The World of Dinosaurs The Discovery and Lives of These Legendary Creatures by Mark Norell (z-lib.org)

and theropods. Primitive sauropods are called such animals as the eponymous Ceratosaurus group of Theropoda, the Coelurosauria.
prosauropods. This may not be a monophyletic and the primarily southern hemisphere Coelurosaurs include a huge range, from
group, as some may be more closely related to abelisaurs. All of these were large bipedal
more advanced members than others. Some carnivores and many sported elaborate head Tyrannosaurus rex (see p.72) to hummingbirds,
like Plateosaurus are more primitive, others like crests and horns. incorporating all feathered, bird-like animals
Anchisaurus are probably more closely related to and true birds. They had big brains, advanced
more advanced animals such as Diplodocus. More As we move up the family tree, the animals behaviours, and evolved almost all the traits
primitive sauropods were bipedal, with relatively become both more familiar and better known. that most perceive as bird characters.
short necks and tails. More advanced sauropods The large and diverse group called the
had long necks and long tails. Members of this Tetanurae includes most of the best-known The other side of the tree, the Ornithischia,
group were the largest animals ever to walk on theropods as well as birds. The most basal is similarly complex. At the base are small,
land. All were thought to be herbivorous. dinosaurs in this group are the megalosaurs; primitive, bipedal dinosaurs, such as
Megalosaurus was one of the first dinosaurs to Heterodontosaurus and Lesothosaurus. Like all
Theropods were for the most part bipedal, be recognized. The megalosaurs include some ornithischians they were herbivores. It was not
yet a few, such as Spinosaurus, may have been of the most peculiar identified dinosaurs. Also until the Early Jurassic that more derived forms
secondarily quadrupedal. Most members are known as spinosaurs, they measured up to 14m begin to radiate and diversify. Collectively these
poorly understood but include animals such as (46ft) long, sported huge sails on their backs, animals are called Genasauria and the first
Herrerasaurus and Tawa – small bipedal cursors and had long muzzles with a mouthful of branch to split off were the thyreophorans.
(rapid runners). The next level of hierarchy pointy teeth. They are thought to have occupied
is the Neotheropoda, the most primitive of littoral habitats and fed on fish. Among dinosaur groups Thyreophora is
these are the coleophysids. For the species one of the most perplexing. The members
covered in this book, Coelophysis is a good When we reach Avetheropoda the animals of this group are known for their external
example (see p.56). As we move to more become even more advanced. The first group accoutrements, namely body armour, spikes,
advanced theropods the next group is called to branch off here are the Allosauroidea. In plates and tail clubs. Some grew very big,
Averostra, and the first group to diverge off of general, this group is widely distributed but not and a paleontological conundrum exists over
this line is the Ceratosauria, which includes particularly well known, except for Allosaurus (see how to reconcile such large animals with
p.64). Beyond the Allosauroidea is the crowning their preposterously small mouths and feeble
teeth. These unusual animals had a global

50 DINOSAUR CLASSIFICATION

distribution and are typically divided into two A technician dusts off a A small bat-sized pterosaur
groups. One of these, the stegosaurs, are often skeletal mount of spinosaur from the Early Cretaceous of
called plated dinosaurs. This is something Suchomimus, a truly bizarre China. This one is covered
of a misnomer because some species did not animal. The diversity of with fuzz that may be related
have plates, but instead sported large spikes. dinosaur body forms never to dinosaur type 1 feathers.
The ankylosaurs comprise the other group. In ceases to amaze even Pterosaurs are close dinosaur
general these were large, lumbering tank-like professionals with every new relatives but are not
animals; their most primitive members were discovery. dinosaurs.
small forms. Thyreophorans have a good but
puzzling fossil record in that, while we know a
great deal about their morphology, we know
relatively little about what their plates were
used for, or their diets.

Moving up the tree to more advanced
forms we have a group called the Cerapoda.
Within Cerapoda is the great flowering of
ornithischian diversity. As with herbivorous
animals today, these creatures evolved in
concert with evolving geographies and plant
evolution. They are very numerous. Just as
today in any community there are more kinds
of herbivorous animals than carnivores, so it
was in the Mesozoic era. Cerapods include two
ubiquitous and familiar kinds of dinosaurs.

One group is Ornithopoda. They were
named ornithopods in the nineteenth century
because their feet have three primary toes that
all point forwards, superficially resembling the
condition in modern birds, even though they
are not closely related. Primitive ornithopods
are often referred to as “hypsilophodontids”
and include such animals as Thescelosaurus
and Hypsilophodon (see p.206–209). While very
common and interesting because of unusual
features such as weird teeth and large eyes,
animals like Hypsilophodon are considered
more closely related to the more advanced
ornithopod group, the hadrosaurs, than
Thescelosaurus.

Hadrosaurs are one of the most fascinating
groups of dinosaurs and are unmatched in
their diversity and uniqueness from other
dinosaurs. They are known from dozens
of species, almost all with a large flattened
muzzle (leading to their nickname “duck-billed
dinosaurs”) and many sported elaborate crests
on their skulls. Although the use of these crests
in life in specific hadrosaurs is hotly debated,
it is almost uniformly agreed that they played
some display function, similar to horned
animals like antelope do today.

DINOSAUR CLASSIFICATION 51

ARCHOSAUR FAMILY TREE

Crocodilia Ornithischia Sauropoda Ceratosauria Tyrannosauria Ornithomimosauria Deinonycchosauria Archaeopteryx Birds

Aves

Avialae
Maniraptora
Coelurosauria
Tetanurae
Theropoda
Saurischia
Dinosauria
Archosauria

The final group of cerapods are the 0 cm 1 2 3 45
marginocephalians. This group is formed
of strange, dome-headed dinosaurs – the Anhanguera cervical vertebra
pachycephalosaurs; and the horned dinosaurs
– the ceratopsians. Collectively these are known Romanian Pterosaur cervical vertebra
as Marginocephalia, referring to the bony
outgrowths on the perimeter of the back of the
skull. Like hadrosaurs, this group was successful,
fairly cosmopolitan and very diverse, and they
also exhibited many strange structures on their
skulls. Although they look fearsome, the spikes
and frills would have proven little defence
against a megapredator. Instead they were most
likely objects of display; whether for recognizing
their own species, frightening predators or
attracting mates, these head ornaments are
unmatched in the dinosaur world.

A very simplified archosaur
family tree.

Some pterosaurs became
giants. The neck vertebra on
the right comes from an animal
that may have had a wingspan
in excess of 17m (55¾ft).

52 DINOSAUR CLASSIFICATION

SAU R I S C H I A

THEROPODA SAUROPODOMORPHA
56 136

PHYLOGENETIC/FAMILY TREE

Theropoda Coelophysis
Dilophosaurus
Saurischia Allosaurus
Dinosauria Tyrannosaurus
Albertosaurus
Sauropodomorpha Ornitholestes
Compsognathus
Ornithischia Thyreophora Struthiomimus
Ornithopoda Deinocheirus
Mononykus
Neornithischia Oviraptor
Marginocephalia
Citipati
Khaan
Deinonychus
Velociraptor
Saurornithoides

Archaeopteryx
Hesperornis
Gastornis
Phorusrhacos
Plateosaurus
Camarasaurus

Hypselosaurus
Patagotitan
Brontosaurus
Diplodocus
Barosaurus
Heterodontosaurus
Stegosaurus
Sauropelta
Euoplocephalus
Ankylosaurus
Hypsilophodon
Tenontosaurus
Edmontosaurus
Saurolophus
Hypacrosaurus
Corythosaurus
Pachycephalosaurus
Psittacosaurus
Protoceratops
Styracosaurus
Monoclonius
Triceratops

DINOSAUR CLASSIFICATION 53



COELOPHYSIS
BAURI

LATE TRIASSIC
CHINLE FORMATION
SOUTHWESTERN UNITED STATES

COELOPHYSIS WAS ONE OF THE FIRST PRIMITIVE THEROPOD
DINOSAURS TO BE RECOGNIZED . TH E NA ME LITER A LLY
TRANSLATES AS “HOLLOW BONE”. THIS IS BECAUSE THE
FIRST SPECIMENS TO BE DISCOVERED SHOWED A FEATURE
CHARACTERISTIC OF THEROPOD DINOSAURS, INCLUDING
LIVING BIRDS, OF BONES CONTAINING LARGE AIR SPACES.

