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New fauna of archaeocete whales (Mammalia, Cetacea) from the
Bartonian middle Eocene of southern Morocco
Philip D. Gingerich
a
,
*
, Samir Zouhri
b
a
Museum of Paleontology, University of Michigan, Ann Arbor, MI 48109-1079, USA
b
Laboratoire de G
eosciences, Faculty of Sciences Aïn Chock, University Hassan II de Casablanca, Morocco
article info
Article history:
Received 11 June 2015
Received in revised form
3 August 2015
Accepted 5 August 2015
Available online 10 August 2015
Keywords:
Eocene
Archaeoceti
Protocetidae
Basilosauridae
Aridal Formation
abstract
Six genera and species of archaic whales are present in a new fauna from the Aridal Formation at Gueran
in the Sahara Desert of southwestern Morocco. Three of the archaeocete species represent semiaquatic
Protocetidae and three species are fully aquatic Basilosauridae. Protocetids are characteristic of Lutetian
lower middle Eocene strata, and basilosaurids are characteristic of Priabonian late Eocene beds. Similar
representation of both families is restricted to intervening Bartonian strata and indicative of a late middle
Eocene age. Archaeocetes from Gueran include (1) a small protocetid represented by a partial humerus,
teeth, and vertebrae; (2) a middle-sized protocetid represented by a partial innominate and proximal
femur; (3) the very large protocetid Pappocetus lugardi represented by teeth, a partial innominate, and
two partial femora; (4) a new species of the small basilosaurid Chrysocetus represented by a dentary,
teeth, humeri, and many vertebrae; (5) a new species of the larger basilosaurid Platyosphys (resurrected
as a distinct genus) represented by a partial braincase, tympanic bulla, and many vertebrae; and (6) the
large basilosaurid Eocetus schweinfurthi represented by teeth, a tympanic bulla, and lumbar vertebrae.
The Gueran locality is important geologically because it constrains the age of a part of the Aridal For-
mation, and biologically because it includes a diversity of archaic whales represented by partial skeletons
with vertebrae in sequence and by forelimb and hind limb remains. With further collecting, Gueran
archaeocete skeletons promise to clarify the important evolutionary transition from foot-powered
swimming in Protocetidae to the tail-powered swimming of Basilosauridae and all later Cetacea.
©2015 Elsevier Ltd. All rights reserved.
1. Introduction
The evolutionary transition of fully aquatic cetaceans from their
land-mammal ancestors can be traced in stages from early artio-
dactyls that made their first appearance in the fossil record during
the Paleocene-Eocene thermal maximum or PETM (Rose, 1982,
1996; Gingerich, 2006) to semiaquatic Pakicetidae in the early
Eocene (Gingerich et al., 1983; Madar, 2007), semiaquatic Proto-
cetidae in the early middle Eocene (Gingerich et al., 1994, 2001a,
2009), and fully aquatic Basilosauridae in the late middle Eocene
(Kellogg, 1936; Gingerich et al., 1990; Uhen, 2004; Martínez-
C
aceres and Muizon, 2011). Gaps in documentation remain in the
transition from artiodactyls to the first semiaquatic Pakicetidae,
and in the transition from foot-powered swimming in Protocetidae
to tail-powered swimming in Basilosauridae (Gingerich, 2012). We
recently described a late Eocene archaeocete fauna from Dakhla in
southwestern Morocco with five species, all basilosaurids (Zouhri
et al., 2014). Here we provide initial documentation of a new
archaeocete fauna that includes both protocetids and basilosaurids.
With further field work and recovery of more complete skeletons
the new fauna has the potential to clarify the transition from foot-
powered swimming in Protocetidae to tail-powered swimming in
Basilosauridae.
2. Geological setting
The new archaeocete fauna comes from Gueran (also called
Guerran, Garouaz, Punta Güera, and Krebb Afedeira), a remote
uninhabited depression in the Sahara Desert of southwestern
Morocco (Fig. 1). Geologically this is in the middle of a much larger
southwest-to-northeast trending structural basin paralleling the
Atlantic coast. The basin is variously called the Aaiun-Tarfaya Basin
(Ranke et al., 1982), the Tarfaya-Laayoune-Dakhla Basin (Davison
*Corresponding author.
E-mail addresses: gingeric@umich.edu (P.D. Gingerich), s.zouhri@fsac.ac.ma
(S. Zouhri).
Contents lists available at ScienceDirect
Journal of African Earth Sciences
journal homepage: www.elsevier.com/locate/jafrearsci
http://dx.doi.org/10.1016/j.jafrearsci.2015.08.006
1464-343X/©2015 Elsevier Ltd. All rights reserved.
Journal of African Earth Sciences 111 (2015) 273e286
and Dailly, 2010), or sometimes simply the Boujdour Basin. Gueran
is approximately 125 km inland from Boujdour, which is the
nearest town on the coast (Fig. 2).
Lafitte et al. (1952) and G
evin (1962) mapped the Gueran
depression as Cretaceous. Medina et al. (1958) mapped this as
‘Neogene.’Ratschiller (1967, 1970) published a more detailed
geological map and discussion of stratigraphy. He placed the strata
of interest here in the Gueran Member of his Samlat Formation. The
Gueran Member was named for strata exposed at Gueran, and the
Samlat Formation as a whole was named for strata exposed at
Samlat Amgrach farther to the west. Ratschiller regarded the
Samlat Formation as Paleocene through Oligocene in age, possibly
even Miocene, and he regarded the Gueran Member of interest here
as Eocene based on studies of foraminifera (Ratschiller, 1970, p. 25).
The type section of the Gueran Member is on the eastern flank of
the Gueran depression, where Ratschiller reported an outcrop
thickness of 45 m in a section lacking both the base and top of the
member. Much of this is chalk, but Ratschiller (1970, p. 75) also
mentioned an intercalation in the lower chalk of white, coarse-
grained conglomeratic sandstone up to 1.5 m thick that contains
shark teeth, fish bones, and coprolites, which is the sandstone
yielding archaeocete remains.
Lindner and Querol (1971) published a map of Spanish Sahara in
which they included a new Aridal Formation. This was named for
exposures at Aridal east of Boujdour (Fig. 2). Aridal is a large
internally-drained, sebjet- or sabkha-filled solution crater perfo-
rating the surrounding Mio-Pliocene hamada. Aridal is also the
name of an early astronomical observation point south of Sabkha
Aridal on the original track connecting Laayoune and Dakhla
(‘Aaiun and Cisneros’). Lindner and Querol (1971) mapped the
Aridal Formation over a large area including Gueran. At Gueran the
Aridal Formation of Lindner and Querol (1971) is clearly equivalent
to the Gueran Member of the Samlat Formation of Ratschiller (1967,
1970). Aridal Formation is the name used on the current Carte
G
eologique du Maroc (Hollard et al., 1985).
Lindner and Querol (1971) regarded the Aridal Formation as late
Fig. 1. Map showing the geographic distribution of Eocene Archaeoceti on the African continent. The principal localities of interest are numbered from 1 to 7.1, Gueran locality in
southwestern Morocco yielding protocetids and basilosaurids of Bartonian age documented here. 2, Garitas and nearby sites south of Dakhla in southwestern Morocco yielding
basilosaurids of Priabonian age (Zouhri et al., 2014). 3, Ndomor Diop site near Taïba Ndiaye in Senegal yielding a protocetid innominate of Lutetian age (Hautier et al., 2014). 4,
Tiavandou in Senegal where the partial skeleton of a Dorudon-like basilosaurid of Priabonian age was found (Elouard, 1981). 5, Kpogam
e in Togo that yielded Togocetus traversei and
other protocetid remains of Lutetian age (Gingerich and Cappetta, 2014). 6, Ameke in southern Nigeria yielding dentaries and vertebrae of the protocetid Pappocetus lugardi of
Bartonian age (Andrews, 1920; Halstead and Middleton, 1974, 1976). 7, Gebel Mokattam near Cairo in Egypt, which yielded a mixture of protocetid and basilosaurid teeth and
vertebrae of Bartonian age resembling some specimens reported here.
