Chapter 10 Outline
INTRODUCTION TO ORNITHOPODA (BIRD FOOT)
- WIDE RANGE OF CHARACTERISTICS AMONG DIFFERENT GROUPS
- RHAMOTHECAE COMMON TO ALL
- IMPRESSIVE TEETH (FROM CHISELS TO DENTAL BATTERIES) FOR CHEWING PLANT
MATERIAL
- QUADRUPEDAL (FACULTATIVE) LIMB POSTURE AMONG LATER, LARGER ORNITHOPODS
- Bipedal stance for earlier, smaller Ornithopods
- FORELIMBS SHORTER THAN HINDLIMBS
- Toes & some fingers ended in hooves in later, larger
Ornithopods
- Toes & fingers clawed in earlier, smaller Ornithopods
- BASAL IGUANODONTIANS HAD SPIKES FOR THUMBS!
- NESTS, EGGS AND EMBRYOES, HATCHLINGS, JUVENILES, & ADOLESCENTS
FOUND FOR LATER, LARGER ORNITHOPODS
- ARRAY OF BIZARRE CRESTED FORMS
- FOUR TO THIRTEEN METERS IN LENGTH; UP TO 3000 KILOGRAMS (LARGER ORNITHOPODS)
- Smaller Ornithopods were 1 to 4 meters long
- GEOLOGICAL RANGE & DIVERSITY
- EARLY JURASSIC TO LATE CRETACEOUS (~200 - 65 MILLION YEARS)
- MAXIMUM DIVERSITY - 33 GENERA DURING THE LATE CRETACEOUS
- At least 55 genera (more than 80 species) throughout their
time on earth
- FOUND ON ALL CONTINENTS (MOSTLY NORTH AMERICA & ASIA)
HISTORY OF ORNITHOPOD DISCOVERIES
- 19TH CENTURY
- EUROPE
- Iguanodon - one of the three original members of
Owen's Dinosauria
- FOUND IN 1822 BY GIDEON & MARY ANN MANTELL; NAMED IN 1825; LATE
JURASSIC TO EARLY CRETACEOUS IN AGE
- 31 COMPLETE SKELETONS FOUND IN BERNISSART, BELGIUM IN 1878, & DESCRIBED
BY L. DOLLO
- Hypsilophodon (1869)
- DESCRIBED BY T. H. HUXLEY & P. MATHERON; EARLY CRETACEOUS IN AGE
- Two other genera (Iguanodont) from Late Cretaceous beds
(1860's, 1880's)
- NORTH AMERICA
- Hadrosaurus from Late Cretaceous beds of New
Jersey! (1858)
- Dryosaurus from Late Jurassic beds of the Western Interior
of U.S. (1894)
- ALSO LATER FOUND IN TANZANIA
- Two other genera (Iguanodont & Hadrosaurid) from Late
Jurassic beds of Wyoming and Late Cretaceous beds of Kansas (1870's,
1880's)
- 20TH CENTURY
- EUROPE (1900, 1960'S)
- Two genera (Iguanodont & Hadrosaurid) from Early and
Late Cretaceous beds
- ONE GENUS FOUND IN NIGER AS WELL
- NORTH AMERICA
- Lambeosaurus , Corythosaurus ,
Parasaurolophus & Hypacrosaurus (Lambeosaurine);
Saurolophus , Gryposaurus & 3 other
genera (Hadrosaurine); and one Hypsilophodontid genus from Late
Cretaceous beds in Canada (1912-1923, 1937, 1953)
- Maiasaura , Orodromeus & Anatotitan from
Late Cretaceous beds, and 2 other genera (Iguanodont & Hypsilophodontid)
from Early Cretaceous beds in Montana (1979-1990)
- Three genera (Hadrosaurid) from Late Cretaceous beds in New
Mexico and two genera (Hypsilophodontid) from Late Jurassic and
Late Cretaceous beds of Wyoming (1910's, 1990's)
- One genus (Hadrosaurine) from Late Cretaceous beds in Alabama!