The first specimens found were a similar fauna as continents with large This representation of Coelophysis
highly fragmentary. These were land masses do today. Because the name portrays it as a snake-necked
collected by David Baldwin, a Syntarsus is preoccupied by a beetle, many carnivore. Stomach contents show
talented member of E.D. Cope’s teams paleontologists now feel the name should be that it fed on
in the 1870s in Northern New Mexico, replaced by Megapnosaurus. small reptiles.
in what was at the time contested Native
American territory. Although very Besides being primitive, Coelophysis is In 1947 Museum paleontologists
incomplete, Cope immediately recognized noteworthy for other reasons. In 1947, Edwin Colbert and George Whitaker
the importance of these specimens as a very expeditions by the American Museum of discovered the Coelophysis quarry
primitive theropod dinosaur. at Ghost Ranch, New Mexico.

Coelophysis lived during the Late Triassic
Period and is about 200 million years old; its
remains are known from the Southwestern
United States. Several other animals
have been named that are very similar to
Coelophysis. Among these, Rioarribasaurus,
Longosaurus and Megapnosaurus, all discovered
in close geographical proximity to the
original Coelophysis finds, are now considered
to be the same species as Coelophysis.
Others, like Syntarsus from Zimbabwe,
are known from finds thousands of miles
away. Yet this can easily be explained by
the fact that during the time Coelophysis
lived, the continents were not arranged as
they are now: they were still united into a
single supercontinent, Pangea, so it is not
surprising that the entire area comprised

56 THEROPODA

Natural History to Northwestern New Mexico
discovered an exceptional accumulation
of Coelophysis specimens. These were found
at a place that goes by the colourful name
Ghost Ranch, which at the time was a tourist
destination for “greenhorns” who wanted to
try their hand at horse riding and camping. It
was also the seasonal home of artist Georgia
O’Keefe, who was a frequent visitor to the
excavations, and many of her paintings portray
the landscape and the exact rocks where the
specimens were found. What the Museum
field parties found was a mass accumulation
of Coelophysis specimens ranging from small
animals to adults. As Coelophysis was not a
huge animal – the adults were only about 3m
(10ft) in length and most of this was neck and
tail – large numbers of individuals could be
excavated in single blocks.

Almost all of the animals found in the Ghost
Ranch quarries are remains of Coelophysis.
A few other species have also been found,
however, including the remains of terrestrial
crocodile-line archosaurs, fishes, varied
unusual reptiles called drepanosaurs and
non-dinosaurian dinosauromorphs. The
circumstances behind these accumulations
have been difficult to determine. The fossils
are usually found in single bedding planes

COELOPHYSIS BAURI 57

indicative of a single event; however, it was Ghost Ranch quarry. Unlike nearly all at the specimen on display, he confirmed
probably not a catastrophic one. According dinosaur deposits, most of the specimens his original observation. Following careful
to the most recent interpretations, the Ghost were completely articulated. Many even comparison, he was able to show both on the
Ranch deposits represent ephemeral ponds, showed their necks pulled back, suggesting basis of general shape, and with the assistance
much like the seasonal watering holes that that there may have been some desiccation of a small team, that the architecture of
occur in East Africa today. During the rainy before burial. A couple of the specimens the bones indicated that these were not the
season these attract vast numbers of animals, even showed remnants of their last meal in bones of juvenile or baby Coelophysis. Instead
which when the seasons change sometimes the abdominal cavity. The first interpretation they were the remains of crocodile-line
succumb to dehydration. Perhaps an aspect of of these remains is that they are the bones archosaurs. Instead of the fearsome cannibal
their behaviour facilitated this preservation. of small juvenile Coelophysis. Consequently, midget dinosaurs popularized in the book
This is further suggested by the fact that the Coelophysis was given the reputation as a The Little Dinosaurs of Ghost Ranch, by Museum
closely related Syntarsus has been found in cannibal dinosaur, consuming its own young curator Ned Colbert, Coelophysis was an active,
exactly the same sort of bone beds in southern in what was, at the time, considered to be a opportunistic predator.
Africa. One problem with this explanation monospecific assemblage.
is that it does not explain why most of The Late Triassic
the animals found at the deposit were the The main specimen in question is on display Coelophysis bonebed at Ghost
carnivorous Coelophysis. In ecosystems today, in the Hall of Saurischian Dinosaurs at the Ranch New Mexico preserves
herbivores vastly outnumber carnivores. There Museum. It is such a beautiful example that hundreds of animals.
are far more deer, antelope, rabbits and gazelles a bronze cast of it was made to adorn the
than there are wolves, cheetahs, snow leopards wall of the downtown B and C train stop Early on it had been
and coyotes. Yet Ghost Ranch is not unusual at the 81st Street–Museum subway station. proposed that Coelophysis
in this regard, as several dinosaur-dominated One night a graduate student was leaving the was a cannibal due to bones
communities show this same pattern, where Museum after work. Thoroughly acquainted found in its abdominal cavity.
a much higher percentage of carnivorous with the anatomy of both Coelophysis and Subsequent research has shown
animals are found relative to herbivores. other Late Triassic archosaurs, he spent time that these were the remains of
looking at the bronze Coelophysis on the wall small crocodile-line animals.
The number and quality of preservation while waiting for the train. His immediate
allowed a good deal of early paleobiology thought was, “Those don’t look like Coelophysis The intimate association
to be done on the specimens found in the bones.” Over the next few days, after looking between many of the specimens
at Ghost Ranch indicates that
there was a mass death event.

58 THEROPODA

COELOPHYSIS BAURI 59

DILOPHOSAURUS
WETHERILLI

EARLY JURASSIC
KAYENTA FORMATION
NORTH AMERICA

ONE OF THE MEMORABLE VILLAINS OF THE MOVIE JURASSIC
PARK, DILOPHOSAURUS WAS PORTRAYED AS A FRILLED,
POISON-SPITTING CARNIVORE. IS THERE ANY EVIDENCE FOR
THIS? NO. DILOPHOSAURUS WAS A 6M (19½FT) LONG, BIPEDAL
DINOSAUR THAT LIVED IN AN ARID AREA OF WHAT IS NOW
NORTHERN ARIZONA ABOUT 196–183 MILLION YEARS AGO.

D ilophosaurus is an important However, in some living animals (like
dinosaur for many reasons. It rhinoceros, antelope, and elephant), tusks
fills an important intermediate and horns are present in both sexes, albeit
phylogenetic position between more of different sizes. The larger structures
primitive theropod dinosaurs, such as in males are thought to be ornaments to
coelophysids, and the advanced tetanurans. attract mates: this is called mutual sexual
It is also notable in that it has two crests selection. Unfortunately, we do not have
on its head, hence its name that translates a large enough sample of Dilophosaurus
as “two-crested lizard”. Head crests are specimens to test this hypothesis (or of
ubiquitous features of dinosaurs in general, almost any other dinosaur).
and many theropods in particular, and
evolved independently in several groups Dilophosaurus is also one of those rare
of dinosaurs. dinosaurs for which we have evidence
of trackways. While dinosaur tracks are
In many species, crests are found on the very common across the globe, it is often
top of the muzzle. One thing that most very difficult to assign specific tracks to
crests had in common is that they were very a particular dinosaur species. The case
thin – so thin, in fact, that it is difficult to for Dilophosaurus is a good one, but not
understand how they could have survived 100 per cent definitive. A few decades
if the animal was an active carnivore. The after the original discovery on the Navajo
crests of Dilophosaurus and the tyrannosaur Nation reservation, paleontologists found
Guanlong are paper-thin. Several functions a significant number of dinosaur tracks in
have been suggested, which range from
thermoregulation (now discredited), to Dilophosaurus depicted
species recognition and sexual selection. laying down. This was probably
Because all of the known specimens with not its regular resting
skulls have crests, it could be argued that posture; rather, it would have
sexual selection is not a viable explanation. crouched like a chicken.