P.D. Gingerich, S. Zouhri / Journal of African Earth Sciences 111 (2015) 273e286274
Fig. 2. Geological map of the desert south and east of Boujdour in southwestern Morocco. Red symbols at Gueran mark sites yielding the archaeocete remains described here. These
are numbered 1e6 from north to south. Aridal east of Boujdour is the type section of the Aridal Formation named by Lindner and Querol (1971). Gueran itself is the type section of
the Gueran Member of the Samlat Formation named by Ratschiller (1967, 1970).‘S. Aridal,’etc., are internally-drained sebjet or sabkha depressions in the surrounding Mio-Pliocene
hamada. Geology is from Hollard et al. (1985) (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.).
P.D. Gingerich, S. Zouhri / Journal of African Earth Sciences 111 (2015) 273e286 275
Eocene in age without explanation. Subsequent authors have
generally considered the Aridal Formation to represent the middle
and late Eocene (Hollard et al., 1985), or sometimes more generally
to span the combined Paleocene and Eocene (Rjimati et al., 2011).
Ranke et al. (1982) located Gueran in the neritic zone of a shallow
shelf paleoenvironmentally, with marine carbonates accumulating
farther offshore to the northwest and terrestrial clastics accumu-
lating onshore farther to the southeast.
All of the fossils described here came from a single sandstone
that can be traced for many kilometers near the base of the es-
carpments surrounding the Gueran depression (Fig. 3). The sand-
stone is white to light gray in color, clayey, silty, poorly-sorted, and
very fine to coarse in grain size (
F
¼þ4to1). The larger sand
grains include clear quartz grains and opaque lithic fragments, all
subrounded to rounded, and polished. Sandstone cement is
calcareous. Marl and clay casts up to several centimeters in diam-
eter are common, and fish coprolites on the order of 1.0e1.5 cm
long and 4e5 mm in diameter are present.
Archaeocetes at Gueran are preserved as associated skeletons
and partial skeletons, partially articulated and disarticulated. Some
of the larger bones were clearly broken before burial, and their
freshly broken surfaces are preserved embedded in matrix. Bones
are also commonly bored by an unknown organism making a
tubular burrow. Selachian teeth are frequent, including large 10 cm
diameter teeth of Otodus or Carcharocles. Minute teleost vertebrae
are present, as are occasional bones of larger fish, turtles, and
crocodiles. Sirenian bones and teeth are conspicuously absent.
Bone breakage and compression fractures on unbroken bones
suggest predation or scavenging eby other archaeocetes or by
large sharks. Some multi-element specimens are clearly associated,
while elements from others are seemingly isolated. Disarticulation,
breakage, and boring indicate that some bones were exposed on
the sea bed before burial. However, preservation in poorly sorted
sediment suggests rapid burial, possibly in a storm surge.
3. Materials and methods
The study area was discovered by commercial fossil collectors in
2014, and we carried out a 10-day reconnaissance in November,
2014, salvaging specimens whenever possible. We were assisted by
experienced collectors Amer Ait Ha and M'Barek Fouadassi. Com-
mercial collectors are primarily interested in teeth and tooth-
bearing crania and dentaries. Our interest included postcranial re-
mains as well. Vertebrae and limb bones are often as diagnostic as
tooth-bearing crania and dentaries for identification of protocetids
and basilosaurids, and they are important for understanding the
mode of swimming of early cetaceans. Cranial terminology gener-
ally follows Mead and Fordyce (2009), and postcranial terminology
follows Kellogg (1936).
Specimens described here are permanently archived in the
Department of Geology, Faculty of Sciences Aïn Chock, University
Hassan II, in Casablanca. Casts of some specimens are archived in
the University of Michigan Museum of Paleontology, Ann Arbor.
Museum abbreviations: FSAC Bouj, Faculty of Sciences Aïn
Chock, Boujdour collection, Casablanca (Morocco); NHML, Natural
History Museum, London (England); SCSM, South Carolina State
Museum, Columbia (U.S.A.); SFNF, Senckenberg Forschungsinstitut
und Naturmuseum, Frankfurt; SMNS, Staatliches Museum fur
Naturkunde, Stuttgart (Germany); USNM, U. S. National Museum of
Natural History, Washington (U.S.A.).
4. Systematic paleontology
Protocetid archaeocetes are distinguished from basilosaurids in
having premolar and molar teeth that are simpler in shape, lacking
accessory denticles; in retaining an upper third molar (M
3
); in
lacking well-developed pterygoid sinuses in the basicranium; in
having cervical and thoracic vertebrae with relatively small neural
canals; and in having the large innominates and femora required of
a foot-powered swimmer. Basilosaurids in contrast are distin-
guished in having more complex premolar and molar teeth with
accessory denticles; in lacking M
3
; in having well-developed pter-
ygoid sinuses; in having cervical and thoracic vertebrae with rela-
tively large neural canals; and in having the reduced innominates
and femora consistent with tail-powered swimming (Kellogg,1936;
Gingerich, 2010).
Archaeocetes grow ontogeneticallylike other mammals to reach
adefinitive adult size. Young individuals can be recognized by the
presence of deciduous teeth that have distinctive shapes compared
to adult teeth, and by the presence of porous skeletal bone
retaining juvenile cartilage. Fusion of long-bone and vertebral
epiphyses is an indication of adulthood, but in marine mammals
the epiphyses do not always fuse in adults. Judging from tooth form
and bone texture, all of the specimens described here are full-
grown subadults to adults. Differences in the reported sizes of
long bones and vertebrae are not due to ontogenetic differences.
Class Mammalia.
Order Cetacea.
Suborder Archaeoceti.
Family Protocetidae Stromer, 1908.
Protocetid species A.
Figs. 4AeB, 5AeE.
The smallest of three protocetid species at Gueran is repre-
sented by (1) a left distal humerus, FSAC Bouj-12 (Fig. 4AeB); (2) a
left upper molar M
1
, FSAC Bouj-13 (Fig. 5AeB); and (3) a middle
thoracic vertebra, FSAC Bouj-4 (Fig. 5 CeE). All three specimens are
similar in size to comparable elements of the Lutetian protocetids
Protocetus,Artiocetus,Rodhocetus,Maiacetus, and Togocetus (Fraas,
1904a; Gingerich et al., 2001a, 2009; Gingerich and Cappetta,
2014). The distal humerus of Protocetid A is similar in size to that
of Rodhocetus balochistanensis, but it is distinctive in two ways: first,
the distal medial and lateral condyles are more rounded; and sec-
ond, the deltopectoral crest is virtually absent. Both are seemingly
primitive traits in protocetids. The humerus measures 9.6 cm in
length as preserved, 2.9 2.2 cm in cross section at the midshaft of
the diaphysis, and 3.6 cm in width across the distal end. The con-
dyles are 2.8 cm in width.
The upper molar, M
1
, has a prominent paracone and a smaller
metacone posterior to the paracone. There is a small parastyle on
the enamel crest anterior to the paracone. The protocone is missing
Fig. 3. Panoramic view of the Gueran depression in southwestern Morocco. View is to
the southwest. An archaeocete excavation in the foreground (arrows) is at M'Barek site
2 (site 2 in Fig. 2). Note the two collectors standing in the lower right excavation
providing scale. White sediment below the excavation is the Gueran Member lower
white chalk of Ratschiller (1970).
P.D. Gingerich, S. Zouhri / Journal of African Earth Sciences 111 (2015) 273e286276
but, judging from the shape of the remaining crown, the protocone
was positioned medial to the paracone and not posteromedial to it,
a feature distinguishing M
1
from M
2
. The full anteroposterior
length of the crown is 2.3 cm, making it similar in size to M
1
in
Protocetus,Artiocetus, and Maiacetus, but the width of the crown
cannot be measured. Enamel on the surface of the crown is finely
crenulated.
