JURASSIC, CRETACEOUS, AND TERTIARY MEGAFOSSILS
FROM THE RIYADH REGION OF EAST-CENTRAL
SAUDI ARABIA
SENIOR THESIS
Presented in Partial Fulfillment • of the Requirements for the Degree, Bachelor of Science
By
Richard E. Mccutchen
The Ohio State University
Department of Geology and Mineralogy
1985
• TABLE OF CONTENTS • PAGE ABSTRACT------1
INTRODUCTION------1
GEOLOGY OF THE AREA------2
LOCALITY INFORMATION------7
PRESERVATION OF THE MACROFOSSILS------8
BIOSTRATIGRAPHY------8
FOSSIL DESCRIPTIONS------12
PHYLUM MOLLUSCA CLASS GASTROPODA GENUS PLANORBIS PLANORBIS sp.------12
GENUS MITRA MITRA sp.------13
GENUS ARCHITECTONICA • ARCHITECTONICA sp.------14 GENUS CYPRAEA CYPRAEA sp.------15
GENUS BOLIS BOLIS LISBOA------16
GENUS AMAUROPSIS AMAUROPSIS BULBIFORMIS------17
GENUS TURRITELLA TURRITELLA sp.------18
GENUS EPITONIUM EPITONIUM sp.------19
GENUS GYRODES GYRODES CONRADI------19
GENUS NERITOMA NERITOMA (NERIDOMUS)sp.------20
GENUS OLIVA OLIVA sp.------21 • i PAGE • GENUS NATICA "NATICA" WILLIAMSI------21
GENUS POLINICES POLINICES (EUSPIRA) HALLI------· 22
GENUS VALVATA VALVATA SCABRIDA------23
GENUS LUNATIA LUNATIA HALLI------· 23
GENUS LAPPARIA LAPPARIA DUMOSA------24
GENUS CYLICHNA CYLICHNA SECALINA------25
GENUS NATICOPSIS NATICOPSIS (NATICOPSIS)sp.------25
CLASS CEPHALOPODA SUBCLASS AMMONOIDEA GENUS SPHENODISCUS • SPHENODISCUS (AUSTROSPENODISCUS)sp.------26 GENUS LIBYCOCERAS LIBYCOCERAS sp.------27
GENUS PSEUDOCENOCERAS PSEUDOCENOCERAS sp.------28
CLASS PELECYPODA GENUS AMBOCARDIA AMBOCARDIA sp.------29
GENUS CARDIUM (GRANOCARDIUM) DUMOSUM------29
CARDIUM (GRANOCARDIUM) DUMOSUM------30
GENUS GRANOCARDIUM GRANOCARDIUM (GRANOCARDIUM)sp.------30
GENUS CARDIUM CARDIUM (PAUPERCULUM)sp.------31
GENUS CARDIUM CARDIUM sp.------31
• ii PAGE • GENUS VENERICARDIA VENERICARDIA (VENERICARDIA)sp.------32
GENUS CYMBOPHORA CYMBOPHORA sp.------32
GENUS DICTYOPTYCHUS DICTYOPTYCHUSsp.·------33
GENUS PHOLADOMYA PHOLADOMYA (BUCARDIOMYA)sp.------33
GENUS PHOLADOMYA PHOLADOMYA (PHOLADOMYA)sp.------34
GENUS PLATYCARDIA PLATYCARDIA sp.------35
GENUS MYTILUS MYTILUS sp.------35
GENUS DENTONIA DENTONIA sp.------36
GENUS PARAMEGALODUS • PARAMEGALODUS sp.------37 GENUS ALECTRYONELLA ALECTRYONELLA sp.------37
PHYLUM COELENTERATA CLASS ANTHOZOA GENUS CYCLOLITES CYC£0DITES sp. ------38
GENUS CYCLOSERIS CYCLOSERIS sp.------39
GENUS TROCHAREA TROCHAREA sp.------40
GENUS LEPTOPHYLLASTRAEA LEPTOPHYLLASTRAEAsp.------41
PHYLUM BRACHIOPODA CLASS ARTICULATA GENUS OLENEOTHYRIS OLENEOTHYRISsp.------41
• iii PAGE • GENUS TEREBRATALIA TEREBRATALIA TRANSVERSA------41
GENUS TEREBRATULINA TEREBRATULINA FLORIDANA------41
SUMMARY------42
ACKNOWLEDGEMENTS------43
REFERENCES------44
FIGURES AND PLATES------46
•
• iv • JURASSIC, CRETACEOUS, AND TERTIARY MEGAFOSSILS FROM THE RIYADH REGION OF EAST-CENTRAL SAUDI ARABIA
RICHARD E. McCUTCHEN Department of Geology and Mineralogy, The Ohio State University, Columbus, Ohio 43210
ABSTRACT - Gastropods, bivalves, cephalopods, corals, and
other fossils collected from Riyadh area, Saudi Arabia are
significant for interpreting the age of the host rocks. The
fossils range from Late Jurassic to Eocene in age.
Descriptions are given of the significant components of the
fauna. The state of preservation is generally good although
the specimens are preserved as steinkerns. Stratigraphic • information is provided for the several fossil-bearing sections yielding these fossils.
INTRODUCTION
The Riyadh region in east-central Saudi Arabia was a
platform extending across many hundreds of thousands of
square miles during Phanerozoic time. In east-central Saudi
Arabia sedimentary rocks making up this platform are exposed
in a great curved belt flanking the eastern margin of the
Arabian Shield. They reflect the attitude of the basement,
dipping from 1° 00' (Pre-Cretaceous) to less than o0 30' • (Upper Cretaceous and Eocene) uniformly in a northeast, east, and southeast direction. This structural province of Saudi • Arabia is the Interior Homocline, which borders the Arabian Shield (Figure 1). Parallel, west-facing, strike escarpments
supported by resistant limestone caps are characteristic of
this province. In the valleys and plains between these
escarpments there are sandstones and shales, partially
hidden beneath Tertiary and Quaternary gravels and sands
(Powers et al., 1966).
The purpose of this project is to describe the megafossils
in a collection gathered from an area west and northeast of
Riyadh in east-central Saudi Arabia. The identified fossils
will be used to determine the age of the rocks they came
from. In this investigation I consider only major types of
fossils in the collection and their significance. A serious • unsatisfactory limitation to this investigation is the
state of preservation of many of the fossils that may intro
duce errors in the determination of fossils from a particular
locality. GEOLOGY OF THE AREA
Below I will review the geologic history of the area,
the lithology of the formations, and the depositional environ
ments. During the time interval considered (Late Jurassic
to Middle Tertiary) several distinctive rock units were
deposited (Figure 2). West of Riyadh 50 miles and 75 miles
respectively, along the road to Mecca are two fossil
localities with the oldest rocks. They are located along
• 2 Jabal Tuwayq, a sequence of nearly parallel west-facing • scarps of Jurassic rocks (Figure 1). The Tuwayq Mountain Limestone constitutes the backbone of Jabal Tuwayq (Powers
et al., 1966). At the base of the Tuwayq escarpment in these
areas is the Dhruma Formation, which is subdivided into the
Lower, Middle, and Upper Dhruma (Figure 2,3). The Lower
Dhruma is shale with some limestone. The Middle Dhruma is
a limestone containing at some levels beds of clean current
washed calcarenite, many of which have high lateral per
sistance, and an upper oolitic bed that is cliff-forming.
