Chapter 9 –Dinosaur Feeding Habits
Importance of Studying Dinosaur
Feeding Habits
You are what you eat
What dinosaurs ate is interpreted
mostly from their teeth
Supplemented with toothmarks,
gastroliths, rarely preserved stomach contents, coprolites and tracks
Most dinosaurs were herbivores
Interrelationships of herbivorous dinosaurs and their food plants a
important part of the Mesozoic terrestrial ecosystem
Especially important are the effect that sauropods, hadrosaurids and ceratopsians had in
giving an adaptive advantage to fast growing plants
Carnivorous dinosaurs were either
predators, scavengers or a mixture of the two and would have been present in
smaller numbers than herbivorous dinosaurs
Ratios of herbivorous to carnivorous dinosaurs are comparable to those
of modern large-mammal communities and bear on the discussion as to whether
dinosaurs were warm- or cold-blooded
Dinosaur Teeth and Toothmarks
Basic Tooth Terminology
Chordate teeth
Fish, Amphibians, Reptiles, Mammals
Modern birds don’t, but
fossil birds did, and
some embryonic birds do
Terms (see Figures 9.1 and 9.2)
Enamel and dentine
Crown and root
The majority of most dinosaur teeth are roots
Lingual and labial sides
Denticles, carinae, serrations and
cellae
Occlusion
Heterodont dentition
Tooth shape
Leaf-like, peg-like, conical and bladed
Dental batteries
Secondary wear and lost teeth
Herbivorous Dinosaur Teeth
Leaf-shaped
Prosauropods (roughly serrated),
Thyreophorans and Pachycephalosaurs
Nipping off vegetation from limbs and stems
Originally interpreted as carnivorous for prosauropods
Peg-like
Sauropods
Strip vegetation from limbs, like
a rake
Leaves and needles are not chewed, but swallowed and processed internally by gastroliths or
bacteria
Dental batteries
Ornithopods and Ceratopsians
Well-developed in hadrosaurids
Less elaborate in smaller ornithopods
Carnivorous Dinosaur Teeth
Normally serrated and curved
posteriorally
Referred to as ziphodont teeth and
restricted to theropods among dinosaurs
Similar to archosaur ancestors of
dinosaurs
Plesiomorphic (ancestral) trait
Seen in ancestral dinosaur species like Herrerasaurus and Eoraptor
Adapted for grasping and cutting
through flesh and for crushing or punching through bone
Most theropod teeth are conical
Chunks of flesh torn off and
swallowed, not chewed
For most theropods, in the same
jaw, teeth are the same shape but different sizes
Various levels for cutting flesh
Serrations in theropod teeth,
particulary for tyrannosaurids have been related to those of the Komodo Dragon
of Indonesia
Fibers of flesh retained by the cellae
putrify and produce a septic culture
Bites lead to fatal infection
Variations from strict carnivory
Piscivory
Some theropods, notably spinosaurs and
therizinosaurs
Based on their numerous small,
similarly shaped teeth, in
conjunction with other anatomical features
Omnivory, Insectivory and Egg eating
Some theropods, notably ornithomimosaurs and
oviraptorids
Theropod teeth in the bones of
other animals
Tyrannosaurus in Hypacrosaurus fibula
Saurornitholestes in pterosaur bone
Dinosaur Toothmarks
Definitions
An impression left by the bite of an animal with teeth, regardless of what was bitten
Scrape vs puncture marks
Puncture marks best for determining the identity of the tracemaker
Can be used to re-create the
feeding procedure
Most toothmarks were accidental byproducts
of meat eating, not of preferential bone consumption
Examples of toothmarks attributable
to specific dinosaurs
Troodon on ceratopsian bones
Saurornitholestes in ornithomimid and Edmontosaurus bones
Tyrannosaurus in Triceratops, Edmontosaurus and Saurornitholestes bones
Albertosaurus in Edmontosaurus bones
NOTE – Edmontosaurus didn’t always succomb; Healed
tyrannosaurid toothmarks reported for one Edmontosaurus specimen
Can be used to estimate biting
force
Tyrannosaurus has a biting force greater than that for any
known animal
Taphonomy of Teeth and Toothmarks
Teeth more commonly found separate
from their jaws and in relatively great abundance
Can be reworked easily
Often separated by loss during life,
as a result of feeding
Replaced subsequently