60 THEROPODA

DILOPHOSAURUS WETHERILLI 61

almost the same beds where the Dilophosaurus It is one of the few instances where there A computer reconstruction
material was collected. Some have suggested is evidence of imprints of the hands. The of Dilophosaurus depicting it
that these trackways indicate that these animals resting depression is on an incline with the sprinting.
travelled in groups, while others dispute this. head oriented uphill. This may suggest that
What is apparent in these tracks, however, is it was easier for the animal to stand up on an A Dilophosaurus specimen as
something extremely unusual. incline than on flat ground, though there is no it was found with the classic
evidence that it used its forelimbs to prop itself death pose with head pulled
In the presumed Dilophosaurus trackways, up. A footprint right in the middle of the body back.
there are a few furrows that show a dragging depression is evidence that the animal moved
tail. This is rarely found in any other dinosaur off in a healthy, sprightly fashion.
trackways, as all evidence indicates that the tails
were held parallel to the ground, supported by Many trackways that are
stiff tendons attached to the pelvis. The furrows nearly coeval with the
are not continuous, so there is no evidence that Dilophosaurus bones have been
they dragged their tails “Godzilla”-style, but ascribed to this dinosaur.
rather in a few individuals the tails did come However, tracks are difficult
into contact with sediments. These trackways to interpret. What we can
also preserve something that is rarer still, and determine is that these sorts
that is the preservation of an animal resting. of animals were common in
their day.

62 THEROPODA

DILOPHOSAURUS WETHERILLI 63

ALLOSAURUS
FRAGILIS

LATE JURASSIC
MORRISON FORMATION
WESTERN NORTH AMERICA

THE FIRST OF THE WELL-KNOWN BIPEDAL MEGA CARNIVORES
WAS ALLOSAURUS. A MEDIUM-SIZED THEROPOD, ABOUT 8M
(26¼FT) LONG, ALLOSAURUS LIVED ABOUT 155 MILLION YEARS
AGO IN WHAT IS NOW WEST-CENTRAL NORTH AMERICA. ALONG
WITH TORVOSAURUS AND CERATOSAURUS, IT FILLED THE APEX
PREDATOR POSITION IN THE LOCAL ECOSYSTEMS.

Allosaurus is known from literally One remarkable site has produced
hundreds of specimens. The thousands of Allosaurus bones representing
early ones found by O.C. Marsh several different age classes. Known as
and E.D. Cope’s field parties were very the Cleveland Lloyd Dinosaur Quarry,
fragmentary. However, one specimen was it lies south of Provo, Utah. While other
excavated by Cope’s collectors in 1877 at species have also been found at the site, it
the legendary Como Bluff site in Wyoming, is unusual in that there are so many bones
and this was purchased together with the from a carnivorous species – usually the
body of Cope’s fossil collection by the skeletons of carnivorous animals are far less
American Museum of Natural History common than the remains of their prey. It
in the 1890s. Cope had never unpacked has been suggested that the area that would
the specimen, and when it was opened become the Cleveland Lloyd Dinosaur
and studied, it turned out to be the most Quarry was a predator trap around a water
complete large theropod dinosaur known hole. Here Allosaurus may have become
at that time. By 1898 it had been mounted mired in sticky, muddy sediment, only
for public display, and this mount is notable for their skeletons to decay and become
in that museum president Henry Fairfield disarticulated. Although some have
Osborn had it articulated in a lifelike suggested that Allosaurus may have hunted
action pose feeding on the carcass of an communally, there is little if no actual fossil
Apatosaurus. This scene inspired a well- evidence in support of this.
known painting by Charles R. Knight,
depicting the scene 155 million years ago. There is a great deal of evidence
This skeleton has never been studied in suggesting that Allosaurus was an active
depth. Since then many new Allosaurus
skeletons have been collected and several of Allosaurus holds a
these are virtually complete. Closely allied commanding presence, both
animals have been found in similarly aged in the history of dinosaur
rocks in Portugal and possibly Tanzania. discovery and its impact on
dinosaur science. This is a
juvenile.

64 THEROPODA

ALLOSAURUS FRAGILIS 65

predator. For example, there is an example of inter-species battles for territory or mates or the egg-laying females of modern birds, has been
an Allosaurus vertebra that may have a puncture consequences of predation gone wrong. reported for one specimen, and while it could
wound caused by the flailing tail of a stegosaur. be that this may allow us to determine males
And as is typical of large theropods such as Because of the number of specimens that are from females, this evidence has been contested.
Tyrannosaurus, many Allosaurus specimens show known, we understand a great deal about the
signs of a tough life – multiple healed fractures paleobiology of Allosaurus. It was the dominant The specimens vary in size and it has been
occur in several specimens, and stress fractures predator in Late Jurassic rocks of what is now determined that in young animals the legs
are even more common. One of these is North America; other large predators are also were proportionally longer – just as puppies
nicknamed “Big Al”; 19 of its bones were either known from these sediments, but these occur grow into their disproportionately big feet,
broken or showed signs of bone infections. with far less frequency. We know that Allosaurus large carnivorous dinosaurs grew into their
These injuries may have been the result of stopped growing between the ages of 20 and legs. This also probably indicates that the
28. Medullary bone, which occurs only in young had different hunting strategies to the
adults. This occurs in some animals today:
Komodo dragons, the largest living lizards (up
to 3m/10ft) in length) have hatchlings that
are only 50cm (19½in) long. The young are
largely arboreal and feed on insects and other
small animals, while the adults are capable
of killing large pigs and even humans. Like
Komodo dragons, Allosaurus is likely to have
changed its diet, habitat, and hunting habits as
it grew. There is possible evidence of cannibal
behaviour, as juvenile Allosaurus teeth have been
collected near the ribs of reasonably complete
Allosaurus adults. Finally, the Allosaurus brain
was much less birdlike than more advanced
theropods, and it had only limited binocular
vision. This further suggests that its social
system may not have been as sophisticated as
the more advanced dinosaurs that occurred
closer to the origin of birds.

66 THEROPODA

This Allosaurus mount at the
Museum depicts the animal feasting
on a carcass. Completed in 1915,
it was the first time a dinosaur
had been mounted in an active,
lifelike scenario.

This excellent painting of
Allosaurus by Charles R. Knight,
was a study of the eventual mount.

The craftsmanship that went into
the early mounts of fossil animals
is an aesthetic that is difficult
to replicate today.

The Cleveland Lloyd Quarry south
of Provo, Utah is an Allosaurus
bonebed where innumerable
individuals are preserved.

ALLOSAURUS FRAGILIS 67

ALBERTOSAURUS
S A RC O P H A G U S

LATE CRETACEOUS
HORSESHOE CANYON FORMATION AND OTHER LOCATIONS
WESTERN NORTH AMERICA

ALBERTOSAURUS WAS THE APEX CARNIVORE OF MUCH
OF NORTH AMERICA BEFORE THE APPEARANCE OF
TYRANNOSAURUS REX. IT IS CLOSELY RELATED
TO TYRANNOSAURUS REX, BUT MORE
LITHE IN APPEARANCE THAN ITS
LARGER RELATIVE. IT GREW
TO A MAXIMUM SIZE
OF AROUND 10M (32¾FT)
AND 2 TONNES.

R ecent decades have seen the Bering Strait into what is now modern Albertosaurus was a small,
discovery of many new species Asia. In both of these areas, large more lightly built version of
of tyrannosaurs in the northern tyrannosaurs that are closely related to Tyrannosaurus. It also lived a
hemisphere. Nearly all are from North Tyrannosaurus rex appear. In eastern North little earlier in time, yet it
America, but some have also been found America this was Appalachiosaurus, with is still very well represented
in Asia. This has much to do with the Zhuchengtyrannus and Tarbosaurus in Asia. in the fossil record.
geography of the northern hemisphere The southern part of North America
at the time these animals lived: what we also appears to have been a tyrannosaur The fossil hunter Charles H.
think of as North America today was incubator, where animals such as Sternberg in the preliminary
divided into two provinces, a western one Lythronax, Bistahieversor and Teratophoneus stages of the excavation of a
and an eastern one, separated by a vast, have been found. juvenile Albertosaurus. This
shallow inland sea that extended from specimen is now on display
today’s Gulf of Mexico as far as Canada. Many specimens of Albertosaurus have in the Museum saurischian
This sea was populated by a diverse group been discovered, and there could be more as dinosaur hall.
of creatures, including large, seagoing there has been some dispute and confusion
reptiles like mosasaurs and plesiosaurs, over whether another named species,
together with giant turtles and immense Gorgosaurus, is in fact Albertosaurus, rather than
predatory fish; toothed flightless birds a species in its own right. After extensive
chased fish in these waters and giant study, however, it appears that specimens
pterosaurs filled the skies. Later in the
Cretaceous, sea levels began to fall, and
many believe that large tyrannosaurs
emigrated out of western North America
to the eastern provinces and across the

68 THEROPODA

attributed to Gorgosaurus are likely to represent a It was discovered in Alberta, Canada, in
distinct species. As with Tyrannosaurus rex, both 1910 by American Museum of Natural
dinosaurs were large and two-fingered, but they History paleontologist Barnum Brown.
undoubtedly had a bite force that was much These expeditions to Alberta, along the Red
weaker than that of Tyrannosaurus rex. The Deer River, were novel in the sense that the
more that is discovered about Late Cretaceous intrepid paleontologists lived on a flatboat
ecosystems, the more it appears that two types and endured harsh, mosquito-infested
of large predators existed that seem to partition conditions. They paddled and motored the
niches and food supplies. This is much the boat down the river, stopping and mooring
same as modern systems, where big cats (lions, every few days to carry out their excavations.
cheetahs and leopards) all live in the same area, This locality was later rediscovered in 1997
but take advantage of specialized habitats and by Canadian paleontologists using Brown’s
specific prey. photographs and notes, and excavations
continued until 2005. Not only did they
The great majority of the known find some of Brown’s collecting artefacts,
Albertosaurus specimens were excavated at they even located parts of some of the same
one site, called the Dry Island Bone Bed.