The Upper Dhruma consists of shale with some limestone in the
lower part (Powers et al., 1966). Above the Dhruma Formation
is the Tuwayq Mountain Limestone (Figure 2, 3). Its base • consists of soft calcarenitic limestone which overlies olive-green shale of the Dhruma. It is divided into three
units: Tl, T2, and T3. Tl consists to a great part of
interbedded calcarenite and yellow fossiliferous carbonate
clay. The remaining part is a finely bioclastic, nodular,
clayey limestone and calcarenite. It forms the base of the
Tuwayq escarpment. T2 is a cream colored, very fine-grained,
massive limestone, commonly very bioturbated, which has rare
bioclastic layers. T3 at the top of the escarpment is made
up of a fine-grained, granular, more-or-less clayey, bio
clastic limestone (Vaslet et al., 1983). This is overlain
by the Upper Jurassic Hanifa Formation (Oxfordian) of which
only the Hawtah Member needs be mentioned (Figure 2, 3). It • 3 is made up of a lower white or yellowish calcareous clay, • fossiliferous clayey limestone, and rare beds of massive, vioclastic and pelletoid limestone containing corals. The
upper part is a brown, bioclastic intraclastic limestone
(Ibid.) .
Northeast of Riyadh are three fossil localities with
younger rocks. The one nearest Riyadh (10 miles) is located
near the unconformable contact of the Sulaiy Formation (Lower
Cretaceous) and the Kharj Formation (Miocene and Pliocene)
(Figure 2, 3). Here, the Sulaiy Formation is a tan, chalky,
massively bedded, aphanitic limestone. The Kahrj Formation
is normally lacustrine limestone with included gypsum and
gravel (Powers et al., 1966). A west-facing slump escarpment • (Hit) is present in this area and theKharj forms the top of this escarpment (Figure 1).
The second locality, 20 miles from Riyadh, is located
within the Yamama Formation (Lower Cretaceous) (Figure 2, 3).
It consists of calcarenite, calcarenitic limestone, and
aphanitic limestone (Ibid.).
The third locality (65 to 70 miles northeast of Riyadh)
is situated in the Al Arumah plateau region (Figure 1). The
Aruma Formation makes up this plateau and it is made up of
shallow-water limestone with massive dolomite and smaller
amounts of shale and impure dolomite in the upper part
(Ibid.) (Figure 2, 3) .
The paleoenvironments of the area were as follows. In
• 4 the Late Jurassic (Callovian Stage), at the time of deposition • of the Dhruma, Tuwaiq Mountain Limestone, and Hawtah Member of the Hanifa Formation, the oldest units represented in the
collection, a major inundation of the Middle East platform
began, which continued until the beginning of the Early
Cretaceous (Murris, 1980). The carbonate platform was made
up of limestone, shale/marl, and dolomitic limestone. The
areas east and west of Riyadh were covered by this platform.
In late Oxfordian-early Kimmeridian time the platform became
more differentiated. Intrashelf basins began breaking up
the shallow carbonate platform. elastics were not present
(Ibid.). The area southwest of Riyadh was still covered
by aphanitic limestone of the carbonate platform. During • the last part of the Late Jurassic, sea level rose. Shallow water carbonate deposition increased and finally surpassed
the flooding of the platform. In the Tithonian Stage, the
climate again became arid. Extensive evaporites (anhydrite
halite) were deposited on the platform in a sabka environ
ment (Ibid.). During the early Cretaceous there was a
return to a humid environment and a reoccurrence of ramp-type
carbonate deposition. The Sulaiy and Yamama Formations were
deposited during these humid conditions. During the
Hauterivian and Barremian, the deposition of terrigenous
material increased. This lithofacies extended north and
south through the region just west of Riyadh. The main • constituent of this lithofacies was sandstone. During 5 the Aptian, inundation occurred again. A shallow, carbonate • shelf spread westward and thoroughly covered the elastic rocks. The sea transgressed in an opposite direction in
mid-Albian time. Then a regression occurred and different
elastic lithofacies dominated Saudi Arabia east of Riyadh.
During the late Albian and early and late Cenomanian trans
gression and regressions of the sea alternated, producing
carbonate and elastic regimes. In the Campanian (Late
Cretaceous) the Aruma Formation was deposited. The shelf
became more differentiated. In an arc south to southwest
of Riyadh different elastic facies were present. In the
region north of Riyadh was a carbonate platform, and there
was an evaporitics pan in this platform's center. The • nucleus of activity during the Cretaceous was a narrow ovoid area centered on the present Iranian shore of the
Persian Gulf. This ovoid area is suggested to have been
a developing arch, one of shoaling (Kamen-Kaye, 1970). During
the Tertiary the whole Riyadh area became part of a regional
synclinorial region which consisted of the Iranian fold
belt to the east and the present platform to the west. On
the present platform, limestone predominates in the lower
Tertiary, but an evaporite sequence (anhydrite) appears in
the Eocene. The area of the present platform was unaffected
by the forces which deformed the fold belt (Ibid.) .
• 6 LOCALITY INFORMATION • This £ossil collection originated £rom the region 0£ Riyadh in east-central Saudi Arabia. There are five
localities in this region which were collected for fossils.
The geographic and stratigraphic locations of the sampled
fossils are given in Figure 1 and 3. The geographic locations
of the fossil localities are as follows:
Loe. 1. - 75 miles southwest of Riyadh on the road to
Mecca. Fossils were collected from the top of the cliffs.
Loe. 2. - 50 miles southwest of Riyadh along the road
to Mecca. The fossils came from the dip slope near the
top of the cliffs (Figure 5-9).
Loe. 3. - The locality is at a point reached by driving • 10 miles northeast of Riyadh on Dammam Road and then two miles to the north.
Loe. 4. - Northeast of Riyadh about 5 miles off the
Buwayb Road, 20 miles from the Dammam Road at turnoff in a
cliff area (Figure 10).
Loe. 5. - The Damman Road out of Riyadh was traveled
for 15 to 20 miles. Two miles to the north at that place
there is a new highway running roughly parallel to the old
road to Dammam. This new road was followed for 50 miles.
