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
        
        

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