A Giant Sauropod Dinosaur from an Upper Cretaceous Mangrove Deposit in Egypt

Abstract

We describe a giant titanosaurid sauropod dinosaur discovered in coastal deposits in the Upper Cretaceous Bahariya Formation of Egypt, a unit that has produced three Tyrannosaurus-sized theropods and numerous other vertebrate taxa. Paralititan stromeri is the first tetrapod reported from Bahariya since 1935. Its 1.69-meter-long humerus is longer than that of any known Cretaceous sauropod. The autochthonous scavenged skeleton was preserved in mangrove deposits, raising the possibility that titanosaurids and their predators habitually entered such environments.

Full text

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1701/DC1.
39. We thank R. Riding and P. Westbroek for com-
ments on an earlier draft and the Pyramid Lake
Paiute Tribal Council and the Western Australian
Department of Conservation and Land Manage-
ment for sampling permits. Funded by the German
Research Foundation and the Studienstiftung des
deutschen Volkes (G.A.).
6 November 2000; accepted 10 April 2001
A Giant Sauropod Dinosaur
from an Upper Cretaceous
Mangrove Deposit in Egypt
Joshua B. Smith,
1
* Matthew C. Lamanna,
1
Kenneth J. Lacovara,
2
Peter Dodson,
1,3
Jennifer R. Smith,
1
Jason C. Poole,
4
Robert Giegengack,
1
Yousry Attia
5
We describe a giant titanosaurid sauropod dinosaur discovered in coastal de-
posits in the Upper Cretaceous Bahariya Formation of Egypt, a unit that has
produced three Tyrannosaurus-sized theropods and numerous other vertebrate
taxa. Paralititan stromeri is the first tetrapod reported from Bahariya since
1935. Its 1.69-meter-long humerus is longer than that of any known Cretaceous
sauropod. The autochthonous scavenged skeleton was preserved in mangrove
deposits, raising the possibility that titanosaurids and their predators habitually
entered such environments.
In the early 20th century, the Bavarian geologist
Ernst Stromer described a diverse biota from
the Upper Cretaceous [Cenomanian: 93.5 to
99.0 million years ago (Ma)] Bahariya Forma-
tion (1) of the Bahariya Oasis, Egypt (Fig. 1).
The vertebrate discoveries included fish, turtles,
plesiosaurs, squamates, crocodyliforms, and
four dinosaurs: the theropods Spinosaurus,
Carcharodontosaurus, and Bahariasaurus, and
the sauropod Aegyptosaurus (2). Tragically,
Stromer’s collections were largely destroyed
during an Allied bombing of Munich in 1944
(3). With exceptions from Morocco (4–6) and
Algeria (7), evidence of Late Cretaceous Afri-
can dinosaurs remains limited. An improved
understanding of Late Cretaceous African ter-
restrial vertebrates is important for the paleo-
ecology of this region and is needed to evaluate
biogeographic hypotheses pertaining to Gond-
wanan fragmentation (5, 8–10). Here we de-
scribe the partial skeleton of an extremely large
sauropod dinosaur, the first tetrapod reported
from Bahariya since 1935 (11). The specimen
consists largely of vertebrae, pectoral girdle,
and forelimb elements and is preserved in sed-
iments indicative of intertidal deposits. A num-
ber of morphological differences distinguish the
humerus of the specimen (Fig. 2A) from that of
Aegyptosaurus, precluding referral to that ge-
nus (12). Because of these distinctions and its
possession of several autapomorphies, we des-
ignate the new specimen as Paralititan stro-
meri, gen. et sp. nov. (13).
Two preserved caudal sacral centra of
Paralititan lack pleurocoels. The centrum of
the first caudal vertebra (Fig. 2B) is wider
than high and procoelous, and has a convex
distal articular condyle. The centrum is not
biconvex, as in the titanosaurids Alamosau-
rus (14), Neuquensaurus (14 ), and Pelle-
grinisaurus (15). Its ventral surface has
weakly developed longitudinal ridges lateral-
ly bordering a sagittal concavity. A postspi-
nal lamina is present between spinopostzyg-
apophyseal laminae on the distal surface of
the neural spine. A second proximal caudal
(Fig. 2C) is strongly procoelous and has a
well-developed distal condyle.
The scapula is concave medially. A prom-
inent dorsomedial rugosity borders the medi-
al concavity as in the titanosaurids Aeolo-
saurus, Lirainosaurus, Neuquensaurus, and
Saltasaurus (14, 16). Distal to the glenoid, a
well-developed tabular process projects from
the caudoventral margin of the scapula. The
development of this structure in Paralititan is
equaled only in a scapulocoracoid referred to
the brachiosaurid Brachiosaurus altithorax
(17).
The humerus is strongly expanded proxi-
mally and distally. Because of the modest de-
1
Department of Earth and Environmental Science,
University of Pennsylvania, 240 South 33rd Street,
Philadelphia, PA 19104– 6316, USA.
2
Engineering Ge-
ology, Drexel University, 3141 Chestnut Street, Phil-
adelphia, PA 19104, USA.
