Chapter 11 Outline
INTRODUCTION TO SAUROPODOMORPHS (LIZARD FOOT FORM)
- MANY BIG! SAUROPODOMORPHS, ESPECIALLY SAURPODS
- LONG NECK
- System of girders and air pockets to maximize lightness and strength
- RELATIVELY SMALL HEAD
- Simple peglike or spatulate teeth
- Nostrils tend to migrate toward the top of the head
- PILLAR-LIKE LEGS MADE OF DENSER BONE THAN FOUND IN UPPER PARTS OF SKELETON
- UP TO 40 METERS IN LENGTH & SIX METERS AT THE SHOULDER; UP TO 75,000
KILOGRAMS
- GEOLOGICAL RANGE & DIVERSITY
- LATE TRIASSIC TO LATE CRETACEOUS (~220 - 65 MILLION YEARS)
- MAXIMUM DIVERSITY - AT LEAST 17 GENERA DURING THE LATE JURASSIC (A
LITTLE OVER A QUARTER OF THE GENERA)
- At least 65 genera (more than 100 species) throughout their
time on earth
- FOUND ON ALL CONTINENTS
HISTORY OF SAUROPODOMORPH DISCOVERIES
- 19TH CENTURY
- EUROPE (1830'S; 1840'S; 1870'S)
- Plateosaurus from Late Triassic beds in Germany
- Hypselosaurus from Late Cretaceous beds in southern
France
- Two other genera (Prosauropod & Sauropod) from Late Triassic
to Middle Jurassic beds
- NORTH AMERICA (1870'S; 1880'S, 1890'S)
- Camarasaurus , Apatosaurus & Diplodocus
from Late Jurassic Morrison Formation
- Two prosauropod genera from Early Jurassic beds of New England
- ASIA (1870'S)
- Titanosaurus from Cretaceous beds in India
- 20TH CENTURY
- NORTH AMERICA
- Brachiosaurus & Barosaurus
from Late Jurassic Morrison Formation (1900'S)
- Alamosaurus from Late Cretaceous beds in New Mexico
(1920's or 1930's)
- Ultrasauros , Supersaurus & Seismosaurus
and one other sauropod genus from Late Jurassic Morrison Formation
(1980's, 1990's)
- ASIA
- Mamenchisaurus & three other genera
(Prosauropod & Sauropod) from Early & Late Jurassic beds in
China (1930's, 1940's, 1950's)
- Two sauropod genera from Late Cretaceous beds in Mongolia (1960's,
1970's, 1980's)
- One sauropod genus from Early Jurassic beds in India (1960's,
1970's, 1980's)
- Four sauropod genera from Middle Jurassic and Late Cretaceous beds
in Mongolia & China (1980's, 1990's)
- AFRICA
- Brachiosaurus , Barosaurus & 2 other sauropod
genera from Late Jurassic beds at Tendaguru in Tanzania (1907-1912)
- ALSO FOUND IN NORTH AMERICA (see above)
- One sauropod genus from Early Jurassic beds in Zimbabwe (1960's,
1970's, 1980's)
- SOUTH AMERICA
- Coloradisaurus / Mussaurus ,
Saltosaurus & four other genera (Prosauropod & Sauropod)
from Late Triassic to Late Cretaceous beds in Argentina (1960's,
1970's, 1980's)
- Amargasaurus & one other sauropod genus from mid-to-Late
Cretaceous beds in Argentina (1990's)
- NOTE: THIS IS LESS THAN 60% OF THE GENERA LISTED IN YOUR TEXT (INCLUDING
CHAPTER 11 AFTER THE "HISTORY OF SAUROPODOMORPH DISCOVERIES"
SECTION & IN CHAPTER 15)
SAUROPODOMORPH DIVERSITY
- SEVERAL CLADES OF SAUROPODOMORPHS
- PROSAUROPODA
- LATE TRIASSIC TO EARLY JURASSIC HERBIVOROUS DINOSAURS, WITH SMALL HEADS,
LONG NECKS & LARGE BODIES
- Mostly facultatively bipedal
- Range from 2.5 to 11 meter in length
- Simple serrated teeth
- PLATEOSAURUS , COLORADISAURUS / MUSSAURUS &
AT LEAST 10 OTHER GENERA WITH A WORLD-WIDE DISTRIBUTION
- PROBABLY NOT ANCESTRAL TO SAUROPODS
- SAUROPODA - ALL OTHER SAUROPODOMORPHS; DIVIDED INTO
SEVERAL CLADES, INCLUDING BASAL FORMS, "CETIOSAURIDS"
AND CAMAROSAURS & TITANOSAURS
- MEDIUM TO HUGE QUADRUPEDAL HERBIVOUROUS DINOSAURS, WITH THE SMALLEST
ABOUT 6 METERS LONG AND THE LARGEST 40 METERS LONG, IN EXISTENCE FROM THE
EARLY JURASSIC TO THE LATE CRETACEOUS
- Spatulate to pencil-like teeth
- CAMAROSAURS
- LARGE CLADE IN EXISTENCE FROM THE LATE JURASSIC TO THE LATE CRETACEOUS
- CONSISTS OF TWO CLADES: CAMARASAURIDAE & BRACHIOSAURIDAE
- CAMARASAURIDAE
- SAUROPODS WITH SHORT, HIGH AND POWERFULLY BUILT HEADS