and one genus (Hypsilophodontid) from Late Jurassic beds of the
Western Interior of U.S. (1950's, 1960's)
- ASIA
- Seven genera (Lambeosaurine, Hadrosaurine, Hadrosaurid, Hypsilophodontid)
from Late Cretaceous beds and three genera (Iguanodont & Hypsilophodontid)
from Middle Jurassic, Late Jurassic & Early Cretaceous beds in Mongolia
& China (1929, 1933, 1958, 1966, 1970's, 1980's, 1990)
- Two genera (Hadrosaurine & Hadrosaurid) from Late Cretaceous
beds in Kazakhstan (1939, 1968)
- One genus (Hadrosaurid) from Late Cretaceous beds in Japan
(1936)
- AFRICA
- Heterodontosaurus & 3 other genera (Heterodontodaurid)
from Early Jurassic beds in South Africa (1924, 1962, 1975)
- Ouranosaurus from Early Cretaceous beds in Nigeria (1976)
- Dryosaurus described from Late Jurassic Tendaguru beds in
Tanzania (1955)
- One genus from Early Cretaceous beds in Niger (see above for
Europe)
- AUSTRALIA
- Four genera (Iguanodont & Hypsilophodontid) from Early
Cretaceous beds (1980's)
- SOUTH AMERICA
- One genus (Hadrosaurid) from Late Cretaceous beds in Argentina
(1979)
ORNITHOPOD DIVERSITY
- SEVERAL CLADES OF ORNITHOPODS
- HETERODONTOSAURIDAE
- EARLY JURASSIC BIPEDAL DINOSAURS, ABOUT 1-2 M LONG
- HETERODONTOSAURUS & 3 OTHER GENERA FROM SOUTH AFRICA
- NAME COMES FROM CANINE-LIKE TEETH AT FRONT OF MOUTH
- Otherwise teeth are high-crowned & chisel-shaped
- EUORNITHOPODA - ALL OTHER ORNITHOPODS; DIVIDED INTO SEVERAL CLADES
- HYPSILOPHODONTIDAE
- SMALL TO MEDIUM BIPEDAL DINOSAURS, ABOUT 2-4 M LONG, IN EXISTENCE FROM
THE MIDDLE JURASSIC TO THE LATE CRETACEOUS
- HYPSILOPHODON , ORODROMEUS & 12 OTHER GENERA
- IGUANODONTIA
- LARGE FACULTATIVE QUADRUPEDAL DINOSAURS, 4-13 M LONG, IN EXISTENCE
FROM THE LATE JURASSIC TO THE LATE CRETACEOUS
- CONSISTS OF BASAL FORMS LIKE IGUANODON , DRYOSAURUS
& OURANOSAURUS PLUS THE VERY DIVERSE HADROSAURIDAE
- HADROSAURIDAE
- "DUCK-BILLED" DINOSAURS, IN EXISTENCE ONLY IN THE LATE CRETACEOUS,
& COMPRISING ONE-HALF OF ORNITHOPOD GENERA (AT LEAST 28)
- DIVIDED INTO HADROSAURINAE & LAMBEOSAURINAE
- HADROSAURINAE
- FLAT-HEADED HADROSAURS & THOSE WITH SOLID BONE CRESTS, INCLUDING
MAIASAURA , GRYPOSAURUS , ANATOTITAN & SAUROLOPHUS
& POSSIBLY HADROSAURUS
- LAMBEOSAURINAE
- HOLLOW-CRESTED HADROSAURS, INCLUDING LAMBEOSAURUS , CORYTHOSAURUS
, PARASAUROLOPHUS & HYPACROSAURUS
ORNITHOPOD PALEOBIOLOGY AND PALEOECOLOGY
- GEOGRAPHY
- ORNITHOPODS ARE FOUND FROM THE PALEOEQUATOR TO HIGH-PALEOLATITUDES
LIKE THE NORTH SLOPE OF ALASKA AND SEYMOUR ISLAND, ANTARCTICA
- Heterodontosaurids are found in semi-arid paleoenvironments
- Most other ornithopods found in paleoenvironments ranging from coastal
plain to fluvial to near-marine deltas
- HORNER REPORTS HABITAT PARTITIONING FOR ORNITHOPODS OF WESTERN NORTH
AMERICA
- Many hadrosaurines are found in near-marine, deltaic sediments