Risky to name a dinosaur species based
only on teeth
Toothmarks preserved only if made
in bone and are relatively rare
Bias toward those of larger dinosaurs,
both as predators and prey
Might be more common, but overlooked
Dinosaur Gastroliths
Gastroliths
Stones used primarily to help in
the mechanical breakdown of food within a digestive tract
Modern birds and crocodilians have
gastroliths, although crocodilians use theirs for ballast
Definitive dinosaur gastroliths are
found within their chest and abdominal cavities
Dinosaur gastroliths generally are
smooth, polished, rounded and oblate to semispherical
They range in size from less than 1 cm
to as large as 10 cm
They are generally silica rich, like
chert or quartzite
Limestone and dolostone would dissolve, and, like
shales, are too soft
Gastroliths are trace fossils
History of gastrolith reports
Barnum Brown in the early 20th
century for Claosaurus, a
hadrosaurid
Friedrich von Huene in 1931 for Sellosaurus, a prosauropod
William Lee Stokes in 1942 for a sauropod
General reluctance to identify
gastroliths
Difficult to distinguish from other
smooth, rounded stones
Must clearly demonstrate that they are not stream pebbles washed into
a carcass deposited in a river setting
Gastroliths can be evidence for dinosaur presence in the absence of body fossils or other trace fossils
Concentrated deposits of well-polished, rounded stones in otherwise fine-grained (muddy or
sandy) deposits
Dinosaurs with well-supported evidence
for gastroliths
Sauropodomorphs
Nodosaurids (a type of ankylosaur)
Psittacosaurids (primitive
ceratopsians)
But had well-developed dental
batteries
Theropods
Stomach Remains and Digestion
Other Species
Mostly other vertebrates are
recognized
Plants and insects unlikely to be
preserved
One specimen of Edmontosaurus reported with seeds, twigs and conifer needles
Digestion in dinosaurs
Aided by anaerobic bacteria and
specialized organs
Methane a byproduct of this symbiosis with methanogenic bacteria
Examples from theropods
Compsognathus with a complete lizard (Bavarisaurus) from the Late Jurassic Solnhofen Limestone of
Germany
Note – this is the same unit that has yielded the specimens of Archeopteryx
Sinosauropteryx with a small mammalian dentary from the Early
Cretaceous of China
Daspletosaurus with an etched vertebra from a juvenile
hadrosaurid from the Late Cretaceous Two Medicine Formation of Montana
Regurgitates
Can be to rid body of toxins or from
poor health or indigestible material
Only one dinosaur example from the
Early Cretaceous of Mongolia
Recent report of ichthyosaur regurgitate from the Late Jurassic of
England
Cannibalism
Coelophysis
Two adult specimens with remains of
smaller, possible juvenile individuals (see Figure 9.6)
Dinosaur Coprolites
Terminology
Coprolite – remains of solid
or semi-solid fecal material
Coprolites are trace fossils
Important source of information
related to the feeding habits of extinct animals
May contain evidence of coprophagy
(see Figure 9.7)
Late Cretaceous hadrosaurid coprolite with dung-beetle traces
Pseudocoprolites – inorganically
formed deposits that superficially resemble coprolites
Things to look for
Relative flattening
Water content
Height of animal
Size
Large coprolites imply large animal
Small coprolites generally imply small animals, but not always, and small coprolites sometimes will
be merged into a larger mass
Surface features
Folding of lower intestines
Coprolite contents
Plant material or bones are convincing evidence for coprolites
Two examples of tyrannosaurid
coprolites
Both from the Late Cretaceous of
Alberta in tyrannosaurid bearing strata
Both are large - 44-cm and 64-cm long
One has numerous small bone fragments
of a juvenile hadrosaurid
The other has 3-d impressions of
muscle tissue and finely ground bone
Taphonomy of Coprolites
Rapid phosphatization increases
chance of preservation
Especially prevalent for theropod
coprolites
Bone or tooth dahllite serves as nucleation sites for phosphatization
Rapid burial increases chance of
preservation
Especially good in “aqueous”
environments like floodplains, watering holes, and lake or estuary margins