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A Middle-Late Eocene vertebrate fauna (marine fish and mammals) from southwestern Morocco; preliminary report: Age and palaeobiogeographical implications

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Recent field work in the southern Moroccan Sahara (‘Western Sahara’), south of the city of ad-Dakhla, has led to the discovery of several new fossiliferous sites with fossil vertebrates in sedimentary deposits previously reported for the Mio-Pliocene. The sedimentology and geological setting of the studied area are briefly reported here, and at least three units have been identified in successive stratigraphical sequences according to their fossil content. The first preliminary list of vertebrate associations is reported and consists mainly of isolated teeth belonging to selachian and bony fishes, a proboscidean tooth currently assigned to ?Numidotherium sp. and many remains of archaeocete whales (Basilosauridae). At least 48 species of selachians are presently identified; many of them are new and others are recorded in the late Middle Eocene (Bartonian) and Late Eocene (Priabonian) of Wadi Al-Hitan (Egypt) or Wadi Esh-Shallala Formation (Jordan) as in other African localities (e.g. Otodus cf. sokolowi, ‘Cretolamna’ twiggsensis, Xiphodolamia serrata, Misrichthys stromeri, Hemipristis curvatus, Galeocerdo cf. eaglesomi, Propristis schweinfurthi), probably indicating a Late Eocene age for unit 2 of the bedrock successions. The evolutionary trend noticeable on the proboscidean tooth is in agreement with such an assumption, by comparison with the close relative species known from the Eocene of Egypt, Libya and Algeria. Indeed, the faunal associations from the Dakhla area clearly demonstrate the erroneous age of these deposits, previously thought to be Mio-Pliocene. It suggests a correlation in age (late Middle Eocene–Late Eocene) and a similar environment with the famous marine deposits from Egypt and Jordan. It opens new opportunities to understand the biogeography and the surprising similarity of landscape between West and Northeast Africa during the Bartonian–Priabonian period.
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Geol. Mag. 147 (6), 2010, pp. 860–870.
c
Cambridge University Press 2010 860
doi:10.1017/S0016756810000348
A Middle–Late Eocene vertebrate fauna (marine fish
and mammals) from southwestern Morocco; preliminary
report: age and palaeobiogeographical implications
SYLVAIN ADNET
, HENRI CAPPETTA &RODOLPHE TABUCE
UMR 5554: Institut des Sciences de l’Evolution de Montpellier, Universit
´
e de Montpellier 2, Place E. Bataillon,
34095 Montpellier cedex 5, France
(Received 23 September 2009; accepted 1 March 2010; first published online 4 May 2010)
Abstract Recent field work in the southern Moroccan Sahara (‘Western Sahara’), south of the city
of ad-Dakhla, has led to the discovery of several new fossiliferous sites with fossil vertebrates in
sedimentary deposits previously reported for the Mio-Pliocene. The sedimentology and geological
setting of the studied area are briefly reported here, and at least three units have been identified
in successive stratigraphical sequences according to their fossil content. The first preliminary list of
vertebrate associations is reported and consists mainly of isolated teeth belonging to selachian and bony
fishes, a proboscidean tooth currently assigned to ?Numidotherium sp. and many remains of archaeocete
whales (Basilosauridae). At least 48 species of selachians are presently identified; many of them are new
and others are recorded in the late Middle Eocene (Bartonian) and Late Eocene (Priabonian) of Wadi
Al-Hitan (Egypt) or Wadi Esh-Shallala Formation (Jordan) as in other African localities (e.g. Otodus
cf. sokolowi, ‘Cretolamna’ twiggsensis, Xiphodolamia serrata, Misrichthys stromeri, Hemipristis
curvatus, Galeocerdo cf. eaglesomi, Propristis schweinfurthi), probably indicating a Late Eocene
age for unit 2 of the bedrock successions. The evolutionary trend noticeable on the proboscidean tooth
is in agreement with such an assumption, by comparison with the close relative species known from
the Eocene of Egypt, Libya and Algeria. Indeed, the faunal associations from the Dakhla area clearly
demonstrate the erroneous age of these deposits, previously thought to be Mio-Pliocene. It suggests a
correlation in age (late Middle Eocene–Late Eocene) and a similar environment with the famous marine
deposits from Egypt and Jordan. It opens new opportunities to understand the biogeography and the
surprising similarity of landscape between West and Northeast Africa during the Bartonian–Priabonian
period.
Keywords: southwestern Morocco, Eocene, selachians, mammals, stratigraphy, palaeobiogeography.
1. Introduction
Since the 19th century, northern Morocco (north of the
Anti-Atlas) has been famous for its abundant and diver-
sified fossil vertebrate faunas, ranging from Palaeozoic
to Pliocene. For the Palaeogene, major fossils of both
marine (e.g. Noubhani & Cappetta, 1997; Cavin et al.
2000; Gheerbrant et al. 1993; Hua & Jouves, 2004)
and terrestrial vertebrates (e.g. Gheerbrant et al. 2002,
2006; Gheerbrant, Domning & Tassy, 2005; Bourdon,
2006) have been discovered, including, for example,
the oldest evidence of Afrotheria (Gheerbrant, Sudre
& Cappetta, 1996; Gheerbrant, 2009).
In contrast, and probably due to the difficult access,
little attention has been paid to the Cenozoic depos-
its cropping out along the southwestern Moroccan
Sahara (‘Western Sahara’) and observed until the
1950s by Spanish, French and Moroccan geologists,
successively. Mainly composed of clastic deposits,
geological formations in the south of the Dakhla–
Boujdour–Laayoune basin (Fig. 1a) were until now
usually mapped as Mio-Pliocene (Saadi, 1988; Rjimati
et al. 2008). No evidence of fossil vertebrates older
Author for correspondence: sylvain.adnet@univ-montp2.fr
than the Neogene has been reported in previous
literature (Joleaud, 1907; Arambourg in Choubert
et al. 1966) until the recent discovery of shark teeth
and bone remains of archaeocete whales by local
people. Thanks to their information, an exploratory
field trip in 2009 in the south of the Dakhla peninsula
allowed us to locate these fossiliferous levels and to
discover many vertebrate fossils, collected in several
close localities. Dating interest becomes obvious,
considering that all taxa display many characteristics
of the Middle–Late Eocene assemblages known from
other African fossiliferous localities. The purpose of
this paper is to provide the first detailed sedimentary
log of the new fossiliferous localities, a preliminary
account of the taxa recovered, and to compare this
assemblage to other known Eocene assemblages that
have been reported elsewhere. In addition, we discuss
the stratigraphy and palaeoecological significance of
the new assemblages.
2. Geological setting
The sub-horizontal stratigraphical sequences visible
near Dakhla (Fig. 1b) show a slight syntectonic activity,
only marked at the top by some clastic dykes of yellow
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New Eocene vertebrates from southwestern Morocco 861
Figure 1. (a) Location of the new fossiliferous deposits (star), south of the city of ad-Dakhla, Moroccan Sahara, Morocco. Principal
geological structures simplified from Von Raad & Wissmann (1982), Saadi (1988) and Villeneuve (2005). (b) Outcrop on beach
illustrating the stratigraphical sequence as observed south of El Argoub (23
21
17.76

N, 16
01
55.28

W). Lithology is detailed in
text.
sandstone intersecting the underlying silt–chert suite.
This field observation is in agreement with that of
Labails et al. (2009), who noticed thick sedimentary
deposits offshore of Daklha, as indicated by seismic re-
flection data. This suggests a slight subsidence process
on this passive continental margin as a result of a tec-
tonic inheritance of the great Western African Craton
(Fig. 1a, anteclise of Reguibat; see Villeneuve, 2005).
The stratigraphical sequences (Fig. 2) crop out on
cliffs along the shoreline in a succession of beaches
from south of El Argoub to the commonly named
‘Garitas’ in a restricted military area. The bedrock
succession studied here is entirely observable from
the beach core (Fig. 1b) and accessible in few track
roads used by the local fishermen. Lateral variations of
facies are obvious, especially regarding the thickness
of sequences (see Fig. 2). We have divided these
sequences into three lithological units. Their ages,
mainly based on fossil marine vertebrates, will be
discussed hereafter.
