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Biggest of the big: a critical re-evaluation of the mega-sauropod Amphicoelias fragillimus Cope, 1878

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Foster, J.R. and Lucas, S. G., eds., 2006, Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin 36.
BIGGEST OF THE BIG: A CRITICAL RE-EVALUATION OF THE MEGA-SAUROPOD
AMPHICOELIAS FRAGILLIMUS COPE, 1878
KENNETH CARPENTER
Department of Earth Sciences, Denver Museum of Nature & Science, Denver, CO 80205 Ken.Carpenter@dmns.org
Abstract—Questions about the largest dinosaur have largely ignored or downplayed a discovery made in 1878 of a
1.5 m tall neural arch. The specimen is lost, but the original description by E.D. Cope of Amphicoelias fragillimus
provides enough information to reconstruct the vertebra as a posterior dorsal of a diplodocid. The estimated 2.7 m
height of the dorsal suggests a skeleton 58 m long, about 9.25 m at the highest point of the back, and with a body mass
of 122,400 kg. These dimensions indicate that A. fragillimus was several orders of magnitude larger than any other
sauropod. A. fragillimus existed at the peak of a trend toward gigantism in sauropods that progressed since their
origin in the Late Triassic. One possible cause for large body size in sauropods, based on studies of extant mammalian
megaherbivores, may be due to increased gut size for more efficient digestion of low quality browse by hindgut
fermentation.
INTRODUCTION
Discoveries during the past decade or so of very large sauropods
(>30 m) have led to the question about which was the largest dinosaur.
Van Valen (1969) attempted to answer that question before many of the
recent discoveries of large sauropods, such as of Argentinosaurus, thus
was limited in the data available for his analysis. Contenders today include
the diplodocids Seismosaurus hallorum from the Upper Jurassic of New
Mexico (Gillette, 1991; as Diplodocus hallorum by Lucas et al., 2004 and
Lucas et al. this volume) and Supersaurus vivianae from the Upper Juras-
sic of Colorado and Wyoming (Jensen, 1985; Lovelace et al., 2005), and
the titanosaurids Argentinosaurus huinculensis from the Lower Cretaceous
of Argentina (Bonaparte and Coria, 1993) and “Antarctosaurusgiganteus
from the Upper Cretaceous of Argentina (Huene, 1929; Powell, 2003). All
of these sauropods have estimated lengths of 30-35 m and estimated weights
of between 30-90 tons (Mazzetta et al., 2004; Paul,1994) one possible
contender, Paralatitan stromeri (Smith et al., 2001) is apparently shorter
than 30 m. Intriguingly, these sauropods are only known from fragmentary
remains. Based on the bone sample study in Amboseli Park by
Behrensmeyer and Dechant Boaz (1980), most of the skeleton for such
giant sauropods should be present. Although some of the loss is undoubt-
edly due to erosion of the fossils, most of the specimens consist of disar-
ticulated and scattered skeletons. Considering the great mass of the bones,
this dispersal is remarkable in light of the bone dispersal studies by Voorhies
(1969) and Behrensmeyer (1975).
One other giant sauropod from the Upper Jurassic of North America,
Amphicoelias fragillimus Cope, 1878b, is either ignored (e.g., Gillette,
1991) or only briefly mentioned (e.g., Mazzetta et al., 2004). Only Paul
(1997), following preliminary work by Carpenter (1996), has discussed
this taxon, but even this is brief. Because this taxon may indeed be the
largest dinosaur known, a fuller assessment is presented below.
The holotype of A. fragillimus consists of a neural arch and spine
(Fig. 1) believed to have been from the last or second to last dorsal (D10 or
D9). It was collect by Oramel Lucas near the main Camarasaurus supremus
localities in Garden Park, north of Cañon City, Colorado, as indicated
by E.D. Cope’s field notes (Fig. 2). Lucas began collecting for Cope in
late 1877, and shipped the specimen to Cope during the spring or early
summer of 1878 (McIntosh, 1998), who then published it in August
1878. Cope visited Lucas in July, 1879 and recorded in a small note-
book the various quarries from which Lucas had been excavating (McIn-
tosh, 1998; Monaco, 1998). Among the entries is “III Amphicoelias
fragillissimus [sic] from between the two lots” (lots refers to quarries
or sites). Specifically, the site is southwest of the “hill” of Cope’s notes
(now referred to as Cope’s Nipple), and south of the Camarasaurus
supremus I Quarry. The matrix in the vicinity of the quarry is a reddish
mudstone and the specimen was probably very pale tan, tinted with a
maroon red, as are all the surviving specimens from this level. Cope
also records “IV Immense distal end of femur near 1st broken smaller
femur.” It seems very likely that this femur belonged to the same speci-
men as the neural arch and spine because it was found in the next site
a few tens of meters away. Unfortunately, the whereabouts of both the
neural spine and femur are unknown as first reported by Osborn and
Mook (1921), and all attempts to locate the specimens have failed
FIGURE 1. A. Amphicoelias fragillimus (AMNH 5777) as figured by Cope
(1878b), modified with identification of features. B. Dorsal reconstructed based on
modified A. altus (extensively modified from Osborn and Mook, 1921, fig. 21. C.
Dorsal of A. altus (AMNH 5764) for comparison (modified from Osborn and Mook,
1921, fig. 21). C. cavities bounded by lamina within the neural arch; h, hyposphene;
l, lamina within the neural arch (outer bone eroded away exposing interior); lat
spol, lateral spinopostzygapophyseal lamina; med spol, medial
spinopostzygopophyseal lamina; pcdl, posterior centroparapophyseal lamina; posl,
postspinal lamina; poz, postzygapophysis; spol, spinopostzygapophyseal lamina.
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(McIntosh, 1998).
An attempt was made to relocate the quarry in 1994 including using
ground penetrating radar. However, because the density of fossilized bone
is the same as the encasing matrix, the technique, which relies on density
differences, did not work. In addition, the mudstone containing lots I-IV is
nearly stripped down to the underlying sandstone. The local topography
suggests that most of the strata had already been stripped off by the time
Lucas made his first dinosaur bone discovery in 1877. Thus, it is probable
that most of the Amphicoelias skeleton was destroyed long before the neu-
ral spine was found.
