurrence of the genus *Elsaella*. Two subzones can be distinguished.

885

886 *Elsaella tiskatinensis* Subzone, new this paper

887

888 *Index species*. As for the zone.

889 *Reference section*. Tiskatine – bed **TK 206** to **TK 220**.

890

891 *Definition*. The first occurrence of the genus *Elsaella* marks the base of the subzone. In all studied sections the fauna is marked by the evolutive radiation of the Acanthohoplitidae. The various morphologies of *Elsaella* dominate in the lower part of the subzone. In the upper part of the subzone a fairly diverse assemblage of Acanthohoplitidae develops and includes *Diadochoceras* of the *nodosocostatum* group, *Nodosohoplites* of the *subplanatus* group, and various species of *Protacanthoplites*. *Epicheloniceras clansayense* (Jacob, 1905) is a secondary element of the fauna in the marginal parts of the **EAB**.

898

899 "Hypacanthoplites" spp. Subzone, new this paper

900

901 *Index species*. Hypacanthoplitids with a tabulate venter ("Hypacanthoplites" sp. 1, "H." sp. 2 and "H." sp. 3).

902 *Reference section*. Tiskatine – bed **TK 221** to **TK 247**.

904
905 *Definition*. The fauna is dominated by "Hypacanthoplites" sp. 1, "H." sp. 2 and "H." sp. 3 but also

906 contains relict elements from the underlying subzone such as *Protacanthoplites abichi* and

907 *Nodosohoplites gr. subplanatus*. Other noteworthy taxa are *Pseudosilesites seranoniformis* Egoian,

908 1969 (Fig.11.12-14), *Puzosiella minuta* Egoian, 1969 and *Melchiorites problematicus* (Fallot and

909 Termier, 1923).

910

911 *Correlations*. The detailed range of the ammonite faunas of the *A. nolani* Zone of the **SMAS** is still

912 not documented. Nevertheless, it seems reasonable to consider that the first occurrence of

913 *Diadochoceras* in the lower part of the *E. tiskatinensis* Zone suggests a correlation with a level close

914 to the base *D. nodosocostatum* Subzone. Co-occurrence of primitive "Hypacanthoplites" spp. and

915 *Pseudosilesites seranoniformis* in the upper part of the *A. nolani* Zone was reported from North-eastern Spain by Robert et al. (2001). This suggests that the base of the *Hypacanthoplites* spp.

916 Subzone is likely older than the base of the *H. jacobi* Zone even so correlation with a slightly younger
917 level cannot be excluded.

919

920 In agreement with Latil (2011), the base of the Lower Albian (*M. chihaouiae* Zone) is marked by the

921 co-occurrence of first representatives of the genus *Douvilleiceras* (Fig. 9.33) with *Mellegueiceras*

922 *chihaouiae*. This boundary is clearly documented at Tiskatine and Mramer. At Mramer, the index
923 species of the overlying lower Albian "Hypacanthoplites paucicostatus* Zone was also identified.

924

925 It should be noted that the beds that contain the first Lower Albian faunas with *Douvilleiceras* (see

926 details below) directly overlie the "Hypacanthoplites" spp. Subzone. As a consequence we suspect a
927 hiatus that would embrace the uppermost part of the *H. jacobi* Zone and lower part of the *L.*

928 *tardefurcata* Zone.

929

930 **6. Conclusions**
931

932

High-resolution bed by bed sampling of five sections in the west-central **Essaouira Agadir Basin**

933

(EAB) has yielded the largest Aptian published ammonite collection in NW Africa. The results provide

934

new information on the age range of previously defined formations, and a type section with fully

935

documented collections correlated against type species. In addition, new species have been

936

identified and the collections provide new insights into the regional endemism of species in this part

937

of NW Africa.

938

939

The main conclusions from the study are:

940

* A diverse Aptian and early Albian ammonite fauna is documented, comprising 26 different genera and 43 species.