ALBERTOSAURUS SARCOPHAGUS 69

specimens held in the Museum collections. 17 years of age. The oldest individual in the This is the old way to look
In all, about 26 individuals were found in group was 28 years old and 8.5m (28ft) in at dinosaurs. While the tail
this quarry, providing a great representative length, the smallest was two years old and is not dragging on the ground,
population sample. weighed about 50kg (110lb). The average the entire front part of the
age of Albertosaurus specimens that have been skeleton should fall forward
Detailed analyses of these bones showed analyzed is 14 years. Although Albertosaurus so the spine is parallel with
that an age distribution, or growth curve, didn’t grow as fast as Tyrannosaurus, it did the ground.
could be constructed for these individuals. grow quickly, which means that the behaviour,
This told us that very few of these animals habits and diet of subadults was probably not
had reached adult size, which, as for other unlike those of fully grown individuals.
advanced tyrannosaurs, occurred at about

70 THEROPODA

Many exceptional specimens Conditions in Alberta for
of Albertosaurus have been Barnum Brown’s crew were
found, including several tough. Access to exposures
three-dimensional skulls. was limited so they lived on
a flatboat. According to their
notes, they were almost eaten
alive by mosquitos, black flies,
and deer flies.

ALBERTOSAURUS SARCOPHAGUS 71

TYRANNOSAURUS
REX

LATE CRETACEOUS
HELL CREEK FORMATION
WESTERN NORTH AMERICA

IF I DID A WORD CHECK ON THIS
BOOK, TYRANNOSAURUS REX WOULD
GET THE MOST MENTIONS WHEN IT
COMES TO A SPECIES OF DINOSAUR. IF
A PERSON KNOWS A SINGLE DINOSAUR
NAME, IT IS APT TO BE TYRANNOSAURUS.

The first recognized Tyrannosaurus The original specimen was not complete, Three years later in 1905, Brown found
rex specimen was excavated yet the magnitude and importance of another specimen that was much better
in 1902 by Barnum Brown in this animal was immediately apparent, as preserved. This is the iconic T. rex specimen
eastern Montana. It was given the name expressed in Brown’s letter to Osborn at in the dinosaur halls of the American
Tyrannosaurus rex by Henry Fairfield Osborn the time: “Quarry No. 1 contains the Museum of Natural History. When this
in 1905. However, numerous fragmentary femur, pubes, part of the humerus, specimen was mounted at the Museum
fossils of what would come to be known three vertebrae and two indeterminate in 1915, it created quite the sensation,
as Tyrannosaurus had been found decades bones of a large Carnivorous Dinosaur, not and people lined up in droves to view this
earlier from the same general area, but not described by Marsh. … I have never seen giant prehistoric carnivore. According to
recognized as particularly special. anything like it from the Cretaceous.” Brown, the original specimen was sold to
the Carnegie Museum in Pittsburgh in
1941. It was wartime and Brown stated
that this was because “we were afraid that
the Germans might bomb the American
Museum in New York as a war measure,
and we hoped that at least one specimen
would be preserved.”

Very little was known about dinosaur
posture and biomechanics when the iconic
specimen was mounted. When originally
conceived by Osborn, he was going to
mount two Tyrannosaurus together in a
snarling duel over a carcass of a deceased

72 THEROPODA

As relatives of
Tyrannosaurus have been found
with a covering of simple
feathers, it is possible
that it may have had them on
portions of its body as well.

The Museum's Tyrannosaurus
skeleton was excavated in the
Hell Creek badlands of Montana
in 1905.

herbivore. Instead, the single specimen was Ancient Exemplar Organisms”. Basically, it
mounted in the pose that still remains etched laid out the general outline of what we knew
into the minds of billions worldwide – that then about T. rex and its close relatives. Our
of a towering, tail-dragging carnivore with agenda was to use the charisma of T. rex to talk
preposterously small forelimbs leering out into about what is generally being done in dinosaur
the distance. The entire pose radiated a sense science. The paper said a lot and focused on
of primitive, extinct, and lumbering. It was the all aspects of tyrannosaur biology. But that was
inspiration for lots of media monsters, most then, this is now. Work on all aspects of this
notably Godzilla in all of its incarnations. magnificent animal has since been honed and
refined. New technologies have come into play
In 1995 the Museum opened its renovated and more specimens have been found. Let’s
dinosaur halls. The highlight of the saurischian just examine a few.
dinosaur hall was the remounted T. rex. Instead
of Godzilla, the new mount was posed in a If I was writing about a living animal, I
way that looked like it was stalking you. This would start with some specifics. The weight of
new pose was dramatic in that the tail was held T. rex varied between 5,900kg (13,000lb) and
aloft, parallel to the backbone, and the head a top end estimate of 14,500kg (32,000lb).
was supported by an S-shaped neck. The new Wow! This is a variance of over 2.5 times. This
pose looked more like a giant-toothed pigeon speaks loudly to how difficult it is to empirically
than a reptilian kangaroo. measure how much extinct animals weighed.
Most reasonable estimates are in the high
In 2010 my colleagues and I authored a 8,400kg (13,000lb) approaching the 14,000kg
paper in the prestigious journal Science called (30,000lb) level.
“Tyrannosaur Paleobiology: New Research on

TYRANNOSAURUS REX 73

Physical measurements – tooth length, allowing us to suggest that some of the Rock overlying the
leg length, brain size – are easy to quantify. specimens may have been gravid females. Tyrannosaurus bones in the
Information such as growth bite force, hunting quarry was removed using a
strategy, or telling males from females is Moving towards physical properties, the team and shovel by Barnum
more difficult. Let’s start with reproduction. speed of an adult T. rex has been recalculated. Brown and field crew.
Making an egg requires a huge amount of Previously it had been suggested that it could
calcium mobilization. Calcium is hormonally move in the range of 20 miles an hour (32 A head-on view of
regulated, even in our bodies, and is the reason kilometres per hour). Using new computer the imposing skull of
that women are much more susceptible to models, we can calculate that it was much more Tyrannosaurus. Its eyes
osteoporosis than men. In many archosaurs, of a sloth at 12mph (19kph), which the fittest probably faced more forward
including T. rex, a specific kind of bone may of us could outrun. than those of other large
have been found. This bone type is called carnivorous dinosaurs, giving
medullary bone. Medullary bone serves as Other interesting facts are that it was one it better binocular vision.
a calcium reservoir for building eggshell. It of the animals which saw the asteroid at the
is found in living female birds and has also end of the Cretaceous period, and although it
reportedly been found in T. rex specimens, was giant, its brain size was proportional to its
body weight compared to other closely related
dinosaurs. We also know from damage to the

74 THEROPODA

TYRANNOSAURUS REX 75

76 THEROPODA

skulls, that they (presumably the males) bashed
their heads and bit each other. Presumably,
this was, like in many living animals, done in
competition for territory, food or mates.

Body covering for Tyrannosaurus rex has until
recently been the subject of much conjecture.
T. rex has traditionally been depicted as fairly
grotesque and reptilian, with large scales, and
sometimes horns and spikes. New specimens
of Tyrannosaurus rex and its close relatives give
direct evidential support to what it looked
like. These include specimens of Yutyrannus
(see p. 17) which are completely cloaked in
feathers. Small patches of preserved skin have
been found associated with newly collected
T. rex specimens. These scales are actually
small raised tubercles, only about 3mm in
diameter. We do not have skin from all over
the body, so we don’t know if tubercle size was
heterogenous. Nevertheless, with the evidence
at hand, we would predict that T. rex was less
grotesque, covered by an almost velvety fabric
of supple scales, with small primitive feathers
sparsely planted over the body.