The fossils come from a locality two miles north into the
desert off this road at this point (Figure 4).
All the fossils were collected by Mr. Curtis M. Queen,
who was not a geologist but a telephone operator in Riyadh.
• 7 On weekends he went fossil collecting with his friends. The • total weight of the fossils amounted to about 300 pounds. He donated the fossils to the Orton Geological Museum of
The Ohio State University.
PRESERVATION OF THE MACROFOSSILS
Virtually all the specimens in this collection are
preserved as sediment cores (steinkerns). A core is defined
as the filling of space between two valves or inside the
shell by sediment. The surface of a steinkern is an internal
mould of the fossil shell, andipreserves interior features
of the shell. The mineral filling of this hollow space is
CaC03 in the specimens studied. Some specimens of bivalves
reveal evidence of duripartic preservation, that is, the • original parts have been resistant to physical change, but the skeletal material is altered or replaced.
BIOSTRATIGRAPHY
The age of rocks from the five localities described
in this report will be discussed based on fossils of each
locality.
Loe. 5. - The specimens of the locality 65-70 miles
northeast of Riyadh on the Dammam road (Figure 1) would be
given a Late Cretaceous age following the geologic map of
Saudi Arabia (Figure 2). The formation of this age is the
Aruma (Figure 3). The gastropods from this locality
indicating a Late Cretaceous age are Planorbis sp. (Figure
• 8 11:13 and 17), Architectonica sp. (Figure 11:16), Amaurop • sis bulbi£ormis (Figure 11:9), Gyrodes conradi (Figure 11:4), Neritoma (Neridomus) sp. (Figure 11:15), and Turritella sp.
(Figure 11:11, 12). However, there are also gastropods that
complicate this age determination. These include Bolis sp.
(Figure 11:8, 20), Mitra sp. (Figure 11:10), and Cypraea
sp. (Figure 11:6). These are likely to indicate a Tertiary
age. I conclude that the Upper Cretaceous Aruma Formation
might have been capped by Tertiary age rocks. The bivalves
of this locality reveal a consistent age. Ambocardia sp.
(Figure 12:12), Cardium (Granocardium) dumosum (Figure 12:4),
Venericardia (Venericardia) sp. (Figure 12:13), Cymbophora
sp. (Figure 12:3), and Dictyoptychus sp. (Figure 12:10),
are all of Late Cretaceous age. Dictyoptychus, a rudist, is • stratigraphic marker for this locality. The a very good
cephalopods are also very good stratigraphic ma~kers.
Spenodiscus (Figure 13:9) and Libycoceras (Figure 13:8)
indicate a Late Cretaceous age. Even weak suture markings
make identification possible.
Loe. 4. - The specimens from the locality northeast
of Riyadh, right about five miles off the Buwayb Road, 20
miles from the Dammam Road at turnoff in a cliff area would
be Early Cretaceous in age according to the geologic map
(Figure 2). The formation deposited in this time was the
Yamama Formation (Figure 3). Based on the entire collection
from this locality, I date the rocks as representing an
• 9 age within the Late Cretaceous-Eocene interval. The gastro • pod Lapparia durnosa (Figure 11:5) is a form (with shoulder spines) unknown in the reference books older than Tertiary
(it is Eocene in age). Because of this, I place it at the
youngest end of the age interval. Dentonia sp. (Figure 12:2)
a bivalve which is questionably identified, has a range of
Late Cretaceous to Eocene. Therefore, Tertiary can be at
least considered as the late part of this age interval.
There are many fossils which suggest the lower end of the
age interval as Late Cretaceous. Lunatia halli (Figure 11:3),
Polinices (Euspira) halli (Figure 11:18), Cylichna secalina
(not photographed), and Neritom (Neridomus) are gastropods
and Cardiurn (Pauperculum) sp. (Figure 12:1) is a bivalve • which agrees with the above age. The difference between the Early Cretaceous age (map) and the Late Cretaceous
to Eocene age (index fossils) could be accounted for by
either an error in the geographic placing of the locality,
or an outcrop of younger rock might occur in this area.
Loe. 3. - The fossils found only 10 miles northeast of
Riyadh are either Early Cretaceous or Tertiary (Miocene/
Pliocene) according to the geologic map. The formations
of these ages are the Sulaiy and Kharj Formations. Alec
tryonella (Figure 13:13), the oyster of this locality, is
the only definitely identified index fossil. It is Miocene,
Pliocene, or Recent in age. The other fossils indicate no
clear-cut age. • 10 Loe. 1 and 2. - The other two fossil locations are • 50 miles and 75 miles west 0£ Riyadh, respectively. The one 50 miles from Riyadh (Loe. 2) is Late Jurassic (Callovian
Stage) according to the map. I date this locality as Late
Cretaceous based on the results of my fossil study. The
corals Cyclolites sp. (Figure 13:5), Leptophyllastrea sp. (Figure
13:4), and Cycloseris sp. (Figure 13:3), suggest an approximate
Middle Cretaceous to Eocene age. The specimen Trocharea
sp. (Figure 13:1) conflicts with the above results because
it is Middle Jurassic to Cretaceous in age. The other
fossils from 50 miles west of Riyadh (Loe. 2) are from another
collection and I date them as Late Jurassic. There may be
possible Eocene outcrops at the top of the escarpment. The • justification for this is that Pholadomya (Bucardiomya) sp. (Figure 12:8), Oleneothyris sp. (Figure 13:12), and Oliva
sp. (Figure 11:7) are Late Cretaceous to Eocene in age
whereas the specimens "Natica" williamsi (Figure 11:1) and
Valvata sp. (Figure 11:2) are Late Jurassic in age.
Loe. 1. - The locality 75 miles west of Riyadh is of
Late Jurassic age according to the geologic map (Figure 2).
The formations there are the Tuwaiq Mountain Limestone and
the Daruma Formation. I speculate that the age of the rocks
producing the fossils is Triassic. The collection includes
Naticopsis (Naticopsis) sp. (Figure 11:14) a gastropod which
is Triassic in age. Also I conclude that the bivalve • Pholadomya (Pholadomya) sp. (Figure 12:6) is of similar age. 11 Both these fossils are badly preserved and weathered. The • difference between the age determination from the map and the fossils might possibly be accounted for by error in the
geographic location of the fossil site.
FOSSIL DESCRIPTIONS
Phylum MOLLUSCA
Class GASTROPODA
Genus PLANORBIS?
PLANORBIS? sp.
Figure 11:13 and 17
Description. - Small to large, nearly discoid with the entire
spire below body whorl or flattened. Spire is not symmetrically
involute. The umbilicus is small and deep; the aperture • crescent-shaped. Apertures have a sharp outer margin.
Table 1 - Measurements in mm of Planorbis sp.