3
Department of Animal
Biology, School of Veterinary Medicine, University of
Pennsylvania, 3800 Spruce Street, Philadelphia, PA
19104–6045, USA.
4
Academy of Natural Sciences,
1900 Ben Franklin Parkway, Philadelphia, PA 19103,
USA.
5
Egyptian Geological Museum, Egyptian Geolog-
ical Survey and Mining Authority, Athar El Nabi,
Maadi, Cairo, Egypt.
*To whom correspondence should be addressed. E-
mail: smithjb@sas.upenn.edu
Table 1. Phylogenetic data matrix. The macronarian Camarasaurus is postulated as an outgroup of titanosauriformes (45, 46). Character codings are as follows:
0, hypothesized plesiomorphic states; 1 and 2, hypothesized derived states; ?, missing or uncertain data (19).
Taxa
Characters
5 10152025303540455055
Outgroup
Camarasaurus 00000 00000 00000 00000 00000 00000 00000 00000 00000 00000 00000 0
Ingroup
Brachiosaurus brancai 11001 01000 00000 00000 00000 001?1 00000 001?0 00001 01010 01000 0
Andesaurus ??111 11000 1100? ?0?00 00??0 001?? ????? ????? ????? ??111 ????? ?
Epachthosaurus ??111 ??010 11011 ?0?01 1?011 1110? 1???? ???1? ???11 111?1 ?101? 0
Opisthocoelicaudia ???12 11101 ?1111 1?002 01110 10111 11011 01111 11111 11101 11011 0
Alamosaurus ????? ????? ????? ??101 10011 11101 11?11 101?1 1111? ?1??1 1???? ?
Malawisaurus 11?12 1???1 1100? ?0101 10011 00111 1???0 ????? ????? ????1 ????? 1
Paralititan ????? ????? ????? ??011 1101? ????? ??1?? ?111? ???1? ????? ????? ?
Saltasaurus ??112 11111 11001 11111 11101 11101 1?111 11111 1???1 11?11 ?1111 1
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velopment of a proximolateral process, the
proximal end is sinusoidal in cranial view, as in
Saltasaurus and Opisthocoelicaudia (18). A
well-defined muscular depression occupies the
proximal region of the cranial surface. The
deltopectoral crest is extremely developed and
medially deflected, extending more than 53%
of the length of the element. The rectangular
radial condyle is well developed distally. A
shallow fossa, bounded by medial and lateral
ridges, occupies most of the proximocaudal
surface of the humerus. The lateral ridge devel-
ops into a tuberosity approximately 350 mm
from the proximal margin, as in Lirainosaurus
and Saltasaurus (16), whereas the medial ridge,
unknown in titanosaurids, is most developed
560 mm from the proximal end. Elongate su-
pracondylar ridges that extend over one-third of
the length of the humerus define an extensive
olecranon fossa. The distal surface of the pre-
served metacarpal is rectangular and flattened,
suggesting phalangeal reduction or absence on
this digit.
Phylogenetic analysis of titanosauriform
sauropods (19) places Paralititan within Ti-
tanosauridae (Fig. 3 and Table 1). Characters
supporting its inclusion within the clade include
strongly procoelous proximal caudal centra
with well-developed postspinal laminae, a
proximolateral process on the humerus, and
reduced manual phalanges. The position of
Paralititan within Titanosauridae permits an
estimation of its body size (Fig. 2D). The hu-
merus is 1.69 m in length, ⬃14% longer than
the next longest known humerus from a Creta-
ceous sauropod (20). The South American ti-
tanosaurid Argentinosaurus is regarded as the
most massive terrestrial animal known and may
have approached 90 metric tons (21) and 30 m
in length (22). The humerus of Argentinosaurus
is unknown, but we estimate its length at 1.81 m
(7.5% longer than that of Paralititan), using
more complete titanosauriforms (23). There-
fore, Paralititan is probably not as large as
Argentinosaurus but represents one of the
heaviest terrestrial vertebrates yet discovered.
Fig. 1. (A) The Bahariya Oasis, ⬃300 km south-
west of Cairo, Egypt. (B) Location of BDP 2000-
18.
Fig. 2. Anatomy, taphonomy, and estimated size of Paralititan.(A) Right humerus in cranial and
caudal views. (B) First caudal vertebra in distal and right lateral views. (C) Proximal caudal
vertebra in proximal and right lateral view. Scale bars in (A) through (C) equal 10 cm. (D) Size
comparisons between Paralititan and an African elephant. (E) Quarry map of BDP 2000-18.
Fig. 3. Summary of
phylogenetic, temporal,
and geographic relation-
ships among titano-
sauriform sauropods.
The cladogram depicts
the strict consensus of
12 most parsimonious
trees (length, 72 steps;
consistency index, 0.806;
retention index, 0.759)
resulting from a parsi-
mony analysis of eight
titanosauriforms and
56 anatomical charac-
ters (19).