As we indicated in our review article
mentioned above, we probably know more
about T. rex than any other dinosaur. And
there are 50 specimens known of this
amazing animal. It continues to be a subject
of fascination, a popular icon, and probably
the first dinosaur name imprinted in the
minds of children globally. Besides all this, it
is the inspiration for budding paleontologists
worldwide.

Long may the king reign.

Mounted in an active 77
stalking pose, the T. rex
skeleton is a centrepiece
of the Museum's Hall of
Saurischian Dinosaurs.

TYRANNOSAURUS REX

STRUTHIOMIMUS
ALTUS

LATE CRETACEOUS
OLDMAN FORMATION
NORTH AMERICA

EARLY ON IT WAS NOTICED THAT MANY ADAPTATIONS SEEN IN
NON-AVIAN DINOSAURS PRESAGED MORPHOLOGIES SEEN IN
MODERN BIRDS IN A CONVERGENT WAY. OSTRICH DINOSAURS
(ORNITHOMIMIDS) ARE A GOOD EXAMPLE OF THIS. ONE OF THE
BEST-KNOWN OSTRICH DINOSAURS IS STRUTHIOMIMUS.

It lived about 78 million years ago in an ostrich, it had a long neck, large eyes, Early Cretaceous of Spain, the teeth were
what is now western North America and long hind limbs, and there is direct small and closely packed into the jaws. As
and was about 3m (10ft) in length. fossil evidence that it had a keratinous beak the name implies, there is a great deal of
Ornithomimidae, the group to which like a modern bird. Some have estimated soft tissue in the throat region, which may
it belongs, was primarily Laurasian or that it could reach speeds of up to 50mph have been the remnants of a pouch as
northern hemisphere in its distribution. (80kph), which is faster than an African seen in modern pelicans. Other primitive
Ostrich dinosaurs were never a very diverse ostrich, but no rigorous biomechanical ornithomimids, such as Harpymimus and
group, but they do display many interesting studies have been conducted. Shenzhousaurus, had a surprising tooth
features that evolved independently in configuration, with just a few widely
modern birds. Struthiomimus means “ostrich Over the last few years it has been spaced teeth restricted to the lower jaw.
mimic” and one look at the skeleton demonstrated that primitive members Other ornithomimids are toothless. This
affirms why it was given this name. Like of the group had teeth. In one species, diversity of dentition and beak shape
Pelecanimimus (“pelican mimic”) from the

A Struthiomimus specimen
mounted. It is immediately
obvious why these are
colloquially called ostrich
dinosaurs.

A beautiful vintage chalk
drawing by Museum illustrator
Erwin Christman from the early
1900s. This shows that even
early on in dinosaur studies
the animals were sometimes
portrayed as active animals
with their tails aloft.

Two excellent specimens
of another "ostrich dinosaur",
Gallimimus, that thankfully
were repatriated to Mongolia
following their illegal export
by fossil poachers.

78 THEROPODA

indicates that members of this group may like structure reminiscent of the beak of modern ostriches. Juveniles with feathers from
have had very diverse diets. ducks. Modern ducks sieve out food from these same beds preserve only plumulaceous
the water using this structure, and the feathers, thereby supporting the idea that the
The morphology of the hands, especially comb may have had a similar function in pennaceous feathers were only developed in
in the more advanced forms, is unusual in ornithomimids. adults as display structures.
that all three of its fingers were about the
same length and terminated in long, straight Until recently the body covering of Images of more primitive ornithomimids
claws. This, coupled with the fact that the ornithomimids was unknown. In the last from the Early Cretaceous of China circulate
claws on the feet were also not strongly couple of decades specimens of Ornithomimus on the internet. These specimens of animals
recurved, suggests that these animals were from the Late Cretaceous of Canada have like Shenzhousaurus show a complete body
not active hunters. been found which preserve carbonized traces covering of plumulaceous feathers. Sadly,
of what have been interpreted as pennaceous these specimens have not made their way
This view (at least for the Late Cretaceous feathers. These are particularly abundant into public scientific collections and have
Mongolian form Gallimimus) is further along the forelimbs, and it has been suggested disappeared into the burgeoning collectors’
supported by the presence of soft tissue on that these feathers were used in display as in market.
the beak. This specimen preserves a comb-

STRUTHIOMIMUS ALTUS 79

DEINOCHEIRUS
MIRIFICUS

LATE CRETACEOUS
NEMEGT FORMATION
MONGOLIA

ONE OF THE MOST SPECTACULAR
AND UNEXPECTED FINDS OF THE
POLISH–MONGOLIAN EXPEDITIONS
OF THE 1960S AND EARLY 1970S
WAS AN ENORMOUS SET OF ARMS.
THESE WERE FOUND AT THE ALTAN
ULA LOCALITY BY FAMED POLISH
PALEONTOLOGIST ZOFIA KIELAN-
JAWOROWSKA IN SOUTHERN MONGOLIA IN 1965.

The rocks that preserved these fossils therizinosaurs whose remains have also been were scaled up from other ornithomimids,
are part of the Late Cretaceous found in Mongolia. The first therizinosaur Deinocheirus would have had a length of
Nemegt Formation deposited fossil, Therizinosaurus, was found in the about 10.7m (35ft), which is big but not
about 70 million years ago. The Nemegt same fossil beds in which Deinocheirus was necessarily huge. Enormous sizes were
Formation preserves some of the most discovered. Early on, therizinosaurs were originally postulated because people were
famous dinosaurs found in Mongolia; study poorly known and turned out to be among extrapolating from other theropods with
of these rocks has shown that the area was a the strangest of all dinosaurs. They had much smaller forelimbs.
warm, wet, heavily vegetated floodplain. immense bodies supporting tiny heads,
short tails, and huge claws. One of these Our understanding of many specifics of
This set of arms was nearly 2.75m (9ft) from Therizinosaurus itself is over 30cm Deinocheirus and its relationships has changed
long. Only the forelimbs and part of the (11¾in), and this bony part of the claw dramatically over recent years. This has
shoulder girdle were found. When another would have supported a keratinous claw been fuelled by the discovery of several new
Polish paleontologist, Halszka Osmólska, sheath (like a human fingernail) that was specimens. Some of these were excavated
originally described the specimen, she did at least 60 per cent larger. As fearsome as at the original Deinocheirus locality by a
not have much to work with. She named these beasts appeared, they were plant eaters Canadian–Mongolian team, and another
it Deinocheirus, which means “terrible and probably used their long claws to pull was found at the Bugin Tsav locality, which
claw” – a fitting name, since a single talon branches down into their jaws, much in the is not far from the Altan Ula beds. Some
measures 20cm (8in) long and is perched same way that sloths do today. of these specimens showed clear signs of
on a massive hand. Originally it was having been looted; the looting of dinosaur
thought to be a member of what was then Over the years, scientists began to specimens by commercial interests is a
known as “Carnosauria” – a group of large establish that Deinocheirus was neither a major problem, not just in Mongolia but
carnivorous dinosaurs that included many “carnosaur” nor a therizinosaur. Instead it throughout the world.
well-known animals such as Tyrannosaurus was determined to be an ornithomimid, and
and Allosaurus. This group is no longer a giant one at that. Because ornithomimids It became known that the specimen had
recognized as valid. have such long arms, Deinocheirus is not as been trafficked out of Mongolia and sold to
large as it may seem. If the proportions Europeans through a Japanese middleman.
Comparisons were also made initially with Fortunately, it was intercepted by a

80 THEROPODA

legitimate European fossil dealer, who arranged also had bulky feet, suggesting slow, lumbering primitive toothed ornithomimid Shenzhousaurus.
for the specimen to be deposited in a museum movement – rather sloth-like. A cast of the grasping arms of the type
in Belgium. From there it was repatriated to
Mongolia, where it was combined with the rest Skulls tell us a lot about animals: Deinocheirus specimen hangs in the Hall of Saurischian
of the skeleton. This fantastic new material had a smaller than average brain for its size Dinosaurs at the Museum and provides a
gives us a remarkable picture of this very and may have had a better sense of smell frequent frame for many a selfie. They were
unusual animal. than many dinosaurs. A study of its skull rather mysterious until recently. Now we know
biomechanics indicates that it had a weak bite that, although unusual, Deinocheirus fits nicely
The new specimen clearly supports the force and may have simply slurped its food within the paradigm of dinosaur biology
ornithomimid identity of Deinocheirus. The most from the bottom of ponds and lakes. This isn’t developed over the last two decades.
striking thing about its appearance, however, is as odd as it seems: another ornithomimid, a
that it sported a large fin on its back supported specimen of Gallimimus collected by American A big head, huge claws,
by extensions of the backbone segments. Fans Museum of Natural History–Mongolian humped back and a feathery body
like this occur in a broad variety of unrelated Academy of Sciences expeditions in 2000, covering make Deinocheirus look
dinosaurs and there is little consensus on showed the presence of keratinous filters on like a Dr. Seuss animal.
what they were used for; everything from heat the beak, similar to those ducks have today.
regulation to – believe it or not – “wind sails” Associated with the skeleton were nearly When it was first discovered,
has been proposed. It is most likely they were 1,500 gastroliths, or small stones that formed paleontologists had no
used for display in a way similar to many of the a gastric mill in the stomachs of the animal. idea what kind of animal
unusual structures found on living animals. It Such stones have also been found in the Deinocheirus was. Some
suggested it was huge, larger
than any other theropod and
equally grotesque.