H w H/W
B60 30 57 .53 B61 25 48 .52
Remarks. - Specimen 60 (Figure 4:13) has well-defined growth
lines showing the former positions of the outer lip of the
aperture. Shell 60 has one exposed whorl with the other
side embraced by the body whorl. It is not discoid (it is • involute), but its spire is well below the body whorl. Shells 12 61 and 47 (Figure 4:17) are representatives of another • species of Planorbis. Both are coiled in one plane (dis coidal) and have rapidly increasing whorl diameter, but
their spires are not below body whorl, but flattened.
Also, the periphery of the whorls is relatively angulated
and umbilicus is deep. There are three whorls in specimen
61 and one in 47. There is some doubt as to the genus
these were placed in because Planorbis belongs to the
Pulmonata, a subclass of terrestrial fresh water gastropods
which have lungs. Riyadh was generally not a favorable
place for these air-breathing gastropods because of the
submerged marine environment. Identification is thus
tentative. Age of these specimens could be from Late • Jurassic to Recent, but because these specimens are associated with preserved Late Cretaceous index fossils,
this species is likely to be of Late Cretaceous age.
Occurence. - Aruma Formation (Late Cretaceous), 65-70
miles northeast of Riyadh on Dammam Road, 4 specimens; 50
miles west of Riyadh along road to Mecca, 2 specimens.
Genus MITRA
MITRA sp.
Figure 11:10
Description. - Large, high-spirited fusiform gastropod.
The pleural angle is low but the protoconch cannot be described
(missing on all specimens). The surface is smooth and suture
channeled. The aperture is narrow, half the shell length,
and the outer lip is sharpened. • 13 • Table 2 - Measurements in mm of Mitra sp. H w H/W
CC38 90 40 2.25
Remarks. - Age is Tertiary to Recent.
Occurrence. - Aruma Formation (Late Cretaceous), 65-70
miles northeast of Riyadh on Dammam Road, 2 specimens; 50
miles west of Riyadh along the road to Mecca, 2 specimens.
Genus ARCHITECTONICA
ARCHITECTONICA sp.
Figure 11:16
Description. - Depressed-conical shell with five whorls • and deep umbilicus. There is strong peripheral angulation in the mid-body whorl area and in the other ones also. Whorls
increase evenly in width. In apical view, the outline of
whorls is circular. Umbilicus has a spiral shape. The
aperture is quadrilateral.
Table 3 - Measurements in mm of Architectonica sp.
H w H/W
B20 18 44 .41
Remarks. - Age of these specimens is Cretaceous. The
surface has a fine spiral ornamentation in these specimens, • but it is only barely noticeable in the body whorl of the 14 figure. • Occurrence. - Aruma Formation (Late Cretaceous), 65-70 miles northeast of Riyadh on Dammam Road, 2 specimens; 50
miles west of Riyadh along the road to Mecca, 1 specimen.
Genus CYPRAEA
CYPRAEA SP.
Figure 11:6
Description. - Involute shell with adapical umbilicus.
Spire of shell completely covered by outer lip. The
outer lip curves inward and forms a narrow aperture. The
sides of the aperture are lirate. (Lirate is a term referring
to fine linear elevations on shell surface or within outer
lip.) The entire surface is smooth .
• Table 4 - Measurements in mm of Cypraea sp.
H w H/W
CC19 47 38 1.24
Remarks. - The outer lip does curve inward to form a
narrow aperture in some of the specimens, but due to bad
preservation it is facing the front in others. Also, lirate
borders of aperture not noticeable in these specimens. This
genus ranges from the Jurassic to Recent, and the species
described in 'Index Fossils of North America' is of Early • Miocene age, but due to bad preservation and lack of other 15 textbook species, these specimens cannot be given a more • definite age. Occurrence. - Aruma Formation (Late Cretaceous), 65-70
miles northeast of Riyadh, 2 specimens; 50 miles west of
Riyadh, 3 specimens; 75 miles west of Riyadh on the road to Mecca, 1 specimen.
Genus BOLIS
BOLIS LISBOA
Figure 11:8, 20
Description. - Buccinoid, stout inflated shell with high
spire, medium to very large size. Whorls (4 to 5) are
straight-sided or rounded with a sutural shelf. This shelf
is deeply channeled. Ornamentation consists of spiral lines • • The aperture is narrow and long, ending in an umbilicus which is closed by a protuberence (callus) from within shell.
Anterior canal is short. Aperture is elongate-elliposidal.
Table 5 - Measurements in mm of Bolis lisboa.
H w H/W
Bl 120 61 1.97 B24 55 30 1.83
Remarks. - Age is Eocene. Specimen Bl has rounded instead
of straight-sided whorls and has sculpture. These specimens
resemble representatives of the genus Amauropsis in that • the sutural shelf is at a 90 degree angle to sides, but they 16 have the anterior canal that Amauropsis lacks. The identifi • cation is thus tentative. Occurrence. - Aruma Formation (Late Cretaceous), 65-70
miles northeast of Riyadh, 1 specimen; 50 miles west of
Riyadh, 6 specimens.
Genus AMAUROPSIS
AMAUROPSIS BULBIFORMIS
Figure 11:9
Description. - High spired, pear-shaped; nonumbilicate;
sides of whorls nearly flattened, but slightly curved. The
aperture is large and hemisperical. There are incised
sutures between the whorls. The outer lip is nearly
vertical.
• Table 6 - Measurements in mm of Amauropsis bulbiformis
H w H/W
CC43 65 40 1.63
Remarks. - The easily noticeable sutural shelf in the type
species in 'Index Fossils of North America' is not observable
in the majority of the specimens, maybe because of imperfect
preservation. However, the representative of them included
in this report has one such shelf. The age is Late Cretaceous. • Occurrence. - Aruma Formation (Late Cretaceous), 65-70 17 miles northeast of Riyadh, 4 specimens; 50 miles west of
• Riyadh, 3 specimens. Genus TURRITELLA
TURRITELLA sp.
Figure 11:11, 12
Description. - High multispiral shell which has 7-8 convex
whorls. Entire shell is slender and of moderate or large
size. Spiraled whorls are separated by incised sutures. The
outer lip is arcuate (and thin) and aperture is either
oval or round. The inner lip is curved. Spiral ornament
is lacking in all shells due to bad preservation. There
is no siphonal canal in all specimens . • Table 7 - Measurements in mm. of Turritella sp.
H w H/W
BS 64 26 2.46 B28 84 38 2.21
Remarks. - The age is Triassic to Recent.
Occurrence. - Aruma Formation (Late Cretaceous), 65-70
miles northeast of Riyadh, 11 specimens; northeast of Riyadh,
about five miles to the right off the Buwayb Road, 20 miles
from the Dammam Road turnoff-cliff area, 3 specimens . • 18 Genus EPITONIUM • EPITONIUM sp. Figure 11:19
Description. - Shell turreted, with five or six whorls.