The thoracic vertebra has a roughly ‘D-shaped’centrum, and
capitular facets for rib articulations are well developed on the front
and back of the centrum. The neural arch is robust. It is distinctive
in enclosing a relatively small neural canal. A prominent dia-
pophysis is preserved on the left side of the vertebra, rising from
the neural arch, with a tubercular facet for articulation with a rib
tubercle. The diapophysis is surmounted by a distinct meta-
pophysis. The neural spine is broken but appears to have been
posteriorly inclined. All of these characteristics point to a position
in the middle of the thoracic series of vertebrae. Centrum length,
anterior width, and anterior height are 3.73, 5.21, and 3.70 cm,
respectively. The neural canal measures 2.05 1.75 cm in width
and height.
Recovery of the small Protocetid species A is encouraging but
the specimens at hand do not permit detailed comparison with
other small protocetids.
Protocetid species B.
Fig. 5FeI.
The middle-sized protocetid species at Gueran is represented by
(1) a right partial innominate, FSAC Bouj-14 (Fig. 5FeG); and (2) a
left proximal femur, FSAC Bouj-15 (Fig. 5HeI). The innominate is
similar in size to innominates of Georgiacetus and Qaisracetus
(Hulbert et al., 1998; Gingerich et al., 2001b), and while not
identical compares most closely in form to the innominate of
Georgiacetus. The acetabulum of Protocetid B has the concavity to
accommodate a femoral head with a diameter of about 3.8 cm, and
the dorsal surface of the innominate above the acetabulum is
2.75 cm wide in Protocetid B and 2.73 cm wide in Georgiacetus. Both
have a smooth capsular surface dorsal to the acetabulum itself, both
have a deep acetabular fossa for the round ligament or ligamentum
teres and a well developed acetabular notch, and both have a
relatively sharp ischiatic spine. A very short segment is preserved of
the border of the obturator foramen.
The proximal femur is referred here because the femoral head is
the right size to articulate with the acetabulum of the innominate.
Salient features are a shallow fovea for the teres ligament, a rela-
tively short femoral neck, an angled neck, and a prominent lesser
trochanter. The trochanteric crest is broken, but clearly it defined a
deep trochanteric fossa. The femoral head is spherical and mea-
sures 3.5 cm in diameter. The midshaft of the femur is circular in
cross section and measures 3.2 cm in diameter.
Genus Pappocetus Andrews 1920.
Revised diagnosis: Largest protocetid, with M
1
in the type
measuring 44 mm 18.5 mm. P
1
single-rooted. Deciduous pre-
molar dP
3
has two weakly developed accessory cusps, unusual for a
protocetid, following the apical cusp. Molars are elongated, with a
single apical cusp, the protoconid, followed by a robust hypoconid.
Included species:Pappocetus lugardi Andrews (1920; type
species).
Pappocetus lugardi Andrews 1920.
Fig. 5JeP.
The largest of the three protocetid species at Gueran is repre-
sented by (1) the talonid of a left lower molar M
2
, FSAC Bouj-16
(Fig. 5JeK); (2) a left partial innominate, FSAC Bouj-17
(Fig. 5LeM); (3) a right proximal femur, FSAC Bouj-25 (Fig. 5NeO);
and (4) the head ofa second femur, FSAC Bouj-18 (Fig. 5P). These are
protocetids because the talonid of M
1
is simple, and because the
innominate and the more intact femur retain the form of compa-
rable elements in protocetids and in land mammals.
The talonid of M
1
is large, measuring 1.64 cm in transverse
breadth, and it is simple in form in having a single prominent
hypoconid cusp well separated from the trigonid. The trigonid
remnant and the talonid both have heavy attritional wear on the
buccal side of the tooth crown. The talonid described here matches
those of M
1
in the holotype dentary, NHML M114114, and in a
referred dentary, NHML M11086, very closely in form and size.
The left innominate is large and robust, with the concavity to
accommodate a femoral head with a diameter of about 5.2 cm. This
is the largest acetabulum known for any archaic cetacean. The
dorsal surface of the innominate is 4.45 cm wide above the ace-
tabulum, as compared to 2.75 cm recorded above for Protocetid B.
This innominate has a conspicuous, slightly rugose capsular surface
extending 1.7 cm out of the acetabulum dorsally. There is a deep
acetabular fossa for a teres ligament, and a well developed
acetabular notch. Much of the border of the obturator foramen is
preserved posterior to the acetabular notch.
Parts of two femora are known. The most complete femur pre-
serves the head, greater trochanter, and diaphysis extending
distally as far as the lesser trochanter. The femoral neck is longer
and set at a greater angle to the diaphysis than is seen in Protocetid
species B. The head of the second femur is difficult to position
accurately, but it does have a distinct fovea for the teres ligament.
This ligament anchors the femoral head within the acetabulum,
and the presence of a fovea on the femoral head is consistent with
the presence of a deep acetabular notch on the innominate. The
femoral head of FSAC Bouj-18 measures 5.0 cm in diameter.
Pappocetus lugardi is distinguished from other protocetids at
Gueran and indeed from all other protocetids by its large size.
Fig. 4. Distal humeri of the smallest of three protocetids and smallest of three basi-
losaurids found at Gueran in southwestern Morocco. AeB, left distal humerus of
Protocetid sp. A, FSAC Bouj-12, in anterior and lateral view (cast of original). A tubular
burrow of unknown origin is visible above the lateral torus of the trochlea. Note the
virtual absence of a deltopectoral crest. C, left humerus of Chrysocetus fouadassii, FSAC
Bouj-3, in lateral view (proximal epiphysis is missing). Note the virtual absence of a
deltopectoral crest on the humerus of Protocetid sp. A at left, and the great develop-
ment of a deltopectoral crest on the humerus of C. fouadassii at right. Both specimens
are shown at 0.4 natural size. Abbreviations: d, diaphysis; dpc, deltopectoral crest; lc,
lateral condyle; mc, medial condyle.
P.D. Gingerich, S. Zouhri / Journal of African Earth Sciences 111 (2015) 273e286 277
Previously known specimens of P. lugardi came from marine strata
of the Ameki Formation at a single locality near Ameki in Nigeria
(locality 6 in Fig. 1;Andrews, 1920; Halstead and Middleton, 1974,
1976; McLeod and Barnes, 2008; Gingerich, 2010).
Family Basilosauridae Cope 1868.
Genus Chrysocetus Uhen and Gingerich 2001.
Revised diagnosis: Species of Chrysocetus are distinctive among
Basilosauridae in being relatively small (smaller than all except
Saghacetus osiris), and distinctive in having normally proportioned
thoracic, lumbar, and caudal vertebrae (lacking even the moderate
centrum elongation seen in Saghacetus). In addition to being small,
cheek teeth of Chrysocetus are distinctive in being narrow and
gracile, with relatively smooth enamel.
Included species:Chrysocetus healyorum Uhen and Gingerich
(2001; type species), and C. fouadassii (new).
Chrysocetus fouadassii, new species.
Figs. 4C, 6AeT.
The smallest of three basilosaurid species at Gueran is repre-
sented by: (1) a left partial dentary with P
4
eM
1
, FSAC Bouj-1
(Fig. 6AeB; holotype); (2) isolated teeth including left M
2
, FSAC
Bouj-19 (Fig. 6CeE); (3) vertebrae of several specimens including
FSAC Bouj-2 (Fig. 6FeT); and (4) two left humeri, FSAC Bouj-3
(Fig. 4C) and Bouj-24 (not illustrated);.
Holotype: left partial dentary with P
4
eM
1
, FSAC Bouj-1
(Fig. 6AeB).
Etymology: named for the experienced collector M'Barek Foua-
dassi, who guided us in the field in 2014.