DEINOCHEIRUS MIRIFICUS 81

C O M P S O G N AT H U S
LONGIPES

JURASSIC
SOLNHOFEN FORMATION
GERMANY

COMPSOGNATHUS IS A POORLY KNOWN BUT IMPORTANT
SMALL DINOSAUR FOUND IN LAGOONAL SEDIMENTS IN THE
SAME FORMATION AS ARCHAEOPTERYX. IMMEDIATELY IT WAS
RECOGNIZED THAT THE ANATOMY OF COMPSOGNATHUS WAS
VERY SIMILAR TO THE PRIMITIVE “BIRD” ARCHAEOPTERYX.
IT WAS SO SIMILAR THAT IT WAS THE FIRST NON-AVIAN
DINOSAUR TO BE RECONSTRUCTED WITH FEATHERS BY
THOMAS HUXLEY IN 1876.

P erhaps because Compsognathus was so Sinosauropteryx is a revolutionary animal;
apparently birdlike, and was found although it had long been predicted, it was
so early in the history of dinosaur the first non-avian dinosaur to be collected
study – 1859 – a number of strange theories that preserved indisputable evidence of
about it have been proposed. One is that it feathers. This caused quite a stir in the late
used its forelimbs (which were thought at the 1990s and of course there were doubters.
time to have only two fingers, but actually It will suffice to say here that after intensive
have three), to propel itself through water study, the original claims of a feathered
using its arms as oars like a steamer duck. animal are borne out. As an aside, the
All of the evidence now suggests that these first specimen of Sinosauropteryx (like
animals were fairly traditional bipeds with Compsognathus) also preserved a lizard in the
a conservative body plan. They probably body cavity.
lived along the shores of a shallow sea.
Compsognathus is one of the few dinosaurs The feathers of Sinosauropteryx are not
for which we have a very good idea what like the feathers of a modern bird. Instead
they ate: both of the known specimens have of long branching structures, which are
the remains of small lizards in their body very heterogeneous across the body, all of
cavities, providing good evidence that these the Sinosauropteryx feathers were 13–50mm
animals were lacertophages. (½–2in) in length and uniform in structure
over the entire animal. They were short,
While Compsognathus was a small animal,
there are much larger individuals from other A fluffy Compsognathus
closely related species. Huaxiagnathus from reconstruction. It is known
the Early Cretaceous of Northeast China from stomach contents that it
is much larger, approaching 2m (6½ft). fed on lizards, and its diet
Another compsognathid is Sinosauropteryx. probably included insects.

82 THEROPODA

COMPSOGNATHUS LONGIPES 83

tubular bristles with the longest ones just
above the shoulders. Sinosauropteryx is a fairly
primitive theropod, so it is not unexpected
to find primitive, undifferentiated feathers.
On the tail of one of the specimens you
can observe variations in colour, which
indicates that in life the tail was banded.
Most paleontologists think that these feathers,
and feathers in general, originally evolved as
thermal blankets to insulate these animals
from the environment.

The original (and only) specimens of
Compsognathus do not feature traces of feathers,
but this does not mean they were not present.
Some of the Archaeopteryx specimens from these
same localities do not preserve feathers, even
though most specimens do. In addition, there
are other small dinosaurs from these beds that
display surprising integumentary structures.
Two of these are Sciurumimus and Juravenator.
Sciurumimus is difficult to classify because it
is clearly a juvenile animal. Yet most think it
is related to megalosaurs and it clearly had
feather-like filaments. In the first description
of Juravenator it was believed to be featherless,
but more detailed examination under UV light
clearly shows that it had both feathers and
scales. It was originally considered to be a close
relative of Compsognathus; however, more recent
studies suggest that its affinities lie with more
advanced forms.

Compsognathus, even though it is known
primarily from only a single specimen, is a
seminal player in understanding non-avian
dinosaurs. Ever since its discovery it has been
studied by all the luminaries of dinosaur
paleontology. We are lucky that it still exists.
Most of the collection in the institution where
it is housed, the Bayerische Staatssammlung
in Munich, was destroyed during the Allied
bombing of the city in the Second World
War. Specimens that were lost include many
important dinosaurs from Ernst Stromer’s
excavations in Africa, including the type
specimen of Spinosaurus. The only reason
that the Compsognathus specimen survived was
that when it became apparent that the war
was probably going to be lost, one of the
curators took the specimen to his home in the
countryside.

84 THEROPODA

The original specimen of
Compsognathus. Unlike so many
other specimens in the Munich
museum, this slab survived the
bombings of the Second World
War. It was small enough to be
taken to the countryside by
one of the curators.

An excellent lithograph of
Compsognathus. The original
stone currently resides at
Yale University.

This 1903 illustration of
the stomach contents shows
parts of the skull of a lizard
ingested shortly before death.

Some strange ideas have been
floated about the use of the
forelimbs in Compsognathus.
One is that it used them as
oars to swim and dive.

COMPSOGNATHUS LONGIPES 85

MONONYKUS
OLECRANUS

LATE CRETACEOUS
NEMEGT FORMATION
MONGOLIA

IN 1990, DURING THE FIRST AMERICAN MUSEUM OF NATURAL
HISTORY–MONGOLIAN EXPEDITION TO MONGOLIA, WE WERE
IN THE CAPITAL OF ULAANBAATAR, BASED IN A DECREPIT
BUILDING USED BY THE MONGOLIAN ACADEMY OF SCIENCES
AS A STORAGE AREA FOR FOSSILS AND FIELD EQUIPMENT
BEHIND THE NATIONAL NATURAL HISTORY MUSEUM.

Among Russian car parts, boxes bones that this was an animal very closely (like thoroughbred race horses) require a
of unlabelled fossils and various related to modern birds. Certainly it was an unique name. We resolved this by simply
detritus, there were a couple of advanced coelurosaur. But what really took exchanging the “ch” for a “k” to form
small offices. One of these belonged to us by surprise were the forelimbs: instead Mononykus. In this paper, we proposed
Altangerel Perle, a Mongolian paleontologist of the typical long front limbs with three the bold hypothesis that Mononykus was
who had been assigned to work with us by fingered hands, Perle’s animal had a tiny, intimately related to modern birds. At the
the Academy of Sciences. Among various powerfully built, short limb that sported a time, this did not go down well, yet it is clear
fascinating specimens was one that was single, extremely large claw. that Mononykus shares many similarities with
rather strange. We laid much of the small modern birds not found in other non-avian
specimen out on the table; clearly it was A few months later Perle brought the dinosaurs. Most of these are subtleties
something new and we were excited. specimen with him for an extended study of the boney skeleton, but a couple of
trip to New York. Detailed analysis of it important ones include the presence of a
It had been collected by Mongolian there demonstrated that it was, as initially breastbone with a keel and the fusion of
paleontological expeditions a few years thought, a coelurosaur. More analyses all of the wrist elements into a single block
earlier at the Late Cretaceous Bugin Tsav showed that it was related to a group of called the carpometacarpus. Our initial
locality. Bugin Tsav is a blisteringly hot, poorly preserved enigmatic dinosaurs called proposal has not stood the test of time and
dusty, fly- and ant-infested Gobi Desert alvarezsaurs, which at the time were only most now consider Mononykus to hold a more
basin north-west of the Golden Mountain known from the Cretaceous of Argentina; basal position, i.e. that it is not that closely
(Altan Ula) in Ömnögov Province, southern how these are related to other dinosaurs related to birds, and several dinosaurs like
Mongolia. It is the site of many important was at the time unknown. troodontids and dromaeosaurs are much
dinosaur discoveries and this little dinosaur more closely related to the creatures that
was one of them. We initially named the animal Mononychus now populate our skies. But the story is still
in a paper in the journal Nature. Shortly developing. Much is being learned about
In front of us lay leg bones, hips, thereafter we unfortunately found out how Mononykus is related to other dinosaurs
vertebrae, the back of a skull and that the name (meaning “single finger”) through fantastic discoveries of close
importantly, forelimb bones. It was had already been used for a beetle, so Mononykus relatives.
immediately clear from various bumps, we had to change it to conform to the
proportions and processes of the limb rules of scientific nomenclature, which

86 THEROPODA

Mononykus portrayed as a
brightly coloured, feathered
creature.