The lower part of the sequences (unit 1; see
Figs 1b, 2) consists of a thick sequence of marly
siltstone, regularly interrupted by grey chert and black
coprolite-supported conglomerates. This alternating
succession sometimes displays composite marl or yel-
low sand beds, particularly towards the top of the unit.
The boundary between units 1 and 2 is easily detectable
and occurs over a distinctive irregular black quartzite
(except in the south where it disappears), and below
a yellowish-white marly siltstone with micro-remains
of fish. Burrows and flaser bedding are sometimes
observable inside this layer, mixing the fossiliferous
sand coming from the overlying bedrock B1. The
thickness of this layer seems to decrease from north
to south where it sometimes disappears. Unit 2 begins
with the previous bed, followed by the first fossiliferous
bed (B1) that in fact consists of two successive
layers: a fine compact conglomeratic sandstone at
the base (irregularly distributed), with imbedded teeth
and larger allochthonous elements which are badly
preserved; and a 0.8–1.2 m thick medium sandstone
with clay and phosphate grain elements. No calcareous
fossil was found in this sandstone, which can range
from grey to brown or reddish colour. The contact
between B1 and the upper strata is a distinctive irregular
erosion surface, emphasized by many burrows and/or
interbedded pockets of B1. Over a massive bedrock of
5–10 m of composite white siltstone–chert, the upper
fossiliferous bed (B2) consists of a muddy sandstone,
sometimes with a gypsum element present. The contact
between B2 and the overlying series is badly defined
in the sandstone thickness and seems irregular, but B2
always overlies a sandy layer with a high concentration
of gypsum. Unit 2 ends with yellow muddy sandstone
softly consolidated with irregular pockets of red muddy
sandstone. The boundary between units 2 and 3 is not
very distinctive and occurs below white calcareous
cemented sandstone. The upper part of the sequence
(unit 3) consists of a massive sandy to bioclastic
limestone, with ripple stratification (particularly in the
Dakhla peninsula), partially replaced by dolomite and
containing numerous invertebrate fossils or tracks. This
perched bedrock, laterally irregular, caps the sediment-
ary series and constitutes the accessing headland that
runs along the coast line. Many rhizoliths occur in the
calcareous sandstone, just below the sandy limestone
boundary. This unit is thin further south, as observed
in ‘Garitas’.
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862 S. ADNET, H. CAPPETTA & R. TABUCE
Figure 2. Stratigraphical section, position of the main fossil ver-
tebrate levels (B1, B2 and intermediate) and unit interpretation
of study area. Lithology is detailed in text. Location of section
is indicated by distance south from the centre of Dakhla.
Deposits in the lower part of the sequence (unit 1) are
entirely marine, as indicated by the numerous silicate
beds, chert and coprolite-supported conglomerates
dispersed along the column. Very scarce fossil shells
or teeth have been discovered from the visible base of
unit 1 to the top of unit 2. A metre-sized bed with large
black nodules occurs at the extreme base of the series,
when accessible under the beach sand dune.
The upper part of the sequence (unit 3) was mainly
formed by marine processes as well, as it consists of
a thick sandstone complex in the studied area, with
marine fossils (echinids, bivalves and gastropods) from
the base to at least 1 m below the massive sandy
limestone. The presence of a dense root system and/or
burrows in this level may suggest the mangrove soil
(vertical pneumatophores) of a tropical area, overlain
by a coastal deposit, as indicated by the presence
of numerous tracks of marine organisms inside the
massive sandy limestone.
3. Systematic palaeontology
The previously described vertebrate fauna from the Dakhla–
Boujdour area (‘Rio de Oro’ in Joleaud, 1907; Arambourg
in Choubert et al. 1966) probably comes from the massive
limestone or lateral equivalents (formerly molasse; Joleaud,
1907), which sporadically turn into a shelly limestone
(pectinid) in the Dakhla peninsula. These authors cited
Galeocerdo aduncus, Sphyrna prisca, Odontaspis con-
tortidens, O. cuspidata, Oxyrhina hastalis, Carcharodon
megalodon, C. rondeletii, Myliobatis faujasi, Diodon sp.
and Chrysophrys sp.’ The accurate Mio-Pliocene age
attributed to these fossil vertebrates was in agreement with
the contemporaneous geological literature (Font y Sague,
1911; Deperet, 1912; Hernandez et al. 1949) and with
observations of the invertebrate palaeontologists (Lecointre,
1962, 1963a,b, 1966a,b; Roman, 1963) who considered the
massive limestone of ‘Rio de Oro’ (up to 10 km south of
Dakhla) as Pliocene (or younger) in age. The age of the
underlying deposits (white calcareous sandstone with fossil
root mark, unit 3) is currently unknown but we provisionally
propose a Miocene age, as suggested by the presence of
several Miocene equatorial fossil woods discovered in the
Dakhla area (Lecointre & Koeniguer, 1965; Koeniguer, 1967;
updated in Dup
´
eron-Laudoueneix & Dup
´
eron, 1995). The
lower part of the sequence (units 1–2) has never been of
particular interest to palaeontologists. Only Ortlieb (1975)
reported several observations in the ‘Garitas-Amtal’ area,
where he collected fossil shark teeth (sent to one of us, HC)
and bone fragments in ‘the yellow calcareous or muddy sand-
stone, located over (northward) or below (southward) some
marly sand deposits with gypsum’. While this author pointed
out the helpful regularity of the fossiliferous deposit from
‘Garitas’ to Amtal’ towards the south, he only considered
one level and could not propose any age for these layers.
New fossils were collected by surface collecting and
screen-washing. A total of seven samples of sediment were
taken during a short field trip in 2009. Every sample varied
between 2 kg and 20 kg of residue previously concentrated
by screen-washing (mesh width down to 0.4 mm). In a
further step, the insoluble residue was disaggregated by
immersion in diluted acetic acid (6 %) or fresh water. The
selachians represent the largest part of the fossil vertebrate
remains recovered in unit 2, with several thousand specimens
collected, equally distributed in samples. The majority of
the fossil material consists of isolated teeth (plus partial
tooth plates and caudal spines of myliobatid rays, and
undetermined vertebrae) representing at least 48 species of
sharks and rays. A preliminary list is given in Table 1. Some of
them are new and will be described in detail in a forthcoming
work devoted to this vertebrate group. Discussions on
significant taxa regarding dating and correlation have been
favoured in the present study. Isolated teeth, rostral elements
and disarticulated bones of bony fish recovered along unit 2
will not be treated here, awaiting supplementary samples
of matrix. Two other taxonomic groups of vertebrates were
discovered in unit 2 (B1 and B2). These comprise some
remains of archaeocete whales and one broken tooth of
a terrestrial mammal. The former are often reduced to
isolated and badly preserved bones and teeth (DAK.5, Fig. 3j)
that clearly belong to Basilosauridae, but some complete
skeletons, partially disarticulated, were observed in situ.Itis
beyond the scope of this paper to report on this promising
discovery for cetacean palaeobiogeography and, concerning
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New Eocene vertebrates from southwestern Morocco 863
Table 1. Preliminary list of fossil vertebrates recovered in study
area
Taxa B1 B2
Selachians
O. Lamniformes
Otodus cf. sokolovi ++
‘Cretolamna’ twiggsensis +++ +++
Macrorhizodus praecursor +++ +++
Carcharias sp. +++
‘Carcharias’ koerti ?reworked
Alopias aff. alabamensis ++ ++
Xiphodolamia serrata +
O. Orectolobiformes
Nebrius cf. obliquus ++
Chiloscyllium spp. +
O. Carcharhiniformes
Scyliorhinus spp. ++
Carcharhinus frequens +++ +++
Carcharhinus spp. ++++ ++++
Rhizoprionodon sp. +++ +++
Misrichthys stromeri ++
Abdounia spp. ++ ++
Galeocerdo cf. eagleasomi ++ ++
Galeocerdo sp. ++
Physogaleus sp. ++ ++
Hemipristis curvatus ++ ++
Paragaleus sp. ++ ++
Galeorhinus spp. ++
Sphyrna sp. ++
O. Rajiformes
Rhynchobatus sp. ++ ++
Rhinobatos spp. (+ oral teeth of pristids) ++ +
Pristis cf. lathami (rostral teeth) ++
Propristis schweinfurthi (rostral teeth) ++
Anoxypristis sp. (rostral teeth) ++
O. Torpediniformes
cf. Narcine sp. +
O. Myliobatiformes
Dasyatis spp. +++ +++
Himantura spp. +
Gymnura sp. +
Ouledia sp. +
Aturobatis sp. +
Myliobatis spp. +++ +++
Rhinoptera sp. +++ +++
Aetobatus cf. irregularis ++
Garabatis sp. +
Archaeomanta sp. +
Burnhamia sp. +
Mobula sp. ++
Selachian incertae sedis
Odontorhytis sp. ++
Actinopterygians
O. Perciformes
Sphyraena sp. ++ ++
Trichiurides sp. ++ ++
Cyladrincanthus sp. +
Mammals
Archaeocete indet. ++ ++
?Numidotherium sp. ?reworked
Number of +’ symbols indicates the relative abundance in B1 and
B2.
the mammalian remains, we have only focused on the
primitive proboscidean tooth (GTS.1) found in B1.