Sutures are moderately, but not very deep, and impressed.
Sides of whorls are convex and regularly spaced with varices
which are not very prominent. Shell is otherwise smooth.
Aperture is semi-circular.
Table 8 - Measurements in mm of Epitonium sp.
H w H/W • Bl3 41 23 1.78 Remarks. - The range of this genus is Triassic to Recent.
Occurrence. - Aruma Formation (Late Cretaceous), 65-70
miles northeast of Riyadh, 4 specimens.
Genus GYRODES
GYRODES CONRADI
Figure 11:4
Description. - Naticoid (globose last whorl and small spire)
shell with low spire and broad body whorl. The number of
whorls is three to four. Angulation is present on body whorl
below suture. This angulation is called a carina. Also,
a small concave band exists between suture and the shoulder
of the suture of every whorl. The region around the umbilicus
• 19 is funnel-shaped and is bordered by an angulation. Aperture • is large and sub-ellipsoidal.
Table 9 - Measurements in mm of Gyrodes conradi
H w H/W
Bll 37 40 .93
Remarks. - Age is Late Cretaceous.
Occurrence. - Aruma Formation (Late Cretaceous), 65-70
miles northeast of Riyadh, 1 specimen.
Genus NERITOMA
NERITOMA (NERIDOMUS} sp. • Figure 11:15 Description. - Globose with small protruding spire and
aperture that is oblique to shell axis. Aperture is large.
Sutures are adpressed. Outer lip without sinus.
Table 10 - Measurements in mm of Neritoma (Neridomus) sp.
H w H/W
037 28 27 1.04
Remarks. - Age is Late Jurassic to Late Cretaceous. • Occurrence. - Aruma Formation (Late Cretaceous), 65-70 20 miles northeast of Riyadh, 1 specimen; 20 miles northeast of • Riyadh, 1 specimen. Genus OLIVA
OLIVA sp.
Figure 11:7
Description. - Subcylindrical in shape, smooth, with short
spire and long body whorl. Sutures are made up of a narrow
sutural canal occupied by a cordlike posterior appendage of
the mantle. This type of suture is observable only in this
representative specimen. The aperture is broad. The
columella is not visible, but if it were present there would
be folds on it. • Table 11 - Measurements in mm of Oliva sp . H w H/W
CC52 49 28 1.75
Remarks. - Age is Cretaceous to Recent.
Occurrence. - 50 miles west of Riyadh, 3 specimens, fair
preservation.
Genus NATICA
"NATICA" WILLIAMSI
Figure 11:1
Description. - Globose shell with small spire and smooth
surface. Nonumbilicate. Aperture is oval, and a sharp outer • lip surrounds it. The whorls are about four in number. 21 • Table 12 - Measurements in mm of Natica williamsi Thickness between H w H/W 1 and 2 whorl
CC28 25 29 .86 4
Remarks. - Age is Late Jurassic.
Occurrence. - 50 miles west of Riyadh, 1 specimen.
Genus POLINICES
POLINICES (EUSPIRA) HALLI
Figure 11:18
Description. - A naticoid form. Shell is ovate. Large
semilunar aperture. Umbilicus is large. Body whorls are
large, number of whorls is three. Inner lip is thin and • oblique on these shells, and lacking any noticeable callus. Anterior of shell is narrow, ending in a blunt point. Sutures
are channeled on some while adpressed on another. One of
the specimens seems to be different than the others despite
the above similarities because it has a different suture
type, pustules, and spiral lines as ornamentation. Thus,
this one could be of a different family of gastropods.
Table 13 - Measurements in mm of Polinices halli
H w H/W
010 41 30 1.47
• 22 Remarks. - Age is Late Cretaceous. • Occurrence. - 50 miles west of Riyadh, 1 specimen; 20 miles northeast of Riyadh, 3 specimens.
Genus VALVATA
VALVATA SCARBRIDA
Figure 11:2
Description. - Small shells with naticoid form. Whorls
(3) enlarge in regular manner soon to end in a body whorl
which has smooth surface. Spire is depressed-conical and
sutures impressed. Apertures are circular and peristome
is continuous (this is noticeable in the representative
of this genus) . • Table 14 - Measurements in mm of Valvata scabrida
H w H/W
CC35 10 16 .63
Remarks. - Age is Late Jurassic to Early Cretaceous.
Occurrence. - 50 miles west of Riyadh, 1 specimen.
Genus LUNATIA
LUNATIA HALLI
Figure 11:3
Description. - Small, subglobose shell with elevated
spire. Spire ending as a broad apex and making a high • pleural angle. Aperture is semi-lunar, and umbilicus 23 ...------~------
circular without callosity. Sutures are adpressed. Whorls • have a general banded appearance.
Table 15 - Measurements in mm of Lunatia halli
Thickness Between H w H/W 1 & 2 Whorl
017 22 21 3
Remarks. - The identification of my specimens with L. halli
is uncertain. Age is Cretaceous to Recent.
Occurrence. - 50 miles west of Riyadh, 3 specimens; 20
miles northeast of Riyadh, 5 specimens.
Genus LAPPARIA • LAPPARIA DUMOSA Figure 11:5
Description. - Shells with mitroid form, volutid, Number
of whorls is four to five. Aperture is semilunar. Anterior
canal is short and slightly recurved. It possesses an
umbilicus. Ornamentation consists of shoulder spines which
are large on the body whorl and decrease in size on smaller
whorls. Number of countable spines is 15. Protoconch is
missing.
Table 16 - Measurements in mm of Lapparia dumosa
Thickness Between H w H/W 1 & 2 suture • 01 48 33 9
24 Remarks. - Age is Eocene. • Occurrence. - 20 miles northeast of Riyadh, 3 specimens. Genus CYLICHNA
CYLICHNA SECALINA
Not Photographed
Description. - Involute shell with an adapical umbilicus.
Spire depressed with adapical perforations on the surface.
Columella undetectable.
Table 17 - Measurements in mm of Cylichna secalina
Thickness Between H w H/W 1 & 2 Whorl • 019 27 11 2.45 3 Remarks. - Age is Late Cretaceous.
Occurrence. - 20 miles northeast of Riyadh, 1 specimen.
Genus NATICOPSIS
NATICOPSIS (NATICOPSIS) sp.
Figure 11:14
Description. - Large, globular with spire taking up about
30 percent of shell height. Aperture is ellipsoidal,
directed in oblique direction to axis. Whorls are large
and rounded. Flat area around suture. Surface is smooth,
devoid of ornamentation . • 25 • Table 18 - Measurements in mm of Naticopsis (Naticopsis) sp. Thickness Between H w H/W 1 & 2 Suture
Y2 51 40 1.28 12
Remarks. - Age is Triassic.