941

942

* The global palaeobiogeographic character of the fauna is Tethyan, however a high degree of endemism is recognised at the genus and species level.

943

944

* A new genus and species *Elsaella tiskatinensis* is described.

945

* New material also allows re-examination of *Parahoplites marocanus*, provisionally included in the genus *Epicheloniceras*.

946

947

* Based on the ammonite distribution a regional biostratigraphic scale is introduced for the Aptian of the **EAB**. 8 zones and subzones are recognised, 5 of which are new.

948

949

* The section at Tiskatine [Lat.: 30.821463° Long.: -9.702555° (Tiskatine 1) and Lat.: 30.810477° Long.: -9.739966° (Tiskatine 2)] is selected as the type section for the Aptian in the west-central part of the **EAB**. Key taxa are documented, illustrated with collection references. A correlation based on first occurrence of common taxa with the **Standard Mediterranean Ammonite Scale (SMAS)** is proposed when possible.

950

951

952

953

954

* Two basin-scale regional hiatuses are identified. The lower one encompasses the time equivalent of the middle part of the *D. forbesi* Zone to lower part of the *E. martini* Zone of

955
956

the **SMAS**. The upper one includes the *H. jacobi* Zone and the lowermost part of the *L. tardefurcata* Zone equivalent.

957

958

* The age of the Tamzergout Fm. has been clearly defined, ranging from the local and newly introduced *D. dechauxi* to the *E. tiskatinensis* zones

959

960

* The top Bouzergoun / base Tamzergout Fm. is identified as being diachronous, ranging in age from the early to late Aptian (*D. dechauxi* to *C. tobleri* zones)

961

962

* The improved age dating of the Lemgo Fm. (based on collection from the Mramer section) indicates a range from middle upper Aptian *A. ashiltaensis* Zone to the lowermost Albian "H." *paucicostatus* Zone

963

964

965

* An early Albian age for the base of the Oued Tidzi Fm. is established by the lowest occurrence of the genus *Douvilleiceras*

966

967
968 Acknowledgments

969 This study forms part of the lead authors PhD at the University of Manchester with the North Africa

970 Research Group (NARG). The authors would like to thank the sponsoring companies of NARG and

971 L'Office National des Hydrocarbures et des Mines (ONHYM) for their continued financial, logistical

972 and scientific support. The constructive comments of the editor in-chief and reviewers Miguel

973 Company (Granada) and Josep A. Moreno Bedmar (Mexico D.C.) are highly appreciated and

974 improved the manuscript. We thank David Gelsthorpe and the team of the Manchester Museum for

975 curation of all the figured material of this publication. We would further like to acknowledge all field

976 assistants and their invaluable help and input.

977
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1418 Schlager, S., Jenkyns, H., 1976. Cretaceous Oceanic Anoxic Events: Causes and consequences.

1419 Geologie en Mijnbouw 55, 179–184.

1420

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1424

1425 Seunes, J., 1887. Sur quelques ammonites du Gault. Bulletin de la Société Géologique de France,

1426 Série 3 15, 557–571.

1427

1428 Sinzow, I., 1906. Die Beschreibung einiger Douvilleiceras–Arten aus dem oberen Neokom Russlands.

1429 Verhandlungen der Russisch–Kaiserlichen Mineralogischen Gesellschaft zu St.–Petersburg 44, 157–

1430 197.

1431

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1435

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1438 93–117.

1439
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1441 (1921), 1–72.

1442

1443 Stoyanow, A., 1949. Lower Cretaceous stratigraphy in southeastern Arizona. Geological Society of

1444 America, Memoirs 38, 1–169.

1445

1446 Szives, O., Csontos, L., Bujtor, L., Főzy, I., 2007. Aptian-Campanian ammonites of Hungary. Geologica

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1448

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1450 London, Special Publications 369, 337–353.