The material is housed in the Laboratory of Paleontology,
Institut des Sciences de l’Evolution, Montpellier. Abbre-
viations: DAK collection number for material from the
Dakhla area, GTS – collection number for material from the
Dakhla area, locality of ‘Garitas’.
3.a. Fish fauna
The fish fauna currently consists of 48 fossil species of
elasmobranches and 4 fossil species of bony fishes. Forty
genera and seven orders are represented, ranking this fossil
site in the top ten of the most diversified selachian faunas
from the Cenozoic in Africa. Most of these species are
new and under study, awaiting careful comparisons with
those from the contemporaneous deposits of the Whale
Valley (Fayum, Egypt; see Case & Cappetta, 1990) that are
currently undergoing revision (C. Underwood & D. Ward,
pers. comm.). Only a limited sample of selachian taxa having
an interest for correlation is figured and briefly discussed
here.
Locality. Unit 2, B1 and B2 from all sites, ?Samlat Fm.,
?Gerran member (Ratschiller, 1967).
Class CHONDRICHTHYES
Several modern orders of selachians (sensu Compagno,
2005) are represented in the fossil deposits (see Table 1).
However, Hexanchiformes, Squatiniformes, Heterodonti-
formes and Squaliformes are completely lacking.
Lamniformes: Numerous complete and well-preserved
teeth recovered in L1 and L2 (DAK.2–3; Fig. 3c, d) belong to
Cretolamna’ twiggsensis (Case, 1981), the youngest species
of the genus which was discussed and adequately illustrated
by Case & Cappetta (1990, pp. 9–10, pl. 3). This species
is easily recognizable by a pair of double flat cusplets on
anterior (Fig. 3c) and on lateral teeth (Fig. 3d). The range of
this species is restricted to the Middle–Late Eocene interval
and its geographical distribution extends to palaeotropical
seas between the Caribbean, western Tethys (Case, 1981;
Case & Borodin, 2000) and oriental Tethys (Casier, 1971;
Case & Cappetta, 1990; Case & West, 1991; Adnet et al.
2007).
Complete teeth of Otodus cf. sokolowi (Jaekel, 1895)
(often called Carcharocles’) are less common in B1 and
B2 but relatively well preserved also. The teeth can reach
up to 10 cm in height, displaying a large triangular cusp
with a well-marked and regular serration on the cutting
edges (DAK.1; Fig. 3a), and a pair of lateral cusplets,
not very high and often divergent in lateral teeth to less
developed in anterior teeth. Case & Cappetta (1990, pp. 6–7)
have extensively discussed the taxonomic ambiguity within
other Eocene species, and particularly in the smaller species
Otodus auriculatus (Blainville, 1818), commonly recorded
in Eocene deposits worldwide (e.g. Ward & Wiest, 1990;
Dutheil, 1991; Long, 1992; Cappetta & Stringer, 2002).
The occurrence of ‘Carcharias’ koerti (Stromer, 1910)
(genus status unclear, see Strougo, Cappetta & Elnahas,
2007) is quite surprising because this large pelagic shark is
only known from Lutetian deposits widely distributed around
Northern and Western Africa (Strougo, Cappetta & Elnahas,
2007; Cappetta, Pfeil & Schmidt-Killer, 2000; Cappetta,
1987; Cappetta & Traverse, 1988; Noubhani & Cappetta,
1997; White, 1955; Dartevelle & Casier, 1959). However, all
the teeth belonging to ‘C.’ koerti were found in situ inside
the hard bone bed (as DAK.4; Fig. 3i) at the base of B1,
and their state of preservation is clearly different from all the
other taxa, showing a worn patina, blunted cutting edges and
sometimes many marks that suggest a reworking from older
deposits (Fig. 3i2).
The species Xiphodolamia serrata (GTS.2, Fig. 3b),
recently described from Priabonian deposits of Jordan, Iran
and Angola (Adnet et al. 2009), is probably one of the most
important elements for dating of the Dakhla deposits.
Carcharhiniformes: One of the unnamed species of
Carcharhinus (DAK2B.1; Fig. 3g) belongs to the ‘bull-
shark’ group among Requiem sharks (see Adnet et al.
2007) and displays upper teeth with a modern morphology
compared to those of species known in the worldwide
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864 S. ADNET, H. CAPPETTA & R. TABUCE
Figure 3. Fossil selachians from Dakhla area. (a) O. cf. sokolowi (DAK.1), 1 labial view, 2 lingual view; (b) X. serrata (GTS.2),
1–prole,2–labialview;(c,d)‘C.’ twiggsensis (DAK.2–3), 1 – labial view, 2 – lingual view; (e) G. cf. eaglesomi (DAK1.1), 1
labial view, 2 – lingual view; (f) M. stromeri (upper tooth) (DAK2A.1), 1 – labial view, 2 – lingual view; (g) Carcharhinus sp. (upper
tooth) (DAK2B.1), 1 labial view, 2 lingual view; (h) P. schweinfurthi (rostral tooth) (GTS.3), 1 basal view, 2 upper view; (i)
C.’ koerti (partially embedded) (DAK.4), 1 – labial view, 2 – lingual view; (j) posterior (lower) tooth of Basilosauridae (DAK.5).
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New Eocene vertebrates from southwestern Morocco 865
Eocene seas, including those from the Late Eocene of the
southern USA (e.g. C. gilmorei: White, 1956; M
¨
uller, 1999).
If the upper teeth (from B1 and B2) are reminiscent of
the Late Eocene and Oligocene specimens from Pakistan
(Adnet et al. 2007), Egypt (Case & Cappetta, 1990, figs
164, 165; Murray, 2004) or Oman (Thomas et al. 1989),
there are important differences in crown and root shape
(more rectangular) that will require further comparisons.
Nevertheless, the presence of such modern Carcharhinus
species in the Late Eocene of Western Tethys brings into
question the palaeobiogeographical scenarios proposed in
Adnet et al. (2007) about the modern rise of large Requiem
sharks.
The peculiar carcharhinid Misrichthys stromeri (Case &
Cappetta, 1990) seems to be restricted to the Bartonian and
Priabonian of Egypt (Fayum, gebel Mokattam and Western
Desert: pers. obs.) and Priabonian of Jordan (Mustafa &
Zalmout, 2002). This is the first occurrence (DAK2A.1,
Fig. 3f) outside the Near East. Relatively scarce, teeth of
this species have been found in B1 and B2 of unit 2.
Teeth of Galeocerdo cf. eaglesomi (DAK1.1, Fig. 3e)
are similar in shape to G. eaglesomi (White, 1955) but are
two times larger than the type Lutetian material coming
from Ameki, Nigeria (White, 1926, pl. 6 and White, 1955,
holotype included), the upper bone bed (BBR) from Togo
(Cappetta & Traverse, 1988) and from the Western desert in
Egypt (Strougo, Cappetta & Elnahas, 2007). As this material
may be considered to be younger in age (both B1 and
B2), an increase of size in the ‘lineage’ eaglesomi is thus
conceivable and this is the reason we only refer this species
to G. eaglesomi.