Diagnosis:Chrysocetus fouadassii has teeth and vertebrae similar
in size and form to those of C. healyorum Uhen and Gingerich (2001)
from North America, but C. fouadassii differs in retaining cervical
vertebrae with significantly longer centra (Fig. 7) and in having a
substantially longer humerus. The humerus measures 22.5 cm
without the proximal epiphysis, compared to 15.6 cm without this
epiphysis in C. healyorum, a difference in length of about 40%.
Description: The humerus of Chrysocetus fouadassii (Fig. 4C) is
typical of basilosaurids in having a proximal epiphysis that fused to
the diaphysis late in life (the epiphysis is missing here, but surface
texture of the bone appears fully adult); in having a narrow, cy-
lindrical distal articulation for the ulna and radius; and in having a
very prominent deltopectoral crest extending virtually the entire
Fig. 5. Remains of protocetid species of three sizes found at Gueran in southwestern Morocco. These are, from smallest to largest, sp. A, sp. B, and Pappocetus lugardi.AeB, left M
1
molar of protocetid sp. A, FSAC Bouj-13, in buccal and lingual view. CeE, middle thoracic vertebra of protocetid sp. A, FSAC Bouj-4, in anterior, left lateral, and dorsal view. FeG, right
partial innominate of protocetid sp. B, FSAC Bouj-14, in dorsal and lateral view. HeI, left proximal femur of protocetid sp. B, FSAC Bouj-15, in anterior and posterior view. JeK, talonid
of a left M
1
of Pappocetus lugardi, FSAC Bouj-16, in occlusal and lateral view. LeM, left partial inominate of Pappocetus lugardi, FSAC Bouj-17, in dorsal and lateral view. NeO, right
proximal femur of Pappocetus lugardi, FSAC Bouj-25, in anterior and posterior view. P, head of femur of Pappocetus lugardi, FSAC Bouj-18 (orientation uncertain). Illustrations AeB
and JeK are natural size, while remainder are 0.4 natural size. Abbreviations: ac, acetabulum; af, acetabular fossa; an, acetabular notch; cf, capitular facet for rib; cs, capsular surface;
da, diapophysis; ds, dorsal surface; f, fovea; gt, greater trochanter; h, head; hyd, hypoconid; il, ilium; is, ischiatic spine; ls, lunate surface of acetabulum; lt, lesser trochanter; ma,
metapophysis; me, metacone; n, neck; na, neural arch; nc, neural canal; ns, neural spine; of, obturator foramen; pa, paracone; ps, parastyle; trc, trochanteric crest; tf, tubercular facet
for rib; trf, trochanteric fossa.
P.D. Gingerich, S. Zouhri / Journal of African Earth Sciences 111 (2015) 273e286278
length of the anterior surface of the diaphysis. The greatest ante-
roposterior development of this crest occurs about two-thirds of
the distance from the proximal end of the bone. The two humeri of
C. fouadassii measure 22.5 and 22.8 cm long, respectively, without
their proximal epiphyses. Apart from length, they resemble the
humerus of C. healyorum in other measures of size (Uhen and
Gingerich, 2001, p. 16).
The holotype dentary preserves crowns of the teeth P
4
and M
1
(Fig. 6AeB). Both have relatively smooth enamel. P
4
has a long,
narrow, straight, and high crown, with five accessory denticles on
the carina anterior to the central protoconid (counting the denticle
broken from the anterior cingulum) and five accessory denticles on
the carina posterior to the protoconid. It is followed by an M
1
with a
smaller high, narrow crown. There is a distinct groove on the
anterior surface of the crown bordered by two vertical crests of
enamel. The lateral crest has a small denticle at the base and two
more in the middle of the crown before ascending to the proto-
conid. The carina posterior to the protocone is damaged but it
clearly had three accessory denticles. M
2
is better preserved than
M
1
and very similar in most characteristics, but differing in lacking
denticles on the anterior lateral crest (Fig. 6CeE). The dentary itself
has much of the ramus broken away, with tooth roots extending
into what was formerly a large mandibular canal. In the holotype,
P
4
measures 4.72 1.32 4.30 cm in anteroposterior length,
buccolingual width, and crown height, and M
1
measures
3.28 1.16 2.86 cm in length, width, and height.
Representative vertebrae of Chrysocetus fouadassii are illustrated
in Fig. 6FeT, and those of the best vertebral column of C. fouadassii
(FSAC Bouj-2) are compared to vertebrae of C. healyorum in Fig. 7.
Vertebrae of the two species compare closely in form and size, with
one notable exception: cervical vertebrae of C. fouadassii are
significantly longer than those of C. healyorum. Measurements of
vertebrae of C. fouadassii are listed in Table 1.
Genus Platyosphys Kellogg 1936.
Revised diagnosis: Species of Platyosphys are distinctive among
Basilosauridae in being relatively large and in having posterior
Fig. 6. Teeth and representative vertebrae of the smallest basilosaurid, Chrysocetus fouadassii, new species, found at Gueran in southwestern Morocco. AeB, left dentary with
P
4
eM
1
, FSAC Bouj-1 (holotype), in lateral and occlusal view. CeE, isolated left M
2
, FSAC Bouj-19, in occlusal, anterior, and lateral view. FeH, cervical vertebra C5 (?). IeK, thoracic
vertebra T5 (?). LeN, thoracic vertebra T10 (?). OeQ, thoracic vertebra T14 (?). ReT, lumbar vertebra L2 (?). Vertebrae in FeT are part of FSAC Bouj-2, with each shown in anterior,
dorsal, and left lateral view. Vertebral positions are uncertain because the vertebral column of FSAC Bouj-2 is incomplete. Measurements of FSAC Bouj-2 vertebrae are listed in
Table 1 and graphed in comparison to Chrysocetus healyorum in Fig. 6. Neural arches and transverse processes on centra of vertebrae are broken. All illustrations are 0.4 natural
size. Abbreviations: ad, accessory denticles; cf, capitular facet for rib; mc, mandibular canal; prd, protoconid; tf, tubercular facet for rib; tp, transverse process.
P.D. Gingerich, S. Zouhri / Journal of African Earth Sciences 111 (2015) 273e286 279
thoracic, lumbar, and anterior caudal vertebrae that are conspicu-
ously elongated. Lumbar vertebrae have broad and flat transverse
processes that arise along virtually the entire anteroposterior
length of the centrum. Cranial and vertebral bone is unique among
archaeocetes in being pachyostotic and osteosclerotic. Pachyostosis
gives vertebrae a swollen appearance, and nutrient canals opening
at the surface add a pock-marked texture.
Included species:Platyosphys paulsonii (Brandt, 1873a); P. wardii
(Uhen, 1999), and P. aithae (new). Platyosphys einori Gritsenko
(2001) and P. uheni (Gol'din and Zvonok, 2013) may be valid or may
be synonyms of P. paulsonii.
The generic name Platyosphys refers to the broad transverse
processes of the lumbar vertebrae. Platyosphys Kellogg (1936) is
considered a valid genus, contrary to Gol'din and Zvonok (2013);
see Discussion.
Platyosphys aithai, new species.
Figs. 8, 10F.
The middle-sized basilosaurid species at Gueran is represented
by (1) a partial cranium, FSAeC Bouj-20 (Fig. 8AeB); (2) a left
tympanic bulla, FSAC Bouj-26 (Fig. 10F); and (3) vertebrae of several
specimens including FSAC Bouj-6 (Fig. 8CeJ), FSAC Bouj-7
(Fig. 8KeL), and FSAC Bouj-11 (Fig. 8MeR).
Holotype: associated thoracic vertebrae T1eT4 of FSAC Bouj-6
(Fig. 8CeJ) constitute the type specimen. Should there be any
concern about the integrity of the series, the largest vertebra with
the diaphysis (Fig. 8IeJ) is the holotype.
Etymology: named for the experienced collector Amer Ait Ha,
who guided us in the field in 2014.