Occurrence. - 75 miles southwest of Riyadh on road to
Mecca, 4 specimens.
Class CEPHALOPODA
Subclass AMMONOIDEA
GENUS CARINONAUTLLUS
CARINONAUTILUS sp .
Figure 13:2 • Description. - Nautiliconic, very involute, compressed; whorl section a little higher than wide. Umbilicus small
and shallow. Venter sharp, but hard to describe because of
bad preservation. Flanks flat. Suture markings biconvex.
Table 18 - Measurements in mm of Carinonautilus sp.
Whorl Widthj_ Whorl Height
B36 18 50
Remarks. - Age is Upper Cretaceous.
Occurrence. - Aruma Formation (Late Cretaceous), 65-70
miles northeast of Riyadh, 1 specimen.
• 26 Class CEPHALOPODA • Subclass AMMONOIDEA Genus SPHENODISCUS
SPHENODISCUS (AUSTROSPHENODISCUS) sp.
Figure 13:9
Description. - Generally smooth involute oxycone. First
lateral saddle with two adventitious lobes as big as first
lateral lobe. Folioles generally, but not uniformly, with
long narrow necks and kidney-shaped ends.
Table 19 - Measurements in mm of Sphenodiscus sp.
Whorl Width Height of Whorl
• B34 25 63
Remarks. - Evidence of a Late Cretaceous age is very
evident for the locality 65-70 miles northeast of Riyadh
using this specimen.
Occurrence. - Aruma Formation (Late Cretaceous), 65-70
miles northeast of Riyadh, 1 specimen.
Genus LIBYCOCERAS
LIBYCOCERAS sp.
Figure 13:8
Description. - Distinguished from Sphenodiscus by feeble
lateral and ventrolateral tubercles, which are very hard to
• 27 see on this specimen. First lateral saddle of suture with • one adventitious lobe. All saddles entire, but outer ones slightly indented. No definite determinations can be made
of whorl height but whorl width is 15 mm.
Remarks. - Age is Late Cretaceous.
Occurrence. - Aruma Formation, 65-70 miles northeast of
Riyadh, 1 specimen.
Genus PSEUDOCENOCERAS
PSEUDOCENOCERAS sp.
Figure 13-7
Description. - Nautiliconic, compressed, and smooth.
Whorl section subrectangular. The venter is flat and broad.
Flanks are flattened, giving the cross section a rectangular • appearance. Umbilicus small. Sutures missing. Table 20 - Measurements in mm of Pseudocenoceras sp.
H w H/W
B40 55 33 1.67
Remarks. - Age is Cretaceous.
Occurrence. - Aruma Formation, 65-70 miles northeast of
Riyadh on Dammam Road, 1 specimen .
• 28 Class PELECYPODA • Genus AMBOCARDIA AMBOCARDIA sp.
Description. A medium-sized rectangularly ovate shell,
with strong prosogyrous beaks. The beaks are incurved and
almost terminal. The turbinal ridge extends to the posterior
and anterior parts of the shell. The ridge goes to the
ventral margin. Dentition is not observable. No ribs are
noticeable.
Table 21 - Measurements in mm. of Ambocardia sp.
Height Length Thickness
• B6 43 25 31 Remarks. - Age is Late Cretaceous.
Occurrence. - Aruma Formation, 65-70 miles northeast of
Riyadh, 2 specimens.
Genus CARDIUM
CARDIUM (GRANOCARDIUM) DUMOSUM
Figure 12:4
Description. - Convex, equivalve shell with prominent
incurved umbones. The hinge line is curved. The surface is
radically striated. Spaces and ribs are of the same width .
• 29 Table 22 - Measurements in mm. of Cardiurn (Granocardiurn) • durnosurn.
Height Length Thickness
B54 65 56 41
Remarks. - Age is Late Cretaceous.
Occurrence. - Aruma Formation, 65-70 miles northeast of
Riyadh, 1 specimen.
Genus GRANOCARDIUM
GRANOCARDIUM (GRANOCARDIUM) sp.
Not Photographed
Description. - Shell convex; one valve larger than the
other with one urnbo that is also larger than other one.
• and slightly turned forward. Hinge line Umbos prominent
curved. Surface radially striated. Striation consists of
three smaller intercalary ribs between)primaries.
Table 23 - Measurements in mm. of Granocardiurn (Granocardiurn) sp.
Height Length Thickness
CC16 59 48 37
Remarks. - Age is Early Cretaceous to Late Cretaceous. • Occurrence. - 50 miles west of Riyadh, 2 specimens • 30 Genus CARDIUM • CARDIUM {PAUPERCULUM) sp. Figure 12:1
Description. - Shell convex and almost equilateral. Only
one valve present and umbo of this one chipped off. Plications
present, about 18. Plications of higher elevation on posterior
umbonal slope, giving it an angular appearance.
Table 24 - Measurements in cm. of Cardium (Pauperculum) sp.
Height Length
024 2.1 2.2
• Remarks. - Age is Late Cretaceous. Occurrence. - 20 miles northeast of Riyadh, 1 specimen.
Genus CARDIUM
CARDIUM sp.
Figure 12:11
Description. - Convex valves; quadrate. Curved hingeline.
Umbos prominent, incurved, turned slightly forward. No
radial or concentric striations. Equivalve shell.
Table 25 - Measurements in mm. of Cardium sp.
Height Length Thickness
• Pl 69 57 51 31 Remarks. - Age is Triassic to Recent. • Occurrence. - 10 miles northeast of Riyadh, 1 specimen. Genus VENERICARDIA
VENERICARDIA (VENERICARDIA) sp.
Figure 12:13
Description. - Shell round and rigonal with curved hinge
line. Urnbos are strong. Entire shell is inequilateral and
thick. Radiating ribs are squarish.
Table 26 - Measurements in mm. of Venericardia (Venericardia) sp.
Height Length Thickness • B58 45 41 26 Remarks. - Age is Late Cretaceous.
Occurrence. - Aruma Formation, 65-70 miles northeast of
Riyadh, 1 specimen.
Genus CYMBOPHORA
CYMBOPHORA sp.
Figure 12:3
Description. - Equilateral, rounded trigonal. The surface
is concentrically sculptured. Valves are equal. Resilium
elevated above the hingeline.
Table 27 - Measurements in mm. of Cymbophora sp . • 32 • Height Length Thickness B53 55 74 24
Remarks. - Age is Cretaceous.
Occurrence. - Aruma Formation, 65-70 miles northeast of
Riyadh, 2 specimens.
Genus DICTYOPTYCHUS
DICTYOPTYCHUS sp.