Two Carcharhiniform taxa are presently recorded for the
first time in the Eocene: Paragaleus and Sphyrna.Thefirst
is the earliest occurrence for this genus which was unknown
before the Miocene, and the second has been confidently
known since the Lower Oligocene (Adnet et al. 2007).
Rajiformes: Rostral teeth (GTS.3; Fig. 3h) of the sawfish
Propristis schweinfurthi (Dames, 1883) are unusual and
easily distinguishable from other fossil or living Pristidae.
This species is known from the Middle–Late Eocene of
the Tethyan realm from the Caribbean (Case, 1981; Case
& Borodin, 2000; Cappetta & Stringer, 2002) to Egypt
(Case & Cappetta, 1990) and in the north (D. Kemp, unpub.
Ph.D. thesis, Univ. Portsmouth, 1994) and south Atlantic
coasts (White, 1926; Dartevelle & Casier, 1959; Cappetta &
Traverse, 1988).
All the fossil batoids recovered here display an occurrence
compatible with a Bartonian–Priabonian age, except two
fossil Myliobatiformes that were previously unknown after
the middle Eocene: Aturobatis (Ypresian of USA, Lutetian
of southwestern France) and Garabatis (Thanetian–Lutetian
of Morocco).
Selachian incertae sedis: Occurrence of the enigmatic
genus Odontorhytis (see Cappetta, 1987) is not surprising
because it is relatively common in the Eocene coastal deposits
of the Tethyan Realm, from North Morocco (Cappetta, 1981)
to Egypt (Case & Cappetta, 1990; Strougo, Cappetta &
Elnahas, 2007; T. Cook & A. Murray, pers. comm.) and
Pakistan (Case & West, 1991). Recorded in B1 and B2, these
teeth seem different, however, from those of the Bartonian–
Priabonian Egyptian species O. pappenheimi B
¨
ohm, 1926 in
having a more slender cusp and less massive root.
Class ACTINOPTERYGII
Currently restricted to isolated teeth and broken bones,
fossil material of marine bony fishes (Perciformes) has
been identified as Sphyraena sp. (Sphyraenidae), Trichiurides
sp. (Trichiuridae incertae sedis) and Cylindracanthus sp.
(Xiphiidae) with very similar morphologies to those pub-
lished by Case & Borodin (2000), who reported
Sphyraena
sp., Trichiurides sagittidens (Winkler) and Cylindracanthus
cf. rectus (Dixon) from the Late Eocene of the Irwinton Sand
Member, Georgia.
3.b. Class MAMMALIA
The unique tooth comes from the base of B1 and belongs to
a terrestrial mammal. Due to its rarity and importance, it is
here described in detail.
Mirorder TETHYTHERIA McKenna, 1975
Order PROBOSCIDEA Illiger, 1811
Genus Numidotherium Mahboubi et al. 1986
?Numidotherium sp.
Referred specimen. GTS.1; left M
1or2
(Fig. 4) (length =
41 mm; width = 36 mm)
Locality. Unit 2, brown hard ground of the B1 north of
‘Garitas’. ?Samlat Formation, ?Gerran member (Ratschiller,
1967).
Description. The crown is brachyodont and rectangular
in occlusal view; its morphology is characterized by a
bilophodont pattern and a typical true lophodonty without
any trace of conules (Fig. 4a). Protoloph and metaloph are
slightly anteriorly convex. The metaloph does not reach
the top of the acute metacone. Wear affects the mesial
wall of both lophs. The hypocone and the protocone are
labially situated on the crown and their lingual walls are
sloping toward the base of the tooth; the paracone and
metacone are smaller than the lingual cusps. Despite the
poor preservation of the specimen in its external margins,
a mesial cingulum and a small style at the lingual side of
the interloph are visible. The preservation does not allow the
observation of the potential occurrence of both the parastyle
and postentoconule; the number and morphology of the roots
are also unknown. The distocrista reaches the hypocone to the
distal cingulum; there is no postmetacrista or metastyle. The
postparacrista and the crista obliqua are tenuous. The enamel
microstructure, studied according to the method described
by Tabuce, Delmer & Gheerbrant (2007), is characterized by
a schmelzmuster composed of 3-D enamel (thick bundles of
prisms decussate in all directions) (Fig. 4). In large areas the
vertical component of the decussation is attenuated, evoking
Hunter-Schreger bands (Fig. 4b).
Comments. The true lophodont molar morphology and
the bilophodonty of this specimen suggest affinities with
some deinotheriines or ‘barytherioid’ prosboscideans. The
deinotheriines Prodeinotherium and Deinotherium share
with the Dakhla proboscidean a one-layered schmelzmuster
composed of 3-D enamel (Tabuce, Delmer & Gheerbrant,
2007), in addition to their bilophodont M2 (their M1 is
trilophodont). These deinotheriines differ, however, in having
a complete distocrista linking the hypocone to the top of the
metacone. The earliest putative deinotheriid, Chilgatherium
from the Late Oligocene of Ethiopia (Sanders, Kappelman &
Rasmussen, 2004), differs in the bunolophodont morphology
of its cheek teeth. The ‘barytherioids’, which include one
of the oldest representatives of the proboscideans, are
possibly paraphyletic taxa (see Gheerbrant et al. 2005);
they are composed of Numidotherium koholense (Mahboubi
et al. 1986; Noubhani et al. 2008) and Daouitherium
rebouli (Gheerbrant et al. 2002) from the Early Eocene
of Algeria and Morocco, respectively, plus Barytherium
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866 S. ADNET, H. CAPPETTA & R. TABUCE
Figure 4. Dakhla proboscidean, left M
1or2
(GTS.1) in occlusal view (a); vertical section of the enamel under the paracone (b).
Figure 5. Measurements of the M
1or2
of the Dakhla proboscidean
compared with Numidotherium koholense and Barytherium
grave.
grave from the Late Eocene to Early Oligocene of Fayum
(Egypt) and Dor El Talha (Libya) (see Shoshani et al.
1996; C. Delmer, unpub. Ph.D. thesis, MNHN Paris, 2005),
and possibly Phosphatherium escuilliei from the Early
Eocene of Morocco (Gheerbrant, Sudre & Cappetta, 1996;
Gheerbrant et al. 2005). Within ‘barytherioids’, GTS.1 is
intermediate in size between Barytherium grave and N.
koholense or Daouitherium (Fig. 5). Other comparisons with
Daouitherium, unknown by its upper molars, are impossible.
Daouitherium,asPhosphatherium, differs from the Dakhla
proboscidean, however, in having a distinct schmelzmuster
composed of true Hunter-Schreger bands (Tabuce, Delmer
& Gheerbrant, 2007). Phosphatherium differs in addition
in having a much smaller size (nearly four times), a
mesostyle and a premetacrista. Numidotherium koholense
and Barytherium grave are more like the specimen studied
here, with their larger size, a more advanced lophodonty,
and by the schmelzmuster composed of 3-D enamel. The
occurrence of incipient Hunter-Schreger band-like structures
in the enamel microstructure of N. koholense is peculiarly
similar to the morphology observed in the Dakhla specimen.
Moreover, the latter and N. koholense share lophs that are
less convex relative to Barytherium grave. N. koholense also
differs from Barytherium in the occurrence of a parastyle
and postentoconule; unfortunately, these characters cannot
be checked on GTS.1 due to the preservation of the specimen.
According to C. Delmer (unpub. Ph.D. thesis, MNHN Paris,
2005), N. koholense and Barytherium share the occurrence
of a postparacrista II. This structure is lacking in GTS.1,
but we consider that this trait is too variable and tenuous,
at least on N. koholense, to reject the attribution of GTS.1
to ?Numidotherium. Comparisons are also necessary with
Arcanotherium savagei, another bilophodont species from
the Late Eocene to Early Oligocene of Dor El Talha
(Court, 1995). Initially related to N. koholense, notably
based on its bilophodonty, Arcanotherium savagei was
recently excluded from the ‘barytherioid’ proboscideans by
Delmer (2009). This author considers that this taxon is
in fact more related to the bunolophodont proboscideans
such as Moeritherium and Elephantiformes. It differs from
the specimen studied here in having crenulated enamel, a
paraconule, a postprotocrista, and an incipient convolute that
pre-dates the third loph observed on the upper molars of
the elephantiforms Phiomia and Palaeomastodon. The three-
layered schmelzmuster of Arcanotherium savagei is also
reminiscent of these genera (Tabuce, Delmer & Gheerbrant,
2007) and clearly differs from that observed on GTS.1.