Cope (1878b) states that the Amphicoelias “was found in the Da-
kota formation of Colorado...”, which today would imply that the speci-
men is Aptian-Albian in age (Waagé, 1955). However, Cope also notes that
the specimen was found “in the same bed that has thus far produced the
known species of Camarasaurus, Amphicoelias, Hypsirophus, etc.”
Camarasaurus is a classic Morrison sauropod, and is in fact the most com-
mon sauropod found (Dodson et al., 1980). The Morrison has been dated
as latest Oxfordian to early Tithonian (Kowallis et al., 1998). Because the
Lucas quarries which these specimens came from occur near the top of the
Morrison Formation, a Tithonian age for Amphicoelias fragillimus seems
reasonable (Turner and Peterson, 1999).
Institutional Abbreviations: AMNH, American Museum of Natural
History, New York, New York; CM, Carnegie Museum of Natural History,
Pittsburgh, Pennsylvania; DMNH, Denver Museum of Natural History
(now Denver Museum of Nature & Science), Denver, Colorado; USNM,
United States National Museum (now National Museum of Natural His-
tory), Washington, D.C.
DESCRIPTION
It is unfortunate that the specimen of Amphicoelias fragillimus
is missing, and that comparisons with other sauropods must rely on
Cope’s description. Although missing, it has been assigned the catalog
number AMNH 5777. The generic referral by Cope was based on his
(1878b, p. 563) observation that “[i]t exhibits the general characteris-
tics of the genus Amphicoelias, in the hyposphen [sic], antero-posteri-
orly placed neural spine, and elevated diapophysis for the rib articula-
tion. The diapophyses are compressed and supported by a superior [i.e.,
spinodiapophyseal lamina] and inferior [i.e., centrodiapophyseal
lamina], and anterior [i.e., prezygodiapophyseal lamina] and posterior
[i.e., postzygodiapophyseal lamina], thin buttresses [i.e., lamina], sepa-
rated by deep cavities.”
The genus Amphicoelias (as A. altus) was named by Cope in De-
cember, 1877 (published in 1878a) for a mid-dorsal vertebra (D6?), a pos-
terior dorsal vertebra (D10?), a pubis, and a femur (all AMNH 5764) from
Quarry XII located at the north end of a long ridge (Fig. 2) about 1.5 km
northwest of the main quarries. Osborn and Mook (1921) also referred a
scapula, a coracoid, an ulna, and a tooth to the holotype. Quarry XII is
stratigraphically the highest in the Morrison Formation in the Garden Park
area, being about 15 m higher than the Camarasaurus supremus sites (Car-
penter, 1998). As noted by Osborn and Mook (1921), the specimen closely
resembles Diplodocus, especially in the posterior dorsal (best preserved):
tall, slender neural spine, tall neural arch, well developed spinodiapophyseal
laminae, and prominent posterior centroparapophyseal laminae. However,
it also differs from Diplodocus having in a centrum that is as long as tall
rather than taller than long, having an anteroposteriorly elongated, laterally
compressed neural spine, parapophysis separate from the diapophysis, dia-
mond-shaped hyposphene, pleurofossa (defined by Carpenter and Tidwell,
2005, p. 94) restricted to the centrum (not extending onto the neural arch),
and less constricted (“pinched”) centrum. The ulna is significantly longer
relative to the femur length (0.6) than in Diplodocus (0.46); thus, the fore-
limbs were proportionally longer as well. The circular cross-section of the
femur, once used to separate Amphicoelias from Diplodocus, is known to
occur in Diplodocus as well (V. Tidwell, personal commun.).
The species name, fragillimus, apparently reflects the fragility or
delicateness of the specimen produced by the thinness of the numerous
laminae as noted by Cope (1878b, p. 563): “[in] the extreme tenuity [i.e.,
thinness] of all its parts, this vertebra exceeds those of this type [i.e.,
Amphicoelias altus] already described...”. These laminae not only include
the external ones connecting various structures, but also internal struts within
the neural arch (Fig. 1A). These internal struts or laminae are exposed be-
cause the missing outer cortical bone was lost, probably to erosion. The
delicateness of the specimen made collecting difficult, “much care was
requisite to secure its preservation” (Cope, 1878b, p. 563), and may pro-
vide a clue to its disappearance (as discussed below).
Osborn and Mook (1921) provisionally synonymized A. fragillimus
with A. altus, a position accepted by McIntosh (1998). However, there is
reason to suspect that it is a distinct species as noted by Cope (1878b) and
even possibly a distinct genus. A. fragillimus differs from A. altus in hav-
ing a single postspinal lamina (compare Fig. 1B and 1C), prominent lateral
spinopostzygapophyseal lamina, proportionally smaller postzygapophyses
with prominent postzygodiapophyseal laminae, and an apparently taller
neural arch. Some features are not visible in Cope’s figure (Fig. 1A), and
must be inferred from Cope’s statements: the spinodiaopophyseal laminae
are laterally directed so that in horizontal cross section, and the neural spine
is T-shaped, rather than H-shaped. Unfortunately, without the holotype,
the taxonomic validity of the specimen cannot be resolved.
HOW BIG WAS AMPHICOELIAS FRAGILLIMUS?
There is every reason to suspect that Amphicoelias fragillimus was
indeed one of the largest, if not the largest dinosaur to ever walk the earth
(the validity of the immense size is discussed below). As Cope (1878b, p.
563) noted regarding the specimen, it represents “the neural arch of the
FIGURE 2. A. E.D. Cope’s 1879 field notebook contains a map showing the location
of the Lucas brothers quarries. B. This map allowed relocation of many of the quarries.
Amphicoelias fragillimus was found at quarry III in a string of closely spaced quarries
(I-VIII). I-XIII quarries; A.f. Amphicoelias fragillimus; A.l., - Amphicoelias latus
quarry; CS1, 2, Camarasaurus supremus 1 and 2 quarries; H.v., probable site for
Hallopus victor Marsh (see Ague et al., 1995). Most of the quarries along the ridge
have not yet been relocated. See McIntosh (1998) for further discussion of the Cope
map.
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vertebra of the largest saurian I have ever seen.” Indeed the measure-
ments Cope gives support this hyperbole: total height of specimen 1500
mm; from preserved base to postzygapophyses 585 mm; greatest width
of postzygapophyses 190 mm; vertical diameter of the base of the di-
apophysis 390 mm. Cope estimated the total height of the vertebra as
at least 6 feet (1.83 m) and probably more. Indeed, scaling the dorsal of
A. altus to restore the missing parts of A. fragillimus (Fig. 1B) results
in a vertebra 2.7 m tall! Paul (1994) estimated the size as 2.4-2.6m.