Diagnosis:Platyosphys aithai is a small species of Platyosphys
(Fig. 9). P. wardii (Uhen, 1999) from North America is similar in size
but slightly larger. The species P. paulsonii and P. uheni from eastern
Europe are much larger. P. aithai is distinct from all other species of
Platyosphys in having a distinct diapophysis arising from the
vertebral centrum on middle thoracic vertebrae that is not seen in
other species of Platyosphys.
Description: The partial cranium of Platyosphys aithai
(Fig. 8AeB), found in association with vertebrae, is the first cra-
nium described for the genus. Six bones are represented: the right
squamosal, part of the right periotic with an intact posterior pro-
cess, the right exoccipital, the supraoccipital, and parts of both the
left and right parietal. The squamosal contacts the exoccipital and
supraoccipital posteriorly, and has a dorsal projection that rises
high on the corresponding parietal. The squamosal includes a
portion of the glenoid fossa and the external auditory meatus.
Much of the squamosal is fully osteosclerotic with a texture more
typical of the periotic. The body of the periotic is not well pre-
served, but what remains rests in the periotic fossa of the squa-
mosal. The posterior process of the periotic is intact and solidly
wedged between the squamosal and exoccipital. The lateral
margin of the exoccipital is sharply squared. The midline supra-
occipital is notable in being approximately 3.0 cm thick above the
foramen magnum. Left and right parietals meet dorsally to form a
low sagittal crest. Posterolaterally the parietals are wedged tightly
between the supraoccipital and dorsal extensions of the overlying
squamosals. The intertemporal midcranial pons is thick,
measuring 6.6 cm from side to side, and this is very densely ossi-
fied lending both weight and rigidity to the cranium. The parietals
are broken ventrally along the rising course of the long olfactory
stalk, and the parietals are broken anteriorly before contacting the
frontal shield. The width of the cranium, estimated by doubling the
distance from the midline to the lateral surface of the glenoid
fossa, is minimally 32.0 cm.
The braincase as a whole has the conformation typical of basi-
losaurids, but the bone is exceptionally thick and dense. Some
bones like the periotic and squamosal are osteosclerotic. Sur-
rounding bones are thick and dense, but not fully osteosclerotic. All
are brittle in the sense that they seemingly fracture in large pieces
rather than deform. The thick, dense cranial bone of P. aithai, and its
breakage into large pieces rather than deforming by micro-
fracturing are important differences from the type cranium of
Eocetus schweinfurthii (Fraas, 1904a), which is a microfractured
basilosaurid sometimes interpreted as being related to Platyosphys
Fig. 7. Premolar P
4
tooth length and vertebral centrum length of Chrysocetus fouadassii,
new species (FSAC Bouj-1 and Bouj-2; open diamonds) compared to those of Chrys-
ocetus healyorum Uhen and Gingerich, 2001 (SCSM 87.195, P
3
or P
4
; solid circles). Light
gray points and lines enclose a 95% confidence band for centrum length in C. fouadassii
based on the empirical observation that linear measurements have a standard devia-
tion averaging 0.05 on a natural-logarithm scale. Note that the one tooth that can be
compared, premolar P
4
, is similar in mesiodistal crown length in the two species.
Cervical vertebrae of C. fouadassii are significantly longer than those of C. healyorum,
while thoracic vertebrae are similar in length.
Table 1
Measurements of vertebrae of specimen FSAC Bouj-2, Chrysocetus fouadassii, new
species, from Gueran in southwestern Morocco. Associated vertebrae are from site
II-1: ‘Site d'Ali’(locality numbered ‘5’on the map in Fig. 2). Vertebral positions are
uncertain because the series is not complete. See Fig. 7 for a graphical profile.
Measurements are in cm; those with asterisks are estimates. Abbreviations: Vert.,
vertebral position; Len, centrum length; AW, anterior centrum width, AH, anterior
centrum height; PW, posterior centrum width; PH, posterior centrum height; NCW,
neural canal width; NCH, neural canal height.
Vert. Len AW AH PW PH NCW NCH Illustration
C5? 2.6 3.5 3.5 3.7 3.6 2.6 eFig. 6FeH
C6 2.6 3.9 3.8 4.4 3.9 2.8 ee
T2? 3.4 4.7 3.5 4.4 3.7 3.2* ee
T4? 3.9 4.5 3.6 e3.6 3.0* ee
T5? 4.0 4.6 3.6 4.5 3.6 3.7 eFig. 6IeK
T6? 4.2 4.7 3.8 4.8 3.8 3.8 ee
T7? 4.4 4.7 3.8 5.2 4.1 3.9 ee
T8? 4.8 4.8 3.7 5.4 3.7 3.3 ee
T9? 5.0 5.1 4.3 5.9 4.5 3.5 ee
T10? 5.5 5.6 4.6 5.9 4.7 3.5 eFig. 6LeN
T11? 5.8 5.8 4.7 5.9 5.1 3.6 ee
T13? 6.1 5.9 5.0 5.9 5.4 3.1 ee
T14? 6.5 5.9 5.3 6.2 5.4 3.0 2.0 Fig. 6OeQ
L1? 6.6 5.9 5.6 6.4 5.8 3.2 ee
L2? 6.8 6.1 6.0 6.4 6.4 3.2 eFig. 6ReT
L3? 7.1 6.1 5.7 6.5 5.8 3.4 ee
L4? 7.0 6.5 6.2 6.8 6.4 3.3 ee
L5? 6.9 6.0 6.0 6.7 6.1 3.3 ee
L6? 7.0 5.9* 5.9 6.5 5.9 3.1 ee
L7? 6.9 5.9 5.6 6.2 5.8 2.8 ee
L8? 7.1 6.2 5.8 6.5 6.0 3.5* ee
L9? 6.9 6.3* 6.3 6.9 6.3 3.3 ee
L10? 7.2 6.3 6.3 7.0 6.3 3.0 ee
L12? 7.0 6.6 6.3 6.7 6.4 2.5 ee
P.D. Gingerich, S. Zouhri / Journal of African Earth Sciences 111 (2015) 273e286280
Fig. 8. Cranial remains and representative vertebrae of Platyosphys aithai, new species, found at Gueran in southwestern Morocco. AeB, posterior parts of cranium, FSAC Bouj-20, in
posterior and right lateral view. CeD, thoracic vertebra T1. EeF, thoracic vertebra T2. GeH, thoracic vertebra T3. IeJ, thoracic vertebra T4. KeL, thoracic vertebra T12? MeN, lumbar
vertebra L1? OeP, lumbar vertebra L2? QeR, lumbar vertebra L3? Vertebrae in CeJ are FSAC Bouj-6 (P. aithai holotype). Vertebra in KeL is FSAC Bouj-7. Vertebrae in MeR are FSAC
Bouj-11. Each is shown in dorsal and left lateral view. All specimens are shown at 0.25 natural size. Measurements of vertebrae are listed in Table 2. Abbreviations: cf, capitular
facet for rib; da, diapophysis with tubercular facet for rib; Eo, exoccipital bone of cranium; Pa, parietal; pp, posterior process of periotic; So, supraoccipital; Sq, squamosal; tp,
transverse process.
P.D. Gingerich, S. Zouhri / Journal of African Earth Sciences 111 (2015) 273e286 281
(see Discussion). Fracture patterns depend on burial history to
some extent, but these also depend on the thickness and density of
original bone.
Two large tympanic bullae of slightly different sizes and shapes
are known from Gueran. Both are osteosclerotic, and the smaller
appears to belong to P. aithai (Fig. 10F). Neither is complete. The
tympanic of P. aithai measures 7.3 cm in anteroposterior length and
approximately 4.8 cm in transverse diameter. Salient characteristics
distinguishing the smaller tympanic from the larger one are its
smoothly rounded rather than squared inner posterior prominence,
its shallow but distinct interprominential notch, and its shallow but
distinct medial prominential notch. Both have a distinct,
centimeter-sized, circular feature interrupting the smooth texture
of the posterodorsal surface of the involucrum, the inner process of
the posterior pedicle (Tsai and Fordyce, 2015).