- CAMARASAURUS & MANY OTHER GENERA
- BRACHIOSAURIDAE
- AMONG THE LARGEST SAUROPODS, WITH ELONGATE FORELIMBS AND NOSTRILS ON
TOP OF THE HEAD, & IN EXISTENCE ONLY DURING THE LATE JURASSIC
- BRACHIOSAURUS , ULTRASAUROS & SUPERSAURUS
& A FEW OTHER GENERA
- Brachiosaurus found at Tendaguru in Tanzania & in the
Morrison Formation
- TITANOSAURS
- LARGE CLADE IN EXISTENCE FROM THE LATE JURASSIC TO THE LATE CRETACEOUS
- CONSISTS OF TWO CLADES: DIPLODOCIDAE & TITANOSAURIDAE
- DIPLODOSAURIDAE
- HUGE SAUROPODS WITH LONG NECKS & TAILS AND SMALL HEADS, & BUILT
LIKE SUSPENSION BRIDGES
- DIPLODOCUS , APATOSAURUS , BAROSAURUS , MAMENCHISAURUS
, SEISMOSAURUS & AMARGASAURUS AND MANY OTHER GENERA
- Mamenchisaurus has an incredibly long neck - more than half
of its 22 meter body length
- Armargasaurus has incredibly long spines on its neck vertebrae
- Barosaurus found at Tendaguru in Tanzania & in the Morrison
Formation
- TITANOSAURIDAE
- AMONG THE POOREST KNOWN SAUROPODS, FOUND IN CRETACEOUS (PARTICULARLY
LATE CRETACEOUS) STRATA, MOSTLY IN PARTS OF THE FORMER GONDWANA (SOUTHERN)
CONTINENTS, BUT ALSO FOUND IN EUROPE AND NORTH AMERICA
- TITANOSAURUS , ALAMOSAURUS , & SALTOSAURUS
& A FEW OTHER GENERA
- Alamosaurus is perhaps the best known Titanosaurid - a quarter
of an articulated skeleton has been recovered
- ALAMOSAURUS MIGRATED TO NORTH AMERICA FROM SOUTH AMERICA
IN THE LATE CRETACEOUS
- Saltosaurus was covered with a pavement of nodular and buttonlike
osteoderms
SAUROPODOMORPH PALEOBIOLOGY AND PALEOECOLOGY
- DISTIBUTION AND PRESERVATION
- SAUROPODOMORPHS ARE FOUND FROM THE VERY BEGINNING OF DINOSAUR HISTORY
IN THE LATE TRIASSIC UNTIL THE CLOSE OF THE CRETACEOUS
- HOWEVER, THE FOSSIL RECORD OF INDIVIDUAL SAUROPODOMORPHS IS QUITE POOR
- A few basal forms are known form complete skeletons
- Most other Sauropodomorphs are known only from incompletely preserved
material, often missing their heads, parts of their tails,
and their feet
- This probably results from the fact that Sauropodomorphs are so
big that it is difficult to bury them
- HABITS
- SAUROPODOMORPHS ARE FOUND, AND PRESUMABLY LIVED, IN A MYRIAD OF SEDIMENTARY
DEPOSITIONAL ENVIRONMENTS
- Lakes, rivers (floodplain & channel deposits contain remains)
and even eolian environments
- Well studied in Late Jurassic Morrison Formation of the western
U.S.
- STUDIES OF THE MORRISON INDICATE THAT SAUROPODS HERE HAD TO DEAL WITH
SEASONAL DRYNESS & MAY HAVE HAD TO MIGRATE TO MORE LUSH ENVIRONMENTS
- STUDIES IN TENDAGURU, TEXAS & MARYLAND, HOWEVER, INDICATE A SHORELINE
SETTING AND MORE HUMID YEAR-ROUND CONDITONS
- SAUROPODS DID NOT LIVE SUBMERGED IN DEEP LAKES OR RIVERS TO BUOY UP
THEIR HUGE BULK AS SUGGESTED BY THEIR LONG NECKS AND NOSTRILS ON TOP OF
THEIR HEADS
- The lungs of a sauropod under up to 6 meters of water would experience
pressures up close to 2 atmospheres and the animal would not be able to
breath
- Bakker pointed out the the sturdy, pillarlike legs were designed
for walking and that sauropods torsos were narrow and slab-sided, unlike
hippos but like rhinos and elephants
- The long necks would have been used to forage high in trees
- SAUROPODS LIKE BRACHIOSAURUS WOULD HAVE HAD HIGH BLOOD PRESSURE TO
GET BLOOD TO THEIR BRAINS MORE THAN 8 METERS ABOVE THEIR HEARTS
- Humans & most other large mammals have blood pressures of about
110 to 150 mm of mercury; giraffes have blood pressures of about
320 mm of mercury; blood pressure in Brachiosaurus would
have been 629 mm of mercury
- DIPLODOCIDS, IN CONTRAST, MAY HAVE HELD THEIR HEADS IN A MORE HORIZONTAL
CONFIGURATION (THEIR FORELIMBS WERE MUCH SHORTER THAN THEIR HINDLIMBS),
REQUIRING LOWER BLOOD PRESSURES