To conclude, the molar morphology of GTS.1, notably
its slightly convex lophs compared to Barytherium and
its enamel microstructure, suggests more affinities with
Numidotherium than with the other proboscideans. Some
critical characters that define N. koholense (parastyle and
postentoconule) need to be checked on more preserved
material. If these characters were absent, GTS.1 could
represent a new taxon. Its size (intermediate between
N. koholense and Barytherium) and its Middle/Upper Eocene
age (compared to the Ypresian age of N. koholense) could
support this hypothesis.
4. Dating and palaeoenvironment
No mention of outcropping Palaeogene deposits has
been noted in the literature concerning the Dakhla
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New Eocene vertebrates from southwestern Morocco 867
area and the Palaeogene is only mentioned in a core
sample from the offshore basin (C. Labails, unpub.
Ph.D. thesis, Univ. Brest, 2007) or limited to the
northeastern part of the Dakhla–Laayoune–Tarfaya
basins where Palaeogene deposits (Samlat Formation
in Ratschiller, 1967) overlie the Cretaceous, and consist
of marine siliceous chalk (Davison, 2005). Within
this unit, the Eocene Guerran Member (Ratschiller,
1967) is mainly characterized by clastic sediments with
calcareous and marl intercalations, probably belonging
to the clastic event of the Priabonian suggested by
Swezey (2009) for Western North Africa (clastic
dominance between marine mudstone and gypsum
or gypsiferous mudstone). The stratigraphical age of
this member must be pondered, but it seems to be
capped by a regional unconformity, which is labelled
‘end-Eocene’ in Swezey (2009) and ‘Base Oligocene
Unconformity’ in Guiraud et al. (2005). Overlying this
unconformity, the Oligocene Morcba member (in the
Samlat Formation: Ratschiller, 1967) reaches up to
300 m in thickness and consists mainly of continental
sandstone and conglomerate in the Aaiun area. This
member is possibly missing in the Dakhla area. The
Neogene is generally thin (< 100 m) and is only
exposed onshore in the western part of the basin. Sandy
limestone and oyster beds are the main lithologies
reported, as observed in the Dakhla area.
No foraminifera or nannoplankton assemblages were
detected in the sampled clastic sediments along the
observed series, excluding more precise biostratigraph-
ical correlations. However, there is no doubt that units 1
and 2 are Palaeogene in age because unit 2 is currently
dated from the late Middle Eocene (Bartonian) or Late
Eocene (Priabonian) according to its palaeontological
content and evidence as exposed below. Units 1–2
are probably the southwestern equivalent in age of
the Itgui–Gerran members of the Samlat Formation
(‘Boujdour-Aaiun’ area in Ratschiller, 1967). It is
noteworthly that this author mentioned a similar fossil
association with fossil shark teeth, coprolites, fish re-
mains and invertebrates in clastic deposits of the Gerran
Member (dated to Eocene) near Samlat Amgrash. The
majority of taxa recovered in B1 and B2 are known
elsewhere in Bartonian and Priabonian deposits, such
as the Basilosauridae which worldwide are recovered
exclusively in these stages (Uhen, 2008). Only one
taxon, Xiphodolamia serrata Adnet et al. 2009 (GTS.2,
Fig. 3b) is currently restricted to the Late Eocene period
only (Adnet et al. 2009). The other part of the fauna
either (1) shows a stratigraphical range spanning more
Palaeogene stages or (2) has not yet been recorded
in the fossil state until now. Besides this strong clue,
the modern occurrence of some taxa (e.g. presence
of Mobulidae, modern Carcharias and Carcharhinus,
very large C.’ twiggsensis and G. aff. eaglesomi,
many Hemipristis curvatus), as well as the faunal
association type (abundance of Carcharhiniformes,
especially Carcharhinus, few Orectolobiforms) rather
support a Priabonian age, even if we cannot definitively
exclude a late Middle Eocene age for unit 2 also.
The age of the base of unit 2, displaying the brown
hard bone bed (with evidence of reworked early Middle
Eocene sharks and one terrestrial mammal), remains
unclear even if we suspect a Priabonian age as well,
remixing a few older elements coming from areas
nearby (e.g. C. koerti). This peculiar deposit is not
laterally continuous and no evidence of unconformity
was detected. The local presence of early Middle Eo-
cene fossiliferous sediment is only suspected, because
of the very large number of remixed elements that
we found in situ. Further detailed sedimentological
analysis and palaeontological elements must confirm
this assumption. The difference in age between B1
and B2 is not at all obvious, as they display the same
fossil species assemblages (see Table 1). Only future,
precise analyses of fossil samples can resolve this
point. Scarce fossil vertebrates have been discovered
in unit 1 and none in unit 3 of the study area but
the age of the top of the series (unit 3) was largely
discussed in the description of the geological setting
(Section 2). This probably corresponds to the Graret
Fartet member, mapped southwest of El Argoub by
Rjimati et al. (2008) and probably equivalent to the
Aaiun Formation (Ratschiller, 1967).
The selachian association shows great similarity
with those previously published from the Qasr el-
Sagha Formation and Birket-el-Qurun, Egypt (Stromer,
1905; Case & Cappetta, 1990; C. Underwood &
D. Ward, pers. comm.), Qa’Faydat ad Dahikiya in
the Wadi Esh-Shallala Formation, Jordan (Mustafa &
Zalmout, 2002; HC, pers. observ.), or the Dash-I-Goran
Formation, Pakistan (Adnet et al. 2007). It clearly
indicates marine deposits (B1 to B2) with elements of
tropical environment (e.g. numerous Carcharhinidae,
Pristidae, Mobulidae and other Myliobatiforms), an
assumption consistent with its past geographical
position, considering that the African plate moved
northwards and anticlockwise to reach a position during
the Late Eocene of approximately 6–8
latitude south of
its current position (Swezey, 2009), namely at latitude
15–18
N.
The slight differences in faunal composition and
preservation observed laterally or between B1 and
B2 are probably related to local change of tidal
environment, as observed in Wadi Al-Hitan, Egypt
(Peters et al. 2009). In this last work, most of the marine
vertebrate remains occur in condensed stratigraphical
intervals and the taxonomic composition changes
despite their proximity. The proximity of an emerged
land (that probably occurred in the Reguibat shield
to the east) with terrestrial fauna is now confirmed
by the occurrence of ?Numidotherium sp., even if it
is premature to correlate the terrestrial taxa with the
marine sandstone that yielded the main fish fauna.
5. Conclusions
Middle to Late Eocene marine deposits of the Near
East (northern Egypt, eastern Jordan) have yielded
numerous fossil vertebrates, mixing marine mammals
http://journals.cambridge.org Downloaded: 29 Sep 2010 IP address: 162.38.183.2
868 S. ADNET, H. CAPPETTA & R. TABUCE
and selachians (e.g. Case & Cappetta, 1990; Gingerich,
1992; Zalmout, Mustafa & Gingerich, 2000; Mustafa
& Zalmout, 2002). Wadi Al-Hitan (‘the Whale Valley’,
northern Egypt) has been classified as a World Heritage
site since 2005 (UNESCO), partly in recognition of
its palaeontological importance for the knowledge of
cetacean evolution (see Gingerich, 2007). Extensions
of a similar depositional environment and faunal
associations of the same age towards the Atlantic coast
are obviously linked to the high sea-level sequences
(e.g. Miller et al. 2005) and a lack of barrier during this
period (Meulenkamp & Sissingh, 2003; Guiraud et al.