MONONYKUS OLECRANUS 87

And there is also the forelimb to consider. It as large, and because of a paucity of fossils, This skeleton of Mononykus
is certainly one of the most unusual dinosaur little is known about it. We know much more is based on a composite of
forelimbs that has ever been recorded. In about Shuvuuia deserti. In Mongolian, this means Mononykus and Shuvuuia bones.
general, when we encounter really small, “bird of the desert”, a reference to the birdlike
diminutive forelimbs (as in Tyrannosaurus nature of the skeleton. It is known from several
rex), they are vestigial and almost useless, specimens, both adults and juveniles, from
weak appendages. This is not the case for several localities. Not only does it give us a better
Mononykus. The forelimbs in this animal were picture of what the closely related Mononykus
very short, but stout and sturdy. The lower looks like due to its well-preserved skull remains,
arm bone (the ulna) features a large olecranon it also provides other clues to the appearance
process – basically the elbow. This indicates of these animals. During preparation of the
that significant leverage and force could be skull of the type specimen, numerous small,
exerted by the forearm. This force would be thin fibres were found, especially around the
transmitted through the hand via a wrist that forelimbs and the skull. A few years later these
was largely immobile and could move in only filaments were subjected to a type of analysis
a couple of planes. This was topped off by that detects the presence of minute amounts
the large claw on the hand, which must have of preserved protein; these analyses did indeed
been capable of a powerful digging force. Such detect keratin, and specifically the type found
highly modified appendages usually signify a in the feathers of modern birds. This provides
very specialized lifestyle; animals with similar powerful evidence that this advanced non-avian
appendages today tend to be mammals like dinosaur, like other dinosaurs, was a feathered
pangolins and anteaters. So, perhaps, the creature when alive.
lifestyle of Mononykus and its relatives was
not vastly different, and it used its powerful
forelimbs to dismantle insect nests.

Joint AMNH–Mongolian expeditions in
the mid-1990s recovered two new species of
alvarezsaurs from the Ukhaa Tolgod beds. One
of these is a large form called Kol ghuva, which
is known from a single foot. It is about twice

88 THEROPODA

The closely related Shuvuuia
is almost identical to
Mononykus. It lived slightly
earlier in time and occupied
a desert habitat as opposed to
a riverine floodplain.

The powerful aberrant forearm
of Mononykus.

MONONYKUS OLECRANUS 89

OV I R A P TO R
P H I L O C E R ATO P S

LATE CRETACEOUS
DJADOKHTA FORMATION
CENTRAL ASIA

THE CENTRAL ASIATIC EXPEDITIONS WERE SOME
OF THE MOST EXPENSIVE PALEONTOLOGICAL
EXPEDITIONS EVER CONDUCTED. THEY WERE
ORGANIZED BY THE AMERICAN MUSEUM
OF NATURAL HISTORY AND OFFICIALLY
TOOK PLACE FROM 1922 TO 1928.
THESE EXPEDITIONS WERE THE
BRAINCHILD OF HENRY FAIRFIELD
OSBORN, THEN PRESIDENT OF THE
MUSEUM, AND ROY CHAPMAN ANDREWS.

Roy Chapman Andrews was an He regularly appeared on radio shows, Although we don’t have any
intriguing figure. After graduation lectured frequently, penned over 20 books direct fossil evidence for
from Beloit College, Wisconsin, and wrote copious articles. Even though he feathers in Oviraptor, their
he began to pursue his dream of working is not considered a great scientist (he never presence in close relatives
at the Museum. He asked for a job and finished his graduate education), Andrews strongly suggests their
was given one tidying up around the was a charismatic frontman for what presence in this animal.
mammalogy department and plying his self- would arguably become the most famous
taught taxidermy skills. Early in his career paleontological expedition ever.
Andrews was recognized as both prodigal
and a prodigy. Wanderlust and a natural On his return from his initial sojourns to
ability to pick up foreign languages sent Asia, Andrews once again turned his eye
him out on expeditions; his first took him towards the East. At the time the Museum
to the East Indies and to the Arctic. While was led by the powerful – albeit from
pursuing an advanced degree he lived in a today’s perspective, controversial – leader,
Japanese whaling village, taking some of Henry Fairfield Osborn. Osborn founded
the first quality moving pictures of marine the Museum’s Department of Vertebrate
mammals. During his time in the East, Paleontology in 1891 and became President
Andrews indulged himself in the food, the of the Museum Board of Trustees from
culture and all of the pleasures that Asia 1908 to 1935. The scion of a wealthy and
in the early twentieth century had to offer. popular industrialist, Osborn had important
Andrews would go on to become one of the connections in both society and commerce.
greatest and best-known expeditioners and
popularizers of science during this period. One of Osborn’s many interests was the
origin of humans. Although untested, as
no significant fossils had been collected, a

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OVIRAPTOR PHILOCERATOPS 91

92 THEROPODA

prevailing contemporary theory was that the find is related to the discovery of the theropod Roy Chapman Andrews, leader
origin of humans lay in Asia. However, few dinosaur Oviraptor at Bayn Dzak. of the Central Asiatic
intellectuals in Europe or North America at Expeditions, with dinosaur
the time would even consider that modern During the 1923 instalment of the eggs at Bayn Dzak in the early
humans could possibly have originated on the expedition, team member George Olson came 1920s.
Dark Continent. In his zeal for adventure, upon an unusual fossil occurrence: the skeleton
Andrews was able to convince Osborn to let of a reasonably small, new kind of theropod Henry Fairfield Osborn,
him lead a series of expeditions to Central dinosaur. While this was a fine discovery on its founder of the Department of
Asia, in search of the fossils that would own, this dinosaur was found associated with Vertebrate Paleontology and
corroborate Osborn’s ideas. several dinosaur eggs. Earlier in the season, the director of the Museum. It was
expedition had come across a number of eggs, his vision that sparked the
The Central Asiatic Expeditions were sometimes even in nests. When the specimens Central Asiatic Expeditions.
grand undertakings and were also incredibly arrived in New York, they generated huge
expensive, and here Osborn’s connections and excitement and international publicity (and A camel resupply caravan
Andrews’ charisma became key in persuading even a newsreel). Shortly thereafter, in 1924, arriving at Bayn Dzak (the
New York’s wealthy to open their cheque Henry Fairfield Osborn published a seminal Flaming Cliffs).
books. The headquarters for these endeavours paper on some of the Flaming Cliffs finds
was an old royal palace near what is today entitled “Three new Theropoda, Protoceratops
Tiananmen Square in Beijing. These trips zone, central Mongolia”.
were innovative in the sense that instead of the
typical transportation methods of camels and In addition to the iconic Mongolian
donkey carts, the Museum imported motorized Velociraptor (see p.106), Osborn named another
vehicles that were supported by gasoline and dinosaur – the one found by Olson that was
parts sent out by camel caravan to makeshift associated with the nests. Osborn named the
supply depots deep in the Gobi Desert. These animal Oviraptor philoceratops, which means “egg
expeditions were truly modern in every way. eater fond of ceratops”. Why this unusual
name? This is because when the Flaming Cliffs
One of the most famous discoveries came dinosaur eggs were first interpreted they were
at a locality called the Flaming Cliffs (Bayn considered to be the eggs of the ornithischian
Dzak); it was here that the first universally herbivore Protoceratops andrewsi (see p.190). The
recognized dinosaur eggs were found, and this chain of reasoning is that because dinosaur