Regardless of the exact measurements, Cope (1878b, p. 564) rightly
states that “[t]he dimensions of its vertebra much exceed those of any
known land animal.”
In order to put A. fragillimus into perspective, Cope (1878b) specu-
lates on the size of the femur. He notes that the femora of A. altus and
Camarasaurus supremus were about twice as tall as their tallest dorsals,
and he conjectured that the femur of A. fragillimus was over 12 feet (3.6
m) tall. In Diplodocus, the ratio of femur to D10 ranges from 1.6 (CM 84)
to 1.7 (USNM 10865). Assuming a similar range in A. fragillimus, the
femur was 4.3-4.6 m tall (Paul [1994] estimated a femur length of 3.1-4.0
m). Taking speculation further, what are some of the other dimensions for
A. fragillimus? Much of this depends on the relative proportions of the
body, which can be considerably variable in diplodocids (e.g., relative pro-
portion of the ulna to femur as mentioned above for A. altus; proportion-
ally longer distal caudals in Diplodocus than in Barosaurus, or longer neck
in Barosaurus than in Apatosaurus (McIntosh, 2005). Should A. fragillimus
be viewed as a scaled up version of Diplodocus, Barosaurus, or
Apatosaurus? At present this question cannot be answered. For the sake of
illustration, A. fragillimus is shown as a scaled up Diplodocus in Figure
3A. The estimated length is 58 m (190 ft), whereas Paul (1994) estimated
a total length of 40-60 m. In comparison, Seismosaurus is 33.5 m and
Supersaurus is 32.5 m (estimated from Fig. 3C,D). The fragmentary
brachiosaurid Sauroposeidon is estimated to have been about 34 m long
(Fig. 3E). In contrast, the fragmentary titanosaurid sauropods
Argentinosaurus, Paralititan and “Antarctosaurus giganteus are
viewed as scaled up titanosaurid Saltosaurus, rather than a modified
Brachiosaurus (e.g., Smith et al., 2001: fig. 2D). The mega-sauropod
Argentinosaurus is 30 m, and the super-sauropods Paralatitan only 26
m and “A giganteus 23 m (30 m is the arbitrary division between
super- and mega-sauropods).
Some other speculative dimensions of A. fragillimus assuming
Diplodcus proportions include a neck length of 16.75 m, body length (base
of neck-end of sacrum) of 9.25 m, and a tail length of 32 m. The forelimb
is 5.75 m and hind limb 7.5 m.
The mass of mega-sauropods is more difficult to ascertain. Assum-
ing that the mega-diplodocids are scaled up versions of Diplodocus, then
the volume (hence mass) changes in proportion to the third power of the
linear dimension (Schmidt-Nielsen, 1984). Thus, if Diplodocus carnegii
had a length of 26.25 m and mass of 11,500 kg (Paul, 1994), then A.
fragillimus had a mass of around 122,400 kg, which is still within the
hypothesized maximum mass for a terrestrial animal (Hokkanen, 1986).
Seismosaurus and Supersaurus are each estimated to have had a mass of
around 38,800 kg.
DISCUSSION
The present whereabouts of the holotype of A. fragillimus is un-
known. The first to note its absence were Osborn and Mook (1921, p.
279): “The type of this species has not been found in the Cope Collec-
tion...” Subsequent attempts to locate the specimen by McIntosh (personal
FIGURE 3. Body size comparison of mega- and super-sauropods. See text for lengths. Diplodocids: A. Amphicoelias fragillimus; B. Diplodocus; C. Seismosaurus; D.
Supersaurus. Brachiosaurid: E. Sauroposeidon. Titanosaurids: F. Argentinosaurus; G. Paralatitan; H. Antarctosaurusgiganteus. Except for Diplodocus, the body
outlines are conjecture because of the fragmentary nature of the specimens. The titanosaurids are modeled after the titanosaurid Saltosaurus, rather than a brachiosaurid.
Reconstructions are scaled to known bone measurements.
134
commun.) have also failed. The fate of the specimen is intriguing and a
possible hypothesis is presented. As noted by Cope (1878b), the specimen
was very delicate and required great care in its collecting. At the time, pre-
servatives had not yet been employed to harden fossil bone, the first of
which was a sodium silicate solution used in O.C. Marsh’s preparation
lab at Yale University beginning in the early 1880s (M.P. Felch letter to
Marsh, October 30, 1883). The extreme fragility of large bone from the
vicinity of the A. fragillimus quarry is attested to by the crumbling into
small pieces of half of a large dorsal of C. supremus (DMNH 27228) at
the Denver Museum of Nature & Science (the discovery and excava-
tion of this C. supremus partial skeleton is given in Carpenter [2002]).
The stratum in the vicinity of quarries (lots) I-IV is deeply weathered
mixed illitic-smectitic mudstone that breaks into small irregular cubes.
Bone in this level is also weathered, and the battered, incomplete ap-
pearance of the A. fragillimus as figured by Cope (1878b) suggests it
lay partially exposed in the weathered zone. Thus, the specimen was
extremely fragile and it is possible that it crumbled badly and was
discarded by Cope soon after it was figured in posterior view (which
may explain why no other views were offered by Cope in contrast to his
description of other specimens).
The immense size of the measurements given by Cope and the in-
ferred vertebra size have been met with skepticism (several individuals,
verbal to Carpenter), with typographical errors in the measurements being
the most commonly assumed explanation. There is, however, every reason
to accept Cope at his word. First, Cope never made any subsequent correc-
tions in his publications; furthermore, his reputation was at stake. Marsh,
who was ever so ready to humiliate Cope, never called into question the
measurements. Marsh is known to have employed spies to keep tabs on
what Cope was collecting, and it is quite possible that he had independent
confirmation for the immense size of A. fragillimus. Osborn and Mook
(1921) accept Cope’s measurements without question, as does McIntosh
(1998). Thus, there is historical precedence for accepting the measure-
ments as correct.
WHY ARE SAUROPODS SO BIG?