2005). However, the remarkable similarity of tropical
and demersal taxa (e.g. Pristidae, Carcharhinidae,
Myliobatiformes) is noteworthy and implies a large
longitudinal marine faunal exchange along the south
coast of the Tethys and towards the Eastern Atlantic
at the end of the Eocene. Concerning the selachians,
there is no doubt that forthcoming taxonomical study
will strengthen the affinities presently observed with
the Fayum and will present a considerable potential
for broad-scale stratigraphical correlation between
Western North Africa and well-dated sites in the Middle
East. This preliminary report clearly confirms the
palaeontological interest of the Dakhla deposits which
greatly justifies further effort.
Acknowledgements. The authors are indebted to G
´
erard
Barbe and the local people who helped us during the field
trips, as well as B. Marandat and A. Ramdarshan for their
thorough review of the final manuscript. An anonymous
referee is thanked for his/her helpful suggestions to greatly
improve the quality of this paper. Contribution ISE-M no.
2010-007.
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... Studies in other Moroccan External Rif (Asebriy, 1984(Asebriy, , 1994 and Saharan areas (Swezey, 2009;Adnet et al., 2010) have found evidence of similar sedimentary evolution (carbonate platform development), which allows us to propose middle-late Eocene global warming as the main control on sedimentation. Also, studies in the African continent allow us to propose episodes of climatic and tectonic (continent rising since Eocene times) interference as controls on sedimentary evolution and the development of unconformities (Burke and Wilkinson, 2016;Carena et al., 2019). ...
... The data in this paper and the other published data (e.g., Swezey, 2009;Adnet et al., 2010;Melki et al., 2011;Burke and Wilkinson, 2016;Bejaoui et al., 2017;Carena et al., 2019) on the External Betic Zone, Tunisian Tell, and other African regions indicate that a paleogeographic reorganization of the external domains in the westernmost Tethys occurred after the Cretaceous. This reorganization would have caused unconformities and lateral variations of lithofacies and strata thicknesses. ...
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Article
This paper provides an understanding of the sedimentary-tectonic evolution of the Cenozoic strata of the El Habt and Ouezzane Tectonic Units (Intrarif, External Rif) in Morocco. New data provide information about the depositional architecture and enable a correlation of the evolution of the External Rif in Morocco with that of the Betic Cordillera in Spain and the Tunisian Tell, which provides new insights for hydrocarbon exploration in the region regarding possible source, reservoir, and seal rocks. The reconstructed Cenozoic succession was bio-chronologically defined, and the major unconformities and stratigraphic gaps were identified. The presence of these unconformities allowed three main stratigraphic sequences to be defined by age: Danian p.p., early Ypresian-early Bartonian p.p., and the early Rupelian-early Ser-ravallian p.p. Three secondary stratigraphic sequences in the former upper main sequence were also defined by age: early Rupelian-late Chattian p.p., Burdigalian p.p., and the Langhian-Serravallian p.p. The depositional setting evolved from deep basin during the Late Cretaceous-Paleocene to external platform-slope during the Eocene-Miocene. The Cenozoic sandstones contain metamorphic and sedimentary rock fragments derived from a recycled orogen source area. The clay mineralogy in the Cenozoic strata consists of associations of Ill+(I-S) ± Sme, Ill+(I-S) ± Sme+Kln and Ill+(I-S) ± Sme+-Kln+Chl. These associations indicate an initial unroofing in the Paleogene period, then in the Cretaceous period, and finally in the Late Jurassic period during the Eocene-Oligocene. This detritus was followed by variable amounts of a sedimentary mix of Paleogene to Late Jurassic terrains due to several phases of erosion and deposition partly related to syn-sedimentary tectonics during the Miocene. Equivalent features (similar types of sediments, tectofa-cies, gaps, and unroofing) were also recognized along the Betic Cordillera in Spain and Maghrebian Chain (Morocco and Tunisia) and interpreted as related to a pre-nappe tectonic activity of soft basement folding, which occurred during the Paleogene after the generalized tectonic inversion (from extension to compression) occurred in the Late Cretaceous. The Upper Cretaceous is considered to be the hydrocarbon source rock, while the fractured Eocene and the porous Oligo-Miocene suites are proposed as possible hydrocarbon reservoirs. The Cenozoic stratigraphic architecture and the nappe structure of the region could provide the necessary trap structures.
... Recent discoveries in eastern and North Africa, as well as in the Arabian Peninsula, have documented important proboscidean evolutionary steps at the Late Palaeocene-Early Eocene transition [3][4][5][6] and at the Late Eocene-Early Oligocene transition [7][8][9][10][11][12][13]. Two main temporal cohorts could then be identified [1]: the Early Palaeogene basal taxa including eritheres, phosphatheres, daouitheres and numidotheres, characterized by small to medium sizes and more archaic features (e.g. the inferred absence of a trunk or lesser development of incisors); and the Late Palaeogene taxa including barytheres, arcanotheres, moeritheres, deinotheres and elephantiforms (palaeomastodonts and elephantimorphs), characterized by medium to large sizes and more derived cranio-dental characteristics. ...
... In total, we added seven new characters, including two new characters on the enamel microstructure (following [9]): ...
Article
Africa has played a pivotal role in the evolution of early proboscideans (elephants and their extinct relatives), yet vast temporal and geographical zones remain uncharted on the continent. A long hiatus encompassing most of the Eocene (Ypresian to the Early Priabonian, around 13 Myr timespan) considerably hampers our understanding of the early evolutionary history of the group. It is notably the case with the origin of its most successful members, the Elephantiformes, i.e. all elephant-like proboscideans most closely related to modern elephants. Here, we describe a proboscidean lower molar discovered in Lutetian phosphate deposits from Togo, and name a new genus and species, Dagbatitherium tassyi. We show that Dagbatitherium displays several elephantiform dental characteristics such as a three-layered Schmelzmuster, the presence of a mesoconid, transversely enlarged buccal cusps and the individualization of a third lophid closely appressed to a minute distal cingulid. Dagbatitherium represents a stem Elephantiformes, pushing back the origin of the group by about 10 Myr, i.e. a third of its currently known evolutionary history. More importantly, Dagbatitherium potentially unlocks the puzzle of the origin of the unique elephantiform tooth crown organization by bridging a critical temporal and morphological gap between early bunodont incipiently bilophodont proboscidean taxa and more derived elephantiforms.
... Discussion: The morphology of the tooth is highly concordant with other descriptions and illustrations of the species Otodus (Carcharocles) sokolovi (Applegate and Espinosa-Arrubarrena 1996;Mustafa and Zalmout 2002;Adnet et al. 2010). We consider this species to be part of the chronospecies that starts in the Palaeocene with the unserrated species O. (Otodus) obliquus (Agassiz, 1843), that later acquired uneven and unequal serrations in O. (Carcharocles) aksuaticus (Menner 1928) (Purdy 1996;Maisch et al. 2014). ...
... Also, it seems that this species is ignored as a stage of the chronospecies mentioned above, as is the case for the rarely acknowledged O. (C.) aksuaticus. Otodus (C.) sokolovi was reported in Ukraine (Jaekel 1895), Jordan (Mustafa and Zalmout 2002;Mustafa et al. 2005), Egypt (Case and Cappetta 1990;Zalat et al. 2017), Morocco (Adnet et al. 2010), Uzbekistan (Case et al. 1996;Malyshkina and Ward 2016), Kazakhstan (Zhelezko and Kozlov 1999), and even Antarctica (Kriwet et al. 2016). Since our sample is small, the descriptive morphology of the species in the subgenus Carcharocles is complicated, and not enough is known about ontogeny, heterodonty and and intraspecific variation within this taxon we will add the confer abbreviation for the species. ...
Article
The Călata site (north-west of Transilvanian Basin, Romania) includes the Ciuleni Member of the middle Eocene-age Mortănușa Formation, a marine deposit in an outer, open marine facies, from where fossil vertebrates were very poorly known. In the last four years, nearly 150 remains of fish (mostly teeth) were recovered from the Călata site. We identified 21 taxa representing 20 genera that belong to 12 orders of chondrichthys and teleostei fishes. This study is the first to report Rostroraja and Palaeocybium from Romania, and we report seven additional genera from the Bartonian of Romania for the first time. We performed analysis of calcareous nannoplankton and foraminifera which allowed us to refine the age of the deposits and corroborate palaeoecological data. The combined data from the microfossils and fishes document the first middle-late Bartonian (NP17) marine fish fauna from Romania. This fauna was deposited in tropical waters with relatively shallow depths and with increased terrigenous input from a probable closeby shoreline.