Figure 12:10
Description. - Very large, inequivalve, the attached valve
(AV) conical, slightly incurved, with two longitudinal
swellings possibly representing siphonal bands; free valve
(FV) much depressed, with eccentric summit .
• Table 28 - Measurements in mm. of Dictyoptychus sp.
Height Length
B2 71 34
Remarks. - Age is Late Cretaceous.
Occurrence. - Aruma Formation, 65-70 miles northeast of
Riyadh, 2 specimens.
Genus PHOLADOMYA
PHOLADOMYA (Bucardiomya) sp. • Figure 12:8 33 Description. - Subtrigonal and medium sized shells with • strong ineguilateral shape. Anterior side most ventricose. Umbones are very noticeable, strongly incurved, and anteriorly
placed. Posterior side is a prominent extension of the
shell, but variable in these specimens, from 30 to 50 mm
in these specimens. Anterior extension is usually either
a very small bulge or an impression. Ornamentation con
sisting of radial ribs and small concentric undulations.
There is no escutcheca.
Table 29 - Measurements in mm. of Pholadomya (Bucardiomya) sp.
Height Length Thickness
• CC7 70 55 56
Remarks. - Age is Late Jurassic to Early Tertiary, most
likely Eocene.
Occurrence. - 'SO miles west of Riyadh, 4 specimens.
Genus PHOLADOMYA
PHOLADOMYA (Pholadomya) sp.
Figure 12:6
Description. - Elongate rounded with broad prominent
curving umbones. Umbones situated anteriorly. Shell is
strongly ineguilateral. Dorsal umbonal ridge present.
Ligament nymph present below umbones along hingeline. No
ornamentation. • 34 • Table 30 - Measurements in cm of Pholadomya (Pholadomya) sp.
Height Length Thickness
Y-1 9-0 10 6
Remarks. - Age is Late Triassic to Recent.
Occurrence. - 75 miles southwest of Riyadh, 1 specimen.
Genus PLATYCARDIA
PLATYCARDIA sp.
Figure 12:7
Description. - Shell oval, thick, medium-sized with height
much exceeding length. Umbones are strong with prosogyrous
beaks outturned and incoiled. They are anteriorly placed. • Anterior of shell has a sulcus just under the beaks. Posterior side has an umbonal ridge. Surface with growth rugae.
Table 31 - Measurements in mm. of Platycardia sp.
Height Length Thickness
CC4 30 22 22
Remarks. - Age isLat.eTriassic to Late Cretaceous.
Occurrence. - 50 miles west of Riyadh, 1 specimen.
Genus MYTILUS
MYTILUS sp .
Figure 12:5
• 35 Description. - Inequilateral, umbos terminal and pointed. • Shell is long and inflated, wider at ventral margin. It opens at hinge for acceptance of byssus. Concentric striae
present.
Table 32 - Measurements in cm. of Mytilus sp.
Height Length
04 4 8.1
Remarks. - Age is Triassic to Recent.
Occurrence. - 20 miles northeast of Riyadh, 2 specimens . Genus DENTONIA • DENTONIA sp. Figure 12:2
Description. - Subtrigonal. Escutcheon not noticeable;
umbonal ridge small. Concentric sculpture consisting of
striae. Valves thin and equilateral. Lunule present, but
hard to recognize. Umbos small and pointed.
Table 33 - Measurements in mm. of Dentonia sp.
Height Length Thickness
021 34 40 10
• 36 Remarks. - Age is Late Cretaceous to Eocene. • Occurrence. - 20 miles northeast of Riyadh, 2 specimens. Genus PARAMEGALODUS
PARAMEGALODUS sp.
Figure ·112: 9
Description. - Large, tall, trigonal, ho:nnlike, with umbos
that are prominent. Umbos and the space between them have
a horseshoe-like appearance. Internal rounded rib goes to
the umbo, and runs to the posterior end of the ventral
margin.
Table 34 - Measurements in mm. of Paramegalodus sp .
• Height Length Thickness P2 92 58 80
Remarks. - Age is Late Triassic.
Occurrence. - 10 miles northeast of Riyadh, 2 specimen~.
Genus ALECTRYONELLA
ALECTRYONELLA sp.
Figure 13:13
Description. - Small (8 cm. long), almost circular shell.
Inequivalve. Ribs consisting of regularly spaced sharp
crested plicae which come to valve commissure as folds which
are spaced evenly. Number of plicae ranges from 18 to 20 .
Concentric growth wrinkles common. Left valve interior deep
• 37 and right valve interior convex. Adductor muscle imprint • higher than long, concave on its dorsal margin. Umbonal cavity present in le£t valve, although it seems to be filled
in by other material.
Table 35 - Measurements in mm. of Alectryonella sp.
Height Length Thickness
P4 95 80 60
Remarks. - Age is Miocene, Pliocene - Recent.
Occurrence. - 10 miles northeast of Riyadh, 1 specimen .
Phylum COELENTERATA • Class ANTHOZOA Genus ACTINASTREA
ACTINASTREA sp.
Figure 13:2
Description. - Cerioid; ramose. Budding is by extra
tentacular budding. Walls of septa elevated, forming a
hexagonal outline. Columella easily recognized.
Table 35.5 - Measurements in mm of Actinastrea sp.
Septa diameter (approximate) Height of branch • C27 3-5 80 38 Remarks. - Age is Late Triassic to Recent. • Occurrence. - 50 miles west of Riyadh, 1 specimend. Phylum COELENTERATA
Class ANTHOZOA
Genus CYCLOLITES
CYCLOLITES sp.
Figure 13:5
Description. - Solitary coral with convex oral surface and
flat base. Septa perforate and axis of divergence is a1most
vertical. Colony formation by circumoral intratentacular
budding.
Table 36 - Measurements in mm. of Cyclolites sp .
• Width Length Thickness
C6 85 96 29
Remarks. - Age is Cretaceous to Eocene.
Occurrence. - 50 miles west of Riyadh (top of cliffs),
5 specimens.
Genus CYCLOSERIS
CYCLOSERIS sp.
Figure 13:3
Description. - Solitary coral with convex oral surface
and flat base. Cyclolitid in structure. Aboral surface
concave. Septa numerous, perforate, made up from a single
• 39 fan system of compound trabeculae producing simple or com • pound marginal dentations, laterallyunited by stout compound synapticulae.
Table 37 - Measurements in mm. of Cycloseris sp.
Length Width Height
C9 33 29 13
Remarks. - Age is Middle Cretaceous to Recent.
Occurrence. - 50 miles west of Riyadh - top of cliffs, 2
specimens.
Genus TROCHAREA • TROCHAREA sp. Figure 13:1
Description. - Solitary, patellate shape. Colony formed
by intra- and extratentacular budding.
Table 38 - Measurements in mm. of Trocharea sp.
Diameter Height
C20 21 3
Remarks. - Age is Middle Jurassic to Cretaceous.