Vertebrae of Platyosphys aithai are distinctive compared to
those of other archaeocetes. Anterior thoracic vertebrae, such as
T1eT4, taper anteroposteriorly, with the posterior surface of the
centrum being notably wider than the anterior surface. T1eT3
have capitular facets for the heads of ribs on both the anterior and
posterior ends of the centrum, but by T4 there is a capitular facet
at the anterior end of the centrum but not at the posterior end
(Fig. 8J). This vertebra is the first to have a diapophysis arising
from the centrum for articulation with the rib tubercle, and the
capitular articulation is less a facet than a pit. The diapophysis is
lost on posterior thoracics, and the rib articulation is now a large
pit on an elevated parapophyseal surface (Fig. 8L). Lumbar
vertebrae of P. ait hai are not complete but show the ante-
roposteriorly long, robust transverse processes extending virtu-
ally the entire length of the centrum (Fig. 8MeR) that are
characteristic of the genus Platyosphys (Kellogg, 1936, p. 97).
Vertebrae of P. aithai are unusual in having anterior and posterior
cones of cancellous bone tapering toward the center of the
centrum, with intervening parts of the cylindrical diaphysis filled
with laminae of denser cortical bone. This distinctive architecture
is best seen when vertebrae are broken (but it can be seen too at
the posterior end of L3? in Fig. 8QeR). Nutrient foramina pene-
trating the laminae of this dense cortical bone are responsible for
the pock-marked surface typical of Platyosphys (and Eocetus).
Measurements of vertebrae of Platyosphys aithai are listed in
Table 2.
Genus Eocetus Fraas 1904b.
Revised diagnosis: Large basilosaurid with posterior thoracic,
lumbar, and anterior caudal vertebrae elongated and cylindrical.
Differs from Basilosaurus in having a neural arch and neural spine
that are longer anteroposteriorly, with prezygapophyses or meta-
pophyses projecting to or beyond the anterior face of the centrum.
Differs from Platyosphys in having more cylindrical posterior
thoracic, lumbar, and anterior caudal vertebrae, with pachyostosis
and nutrient foramina less developed; differs too in having verte-
brae with anteroposteriorly-shorter transverse processes.
Included species:Eocetus schweinfurthi (Fraas,1904a) and Eocetus
drazindai (Gingerich et al., 1997).
Eocetus schweinfurthi (Fraas, 1904a)
Fig. 10AeE, G.
The largest of the three basilosaurid species at Gueran is
represented by (1) teeth including right upper premolar P
3
, FSAC
Bouj-22 (Fig. 10AeB), and right upper premolar P
4
,FSACBouj-23
(Fig. 10AeB); (2) a right tympanic bulla, FSAC Bouj-21 (Fig. 10G);
and (3) lumbar vertebrae, including FSAC-8 (Fig. 10D) and FSAC-9
(Fig. 10E). These differ from vertebrae of Platyosphys aithai in
being substantially larger (dashed line in Fig. 9) and in lacking the
anteroposteriorly elongated transverse processes characteristic of
Platyosphys. They are referred to Eocetus schweinfurthi because of
their large size, relatively long vertebral centra, and retention of
prezygapophyses reaching anteriorly to a point above the ante-
rior articular surface of the centrum. The latter characteristic is a
clear distinction from Basilosaurus isis and Basilosaurus cetoides.
Teeth referred to Eocetus schweinfurthi include a partial upper
premolar P
3
and a complete P
4
(Fig. 10AeB). Both are double-
rooted. The crowns are heavily worn as is characteristic of mature
larger basilosaurids. P
3
has three denticles decreasing in size pos-
terior to the large central cusp (Fig. 10AeB), and a fourth very small
denticle near the base of the crown (Fig. 10C). P
4
is similar to P
3
but there is no fourth denticle. The anterior part of the crown of P
4
is too worn to reveal the number of denticles. The crown of P
3
is
2.65 cm wide buccolingually, and the crown of P
4
is 5.76 cm
long anteroposteriorly and 3.00 cm wide buccolingually. The
Table 2
Measurements of vertebrae of Platyosphys aithai, new species, from Gueran. Three
specimens are represented: FSAC Bouj-6 (T1eT4, holotype), Bouj-7 (T12?), and Bouj-
11 (L1? eL3?), all from site II-1: ‘Site d'Ali’(locality numbered ‘5’on the map in
Fig. 2). Some vertebral positions are uncertain because the series is not complete.
See Fig. 9 for a graphical profile. Measurements are in cm; those with asterisks are
estimates. Abbreviations: Vert., vertebral position; Len, centrum length; AW, anterior
centrum width, AH, anterior centrum height; PW, posterior centrum width; PH,
posterior centrum height; NCW, neural canal width; NCH, neural canal height.
Vert. Len AW AH PW PH NCW NCH Illustration
T1 5.0 5.4 4.9 6.3 4.8 4.4* eFig. 8CeD
T2 5.7 6.6 5.1 8.0* 5.5 4.9* eFig. 8EeF
T3 6.7 6.7 5.6 8.4* 5.8 4.9* eFig. 8GeH
T4 8.4 8.6 6.7 8.9 7.0 4.6* eFig. 8IeJ
T12? 12.8 9.7* 8.2* 9.6 7.7 4.3 eFig. 8KeL
L1? 15.1 10.0 8.8 10.9 8.9 4.4 eFig. 8MeN
L2? 15.8 10.4 8.7 11.1 9.4 4.4 eFig. 8OeP
L3? 17.5 11.1 10.1 10.8 10.2 4.2 eFig. 8 QeR
Fig. 9. Comparison of the vertebral centrum length profile of Platyosphys aithai,new
species (open diamonds), with those of Platyosphys paul sonii (Brandt, 1873a,b;solid
circles), Platyosphys or B asilotritus wardii (Uhen, 1999; open circles), and Platyosphys
or Basilotritus uheni (Gol'din and Zvonok, 2013; open triangles). Vertebrae of P. a it ha i
are illustrated in Fig. 8 and measurements are listed in Table 2. Light gray points and
lines enclose a 95% confidence band for centrum length in P. aithai based on the
empirical observation that linear measurements have a standard deviation averaging
0.05 on a natural-logarithm scale. Note that vertebrae of P. aithai are slightly smaller
than those of P. wardii, and both have vertebrae significantly smaller than those of
P. paulsonii and P. uheni. Measurements of the type specimen of P. wardii,USNM
310633, are from Uhen (1999). The average length for nine lumbar vertebrae of
Gueran Eocetus schwei nfurthi (Tab le 3 ) is shown by the dashed line in the upper right
portion of the figure.
P.D. Gingerich, S. Zouhri / Journal of African Earth Sciences 111 (2015) 273e286282
posterior surfaces of both of these premolars have small accessory
tubercules in addition to the accessory denticles. These are remi-
niscent of accessory tubercles seen on upper premolars of Pla-
tyosphys or Basilotritus uheni (Gol'din and Zvonok, 2013; Gol'din
et al., 2014), but differ in that they are on the base of the crown
as an incipient or remnant cingulum rather than on the denticles
themselves (Fig. 10C).
The tympanic bulla referred to Eocetus schweinfurthi (Fig. 10G) is
a little smaller but otherwise similar to the tympanic of Basilosaurus
isis (Gingerich et al., in prep.). It measures 8.2 cm in anteroposterior
length and 4.9 cm in transverse diameter. It is a little larger than the
tympanic of Platyosphys aithai, and differs in lacking the rounded
inner posterior prominence, the interprominential notch, and the
medial prominential notch seen in P. aithai.