... Conversely, the other cluster includes most of the other Tethyan localities (SW Morocco, Egypt, and India), which are regarded as tropical shallow marine environments in proximity to emerged coastal areas (Rana et al. 2004(Rana et al. , 2006Adnet et al. 2010;Underwood et al. 2011). Their similarity is due to the presence of several demersal taxa, some of which mostly occur in shallow waters, especially the predatory sharks such as the carcharinids Galeocerdo and Carcharhinus, the triakid Galeorhinus and the odontaspidid Brachycarcharias, along with some pristid and myliobatiform batoids (Rana et al. 2004(Rana et al. , 2006Adnet et al. 2010;Underwood et al. 2011). ...
... Conversely, the other cluster includes most of the other Tethyan localities (SW Morocco, Egypt, and India), which are regarded as tropical shallow marine environments in proximity to emerged coastal areas (Rana et al. 2004(Rana et al. , 2006Adnet et al. 2010;Underwood et al. 2011). Their similarity is due to the presence of several demersal taxa, some of which mostly occur in shallow waters, especially the predatory sharks such as the carcharinids Galeocerdo and Carcharhinus, the triakid Galeorhinus and the odontaspidid Brachycarcharias, along with some pristid and myliobatiform batoids (Rana et al. 2004(Rana et al. , 2006Adnet et al. 2010;Underwood et al. 2011). The non-metric multidimensional scaling plot supports the same pattern (Fig. 4B). ...
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Article
Over the last few years, the morphology, taxonomy and systematics of the cartilaginous fish taxa of the two main sites of the Bolca Lagerstätte, Italy, (Pesciara and Monte Postale sites) have been extensively discussed in a series of papers, resulting in a complete revision of this neglected component of the Eocene Tethyan ichthyofauna. Here, we provide a comprehensive overview of the diversity, palaeoecology and palaeoenvironmental significance of the two chondrichthyan assemblages of the Pesciara and Monte Postale sites. The assemblages include 14 shark species (Lamniformes and Carcharhiniformes) and batoids (Torpediniformes, Rhinopristiformes, Myliobatiformes, Platyrhinidae and Zanobatidae), as well as a single putative chimaeriform. The Pesciara and Monte Postale sites are characterized by eight chondrichthyan taxa each, but the taxonomic compositions are distinctly different reflecting the dissimilarities in the overall composition of both fish assemblages. Palaeoecological interpretations and habitat preferences of the two chondrichthyan assemblages are consistent with previously hypothesized palaeoenvironmental settings based on sedimentological, palaeontological and geochemical evidence. The chondrichthyan assemblages of the two sites appear to be constituted by ecologically vicariant taxa, with both characterized by a predominance of benthic species with durophagous/cancritrophic feeding modes. Taxonomic composition, habitat preferences and palaeobathymetric analyses support the hypothesis that both assemblages occupied tropical marine shallow waters (likely up to 50 m deep) of the inner portion of the Lessini Shelf. The taxonomic composition of both sites is considerably different from that of any other contemporaneous Tethyan and Boreal chondrichthyan assemblages.
... It is known from Europe, North America, Africa and Asia (Paleobiology Database 2018). Fossils have been recovered from rocks ranging in age from Cenomanian (Vullo et al., 2009) to Eocene (Leriche, 1905;Fallaw, 1964;Fierstine, 2001;Ciobanu and Trif, 2016), with one report of an occurrence in sediments tentatively assigned a Miocene age (Adnet et al., 2010). Specimens are most often found in sediments from open marine environments (e.g. ...
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Article
Study of the microscopic anatomy of Cylindracanthus dates to the nineteenth century. It was continued in the early twentieth century using thin sections of Nigerian specimens. This remarkable genus, known only from its distinctive rostral spines, remains enigmatic. We reviewed the surviving historical slides of English and Nigerian specimens in the collections of the British Museum of Natural History, and expanded the histologic study of Cylindracanthus to include the first detailed description of the tooth bases and examination of possible lesions and healed tissue. We repeated the historical comparative studies between Cylindracanthus and modern billfish and expanded comparative histological research to include comparisons between Cylindracanthus and Polyodon (the paddlefish). Billfish rostral structure has no real resemblance to Cylindracanthus. Tooth attachments in billfish are subdermal. The tooth pedicels, lesions, and damaged surfaces in Cylindracanthus give no evidence of having been subdermal. Unlike the acellular calcified tissue of Cylindracanthus, paddlefish bone is cellular. Two of the Cretaceous Cylindracanthus specimens we have examined bear small teeth. Although fish teeth typically are attached to the jaw edge or to oral surfaces of palatal elements, the teeth of Cylindracanthus occupy an extraoral position attached to pedicels within two of the grooves between the radial plates that make up the rostrum. The tooth-bearing grooves are wider than inter-plate grooves that do not bear teeth, and extend the full length of the rostrum. Tooth tips protrude only slightly above the adjacent plates. Their apices point backwards toward the mouth and away from the tapered tip of the rostrum. The tooth pedicels are small (with diameters of only about 1mm) in Cretaceous Cylindracanthus. Tooth pedicels are reduced in size or absent in animals that lived after the K-Pg event. Preservation of associated teeth is rare, and to date has been found only in Cretaceous specimens. Preservation of associated teeth is unknown in Cenozoic specimens. Cylindracanthus tooth tips are covered by transluscent acrodin caps, confirming their taxonomic position within the Actinopterygii.
... This marine fauna on genus level appears to be very persistent, without indications of a turnover at the Eocene-Oligocene (Murray et al. 2014). Some species recovered are known from the latest Eocene sediments of the Fayum Depression in Egypt and from Morocco (Adnet et al. 2010), as well as from the early Oligocene of the Eastern Tethys Ocean (Adnet et al. 2007). For comparison with other Oligocene selachian faunas from the Eastern Tethys Ocean, see Table 5. ...
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Article
2017. A new Oligocene site with terrestrial mammals and a selachian fauna from Minqar Tibaghbagh, the Western Desert of Egypt. Acta Palaeontologica Polonica 62 (3): 509-525. A new fossil site at Minqar Tibaghbagh, east of Siwa, in the Egyptian Western Desert is described. This represents the first place in Egypt outside the Fayum Depression yielding Paleogene, terrestrial mammals. Initial studies indicate the presence of palaeomastodonts, hyracoids, and anthracotheres, presumably early Oligocene in age. As only surface prospecting has been performed, more taxa will almost certainly be discovered in future investigations here and probably also elsewhere in the surroundings. A comparison is made with the most important contemporaneous sites in Libya and Egypt that yield terrestrial mammal remains. The selachian fauna from a higher level in the section confirms the Paleogene age of the subjacent strata. It is compared with selachians faunas from the early Oligocene Eastern Tethys Ocean at other places (the Fayum Depression in Egypt, and sites in Oman and Pakistan), and differs from these sites in being fully marine. Contrary to earlier studies, the open marine mudstones of the Daba'a Formation at Minqar Tibaghbagh are overlain by Paleogene marine sediments of most probably early Oligocene age and not early Miocene marine sediments as previously reported. These strata represent not only a new site with great potential for future finds, but also allows for biostratigraphic correlation.
... interestingly, the description of "Carcharodon" sp. from the middle and late Eocene given by these authors matches the tooth morphology of Otodus poseidoni, which is characterized by lower teeth being large and massive, with elongated root lobes having very deep interspaces (Applegate & Espinosa-Arrubarrena 1996: 29;Zhelezko & Kozlov 1999 & Cappetta 1990;Adnet et al. 2010;underwood et al. 2011;Zalmout et al. 2012;Kriwet et al. 2016 ;Zalat et al. 2017;Zouhri et al. 2021 The specimen figured by Morton (Fig. 10) corresponds to a serrated Eocene Otodus species, and as such, it undoubtedly comes from the Shark river Formation, whose geological age spans from the Lutetian to the Priabonian. Since the precise stratigraphic whereabouts of this find are unknown, its affinity with other species is difficult to assess. ...