1451

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1454

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1458

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1461
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1464

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1467

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1478

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1484

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1488

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1495 PhD thesis, Ruhr-Universität, Bochum, 142 pp.

1496

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1500

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1504
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1507 Revue de Paléobiologie 12, 193–202.

1508

1509 Wright, C.W., Callomon, J.H., Howarth, M.K., 1996. Cretaceous ammonoidea. In: Moore, R. C.,

1510 Kaesler, K.L. (eds.), Treatise on invertebrate palaeontology, Part L, Mollusca 4 revised, 362 pp.

1511 Geological Society American and University Kansas Press, New York.

1512

1513 Zittel, K.A., von 1884. Cephalopoda. In: Zittel, K.A., von, Handbuch der Paläontologie, Band 1, Abt. 2,

1514 Lief 3, pp 329–522. R. Oldenbourg, Munich and Leipzig.

1515

1516 Zittel, K.A., von 1895. Grundzüge der Paläontologie (Paläozoologie). vii + 972 pp. R. Oldenbourg,

1517 Munich and Leipzig.

1518

1519 Zühlke, R., Bouaouda, M.-S., Ouajhain, B., Bechstädt, T., Reinfelder, R., 2004. Quantitative Meso-

1520 /Cenozoic development of the eastern Central Atlantic continental shelf, western High Atlas,

1521 Morocco. Marine and Petroleum Geology 21, 225–276.

1522

1523 Captions ammonite figures

1524

1525 Figure 1. Digital elevation model with sub-crop of geological maps, showing Lower Cretaceous

1526 outcrops of the Essaouira Agadir Basin, studied sections and key locations.

1527
1528 Figure 2. Generalised lithostratigraphy of the upper Bouzergoun to lower Oued Tidzi formations, and
depositional environments in the west-central part of the EAB.

1530
1531 Figure 3. Tiskatine section. Ammonoid distribution and biostratigraphic interpretation.

1532
1533 Figure 4. Tamanar section. Ammonoid distribution and biostratigraphic interpretation.

1534
1535 Figure 5. Zem Zem section. Ammonoid distribution and biostratigraphic interpretation.

1536
1537 Figure 6. Oued Tlit section. Ammonoid distribution and biostratigraphic interpretation.

1538
1539 Figure 7. Mramer section. Ammonoid distribution and biostratigraphic interpretation.

1540
1541 Figure 8. (1–6) *Deshayesites* aff. *euglyphus* (Casey, 1964) *in Delanoy (1995) – (1–2)* and (5–6) from bed **TK 160** ((MANCH) LL.16103 and (MANCH) LL.16105), (3–4) from bed **TR 70** (MANCH) LL.16104; (7–12) *Procheloniceras dechauxi* (Kilian and Reboul, 1915) from bed **TR 69** ((MANCH) LL.16106 – (MANCH) LL.16108). All specimens coated with ammonium chloride prior to photography. Scale bar is 10mm.

1546
1547 Figure 9. (1–8) *Epicheloniceras gr. subbuxtorfi* – *paucinodum* (Burckardt, 1925) from bed **TK 161A** ((MANCH) LL.16109 – (MANCH) LL.16111); (9–12) *Colombiceras tobleri* (Jacob and Tobler, 1906) from bed **TK 161A** ((MANCH) LL.16112 and (MANCH) LL.16113); (13–16) "*Protacanthoplites*" aff. *multinodosus* (Tovbina, 1982) from bed **TK 206** ((MANCH) LL.16114); (17–20) *Protacanthoplites abichi* (Anthula, 1900) from **TK 212/213** ((MANCH) LL.16115); (21–22) *Diadochoceras gr. nodosocostatum* (d'Orbigny, 1841) from bed **TK 206**((MANCH) LL.16116); (23–24) *Pseudoaustraliceras gr. ramososeptatum* (Anthula, 1900) from **TK 196** ((MANCH) LL.16117); (25–28)
1554 "Epicheloniceras" marocanus (Roch, 1930) from bed **TK 166** ((MANCH) LL.16118 and (MANCH)

1555 LL.16119); (29–32) *Epicheloniceras* sp. juv. 1 gr. *waageni* (Anthula, 1900) – *tschernyschewi* (Sinzow,

1556 1906) from bed **TK 163** (MANCH) LL.16120 and (MANCH) LL.16121); (33) *Douvilleiceras* cf.