- In this case they would have foraged on low growing vegetation with
huge horizontal sweeps of their necks
- However, they might still have reared up during intraspecific
combat, while defending themselves from predatory dinosaurs,
during mating, and if they assumed a tripod position for high
foraging (as assumed by Stegosaurids), all cases requiring high
blood pressures as for the Brachiosaurids
- Rearing up would have been facilitated by strong, taut ligaments
laying between bifurcations in the neural spines of their neck & body
vertebrae
- SAUROPODOMORPHS MAY HAVE HAD UNIDIRECTIONAL AIRFLOW IN THEIR LUNGS
& THROUGH A SERIES OF AIRSACS, LIKE BIRDS, WHICH WOULD HAVE INCREASED
THE EFFICIENCY OF OXYGEN ABSORPTION TO 40%
- Other animals like mammals & reptiles have bidirectional airflow
into deadend lungs, limiting efficiency of oxygen absortion to 20%
- Sauropods had pneumatic openings in their bones to hold air sacs
- FEEDING
- SAUROPODOMORPHS WERE NOT GREAT CHEWERS - GENERALLY THEY HAD WEAK JAW
MUSCLES IN THEIR SMALL HEADS AND THEIR TEETH HAD SIMPLE CROWNS THAT WERE
LEAF-SHAPED (IN PROSAUROPODS), SPATULATE (IN BASAL SAUROPODS), OR SLENDER
& PENCIL-SHAPED (IN CAMARASAURS & TITANOSAURS)
- There is a tendency to limit teeth to the front of the mouth
- Sauropodomorphs did not have the full dental arcades or batteries
seen in other dinosaurian herbivores
- BASICALLY, SAUROPODOMORPHS NIPPED OR STRIPPED OFF VEGETATION AND DELIVERED
A BOLUS OF FOLIAGE TO THE GULLET WITHOUT MUCH MODIFICATION IN THE MOUTH
- AT LEAST SOME SAUROPODOMORPHS ( SEISMOSAURUS , PLATEOSAURUS
) HAD GIZZARDS FILLED WITH STONES FOR MECHANICALLY BREAKING FOOD DOWN PRIOR
TO MOVEMENT FURTHER ALONG THE GASTROINTESTINAL TRACT
- SAUROPODOMORPHS HAD LARGE GUTS THAT PROBABLY HOUSED FERMENTATION CHAMBERS
- Sauropodomorphs were probably constant eaters
- SAUROPODOMORPHS WERE HIGH BROWSERS, FROM 3 METERS TO 4 OR 5 STORIES
- LOCOMOTION
- MOST PROSAUROPODS WERE BIPEDAL, ALTHOUGH A COUPLE OF GENERA WERE FULLY
QUADRUPEDAL AND ALL SAUROPODS WERE FULLY QUADRUPEDAL
- Prosauropod trackways all show quadrupedal locomotion, however
- Sauropod trackways show no evidence of tail-drag marks, indicating
that sauropods carried their tails clear of the ground
- SPEED
- Prosauropods were slow - probably no more than 5 kmh
(3 mph)
- Sauropods were quicker - maximum speeds of 20-30 kmh
(12.5-19 mph) & walking speeds were 20-40 km per day (12.5-25
miles per day)
- SOCIAL BEHAVIOUR
- MANY SAUROPODOMORPHS LIVED IN HERDS THAT MIGRATED LARGE DISTANCES
- Plateosaurus bone bed in Trossingen, Germany
- Mass accumulations and extensive trackways for sauropods have been
found in the U.S., Tanzania, India and China
- Migration required if large sauropod herds wreaked severe damage
on local vegetation by stripping or trampling
- SOME SAUROPODS, LIKE BRACHIOSAURUS , APPARENTLY DIDN'T LIVE
IN HERDS & ARE LESS NUMEROUS
- DEFENSE
- Large size
- Herding behaviour to protect young & for smaller prosauropods
- Thumb claw
- SAUROPODOMORPH GROWTH AND DEVELOPMENT
- MATING BETWEEN TRIPODAL MALE AND QUADRUPEDAL FEMALE
- NO DEFINITE EGGS FOR PROSAUROPODS
- A nest of six eggs from the Early Jurassic of South Africa may have
been laid by a Prosauropod, however
- Mussaurus is probably the hatchling for Coloradisaurus
- DEFINITE EGGS FOR SAUROPODS
- Hypselosaurus is associated with nearly spherical eggs laid
in linear pairs & probably covered with mounds of vegetation
- Eggs from Mongolia and India may have been laid by unspecified Sauropods
- SAUROPODOMORPHS PROBABLY GREW SLOWLY AND EPISODICALLY, TAKING 20 YEARS
FOR A SAUROPODOMORPH TO REACH SEXUAL MATURITY
- SAUROPODOMORPHS MAY HAVE HAD LIFE SPANS ON THE ORDER OF 100 YEARS