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Article
In the second issue of Samuel Morton's "Synopsis of the organic remains of the Cretaceous group of the united States" published in June 1835, several otodontid shark teeth from Cenozoic formations of New Jersey are named with authorship of Louis Agassiz and meet the conditions of availability of the international Code of Zoological nomenclature. it has gone largely unnoticed that some of these names were introduced in this work before their publication in Agassiz's masterpiece "Recherches sur les poissons fossiles". The specimens presented by Morton were kept in the John Price Wetherill (1794-1853) collection that found its way into the paleontological collection of the Academy of natural Sciences of Drexel University, Philadelphia, where most of them have been rediscovered. These teeth are part of the type series upon which Agassiz introduced Lamna obliqua Agassiz in Morton, 1835, Lamna lanceolata Agassiz in Morton, 1835, Carcharias lanceolatus Agassiz in Morton, 1835, Carcharias megalotis Agassiz, 1835 and Carcharias polygurus Agassiz in Morton, 1835, all of these species being referred to the genus Otodus in the present work. in order to secure the nomenclatural stability of the Otodontidae, it is established that Otodus lanceolatus is a junior synonym of Otodus obliquus, that "Carcharias" lanceolatus belongs to the genus Otodus Agassiz, 1838 and is invalid as a junior secondary homonym of Otodus lanceolatus, that Otodus megalotis is a junior synonym of Otodus auriculatus (Blainville, 1818), and that Otodus polygurus (Otodus polygyrus being an incorrect subsequent spelling) is a junior synonym of Otodus megalodon (Agassiz, 1835). Furthermore, it is shown that the date of publication of Otodus obliquus (Agassiz in Morton, 1835) is 1835 and not 1838 as previously thought.
... Our material seems closest to teeth of O. (Carcharocles) auriculatus because of the narrow crown of anterior teeth, their broad cusplets and the complete and regular serration of the cutting edges on the main cusp (even in juveniles) as well as on the cusplets(Cappetta 2012). O. (Carcharocles) auriculatus is known from the Early to Late Eocene in many Atlantic and Tethyan realms (Ward & Wiest 1990; Long 1992; van den Eeckhaut & De Schutter 2009; Diedrich 2012; Carlsen & Cuny 2014) and it is likely that this repartition is increased if we consider those of its coeval O. (Carcharocles) sokolowi, known in the same area to the southwestern Morocco(Adnet et al. 2010) and possibly in Antarctica(Welton & Zinsmeister 1980). Agassiz (1838) first described fossil teeth from the contemporaneous deposits of the nearby locality Kressenberg, Germany. ...
Repeated bulk sampling for over a decade in an indurated glauconitic sandy marl horizon at St. Pankraz Salzburg, Austria, has yielded a diverse assemblage of 37 elasmobranchs (sharks and rays) from the early middle Eocene (Lutetian). This elasmobranch fauna is dominated by epipelagic and mesopelagic taxa known today to preferentially inhabit the middle or outer continental shelf and upper slope, indicating that the depositional environment of the top Member of Kressenberg Formation in Austria has a more complex bathymetric history than previously thought. As these new occurrences fill a substantial gap in the sporadic fossil record of Eocene mesopelagic elasmobranchs, comparisons of this assemblage with the coeval mesopelagic faunas indicate that this northwestern Tethyan realm association shares considerable similarities with those recovered from the North Sea Basin and the northeastern Atlantic. This suggests that the faunal homogeneity observed in neritic and coastal elasmobranch communities during the warm early middle Eocene is also characterised in mesopelagic habitats.
Article
Two sirenian species are present in the late Eocene Samlat Formation near Ad-Dakhla in southwestern Morocco. A well preserved mandible with left and right dentaries belongs to a new protosirenid genus and species Dakhlasiren marocensis closely related to the genus Protosiren. An early dugongid of uncertain identification (cf. Eotheroides sp.) is also present, represented by vertebrae and ribs. Protosirenids differ from dugongids in the form of the brain, size and separation of nasal bones, and conformation of the anterior mandible. Protosirenids also differ in having vertebrae with larger neural canals, in having ligamentous rib articulations, and in lacking the pachyostotic ribs characteristic of dugongids. We tentatively interpret the latter differences to be related to feeding on softer vegetation farther offshore, with a thoracic rete mirabile for counter-current heat exchange and a collapsible rib cage to enable deeper dives. Dakhlasiren seemingly carried the divergent specializations of Protosiren a step farther by reduction of tongue musculature and loss of a masticatory surface at the front of the mandible. https://authors.elsevier.com/c/1elPL,XIvblkif
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in this paper we describe two new species of Carcharhinidae Carcharhinus dudoni nov. sp. and Carcharhinus pedronii nov. sp. from the lower Miocene (Burdigalian) of South West of France. A review of the species belonging to the genera Carcharhinus and Negaprion from the lower Miocene lead us to conclude that the genus Negaprion needed to be revised according to the multiplicity of nomen nudum still used by recent authors. As a result the Species belonging to Negaprion which is very common in the Langhian of France needed to be renamed. So Negaprion cossardi is the third species describded and largely depicted in this paper. A new listing of the species of this period is proposed.
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This chapter describes the Basilosaurids, a paraphyletic group of archaeocete cetaceans known from the late middle to early late Eocene of all continents except Antarctica. The family includes 11 species in 8 genera in 2 subfamilies, although some authors elevate the subfamilies to familial rank. They range in size from around 4 m (Saghacetus osiris) to around 16 m (Basilosaurus cetoides). Basilosaurids are probably the earliest fully aquatic cetaceans and are thought to have given rise to modern cetaceans. Like all archaeocetes, basilosaurids lack telescoping of the skull like that seen in modern mysticetes or like that seen in modern odontocetes. In addition, basilosaurids are diphyodont (have two tooth generations: milk and adult teeth), lack polydonty (11 or fewer teeth per jaw half), and retain a heterodont dentition, in which incisors, canines, premolars, and molars are easy to distinguish based on their morphologies. Basilosaurids also share a number of characteristics that distinguish them from other archaeocetes. All basilosaurids lack upper third molars, and the upper molars lack protocones, trigon basins, and lingual third roots. In addition, the cheek teeth of basilosaurids have well-developed accessory denticles on the cheek teeth. The hindlimbs of basilosaurids are greatly reduced and lack a bony connection to the vertebral column.
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Based mainly on published data, we attempt a synthesis of the stratigraphy, facies and tectonic evolution of the onshore Aaiun-Tarfaya Basin and its offshore extension, the West Saharan Marginal Basin. Basement rocks are Precambrian, and folded Paleozoic sediments (Mauritanides belt): they dip gently westward and are overlain by a seaward thickening wedge of Mesozoic to Cenozoic continental to shallow-marine sediments. Jurassic to Cretaceous sediments extend from the onshore basin to the present shelf and upper slope, where they are more than 12 km thick. In the onshore basinTriassic clastic rocks, evaporites, and basalt sills and lower to middle Jurassic evaporites and carbonates are overlain by a 1–2 km thick sequence of upper Jurassic neritic carbonates (Puerto Cansado Formation). These formations document high subsidence rates (80-100 m/m.y.) which were compensated by carbonate buildup after a major transgression, that coincided with the Liassic to Oxfordian breakup of Pangaea. The subsidence rates increased slightly (110-140 m/m.y.) during theEarly Cretaceous, when 1–4 km of regressive continental to marine-deltaic, Wealden-type sediments were deposited as part of two major delta systems (Tan Tan/Jreibichat Formation). Restrictedmid-Cretaceous sediments (Calcaires d’ Aguidir) are overlain by up to 1.0 km of transgressiveLate Cretaceous shallow-marine carbonates Lebtaina Formation) and similar Paleogene sediments (Samlat Formation). The subsidence and accumulation rates decreased considerably during this time. Upper Cretaceous toPaleogene sediments were truncated over a wide area during several erosional cycles. Because of uplift and erosion, theNeogene is thin or missing in the onshore coastal basin; an exception is the 1000 m thick sequence of ?deltaic to estuarine claystones in the northwestern Aaiun Basin. Sediment bypassed the present shelf and slope during this time, to accumulate in a new depocenter as gravitative and hemipelagic deposits along the uppermost continental rise.