The immense size of A. fragillimus raises some very interesting
questions regarding mega-sauropod biology. The trend towards gigantism
in sauropods was established early in their evolution (Fig. 4). The earliest
sauropods from the Late Triassic were already as big as some of the later
ones. Therefore, whatever mechanism caused sauropods to become big
affected them early in their evolution. Some possible clues can be derived
from extant megaherbivores (as defined by Owen-Smith, 1988): elephants,
hippopotamus, giraffe, and rhinoceros. In analyzing possible causes for
sauropod gigantism, it is difficult to separate primary and secondary causes.
For example, large body size confers protection against predators, but is
this a primary or secondary cause? In other words, did gigantism originate
primarily as an anti-predatory feature, or is the anti-predatory role an
exaptation of gigantism that evolved for some other reason?
Several studies of mammalian megaherbivores demonstrate a posi-
tive relation between large body size and digestive efficiency, especially of
low nutrient quality browse (Fritz et al., 2002; Illius and Gordon,
1992;Owen-Smith, 1988). The longer retention time of ingesta in
megaherbivores increases digestive efficiency as compared to small ani-
mals, thus permitting them to survive on lower quality food. Karasov et al.
(1986) noted that passage time of ingesta increased with body size in both
reptiles and mammals, and the same was undoubtedly true for dinosaurian
herbivores as well. Fermentative digestion relies extensively on microbes,
with anaerobes numerically dominating, to hydrolyze and ferment cellu-
lose (Mackie et al., 2004). Although microbes are prevalent throughout the
digestive tract, they are especially abundant in fermentation chambers or
sacs in the foregut or hindgut (Mackie et al., 2004; McBee, 1971). Hind-
gut fermentation, involving enlargement of the cecum or colon, is the most
primitive and most widespread adaptation (Mackie et al., 2004). The cecum
is an expanded sac located between the small and large intestine and oc-
curs in a variety of mammals and birds (McBee, 1971). In contrast, all
extant herbivorous reptiles have elongate intestines and septa or valves
within the enlarged colon that slow the passage of ingesta (Iverson, 1982;
Cooper and Vitt, 2002). Sauropods most likely also used hindgut fermen-
tation, rather than foregut or rumen, but whether it was cecal, colonic, or a
combination is unknown. The elongation and enlargement of the digestive
tract, whether expansion of the cecum or colon, requires a larger body to
accommodate it in both megaherbivores and herbivorous lizards (Cooper
and Vitt, 2002; Illius and Gordon, 1992), and is probably true for sauro-
pods and other large-bodied herbivorous dinosaurs (DiCroce et al., 2005).
The ability to live on low nutrition (i.e., low caloric) plants is com-
mon to all megaherbivores as noted above and suggests it may be the main
reason why large body size occurs in different, unrelated animals (e.g.,
elephant, rhinoceros, hippopotamus). This ability may also explain why
sauropods got so big. The first sauropods appear in the Late Triassic (227-
208 mya) and were already big animals (Fig. 4). They apparently lived in
seasonally dry, semiarid environments (Parrish et al., 1986) where plants,
based on modern studies (e.g., Prior et al., 2003, 2004), probably had low
nutritional value during the dry season. This ability to survive on low nutri-
tion for part of the year explains why sauropods were so successful and
why they mostly occur in dry environments. Sauropod remains are un-
known in perpetually wet environments, such as represented by the Hell
Creek Formation (Russell and Manabe, 2002), but are known from xeric
and semi-arid coastal environments, such as represented by the Bahariya
Formation of Egypt (Smith et al., 2001 with Russell and Paesler, 2004).
The numerical dominance of sauropods in the Morrison Formation
(Dodson et al., 1980) is seemingly at odds with statements that the Morrison
was deposited in a semiarid environment with seasonal rainfall (summa-
rized by Turner and Peterson [2004]). This apparent anomaly lead Tidwell
(1990) to argue for a wet environment to support abundant vegetation that
the sauropods would require. Indeed, large, > 1 m diameter logs (probably
conifer) are known in the Morrison Formation at Escalante Petrified Forest
State Park in southern Utah, as well as a partial 24 m log near Dinosaur
National Monument (F. Peterson, personal commun.). These logs demon-
strate the presence of very tall (20-30+ m) trees during deposition of the
Morrison Formation, but do not necessarily prove the existence of wide-
spread forests of tall trees. Such tall trees can be accommodated in a gallery
(i.e., riverine, Fig. 5A) forest as advocated by Parrish et al. (2004), but
require considerably more water than postulated by climatic models (e.g.,
Moore, et al., 1992; Rees et al., 2000; Sellwood et al., 2000; Valdes and
Sellwood, 1992). Demko et al. (2004) suggested the water, mostly as ground
water, originated as rainfall on the Cordillera to the west (although how
such water managed to flow uphill away from the alleged Lake (Playa?)
FIGURE 4. Graph showing the gradual increase in femur length, which also correlates
with increase in body size. Note peak during the Late Jurassic. The graph also shows
the largest specimens (maximum), average-sized specimens, and smallest adult sizes.
LTr - Late Triassic (227-206 million years ago - mya); EJr - Early Jurassic (206-
180 mya); MJr - Middle Jurassic (180-159 mya); LJr - Late Jurassic (159-144
mya); EK - Early Cretaceous (144-99 mya); LK - Late Cretaceous (99-65 mya).
Data from Carpenter in preparation.
135
T’oodichi in the back-bulge basin as groundwater is not described).
The region between the gallery forests may have been savanna-like
(Parrish et al. 2004). Although a savanna is variously defined (e.g.,
contrast Bourlière and Hadley [1970] and Scholes and Archer [1997]),
grass and scattered trees are today the dominant components. How-
ever, grasses did not appear until the Late Cretaceous, when they are
known from sauropod coprolites (Prasad et al., 2005). During the Late
Jurassic, ferns may have dominated the niche now occupied by grasses
(Litwin et al., 1998). A scattering of sclerophyllous trees (e.g., the co-
FIGURE 5. A. Satellite image of northwestern Ghana in the vicinity of 7o48.5’N,
2o26.5’W showing the dendritic pattern of riverine forests and interfluve savanna
and forests. The soil and vegetation here was described by Markham and Babbedge
(1979). B. Hypothetical, gradational cross-section of the Morrison landscape modeled
on A from gallery forest to savanna. Note that the extremely tall trees in the gallery
forest could easily provide shade to Amphicoelias fragillimus (A) thereby preventing
it from overheating during the day. The gallery forest was probably a two story
canopy: upper canopy of various coniferophytes, a lower canopy of tree ferns and
smaller coniferophytes, and ground cover dominated by ferns. The “savanna”
woodland was probably a single story canopy dominated by ginkgos and
coniferophytes, with a ground cover dominated by ferns and cycadophytes. The
woodland was probably the gradual transition zone to the “savanna.” It was probably
considerably wider in the more northern, wetter regions of the Western Interior (e.g.,
northern Wyoming), than in the southern, drier portions (southern Utah) during the
Late Jurassic. In the northern regions it probably dominated the interfluve regions,
being equivalent to the interfluve forests of Ghana. The “savanna” was probably
dominated by sclerophyllous ferns and cycadophytes, with a scattering of
coniferophytes, predominately Brachyphyllum.
nifer Brachyphyllum) among the ferns would produce a savanna-like
landscape (Parrish et al. 2004; Fig. 5B).