- Lambeosaurines are found in inland lower coastal plain sediments
- Maiasaura is found only in upper coastal plain
sediments
- HABITS
- BIPEDALISM VS QUADRUPEDALISM
- Ornithopods were primarily bipedal terrestrial animals
- HINDLIMBS TEND TO BE AT LEAST, AND SOMETIMES MORE THAN, TWICE THE LENGTH
OF FORELIMBS
- HETERODONTOSAURIDS, HYPSILOPHODONTIDS AND SOME IGUANODONTIANS MUST
HAVE BEEN PRIMARILY BIPEDAL, ALTHOUGH THEY ALSO MAY HAVE ADOPTED A QUADRUPEDAL
STANCE WHEN FORAGING OR STANDING STILL
- SOME OF THE LARGER ORNITHOPODS MAY HAVE ENGAGED IN EXTENSIVE QUADRUPEDAL
LOCOMOTION - THEY HAD SOLIDLY BUILT HANDS
- Juveniles may have been more bipedal than adults because limb elements
change proportion with age
- Ornithopod tails were long, muscular, strengthened by ossified tendons
and held at or near horizontal, making an excellent couterbalannce for
the front of the animal were primarily bipedal terrestrial animals
- SPEED
- Larger ornithopods were not as fast as smaller ornithopods
- LARGER ORNITHOPODS MAY HAVE REACHED 15-20 KPH (9-12.5 MPH) DURING SUSTAINED
RUNNING, WITH SPEEDS UP TO 50 KPH (31 MPH) DURING SHORT BURSTS
- Probably didn't gallop - vertebral column rigid, shoulder lacked movement
against the rib cage and sternum
- SMALLER ORNITHOPODS RAN FASTER WITH MAXIMUM SPEEDS OF 60 KPH (37.5
MPH)
- INTELLIGENCE
- Ornithopods were as smart or smarter than expected
- EQ AVERAGES 1.5
- MAY RELATE TO GREATER RELIANCE ON ACUTE SENSES FOR PROTECTION AND TO
A COMPLEX BEHAVIOR
- HANDS AND FOREARMS
- Heterodontosaurus may have used powerful forelimbs and clawed
hands to grab at vegetation or dig up roots and tubers
- Hypsilophodontids had less powerful forelimbs and hands than Heterodontosaurids
or Iguanodontians but the hands were free to grasp vegetation and bring
foliage closer to the mouth
- Iguanodon , Ouranosaurus & one other genus had
extraordinary hands
- THE THUMB WAS CONICAL AND SHARPLY SPIKED, AND MAY HAVE BEEN USED AS
A STILETTO-LIKE, CLOSE-RANGE WEAPON OR USED FOR BREAKING INTO SEEDS AND
FRUIT
- THE PINKIE WAS FULLY OPPOSABLE AND COULD FOLD AGAINST THE PALM OF THE
HAND
- THE REMAINING THREE DIGITS WERE ALL HOOFED
- Hadrosaurids had reduced hands, with three hoofed digits joined
together in a thickened pad and used for support while the animal was standing
- FEEDING & FOOD
- ORNITHOPOD MUMMIES
- Stomach contents, in addition to skin and dried, stretched
tendons & muscles, have been preserved
- TWIGS, BERRIES AND COARSE PLANT MATTER
- ORNITHOPODS WERE ACTIVE FORAGERS ON GROUND COVER, LOW-LEVEL CONIFER
FOLIAGE, AND FROM DECIDUOUS SHRUBS AND TREES OF NEWLY EVOLVED ANGIOSPERMS
- Browsing apparently was concentrated within the first meter or two,
but larger ornithopods would have been able to reach as high as four meters