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Paralititan is preserved in low-energy
paralic sediments, representing vegetated tidal
flats and tidal channels. These units alternate
vertically and are laterally variable. The tidal flat
facies is a brown friable shale, rich in rhizoliths
and plant remains, often containing leaf com-
pressions and stems of the mangrove (24) tree
fern Weichselia reticulata (25, 26 ). In some
places the facies is found, conformably, above
glauconitic nearshore marine sands, a strati-
graphic relationship that supports a mangrove
interpretation. The relationship appears to be
conformable, as evidenced by a lack of ravine-
ment surfaces between occasional rhizoliths that
extend from lagoonal muds into marine sands.
This succession of environments is known to
occur along modern low-energy coasts, where
mangroves prograde out onto the active shore
face (27, 28). The seaward migration of man-
groves into the open marine realm requires both
a low-energy littoral zone and wave-resistant
salt-tolerant plants, such as Weichselia.
The Paralititan quarry spans both tidal
channel and vegetated tidal flat facies (Fig. 2E).
In situ plant roots, throughout the bone layer,
indicate limited water depth, and fine-grained
sediments suggest low current velocities. The
closely associated elements could not have
been transported to this location as clasts. In
addition, the shallow, vegetated tidal flat would
prevent a large sauropod carcass from float-
ing to this location. Evidence therefore indi-
cates that this individual walked to this loca-
tion, over tidal flats and along tidal channels,
before its death. Furthermore, the specimen
shows indications of being scavenged by a
carnivorous dinosaur (29). Therefore at least
two species of Bahariya dinosaur traversed
paralic environments.
It is interesting that this extremely produc-
tive biota, containing some of the largest known
terrestrial vertebrates (30), occurs during a time
with extremely low thermal gradients from pole
to pole and high global sea levels (31, 32).
Mid-Cretaceous ocean-atmosphere systems are
of particular interest in paleoclimate research,
representing extreme “hothouse” conditions for
post-Pangaean Earth history. The apparently
high productivity of this Cenomanian environ-
ment may reflect a biotic response to some
aspect of this condition.
References and Notes
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convex scapula with no dorsomedial prominence, had a
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13. Etymology: Paralititan stromeri (pa䡠ral⬘i䡠ti⬘䡠tan
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to tidal environments); Titan (Greek), an offspring of
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size (effectively, “tidal giant”); stromeri, in honor of
Ernst Stromer. Holotype: CGM 81119 (Egyptian Geo-
logical Museum, Cairo). Locality: BDP 2000-18, near
Gebel Fagga (28°20⬘10.7⬘⬘N latitude, 28°59⬘04.7⬘⬘E
longitude). Material: Two fused caudal sacral vertebrae
(probably 5 and 6), first caudal vertebra; proximal cau-
dal vertebra; dorsal and sacral ribs; incomplete scapulae;
complete right and incomplete left humeri; distal meta-
carpal; and several additional elements. Diagnosis: Very
large titanosaurid characterized by proximal caudal cen-
tra wider than tall; prominent tabular process on cau-
doventral margin of scapula distal to the proximal ex-
pansion; and humerus with medial ridge on the proxi-
mocaudal face and rectangular radial condyle. Paraliti-
tan shares the following characters with other
titanosaurids: lack of pleurocoels on caudal sacrals;
proximal caudal vertebrae with strongly concave prox-
imal articular surface, well-developed distal articular
condyle, ventral excavation, and postspinal lamina; hu-
merus with proximolateral process and strong supra-
condylar ridges; and reduction or absence of manual
phalanges. Referred material: Stromer (33) described a
very large cranial dorsal vertebra (1912VIII64). Speci-
men 1912VIII64 was opisthocoelous, pleurocoelous,
and caudally wider than tall, as in Epachthosaurus and
Pellegrinisaurus (15), and may pertain to Paralititan.
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iferous (360 to 286 Ma), when salt-tolerant gym-
nosperms and pteridophytes adapted to the habi-
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28. Additional evidence of low-energy environments in-
cludes fine-grained sediments, low-velocity bed-
forms, the absence of ravinement surfaces, in situ
bivalves, and horizontal burrows. All nonfossil clasts
in the Bahariya system are medium sand size or
smaller.
29. A cf. Carcharodontosaurus tooth (crown height ⫽
65 mm), recovered from BDP 2000-18, is larger
than clasts that could have been transported to
this location.
30. Paralititan coexisted with three Tyrannosaurus-sized
carnivores (Carcharodontosaurus, Bahariasaurus, and
Spinosaurus) and with other large vertebrates (such
as the 3.5-m coelacanth Mawsonia and the 10-m
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47. Supported by Cosmos Studios, MPH Entertainment,
the University of Pennsylvania, the Andrew K. Mellon
Foundation, E. de Hellebranth, and the Delaware
Valley Paleontological Society. We thank K. Soleiman
and the Egyptian Geological Survey and Mining Au-
thority, Drexel University, T. Holtz, H. Sues, J. Harris,
K. Curry-Rogers, J. Lacovara, and R. Martı´nez. We also
thank A. Tumarkin, Y. Abdelrazik, M. Said Abdel-
Ghani, P. Kane-Vanni, and J. Caton for assistance in
the field.
9 March 2001; accepted 30 April 2001
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