Vertebrae of Eocetus schweinfurthi, like those of Platyosphys
aithai, are unusual in having anterior and posterior cones of
cancellous bone tapering toward the center of the centrum (ac and
pc in Fig. 10D), with intervening parts of the cylindrical diaphysis
filled with laminae of denser cortical bone. This laminar bone has
spalled away in FSAC-8 (Fig. 10D). A vertebra of E. schweinfurthi
from the Giushi Formation of Gebel Mokattam in Egypt, SMNS
10934 described by Stromer (1903,p.83e85; 1908, p.109) appears
to be similar in this respect. The surface of vertebral bone in
E. schweinfurthi is often pock-marked like the surface of vertebral
bone in Platyosphys (Uhen, 1999,fig. 2). Two series of more com-
plete lumbar vertebrae measured to calculate the average centrum
length shown by the dashed line in Fig. 9 are not illustrated because
they are not yet fully prepared. Vertebral measurements are listed
in Table 3.
5. Discussion
Several points bearing on the Gueran archaeocetes and on their
geological and paleontological significance merit further
discussion.
Fig. 10. Teeth and representative vertebrae of Eocetus schweinfurthi found at Gueran in southwestern Morocco, with a comparison of tympanic bullae of Platyosphys aithai and
E. schweinfurthi.AeB, right upper premolars P
3
and P
4
of E. schweinfurthi, FSAC Bouj-22 and Bouj-23, in buccal and lingual view. C, close-up of the posterior margin of P
3
, FSAC Bouj-
22. Note heavy wear on upper premolars, andthe presence of accessory tubercles bordering the accessory denticle near the base of the crown. D, lumbar vertebra of E. schweinfurthi,
FSAC Bouj-8, in dorsal view. Note cones of cancellous bone. E, caudal vertebra of E. schweinfurthi, FSAC Bouj-9, in dorsal view. F, left tympanic of P. aithai, FSAC Bouj-26, in dorsal
view. G, right tympanic bulla of E. schweinfurthi, FSAC Bouj-21, in dorsal view. Note the presence of a medial and posterior prominential notch on the bulla of P. aithai not seen on
that of E. schweinfurthi.AeB are 0.5 natural size; C is 2 natural size, DeE are 0.25 natural size; and GeH are 0.5 natural size. Abbreviations: ac, anterior cone of cancellous
bone; ad, accessory denticle on carina of premolar; adc, anterodorsal crest of outer lip; ap, anterior prominence; at, accessory tubercle; in, involucrum; ipn, inner prominential
notch; ipp, inner posterior prominence; ippp, inner process of posterior pedicle; mpn, medial prominential notch; opp, outer posterior prominence; pc, posterior cone of cancellous
bone.
Table 3
Measurements of lumbar and caudal vertebrae of Eocetus schweinfurthi (Fraas,
190 4a ) from Gueran in southwestern Morocco. FSAC Bouj-8, Bouj-27, and Bouj-28
are lumbars, and Bouj-9 and Bouj-10 are caudals. Bouj-8 is from site II-1: ‘Site
d'Ali’(locality numbered ‘5’on the map in Fig. 2). Bouj-27 is from site I (locality
numbered ‘1’on map in Fig. 2). Remaining specimens are from unknown localities at
Gueran. Vertebral positions within the lumbar and caudal series are uncertain
because these are not complete. Average lumbar centrum length of 22.9 cm is
compared to lumbar centrum length for Platyosphys aithai in Fig. 9 and to Egyptian
Eocetus schweinfurthi in Fig. 11. Measurements are in cm; those with asterisks are
estimates. Abbreviations: Bouj., specimen number; Len, centrum length; AW, ante-
rior centrum width, AH, anterior centrum height; PW, posterior centrum width; PH,
posterior centrum height; NCW, neural canal width; NCH, neural canal height.
Bouj. Len AW AH PW PH NCW NCH Illustration
8e14.5 11.8 14.7 12.0 eeFig. 10D
9 (c) 20.2* 11.2* 9.0* 10.7* 9.1* 3.7 eFig. 10E
10 (c) 15.4 12.0* 7.3* 11.8* 6.8* eee
27 24.0* 14.0 11.5 eeeee
27 23.0* eeeeeee
27 24.0* eeeeeee
28 22.5 ee16.0 13.0 eee
28 21.0 ee15.0 12.5 eee
28 23.5 ee15.5 13.5 eee
28 24.0 ee16.0 13.5 eee
28 22.5* ee16.0* 13.5* eee
28 21.5 ee15.5 13.0 eee
P.D. Gingerich, S. Zouhri / Journal of African Earth Sciences 111 (2015) 273e286 283
5.1. Size relationships of Gueran archaeocetes
It is not yet possible to make quantitative estimates of body size
for all of the Gueran archaeocetes, but we can group the species into
five size categories that give some sense of their possible ecological
relations. From smallest to largest, the groups are:
(1) Protocetid species A
(2) Basilosaurid Chrysocetus fouadassaii
(3) Protocetid species B
(4) Protocetid Pappocetus lugardi and basilosaurid Platyosphys
aithai
(5) Basilosaurid Eocetus schweinfurthii.
Protocetids are generally smaller than basilosaurids, but in the
Gueran fauna the families overlap considerably in size.
5.2. Age of the Gueran archaeocete fauna
The combination of three species of protocetids with three
species of basilosaurids preserved in the same sandstone unit is
clear evidence of a Bartonian-age fauna. Protocetid teeth and
basilosaurid cranial and vertebral remains are found together in the
Giushi Formation of Bartonian age at Gebel Mokattam in Egypt
(Fraas, 1904a; Stromer, 1908), and the two families are found
together in the Drazinda Formation of Bartonian age flanking the
Rodho anticline in Pakistan (Gingerich et al., 1995, 1997). Archae-
ocetes from the Gueran locality are important geologically because
they constrain the age of the Aridal Formation sandstone to be
Bartonian late middle Eocene in age.
5.3. Systematic position of Platyosphys
Lumbar vertebrae like those in Fig. 8MeR are typical of ‘Zeu-
glodon’paulsonii Brandt (1873a,b) from Ukraine, which Kellogg
(1936) placed in the new genus Platyosphys. Kellogg (1936, p. 97)
distinguished Platyosphys as an archaeocete having elongated
lumbar vertebrae and transverse processes on the lumbar vertebrae
nearly as long anteroposteriorly as the length of the vertebral
centrum. Platyosphys has been little discussed in the archaeocete
literature because the morphology of the vertebrae is so distinctive,
the age was long thought to be Oligocene, and few new specimens
were forthcoming from eastern Europe. This changed when Uhen
(1999, 2001) described new specimens from North America as
Eocetus wardii, and Gol'din et al. (2012) recognized Eocetus sp. in
upper Lutetian to Bartonian strata in Ukraine. Gol'din and Zvonok
(2013) reinterpreted all of these remains, named a new genus
and species Basilotritus uheni, and reclassified ‘Eocetus’wardii as a
species of Basilotritus.
Gol'din and Zvonok (2013) did not clearly state their reason for
separating Basilotritus from Eocetus, but this separation appears
justified based on observations presented here (see 5.4). Gol'din
and Zvonok's separation of Basilotritus from Platyosphys depended
on setting the genus and species Platyosphys paulsonii (Brandt,
1873a) aside as a nomen dubium ein spite of its stated similarity
to Basilotritus uheni ebecause “this type specimen is considered to
be lost”(Gol'din and Zvonok, 2013, p. 263). The validity of a genus
and species does not depend on the continued availability of a type
specimen, but rather on existence of an indication of the
morphology involved and the source of a tangible specimen,
whether lost or not. Both are clearly provided by Brandt (1873a,b)
and by Kellogg (1936, p. 97).
Vertebrae identified as Platyosphys aithai here are smaller than
those of P. paulsonii and P. uheni, but they conform closely in
morphology to specimens described from Ukraine (Brandt, 1873b;
Gol'din et al., 2012, 2014; Gol'din and Zvonok, 2013) and from the
southeastern United States (P. wardii;Uhen, 1999, 2001). Detailed
comparison will require more complete vertebral columns than are
presently available.