above the ground
- ORNITHOPODS HAD GREAT MOUTHS FOR EATING VEGETATION
- A beak for cropping vegetation
- A well-developed dental battery for grinding coarse plant material
- A large, robust coronoid process for serious masticatory
muscles
- Fleshy cheeks
- HETERODONTOSAURIDS AND HYPSILOPHODONTIDS HAD TEETH UNDER THEIR SHARP
BEAKS & PROBABLY HAD SELECTIVE CROPPING ABILITY
- IGUANODONTIANS HAD NO FRONT TEETH, A BROAD SNOUT & A STRONLY SERRATE
MARGIN TO THEIR RHAMOTHECAE, INDICATING THAT THEY WERE NOT SELECTIVE FEEDRS,
BUT INSTEAD, JUST CROPPED WHATEVER THEY COULD GET AT
- ORNITHOPOD CHEWING PATTERNS
- Ostrom suggested in 1961 that Hadrosaurids chewed back to front
(using propalinal jaw movement) on both sides of the mouth at the same
time; Thulborn suggested a similar pattern for Heterodontosaurids
- Galton suggested that Hypsilophodon chewed with a side-to-side jaw
movement, on one side of the mouth at a time (like mammals)
- Recent work shows that Euornithopodans and Heterodontosaurids did
not use propalinal or side-to-side jaw movement, but had distinctive, and
different, chewing patterns that nevertheless resulted in sideways movement
of the upper teeth against the lower teeth
- HETERODONTOSAURIDS CHEWED BY COMBINING VERTICAL LOWER JAW MOVEMENT
WITH A SLIGHT ROTATION OF THE MANDIBLES ABOUT THEIR LONG AXES
- EUORNITHOPODANS HAD MOBILITY OF THEIR UPPER JAWS (PLEUROKENESIS), PARTICULARLY
THE MAXILLARY, AS WELL AS THE LOWER JAW - WHEN THE UPPER AND LOWER TEETH
WERE BROUGHT INTO CONTACT ON BOTH SIDES, THE UPPER JAWS ROTATED OUTWARD,
THE LOWER JAWS MOVED INWARD, AND THE OPPOSING SURFACES OF THE TEETH SHEARED
PAST ONE ANOTHER
- ORNITHOPODS APPARENTLY EMPLOYED FEMENTATION IN THEIR INTERNAL DIGESTIVE
TRACT, BASED ON THE LARGE VOLUME OF THE GUT
- HEAD STRUCTURES & BEHAVIOUR
- ODD-APPEARING HEAD ORNAMENTATION (CRESTS ON HADROSAURIDS, HETERODONTOSAURID
TUSKS, AND OURANOSAURUS BUMPS) SUGGEST SOPHISTICATED SOCIAL BEHAVIOUR
FOR ORNITHOPODS
- HADROSAURID HEADGEAR
- Originally thought to relate to aquatic habits or olfactory functions
- Now thought to relate to combat and display functions as part of
reproductive behaviour
- HOPSON IN 1975 SUGGESTED THAT UNUSUAL CRANIAL FEATURES - PRINCIPALLY
INVOLVING THE NASAL CAVITY - EVOLVED AS VISUAL AND VOCAL SIGNALS TO CONVEY
INFORMATION ABOUT WHAT SPECIES, WHAT SEX, AND EVEN WHAT RANK AN INDIVIDUAL
MIGHT BE
- HE MADE 5 SPECIFIC PREDICTIONS THAT HAVE BEEN SUPPORTED BY FOSSIL EVIDENCE:
- 1) LARGE EYE SOCKETS AND MIDDLE & INNER EAR STRUCTURES INDICATE
THAT HADROSAURIDS HAD GOOD VISION & HEARING TO INTERPRET INCOMING DISPLAY
INFORMATION
- 2) THE EXTERNAL SHAPES OF CRESTS, WHICH ARE MORE ELABORATE AND EXTENSIVE
THAN THE INTERNAL WALLS OF THE CREST, ARE APPARENTLY AS IMPORTANT AS THE
INTERNAL STRUCTURE, INDICATING THAT THE CREST FUNCTIONED AS A VISUAL DISPLAY,