1557 *leightonense* (Casey, 1962) from bed **TK 248** ((MANCH) LL.16122). All specimens coated with
1558 ammonium chloride prior to photography. Scale bar is 10mm.

1559

1560 Figure 10. *Elsaella tiskatinensis* gen. and sp. nov. from bed **TK 206** – (1–2) holotype ((MANCH)

1561 LL.16123), (3–16) paratypes (MANCH) LL.16124 – (MANCH) LL.16131). All specimens coated with
1562 ammonium chloride prior to photography. Scale bar is 10mm.

1563

1564 Figure 11. (1–2) *Acanthohoplites aschiltaensis* (Anthula, 1900) from bed **TK 192** ((MANCH) LL.16132);

1565 (3–11) "*Hypacanthoplites*" sp. 3 – (3–8) are from bed **ZZ 68** ((MANCH) LL.16133 and (MANCH)

1566 LL.16134), (9–11) from bed **TM 80** ((MANCH) LL.16135); (12–14); *Pseudosilesites seranoniformis*

1567 (Egoian, 1969) from bed **TM 80** ((MANCH) LL.16136); (15–25) "*Hypacanthoplites*" sp. 1 from bed **TM 80** ((MANCH) LL.16137 – (MANCH) LL.16140). All specimens coated with ammonium chloride prior to
1568 photography. Scale bar is 10mm.

1570

1571 Figure 12. Chart showing correlation between the **EAB** and **SMAS** ammonite scales (**SMAS** zones and

1572 subzones after Reboulet et al. 2011, 2014).
<figure><img src="image_5.png" /></figure>
<table><tr><td>Rey et al., 1988</td><td>upper Barremian</td><td>lower Aptian</td><td>Albian</td></tr><tr><td>Nouidar and Chellai, 2001</td><td>upper Barremian</td><td>mid. Aptian</td><td>(not studied)</td></tr><tr><td>This Study</td><td>lower Aptian<br>u. Barremian</td><td>upper Aptian</td><td>lower Aptian</td></tr><tr><td></td><td>Bouzergoun Fm.</td><td>Tamzergout Fm.</td><td>Oued Tidzi Fm.</td></tr></table>

<figure><img src="image_6.png" /></figure>

Sandstone

<figure><img src="image_7.png" /></figure>

Red/Green Mudstone

<figure><img src="image_8.png" /></figure>

Ammonite (black=pyritic)

<figure><img src="image_9.png" /></figure>

Aetostreon (Bivalve)

<figure><img src="image_10.png" /></figure>

Bioturbation

<figure><img src="image_11.png" /></figure>

Hummocky Cross-strat.

<figure><img src="image_12.png" /></figure>

Marls

Fe/P/G<sup>++</sup>

Micritic Limestone

Sandy Limestone

Iron/Phosphate/ Glauconite

<figure><img src="image_13.png" /></figure>

Trough Cross-strat.
<figure><img src="image_14.png" /></figure>
<figure><img src="image_15.png" /></figure>
<figure><img src="image_16.png" /></figure>

1

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2

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7

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8

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9

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10

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3

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5

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6

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11

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12

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4
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1

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2

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3

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4

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5

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6

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7

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8

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9

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10

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11

12

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13

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14

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15

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16

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21

<figure><img src="image_44.png" /></figure>

22

<figure><img src="image_45.png" /></figure>

17

<figure><img src="image_46.png" /></figure>

19

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20

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33

<figure><img src="image_49.png" /></figure>

24

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25

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26

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27

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28

<figure><img src="image_54.png" /></figure>

29

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30

<figure><img src="image_56.png" /></figure>

31

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32
<figure><img src="image_58.png" /></figure>