5.4. Vertebrae of Eocetus schweinfurthi
The type specimen of Eocetus schweinfurthi (Fraas, 1904a)isa
large cranium, ‘St. 1’or SMNS 10986, from the Giushi Formation of
Gebel Mokattam in Egypt. This measures 96.0 40.0 cm in length
and width (Kellogg, 1936, p. 247). Fraas regarded the cranium as
enabling identification of the large 24.5 cm long lumbar and an
accompanying vertebra described and illustrated by Stromer from
the same stratigraphic interval (Stromer, 1903,p.83e85: ‘St. 2’or
SMNS 10934). Stromer later added two additional vertebrae of the
same skeleton as SMNS 10934 (Stromer, 1908, p. 109: ‘Fr. 1’or SFNF
4470). In addition, Stromer (1908, p. 109) mentioned three smaller
vertebrae (‘St. 3’) that he interpreted as subadult representatives of
a third specimen of E. schweinfurthi (Stromer, 1908, p. 109: ‘St. 3' or
SFNF unnumbered). Stromer characterized the best vertebra of ‘St.
3’as a centrum that is minimally 13.5 cm long, with transverse
processes arising along the whole lower margin of the centrum that
protrude slightly forward and slightly downward.
Uhen (1999,fig. 2) interpreted Stromer's ‘St. 3,’mislabeled as
SFNF 4470, to represent Eocetus schweinfurthi, in contrast to the
larger vertebra of ‘St. 2’(SNMN 10934), which he referred to Basi-
losaurus drazindai Gingerich et al. (1997). Here we offer an alternate
solution (Fig.11). We know the size of the E. schweinfurthi type skull
(see above), which represents a mature adult. We know the size of
the skulls and the lumbar vertebrae of Basilosaurus cetoides and
B. isis (Kellogg, 1936; Gingerich et al., in preparation), which are
Fig. 11. Comparison of the relative lengths of lumbar vertebrae of Gueran Platyosphys
aithai (Morocco) and Gebel Mokattam Eocetus schweinfurthi (Egypt) to the length ex-
pected from isometric scaling of lumbar length to cranial width in Egyptian and North
American Basilosaurus isis and B. cetoides (dashed lines enclose a 95% confidence band
for centrum length in Basilosaurus based on a 0.05 natural-logarithm-unit standard
deviation). Note that the largest vertebra from Gebel Mokattam, the elongated Basi-
losaurus-like vertebra described by Stromer (1903,p.83e85 and fig. 1), is a little longer
than the average from Gueran (open circle, which lacks a corresponding cranial width).
The Gebel Mokattam vertebra is the right length to belong with the type skull of
E. schweinfurthi named by Fraas (1904a,b), which corroborates Stromer's referral of the
vertebra to E. schweinfurthi (Stromer, 1908, p. 109). An Eocetus-like lumbar vertebra
would be too long to belong with a skull the width of the cranium of Platyosphys aithai
described here, which corroborates association of the cranium and vertebrae shown in
Fig. 8. Measurements for B. cetoides and Gebel Mokattam E. schweinfurthi are from
Kellogg (1936), those from B. isis are from Gingerich et al. (in preparation), and the
average for Gueran E. schweinfurthi is from Table 3. All of these crania represent adult
individuals.
P.D. Gingerich, S. Zouhri / Journal of African Earth Sciences 111 (2015) 273e286284
again both mature adults). Thus we can ask how large a Basilo-
saurus-like lumbar vertebra of E. schweinfurthi is expected to be in
proportion to the size of its skull? The resulting estimate for lumbar
size compared to skull width (bizygomatic breadth) is shown by the
dashed lines in Fig. 11(we use skull width because this is all we can
estimate for comparison in adult Platyosphys aithati). The SMNS
10934 vertebra lies within the dashed lines, corroborating inter-
pretation that it represents Eocetus schweinfurthi (Fraas, 1904a;
Stromer, 1908; Kellogg, 1936). An alternative approach, projecting
the lumbar-to-cranial-width relationship for Platyosphys aithai to
the cranial width for E. schweinfurthi, shows that SMNS 10934 is too
large to represent P. aithai, and too large to represent ‘St. 3’from
Gebel Mokattam.
The partial cranium of Platyosphys aithai described here is
relevant too in showing that Platyosphys had a more heavily built
skull than that of Eocetus, making it less susceptible to the
compression seen in the type skull of Eocetus. Thus, following Fraas
(1904a), Stromer (1908), Kellogg (1936), and Van Valen (1968),we
interpret Eocetus schweinfurthi as a basilosaurid, with vertebrae
proportioned like those of Basilosaurus but lacking reduction of the
neural arch and zygapophyses seen in Basilosaurus itself. Basilo-
saurus drazindai from Bartonian strata of Pakistan has lumbar
vertebrae substantially larger than those of E. schweinfurthi, with a
long neural arch and zygapophyses reaching the anterior limit of
the centrum (Gingerich et al., 1997). We now regard B. drazindai as a
large species of Eocetus.
5.5. Paleobiogeography of Gueran archaeocetes
Protocetid and basilosaurid archaeocetes had broad, essentially
global geographic distributions by the later part of the middle to
late Eocene, being known from Asia, Europe, Africa, North America,
and South America (Uhen, 2010; Martínez and Muizon, 2011).
Basilosaurids are also known from this interval in New Zealand and
Antarctica (Borsuk-Bialynicka,1988; K €
ohler and Fordyce, 1997). The
new fauna from Gueran is interesting in bringing together in one
fauna Pappocetus, previously known only from Nigera in West Af-
rica; Cynthiacetus, previously known only from North America;
Eocetus, previously known with certainty only from North Africa;
and Platyosphys, previously known principally from Ukraine in
eastern Europe. This reinforces the idea of cosmopolitanism in
Bartonian and Priabonian whales, and it highlights the centrality of
Gueran biogeographically for understanding the diversity and
Bartonian history of Archaeoceti.
6. Conclusions
The fossils recovered from Gueran in 2014 indicate that the
Aridal Formation sandstone producing the fossils is Bartonian late
middle Eocene in age. Archaeocetes of the family Protocetidae are
represented by three species, including the first record of Pappo-
cetus lugardi outside Nigeria. Archaeocetes of the family Basilo-
sauridae are also represented by three species. Chrysocetus
fouadassii is a small, new, generalized basilosaurid with gracile
teeth and vertebrae of normal proportions. Platyosphys aithai in
contrast is a larger species, also new, with a skull and elongated
vertebrae composed of unusually dense and thickened bone.
Eocetus schweinfurthi is the largest species, with elongated verte-
brae approaching those of Basilosaurus itself in size and pro-
portions. Further collecting at Gueran focused on recovering
associated skeletons of protocetids and basilosaurids promises to
clarify the important evolutionary transition from foot-powered
swimming in Protocetidae to the tail-powered swimming of Basi-
losauridae and all later Cetacea.
Acknowledgments
We thank Amer Ait Ha and M'Barek Fouadassi for guidance in
the field. N. D. Pyenson providedaccess to specimens of Platyosphys
wardii in the U. S. National Museum of Natural History; J. J. Hooker
provided access to specimens of Pappocetus lugardi in the Natural
History Museum, London; G. Plodowski provided access to speci-
mens from Egypt in the Senckenberg Museum, Frankfurt; and E.
Heizmann and R. Ziegler provided access to and information about
specimens from Egypt in the Staatliches Museum für Naturkunde,
Stuttgart. We thank R. Ewan Fordyce and an anonymous referee for
reviews improving the text. Field research was supported by the
Museum of Paleontology, University of Michigan, Ann Arbor, and by
the Hassan II Academy of Science and Technology, Casablanca.
Appendix A. Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jafrearsci.2015.08.006
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