OVIRAPTOR PHILOCERATOPS 93

eggs of the type found with the Oviraptor are embryo; it was a theropod dinosaur embryo A sculptural representation
ubiquitous at the Flaming Cliffs, they must be on the half shell. At the time this was the of an oviraptorid embryo in
the eggs of the most common dinosaur at the first theropod dinosaur embryo known, and its egg. In 1993 fossils were
same locality. It was hence interpreted that the it conclusively demonstrated that the eggs at found showing Oviraptor was
Oviraptor was predating on the Protoceratops nest Flaming Cliffs were not laid by Protoceratops. not an egg thief.
when it met its demise. In all fairness, Osborn Other discoveries at Ukhaa Tolgod of the
did qualify his analysis by stating he could closely related dinosaur Citipati add even more A drawing of the
not be absolutely certain that the eggs were to the story (see p.98). The preparation and original Oviraptor fossil.
those of Protoceratops. Nevertheless, this became analysis of the embryo back in New York, Interestingly, the numerous
scientific orthodoxy for decades. showed that not only was it a theropod, it was egg shell pieces found
an oviraptorosaur – the group of dinosaurs to associated with the specimen
This all changed in 1993 when the AMNH– which Oviraptor belongs. are not illustrated.
Mongolian Academy of Sciences expeditions
discovered a remarkable locality in southern Returning to the original Oviraptor Oviraptor had fairly long,
Mongolia. Named Ukhaa Tolgod, the site philoceratops, recent analysis has told us even curved claws on its feet, but
has become one of the most important Late more about this unusual animal. Even though lacked the hooked raptorial
Cretaceous dinosaur localities in the world. the type specimen has been studied intensively claws of Velociraptor and its
The first fossils ever found at Ukhaa Tolgod for nearly 100 years, something was missed. relatives (compare with the
were collected in July 1993. On that day I saw Intermixed with the adult skeleton and the claw on p.106).
a dinosaur egg exposed on the ground a few eggshell fragments and partial eggs, are the
paces in front of me. This was not an unusual bones of tiny oviraptorosaurs. Although
occurrence because eggs are commonly found we cannot demonstrate it definitively, the
in these sediments. It was the type of egg that Oviraptor was probably a parent tending to its
is most common at the Flaming Cliffs and nest of hatched chicks when they perished.
the same as that found underneath the 1923 In this highly supported interpretation,
Oviraptor philoceratops skeleton. But when I instead of a predator, it was a good parent.
picked it up I could clearly see it was special: Unfortunately, the strict rules of scientific
it held an embryo of a developing dinosaur nomenclature do not allow us to rename it,
inside. Moreover, it was not a Protoceratops and “egg eater” it remains.

94 THEROPODA

OVIRAPTOR PHILOCERATOPS 95

KHAAN
MCKENNAI

LATE CRETACEOUS
DJADOKTHA FORMATION
CENTRAL ASIA (MONGOLIA)

ONCE CONSIDERED TO BE THE RAREST OF DINOSAURS, IT IS NOW APPARENT
THAT OVIRAPTOROSAURS WERE DIVERSE AND ABUNDANT THROUGHOUT
THE CRETACEOUS (ESPECIALLY THE LATE CRETACEOUS) IN THE NORTHERN
HEMISPHERE. CENTRAL ASIA IS THE CENTRE OF DIVERSITY WITH SEVERAL
SPECIES, INCLUDING CITIPATI (SEE P.98) AND OVIRAPTOR (SEE P.90).

K haan was the first oviraptorosaur to The spectacular Khaan
be collected at the Ukhaa Tolgod specimens “Sid and Nancy” from
locality in Mongolia by Museum Ukhaa Tolgod.
and Mongolian paleontologists. Unlike
the other two oviraptorosaur specimens
described in this book, Khaan lacked a large
cassowary-like crest on its head. It was also
fairly small at under 2m (6½ft) in length.

There are multiple signs that Khaan was
a social animal. The fossils at the Ukhaa
Tolgod locality were killed by the event
that preserved them, with evidence
pointing to the collapse of large, water-
laden sand dunes that liquefied and
buried animals alive. In July 1995,
the tail of a Khaan specimen (the
first one had been found two years
earlier at the same locality) was
found protruding from a small
hill. Usually, in this sort of case,
when you dig into the hill you
are likely to find the rest of the
tail. On this occasion however, a
beautifully preserved specimen of
this small dinosaur was collected.

During the excavation another small
dinosaur – also a Khaan specimen – was found
lying next to it. Both animals had been killed
by the same event and exhibited clear signs of

96 THEROPODA

broken necks. The specimens were nicknamed associations is that, like Sid and Nancy, they A Khaan bonebed from Ukhaa
“Sid and Nancy” after the bassist of the Sex are believed to have perished in a single event. Tolgod. Such bonebeds, this
Pistols and his girlfriend Nancy Spungen, who These specimens are all about the same size, one containing at least seven
met her demise at Manhattan’s Chelsea Hotel showing that they were an age cohort that was individuals, suggest that
in 1978. Two decades later, the specimen was living in a flock. This intensely social behaviour these animals were social in
included in a larger study on determining the may be a characteristic of the entire group. life.
sex of theropod dinosaurs in general. What
had been determined was that the shape of Other oviraptorosaurs have also been found The type specimen of Khaan,
the bottom process of an anterior tail vertebra in bonebeds, including a peculiar example from the Late Cretaceous Ukhaa
differed in male and female crocodiles. The from the Mongolian locality of Khulson. Tolgod beds of Mongolia.
same conditions were found in Sid and Nancy, There are dozens of specimens of juveniles
strongly indicating that they were a male and less than a year old, combined with at least
female pair when alive. three fully grown individuals. This suggests
that like living ostriches, these were very social
Large associations of immature Khaan animals that did not just brood their nests
specimens have also been found at Ukhaa but cared for their young, and enjoyed a long
Tolgod. What is interesting about these family life together.

KHAAN MCKENNAI 97

C I T I PAT I
OSMOLSKAE

LATE CRETACEOUS
DJADOKHTA FORMATION
MONGOLIA

CITIPATI IS AN
OVIRAPTORID DINOSAUR
THAT IS CLOSELY RELATED
TO OVIRAPTOR. OVIRAPTORIDS,
SUCH AS KHAAN (SEE P.96) AND
OVIRAPTOR (SEE P.90), WERE PECULIAR ANIMALS.
THEY WERE TOOTHLESS, SOMETIMES WITH LARGE
CASSOWARY-LIKE CRESTS ON THEIR HEADS AND VARIED IN
SIZE. SOME LIKE CONCHORAPTOR WERE SMALL, WHILE
OTHERS, SUCH AS GIGANTORAPTOR, WERE HUGE. THEY
WERE BIPEDAL WITH LONG ARMS AND BIG CLAWS ON THEIR
HANDS AND MAY HAVE EATEN PLANTS.

So far Citipati has only been found in 1960s and 70s, which excavated so many the circumstances of their preservation
the bright red Late Cretaceous (about important Gobi Desert dinosaurs. supports this. One of the reasons that
78 million years ago) sandstones specimens from the Ukhaa Tolgod locality
of Ukhaa Tolgod, Mongolia. The first Specimens of oviraptorid dinosaurs are are so well-preserved is that they were
specimen was collected in 1994 and several very common at Ukhaa Tolgod. At least apparently buried alive and have been
other individuals have since been found. two species have been found there, both protected by the very agent that killed them.
The somewhat unusual name comes from of which were new to science when we How did this happen?
the Himalayan Buddhist deities that are the discovered the locality. Besides Citipati, we
guardians of the funeral pyre. Fittingly the have excavated several other specimens This high-quality preservation of fossils
Citipati are usually portrayed as a pair of of a smaller but closely related form. This is seen at many localities in the Djadokhta
dancing skeletons surrounded by a halo of species, called Khaan mckennai, is known from Formation of Mongolia and has been
flames. The specific name is in honour of numerous individuals. debated for decades. The usual explanation
Halszka Osmólska, one of the leaders of employed is that these animals were
the Polish–Mongolian Expeditions of the A characteristic of oviraptorids is that overcome by powerful sandstorms, but there
they appear to be gregarious; many are problems with this scenario. One is
specimens collected at Ukhaa Tolgod and

98 THEROPODA

A fully feathered pacing
adult Citipati, the most
common theropod at the Ukhaa
Tolgod locality.

CITIPATI OSMOLSKAE 99