Occurrence. - 50 miles west of Riyadh, top of cliffs, 11
specimens. • 40 • Table 40 - Measurements in mm. of Oleneothyris sp.
Length Width Thickness
CC5 34 29 21
Remarks. - Age is Eocene.
Occurrence. - 50 miles west of Riyadh, 3 specimens.
Genus TEREBRATALIA
TEREBRATALIA sp.
Figure 13:10
Description. - Small, wider than long, biconvex, and has
costellae. Sulcate value. Foramen prominent at beak. Number • of costellae is 22 to 25 with no branching. Shape of costallae is equidimensional.
Table 41 - Measurements in mm. of Terebratalia sp.
Length Width Thickness
028 24 23 16
Remarks. - Age is Terfiary to Recent.
Occurrence. - 20 miles northeast of Riyadh, 1 specimen.
Genus TEREBRATULINA
TEREBRATULINA sp . • Figure 13:11 41 Description. - Small, brachial valve more convex than dorsal • valve. Foramen probably large, although evidence of it has largely been destroyed by erosion at top of brachial valve.
Costellae consist of fine concentric markings.
Table 42 - Measurements in mm. of Terebratulina sp.
Length Width Thickness
029 16 16 7
Remarks. - Age is Late Cretaceous.
Occurrence. - 20 miles northeast of Riyadh, 1 specimen .
SUMMARY • The body fossils described are mainly of late Mesozoic through middle Tertiary age. However, some of the ages of
units determined by the index fossils studied could be in
correct. One of the reasons for this is that there is no
preservation of shell material and the specimens consist of
steinkerns. The cephalopods appear to be the best strati
graphic markers because they are all generally well preserved
and expose diagnostic characters. Sphenodiscus, for instance,
is an excellent marker for the locality 65-70 miles northeast
of Riyadh, showing a Late Cretaceous age for the host rocks
in that area. Also, the gastropods are fairly good markers. • They are useful because the diversity of species in the 42 collection compensated for the fact that present preservation • of the shell's ornamentation and apertural features is in many cases only fair. Architectonica sp. and Amauropsis
bulbiformis are identified as gastropod index fossils. The
present collection shows that much future work is available
for geologists and paleontologists in this region of Saudi
Arabia, but this collection of Curtis Queen has also provided
an insight into both the problems and the possibilities
associated with work on megafossils from the Saudi Arabian
desert.
ACKNOWLEDGEMENTS
I wish to thank Curtis M. Queen, who contributed the
entire collection of Saudi Arabian fossils to Dr. Stig • Bergstrom," Professor of Geology and Curator of the Orton Geological Museum, permitting me to make a report on them
presently. He also generously provided free copies of his
pictures taken during his fossil trips. Dr. Stig Bergstrom"
read preliminary versions of the manuscript and suggested
many improvements. I also thank the photographer who
,filmed the fossils, Dr. Wm. Ausich .
• REFERENCES • ARKELL, W.J., B. KUMMEL, and C.W. WRIGHT. Mesozoic Ammonoidea, 1957, p. L-80-L465. In, R.C. Moore (ed.), Treatise on Invertebrate Paleontology, Mollusca 4, Part L, Ammonoidea, Geological Society of America and University of Kansas Press, Lawrence.
COX, L.R. 1960. General Characteristic of Gastropoda, p. I84-Il69. In, R.C. Moore (ed.), Treatise on Invertebrate Paleontology, Mollusca 1, Part I. Geological Society of America and University of Kansas Press, Lawrence.
and others. 1969. Biralvia, p. N 491-N913. In, R.C. Moore (ed.), Treatise on Invertebrate Paleontology, Mollusca 6, Part N. Geological Society of America and University of Kansas Press, Lawrence.
KAMEN-KAYE, M., 1970. Geology and productivity of Persian Gulf synclinorium. American Association of Petroleum Geologists, Bulletin 54 (12) :2371-2394.
KNIGHT, J.B., and others. 1960. Systematic description (Archaeogastropoda) and Supplemert~Paleozoic and some Mesozoic Caenogastropoda and Ophisthobranchia, p . Il69-I332. In, R.C. Moore (ed.), Treatise on Invertebrate Paleontology, Mollusca 1, Part I. Geological Society • of America and University of Kansas Press, Lawrence. KUMMEL, B., with additions by W. M. Furnish, and B.F. Glenister. 1964. Nautiloidea-Natilida, p. K383-K466. In, R.C. Moore (ed.), Treatise on Invertebrate Paleontology, Mollusca 3, Park K. Geological Society of America and University of Kansas Press, Lawrence.
MURRIS, R.J., 1980. Middle East: Stratigraphic evolution and oil habitat. American Association of Petroleum Geologists Bulletin, 64(5): 597-618.
POWERS, R.W. 1968. Age relationships of Saudi Arabian sedi mentary rock units (Plate II). League Stratigraphique International, Volume III (Asie). Centre National De La Recherche Scientifique, Anatole, France.
and others, 1966. Geology of the Arabian Peninsula: Sedimentary Geology of Saudi Arabia. U.S. Geological Survey Professional Paper 560-D, 127p.
SHIMER, H.W., and R.R. SHROCK. 1944. Index Fossils of North America. John Wiley and Sons, Inc., New York, 837 p. • 44 STENZEL, H.B., with addition by L.R. COX. 1971. Oysters, p. N953-Nl218. In, R.C. Moore (ed.), Treatise on • Invertebrate Paleontology, Mollusca 6, Part N. Geological Society of America and University of Kansas Press, Lawrence.
TEICHERT, c., and others. 1964. Endoceratoidea - Actinocera toidea - Nautiloidea, p. Kl3-Kl27. In, R.C. Moore (ed.), Treatise on Invertebrate Paleontology, Mollusca 3, Park K. Geological Society of America and University of Kansas Press, Lawrence.
VASLET, D., and others. 1983. Explanatory notes to the geologic map of the Wadi Ar Rayn quadrangle, Sheet 23H, Kingdom of Saudi Arabia, p. 23-28. Ministry of Petroleum and Mineral Resources Deputy Ministry For Mineral Re sources, Jiddah, Saudi Arabia.
WELLS, J.W. 1956. Scleractina, p. F728-F444. In, R.C. Moore (ed.), Treatise on Invertebrate Paleontology, Part F, Coelenterata. Geological Society of America and University of Kansas Press, Lawrence .
MAPS
ARABIAN PENINSULA. 1963. Miscellaneous geologic investigations, • Map I-270 B-2. U.S. Geologic Survey and the Arabian American Oil Company.
GEOLOGIC MAP of the Arabian Peninsula. 1963. Miscellaneous geologic investigations, Map I-270A. U.S. Geologic Survey and the Arabian American Oil Company .
• 45