The diversity and abundance of ferns from the Morrison (Litwin
et al., 1998), coupled with the apparently low feeding range of diplodocid
sauropods (Stevens and Parrish, 1999), suggests that ferns may have
played an important role in the diet of diplodocids. Although Fiorillo
(1998) and Engelmann et al. (2004) dismissed ferns as a component of
the sauropod diet following the low rating given by Weaver (1983), in
point of fact the kcal/g data given by Weaver (1983, table 3) for ferns
(3.369-4653 kcal/g, = 4.205 kcal/g) is not that much different for
most of the other plants listed by her (3.347-5.393 kcal/g,= 4.411kcal/
g). In addition, the most of the ferns listed have higher kcal/g values
(4.0-4.16 kcal/g) than that given by Bassey et al. (2001) for the fern
Diplazium sammatii,which is regularly consumed by humans. But even
if Morrison ferns had a low caloric content, the large body size of sau-
ropods, with their large gut, would allow them to easily survive on low
nutrient browse as is true for extant megaherbivores (Owen-Smith 1988).
Whereas diplodocid sauropods increased their gut volume by increas-
ing the entire body size, titanosaurids did so primarily by flaring the
ilium laterally thereby making more room for the enlarged hindgut.
The only possible restriction to a diet of ferns are their phytochemi-
cal defenses, although most target arthropods (Page, 2002). However, there
is reason to believe that not all ferns are equally toxic, as evidenced by
selective browsing of tree ferns (Dicksonia) by deer in New Zealand (Nugent
and Callies, 1988), although it is also true that the distribution of chemical
toxins in modern ferns is poorly known (Page, 2002).
If the origin and evolution of large body size among sauropods is
related to diet as it is in extant megaherbivores, then all other advantages
conferred by large body size are secondary. These would include lower
energy expenditure, protection against predators, and life longevity, among
others. One major disadvantage frequently cited, that of thermal stress (e.g.,
Engelmann et al., 2004), need not be a problem because sauropods, in-
cluding a 10 m tall Amphicoelias fragillimus, could seek shade during the
day in gallery forests (Fig. 5B) and feed primarily at night.
CONCLUSION
The origin and evolution of large body size in sauropods may be
closely linked to a diet of generally poor quality food resources growing on
low nutrient, calcareous soils. This giantism culminated in the largest known
sauropod, Amphicoelias fragillimus during the Late Jurassic. Several lin-
eages of sauropods have independently achieved megasauropod (>30m
length) status. Two different strategies of gut enlargement were utilized:
diplodocids increased the overall size of the body, and titanosaurids increased
the hindgut by flaring the ilium laterally.
ACKNOWLEDGMENTS
Thanks to John Foster for inviting me to contribute to this volume,
and to Jack McIntosh for bringing the existence of E.D. Cope’s description
of Amphicoelias fragillimus to my attention. Thanks also to the University
of Delaware Library for the loan of the microfilms of the Marsh Corre-
spondence, and to Pat Monaco and Donna Engard for a photocopy of the
Garden Park section of Cope’s notebook. Thanks also to the people of Han
Project 21, Nihon Keizai Shimbun and Nihon Hoso Kyokai (NHK) Broad-
casting for asking me “why did sauropods get so big?” It was while trying
to answer that question that led me to similar conclusions that were inde-
pendently arrived at by Engelmann, et al. (2004) and Farlow (1987). Fi-
nally, thanks to Yvonne Wilson and Virginia Tidwell for proofreading an
earlier version of this manuscript, and to Jack McIntosh and Jerry Harris
for review comments.
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... What makes A. fragillimus truly unique in all of dinosaurian paleontology is the reported immense size of the material. As reported by Cope, the fragmentary posterior dorsal vertebra of A. fragillimus was 1.5 meters tall, which when reconstructed resulted in the complete dorsal fragillimus on those of Diplodocus, resulting in body length estimates of 58-60 meters (Paul, 1994;Carpenter, 2006 (McIntosh, 1998;Monaco, 1998;Carpenter, 2006) (AMNH 5777;McIntosh, 1998), so the specimen apparently survived at least until then. In the original description Cope noted the extreme fragile and delicate nature of the material (hence the species name fragillimus), and since fossil preservatives were not used at the time, it has been surmised that at some point prior to Osborn and Mook's survey that the deteriorating material was discarded, potentially even by Cope himself (Carpenter, 2006). ...
... What makes A. fragillimus truly unique in all of dinosaurian paleontology is the reported immense size of the material. As reported by Cope, the fragmentary posterior dorsal vertebra of A. fragillimus was 1.5 meters tall, which when reconstructed resulted in the complete dorsal fragillimus on those of Diplodocus, resulting in body length estimates of 58-60 meters (Paul, 1994;Carpenter, 2006 (McIntosh, 1998;Monaco, 1998;Carpenter, 2006) (AMNH 5777;McIntosh, 1998), so the specimen apparently survived at least until then. In the original description Cope noted the extreme fragile and delicate nature of the material (hence the species name fragillimus), and since fossil preservatives were not used at the time, it has been surmised that at some point prior to Osborn and Mook's survey that the deteriorating material was discarded, potentially even by Cope himself (Carpenter, 2006). ...