1

<figure><img src="image_59.png" /></figure>

2

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3

<figure><img src="image_61.png" /></figure>

4

<figure><img src="image_62.png" /></figure>

5

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6

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7

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8

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9

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10

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11

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12

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13

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14

<figure><img src="image_72.png" /></figure>

15

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16

10mm

<figure><img src="image_74.png" /></figure>
1

<figure><img src="image_75.png" /></figure>

3

<figure><img src="image_76.png" /></figure>

4

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5

6

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7

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8

12

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13

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14

18

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19

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20

23

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24

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25

2

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21

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22

15

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10

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17

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9

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11

<figure><img src="image_92.png" /></figure>

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10mm

<figure><img src="image_94.png" /></figure>
<table><thead><tr><th colspan="2">Stages</th><th>Zones This study EAB</th><th>Subzones This study EAB</th><th>Key Bioevents</th><th>Subzones</th><th>Zones</th><th>Stages</th></tr></thead><tbody><tr><td rowspan="2">Aptian</td><td>Albian</td><td> lower Alb. p.p.</td><td> Mellegueiceras chihaouiae</td><td rowspan="2">Douvilleiceras</td><td rowspan="2">Diadochoceras nodosocostatum</td><td> Leymeriella tardefurcata</td><td rowspan="2"> lower Alb. p.p.</td><td rowspan="2">Albian</td></tr><tr><td> upper</td><td> Suspected Hiatus</td><td> Acanthohoplites ashiltaensis</td><td> Hypacanthoplites jacobi</td></tr><tr><td rowspan="2">Aptian</td><td> lower</td><td> upper</td><td> Acanthohoplites ashiltaensis</td><td> "Hypacanthoplites" spp.</td><td> Nodosohoplites</td><td> Acanthohoplites nolani</td><td rowspan="2"> upper</td><td rowspan="2">Aptian</td></tr><tr><td> lower</td><td> lower</td><td> Colombiceras Tobleri</td><td> "Epicheloniceras" maroccanus</td><td> C. tobleri</td><td> Epicheloniceras buxtorfi</td><td> Parahoplites melchioris</td></tr><tr><td rowspan="2">Aptian</td><td> lower</td><td> upper</td><td> Procheloniceras dechauxi</td><td> Barren Interval</td><td> D. aff. euglyphus P. dechauxi</td><td> Epicheloniceras gracile</td><td> Epicheloniceras martini</td><td> lower</td><td rowspan="2">Aptian</td></tr><tr><td> lower</td><td> lower</td><td> ?</td><td> ?</td><td></td><td> Epicheloniceras debile</td><td></td><td></td></tr><tr><td rowspan="2">Aptian</td><td> lower</td><td> upper</td><td></td><td></td><td></td><td> Dufrenoyia dufrenoyi</td><td> Dufrenoyia furcata</td><td> lower</td><td rowspan="2">Aptian</td></tr><tr><td> lower</td><td> lower</td><td></td><td></td><td></td><td> Dufrenoyia furcata</td><td></td><td></td></tr><tr><td rowspan="2">Aptian</td><td> lower</td><td> upper</td><td></td><td></td><td></td><td> Deshayesites grandis</td><td> Deshayesites deshayesi</td><td> lower</td><td rowspan="2">Aptian</td></tr><tr><td> lower</td><td> lower</td><td></td><td></td><td></td><td> Roloboceras hambrovi</td><td> Deshayesites forbesi</td><td></td></tr><tr><td rowspan="2">Aptian</td><td> lower</td><td> upper</td><td></td><td></td><td></td><td> Deshayesites luppovi</td><td> Deshayesites oglanlensis</td><td> lower</td><td rowspan="2">Aptian</td></tr><tr><td> lower</td><td> lower</td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>