AS WELL AS A VOCAL RESONATOR
- 3) FOR LAMBEOSAURINES CRESTS BECOME MORE PROMINENT AS AN ANIMAL APPROACHED
SEXUAL MATURITY AND EXHIBIT SEXUAL DIMORPHISM
- 4) CRESTS ARE MORE ELABORATE AND DISTINCTIVE WHERE SEVERAL HADROSAURID
SPECIES COEXISTED
- For example, at Alberta's Dinosaur Provincial Park, there are three
lambeosaurines (Parasaurolophus, Lambeosaurus & Corythosaurus
) & three distinctive hadrosaurines
- 5) PARTIAL SUPPORT FOR THE PREDICTION THAT CRESTS SHOULD BECOME MORE
DISTINCTIVE WITH TIME
- Evolution of hadrosaurid headgear
- ACCENTUATED NASAL ARCH AND STOUT CRANIAL CREST IN GRYPOSAURUS
AND MAIASAURA (& OTHERS) LIKELY USED FOR BROADSIDE- OR HEAD-PUSHING
IN MALE-MALE COMBAT
- INFLATABLE FLAPS OF SKIN MAY HAVE COVERED THEIR NOSTILS AND SURROUNDING
REGIONS, TO MAKE A VISIBLE DISPLAY AND NOISE WHEN BLOWN UP
- IN SAUROLOPHUS (& OTHERS) THIS SAC WOULD HAVE EXTENDED
ONTO THE SOLID CREST ABOVE THE EYES
- IN ANATOTITAN (& OTHERS) THIS SAC MAY HAVE BEEN HOUSED
IN THE COMPLEXLY EXCAVATED NOSTRIL REGION (THESE HADROSAURIDS DID NOT HAVE
AN ACCENTUATED NASAL ARCH OR CREST)
- LAMBEOSAURINES DEVELOPED HOLLOW CRESTS THAT WOULD HAVE PROVIDED EXCELLENT
VISUAL AS WELL AS AURAL RECOGNITION
- OTHER ORNITHOPODS
- Canine-like teeth of Heterodontosaurids may have something to do
with intraspecific display and combat for social ranking and courtship
- THESE TEETH ARE PRESENT ONLY IN MATURE "MALES"
- Low, broad bumps on top of the head of Ouranosaurus may have
similar behavioural significance
- OURANOSAURUS , LIKE STEGOSAURUS , HAD EXTREMELY HIGH
SPINES ON THEIR VETEBRAE, FORMING A SAIL-LIKE RIDGE DOWN THEIR BACKS, POSSIBLY
FOR THERMOREGULATION AND/OR DISPLAY
- IGUANODONTIANS, INCLUDING HADROSAURIDS, LIVED IN LARGE, MIGRATORY HERDS
OF BOTH YOUNGSTERS AND ADULTS (SEVERAL EXAMPLES OF SINGLE-SPECIES BONEBEDS)
THAT REQUIRED COMMUNICATION
- BRINGING UP BABY
- WELL-DOCUMENTED NESTS WITH EGGS IN LARGE NESTING COLONIES FOR MAIASAURA
, HYPACROSAURUS & ORODROMEUS
- Orodromeus nests preserve complete yet hatched eggs
- HATCHLINGS WERE PRECOCIAL (RELATIVELY ADULTLIKE) AND LEFT THE
NEST EARLY
- YOUNG ORODROMEUS APPEAR TO HAVE STAYED IN GROUPS
- Maiasaura & Hypacrosaurus
nests are spaced a mother's body size apart, suggesting that
they were regularly attended by parents
- HATCHLINGS WERE ALTRICIAL (DELAYING MATURATION) AND STAYED IN
THE NEST UNDER PARENTAL CARE FOR MANY MONTHS
- PROBABLY ALL HADROSAURID HATCHLINGS WERE ALTRICIAL
- Precociality probably was ancestral for Euornithopoda, while altriciality
evolved sometime prior to the origin of Hadrosauridae
- R-strategy vs K-strategy
- R-STRATEGY = LOTS OF OFFSPRING, NO PARENTAL CARE, MAJORITY OF OFFSPRING
DON'T SURVIVE
- K-STRATEGY = FEW OFFSPRING, MUCH PARENTAL CARE, MAJORITY OF OFFSPRING
SURVIVE