... As reported by Cope, the fragmentary posterior dorsal vertebra of A. fragillimus was 1.5 meters tall, which when reconstructed resulted in the complete dorsal fragillimus on those of Diplodocus, resulting in body length estimates of 58-60 meters (Paul, 1994;Carpenter, 2006 (McIntosh, 1998;Monaco, 1998;Carpenter, 2006) (AMNH 5777;McIntosh, 1998), so the specimen apparently survived at least until then. In the original description Cope noted the extreme fragile and delicate nature of the material (hence the species name fragillimus), and since fossil preservatives were not used at the time, it has been surmised that at some point prior to Osborn and Mook's survey that the deteriorating material was discarded, potentially even by Cope himself (Carpenter, 2006). Regardless of the whereabouts of the holotype material, several works have accepted Cope's measurements without question (Osborn and Mook, 1921;McIntosh, 1998;Carpenter, 2006). ...
Preprint
Full-text available
In the summer of 1878, American paleontologist Edward Drinker Cope published the discovery of a sauropod dinosaur that he named Amphicoelias fragillimus. What distinguishes A. fragillimus in the annals of paleontology is the immense magnitude of the skeletal material. The single incomplete dorsal vertebra as reported by Cope was a meter and a half in height, which when fully reconstructed, would make A. fragillimus the largest vertebrate ever. After this initial description Cope never mentioned A. fragillimus in any of his scientific works for the remainder of his life. More than four decades after its description, a scientific survey at the American Museum of Natural History dedicated to the sauropods collected by Cope failed to locate the remains or whereabouts of A. fragillimus. For nearly a century the remains have yet to resurface. The enormous size of the specimen has generally been accepted despite being well beyond the size of even the largest sauropods known from verifiable fossil material (e.g. Argentinosaurus). By deciphering the ontogenetic change of Diplodocoidea vertebrae, the science of gigantism, and Cope’s own mannerisms, we conclude that the reported size of A. fragillimus is most likely an extreme over-estimation.
... What makes A. fragillimus truly unique in all of dinosaurian paleontology is the reported immense size of the material. As reported by Cope, the fragmentary posterior dorsal vertebra of A. fragillimus was 1.5 meters tall, which when reconstructed resulted in the complete dorsal fragillimus on those of Diplodocus, resulting in body length estimates of 58-60 meters (Paul, 1994;Carpenter, 2006 (McIntosh, 1998;Monaco, 1998;Carpenter, 2006) (AMNH 5777;McIntosh, 1998), so the specimen apparently survived at least until then. In the original description Cope noted the extreme fragile and delicate nature of the material (hence the species name fragillimus), and since fossil preservatives were not used at the time, it has been surmised that at some point prior to Osborn and Mook's survey that the deteriorating material was discarded, potentially even by Cope himself (Carpenter, 2006). ...
... What makes A. fragillimus truly unique in all of dinosaurian paleontology is the reported immense size of the material. As reported by Cope, the fragmentary posterior dorsal vertebra of A. fragillimus was 1.5 meters tall, which when reconstructed resulted in the complete dorsal fragillimus on those of Diplodocus, resulting in body length estimates of 58-60 meters (Paul, 1994;Carpenter, 2006 (McIntosh, 1998;Monaco, 1998;Carpenter, 2006) (AMNH 5777;McIntosh, 1998), so the specimen apparently survived at least until then. In the original description Cope noted the extreme fragile and delicate nature of the material (hence the species name fragillimus), and since fossil preservatives were not used at the time, it has been surmised that at some point prior to Osborn and Mook's survey that the deteriorating material was discarded, potentially even by Cope himself (Carpenter, 2006). ...
... As reported by Cope, the fragmentary posterior dorsal vertebra of A. fragillimus was 1.5 meters tall, which when reconstructed resulted in the complete dorsal fragillimus on those of Diplodocus, resulting in body length estimates of 58-60 meters (Paul, 1994;Carpenter, 2006 (McIntosh, 1998;Monaco, 1998;Carpenter, 2006) (AMNH 5777;McIntosh, 1998), so the specimen apparently survived at least until then. In the original description Cope noted the extreme fragile and delicate nature of the material (hence the species name fragillimus), and since fossil preservatives were not used at the time, it has been surmised that at some point prior to Osborn and Mook's survey that the deteriorating material was discarded, potentially even by Cope himself (Carpenter, 2006). Regardless of the whereabouts of the holotype material, several works have accepted Cope's measurements without question (Osborn and Mook, 1921;McIntosh, 1998;Carpenter, 2006). ...
Preprint
Full-text available
In the summer of 1878, American paleontologist Edward Drinker Cope published the discovery of a sauropod dinosaur that he named Amphicoelias fragillimus. What distinguishes A. fragillimus in the annals of paleontology is the immense magnitude of the skeletal material. The single incomplete dorsal vertebra as reported by Cope was a meter and a half in height, which when fully reconstructed, would make A. fragillimus the largest vertebrate ever. After this initial description Cope never mentioned A. fragillimus in any of his scientific works for the remainder of his life. More than four decades after its description, a scientific survey at the American Museum of Natural History dedicated to the sauropods collected by Cope failed to locate the remains or whereabouts of A. fragillimus. For nearly a century the remains have yet to resurface. The enormous size of the specimen has generally been accepted despite being well beyond the size of even the largest sauropods known from verifiable fossil material (e.g. Argentinosaurus). By deciphering the ontogenetic change of Diplodocoidea vertebrae, the science of gigantism, and Cope’s own mannerisms, we conclude that the reported size of A. fragillimus is most likely an extreme over-estimation.
... This estimation was never challenged by Cope's contemporaries, nor later by Henry Osborn and Charles Mook of the American Museum of Natural History in their monograph of the Cope sauropod collection (Osborn and Mook, 1921). Only more recently have questions been raised about this specimen in the debate about the maximum possible size of terrestrial vertebrates (Paul, 1998;Mazzetta and others, 2004;Carpenter, 2006a;Perry and others, 2009;Woodruff and Foster, 2014). ...
... Traditionally, AMNH FR 5777, Amphicoelias fragillimus, was considered a diplodocid beginning with Osborn and Mook (1921) and continuing to this day (Woodruff and Foster, 2014). Even I had previously considered the specimen a diplodocid (Carpenter, 2006a), but reanalysis of Cope's description and figure suggests otherwise, and that it is a basal rebbachisaurid. ...
... Given the corroborative evidence, what is the estimated restored size of the vertebra AMNH FR 5777? Cope modeled the missing centrum after A. altus, as did I initially (Carpenter, 2006a). Woodruff and Foster (2014) preferred a proportionally larger and rounder centrum modeled on Supersaurus vivianae on the basis that the centrum becomes larger and rounder in diplodocids with increased size. ...
Article
Full-text available
In 1878, Oramel Lucas shipped to E.D. Cope of the Academy of Natural Sciences of Philadelphia, a huge 1.5-m-tall neural spine from the dorsal vertebra of a sauropod (from the Upper Jurassic Morrison Formation) that Cope named and illustrated as Amphicoelis fragillimus.The holotype was lost and all that is known of the specimen is from Cope's original publication. Reanalysis of Cope's publication in light of other sauropods discovered since 1878 indicates that Amphicoelias fragillimus is a basal rebbachisaurid characterized by pneumatic neural spine and arch, and the unambiguous rebbachisaurid character of a festooned spinodiapophyseallamina. Because the specimen can no longer be referred to the basal diplodo­ coid Amphicoelias, the genus name is replaced with Maraapunisaurus n.g. As a rebbachisaurid, revised dimensions indicate a dorsal vertebra 2.4 m tall and a head-to-tail length for the animal of 30.3 to 32m, significantly less than previous estimates.
... This estimation was never challenged by Cope's contemporaries, nor later by Henry Osborn and Charles Mook of the American Museum of Natural History in their monograph of the Cope sauropod collection (Osborn and Mook, 1921). Only more recently have questions been raised about this specimen in the debate about the maximum possible size of terrestrial vertebrates (Paul, 1998;Mazzetta and others, 2004;Carpenter, 2006a;Perry and others, 2009;Woodruff and Foster, 2014). ...
... Traditionally, AMNH FR 5777, Amphicoelias fragillimus, was considered a diplodocid beginning with Osborn and Mook (1921) and continuing to this day (Woodruff and Foster, 2014). Even I had previously considered the specimen a diplodocid (Carpenter, 2006a), but reanalysis of Cope's description and figure suggests otherwise, and that it is a basal rebbachisaurid. ...
... Given the corroborative evidence, what is the estimated restored size of the vertebra AMNH FR 5777? Cope modeled the missing centrum after A. altus, as did I initially (Carpenter, 2006a). Woodruff and Foster (2014) preferred a proportionally larger and rounder centrum modeled on Supersaurus vivianae on the basis that the centrum becomes larger and rounder in diplodocids with increased size. ...
Article
Full-text available
In 1878, Oramel Lucas shipped to E.D. Cope of the Academy of Natural Sciences of Philadelphia, a huge 1.5-m-tall neural spine from the dorsal vertebra of a sauropod (from the Upper Jurassic Morrison Formation) that Cope named and illustrated as Amphicoelis fragillimus.The holotype was lost and all that is known of the specimen is from Cope's original publication. Reanalysis of Cope's publication in light of other sauropods discovered since 1878 indicates that Amphicoelias fragillimus is a basal rebbachisaurid characterized by pneumatic neural spine and arch, and the unambiguous rebbachisaurid character of a festooned spinodiapophyseallamina. Because the specimen can no longer be referred to the basal diplodo­ coid Amphicoelias, the genus name is replaced with Maraapunisaurus n.g. As a rebbachisaurid, revised dimensions indicate a dorsal vertebra 2.4 m tall and a head-to-tail length for the animal of30.3 to 32m, significantly less than previous estimates.
... Based only on a middle-posterior dorsal neural arch (AMNH FARB 5777), Cope [35] erected A. fragillimus. This specimen was unfortunately lost (or destroyed) but, despite this, has been the focus of several studies because of its potentially gigantic size [17,37,98]. Most authors have synonymized it with A. altus (e.g. ...
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Sauropod dinosaurs were an abundant and diverse component of the Upper Jurassic Morrison Formation of the USA, with 24 currently recognized species. However, some authors consider this high diversity to have been ecologically unviable and the validity of some species has been questioned, with suggestions that they represent growth series (ontogimorphs) of other species. Under this scenario, high sauropod diversity in the Late Jurassic of North America is greatly overestimated. One putative ontogimorph is the enigmatic diplodocoid Amphicoelias altus , which has been suggested to be synonymous with Diplodocus . Given that Amphicoelias was named first, it has priority and thus Diplodocus would become its junior synonym. Here, we provide a detailed re-description of A. altus in which we restrict it to the holotype individual and support its validity, based on three autapomorphies. Constraint analyses demonstrate that its phylogenetic position within Diplodocoidea is labile, but it seems unlikely that Amphicoelias is synonymous with Diplodocus . As such, our re-evaluation also leads us to retain Diplodocus as a distinct genus. There is no evidence to support the view that any of the currently recognized Morrison sauropod species are ontogimorphs. Available data indicate that sauropod anatomy did not dramatically alter once individuals approached maturity. Furthermore, subadult sauropod individuals are not prone to stemward slippage in phylogenetic analyses, casting doubt on the possibility that their taxonomic affinities are substantially misinterpreted. An anatomical feature can have both an ontogenetic and phylogenetic signature, but the former does not outweigh the latter when other characters overwhelmingly support the affinities of a taxon. Many Morrison Formation sauropods were spatio-temporally and/or ecologically separated from one another. Combined with the biases that cloud our reading of the fossil record, we contend that the number of sauropod dinosaur species in the Morrison Formation is currently likely to be underestimated, not overestimated.
... Osborn and Mook, in 1921, provisionally synonymized the three species, sinking Amphicoelias latus into Amphicoelias altus, and suggesting also that Amphicoelias fragillimus is just a very large individual of Amphicoelias altus, a position McIntosh agreed with in 1998. Carpenter (2006) disagreed about the synonymy of Amphicoelias altus and Amphicoelias fragillimus, however, citing numerous differences in the construction of the vertebra also noted by Cope, and suggested these differences are enough to warrant a separate species or even a separate genus for Amphicoelias fragillimus. However, he went on to caution that the validity of Amphicoelias fragillimus as a separate species is nearly impossible to determine without the original specimen to study (Wikipedia). ...
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A huge Long-necked Whip-tailed Sauropod Dinosaur (Amphicoelias brontodiplodocus Galiano & Albersdörfer, 2010) skeleton is exhibited at the main lobby Grand Atrium of Dubai Mall, Dubai, United Arab Emirates. The Long-necked Whip-tailed Sauropod Dinosaur skeleton is over 155 million years old, and is 24.4 meters (80 feet) long and 7.6 metres (25 feet) high and was a young adult female about 25 years old. The prehistoric dinosaur remains are from the late Jurassic period and belong to the species Amphicoelias brontodiplodocus, characterised by an endless whip-like tail, long slender neck and small head. Nearly 90 per cent of the fossil’s bones were found intact at the excavation site. Almost all 360 unearthed bones were complete and in good condition. Its tail bones were found broken, either ferociously bitten by a predator, or through battle trauma from a tail fight. The remains of the adult female dinosaur were discovered in a sleeping position in 2008 at the Dana Quarry in the US state of Wyoming. It was excavated over a period of 2 years. She died during a drought at the Dana Quarry, as it was a natural trap for predators and prey. The dinosaur exhibit was air-freighted from the US to its new home at The Dubai Mall. Reference: Khalaf-Sakerfalke von Jaffa, Prof. Dr. Sc. Norman Ali Bassam Ali Taher (2014). The Long-necked Whip-tailed Sauropod Dinosaur (Amphicoelias brontodiplodocus Galiano & Albersdörfer, 2010) Skeleton at Dubai Mall, Dubai, United Arab Emirates. Gazelle: The Palestinian Biological Bulletin. ISSN 0178 – 6288. Volume 32, Number 120, December 2014. pp. 1-29. Dubai and Sharjah, United Arab Emirates. http://palestine-dinosaur.webs.com/sauropod-dubai-mall
... Such estimates, however, are not entirely realistic because of differences among taxa in bone morphology and overall body proportions, as well as effects of individual variation and allometric growth [44]. Nonetheless, simple scaling is commonly used to estimate size, especially when comparative material is scarce (e.g., [45,46]). ...
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The largest reported ichthyosaurs lived during the Late Triassic (~235–200 million years ago), and isolated, fragmentary bones could be easily mistaken for those of dinosaurs because of their size. We report the discovery of an isolated bone from the lower jaw of a giant ichthyosaur from the latest Triassic of Lilstock, Somerset, UK. It documents that giant ichthyosaurs persisted well into the Rhaetian Stage, and close to the time of the Late Triassic extinction event. This specimen has prompted the reinterpretation of several large, roughly cylindrical bones from the latest Triassic (Rhaetian Stage) Westbury Mudstone Formation from Aust Cliff, Gloucestershire, UK. We argue here that the Aust bones, previously identified as those of dinosaurs or large terrestrial archosaurs, are jaw fragments from giant ichthyosaurs. The Lilstock and Aust specimens might represent the largest ichthyosaurs currently known.
... than 10 7 kg or lighter than 10 −5 kg. Therefore our work may also contribute to understanding why we do not observe terrestrial mammals as heavy as the mega sauropods (dinosaurs extinct approximately 100 millions years ago) of mass ~100 tons [40][41][42] , because their chewing frequencies would be presumably confined by the inertial and saliva-based limits in a small frequency range (0.2-0.5 Hz). Similarly, one cannot find any terrestrial mammal approaching the smallest weight limit, since the lightest contemporary mammal (Etruscan shrew) weighs about 1 g. ...
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Previous studies on chewing frequency across animal species have focused on finding a single universal scaling law. Controversy between the different models has been aroused without elucidating the variations in chewing frequency. In the present study we show that vigorous chewing is limited by the maximum force of muscle, so that the upper chewing frequency scales as the −1/3 power of body mass for large animals and as a constant frequency for small animals. On the other hand, gentle chewing to mix food uniformly without excess of saliva describes the lower limit of chewing frequency, scaling approximately as the −1/6 power of body mass. These physical constraints frame the −1/4 power law classically inferred from allometry of animal metabolic rates. All of our experimental data stay within these physical boundaries over six orders of magnitude of body mass regardless of food types.
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The Morrison Formation of the Late Jurassic Period is characterized by its diverse assemblage of sauropods, several species of which reached the size of modern cetaceans. While much scientific attention has concerned their biology in life, researchers have yet to examine how their massive carcasses may have influenced the evolution of other dinosaurs in their communities, such as theropods. Theropod consumers local to this faunal system are typically described as powerful apex predators at the top of local food webs, but instead, may have been shaped by competition for carrion resources generated as a byproduct of their giant sauropod neighbors. To test this hypothesis, we wrote a series of agent-based simulations (ABS). Specifically, we simulated allosaurid consumer behavior versus spatially distributed sauropod carcass resources such as could be expected in ecosystems like that represented in the Morrison Formation. We incorporated conditions to test how competition among consumers, seasonality, and predation success influenced carnosaur survival both with and without carrion-abundant systems. Trials of the ABS resulted in a strong selective advantage for allosaurs as obligate scavengers because of the high metabolic and survival costs associated with predation of large vertebrates. Allosaurs with increased predatory success over peers failed to succeed competitively unless the probability of scavenging opportunities fell below a certain threshold and a significant proportion of herbivores were available as prey targets, which might not have been the case in sauropod-dominated systems. Our results may explain why carnosaurs like Allosaurus did not evolve powerful bite forces, binocular vision, or advanced cursorial adaptations. Given the enormous supply of sauropod carrion, they were under no resource-based selective pressure to overpower prey and may have evolved as terrestrial vulture analogues. This also may explain why the absence of sauropods in certain environments led to more obvious predatory adaptations in theropods such as tyrannosaurs. Tyrannosaurs may have been forced to meet their energy budgets by hunting, because non-sauropod carrion production was too low to support them passively.
Chapter
This introductory chapter of the book provides an overview of the study of cetacean evolution from their first appearance to the present day. It provides basic principles, including a summary of the ecology of living whales and dolphins, cetacean taxonomy, and an explanation of the main techniques and concepts used to study extinct species. This is followed by detailed summaries of the cetacean fossil record and a description of their anatomy, phylogenetic relationships, and diversity. The book provides particular topics and case studies of cetacean paleoecology, functional biology, development, and macroevolution. Modern whales and dolphins form an essential part of the ocean ecosystem as top predators, as large-scale nutrient distributors, and as a food source for many deep-sea organisms. Once fossils have been dated, their occurrence can be correlated with other paleontological and paleoenvironmental data to identify potential biotic or physical factors that may have acted as evolutionary drivers.