Lecture 12: Sauropodomorpha

Question 1

Define saurischia

Answer 1

The “lizard-hipped” dinosaurs in most, the pubis projects forward and downward as is primitive for reptiles, Named by H.G. Seeley in 1887, includes the smallest and the largest dinosaurs, all of the carnivorous dinosaurs, plus more herbivores

Question 2

Derived features of saurischia

Answer 2

Subnarial foramen- opening beneath the nostril area
Elongation of the rearward neck vertebrae (resulting in longer neck)
Increased articulations between vertebrae
Robust thumb supported by a broad metacarpal bone
digit II of hand longer than digit III

Question 3

Eoraptor

Answer 3

Small (~1.3m long) bipedal early saurischian from the late triassic of Argentina, intially described in the 1990s as an early theropod. Reinterpreted in the 2010s as a sauropodomorph and shares with other sauropodomorphs skull features to herbivory, thumb claw rotated forward

Question 4

Sauropodomorpha

Answer 4

Sauro-lizard, pod-foot, morpha-foot (feet retained all five digits, as in lizards)
Includes all of the biggest dinosaurs
Weight up to: 75,000 kg
Length: up to 40m
Height up to 6m at the shoulder

Question 5

Survival over 160 million years

Answer 5

Animals of that size test processes such as: 
Weight support
neural circuitry 
Respiration
digestion

Question 6

Prosauropods

Answer 6

Evolutionary radiation in the last triassic, thriving with worldwide distribution in the early jurassic, including Canada (Nova scotia) and even antarctica, extinct in the middle jurassic. probably not a monophyletic group; some were more closely related to sauropods. Small heads, long necks and bulky bodies but most were bipedal, generally smaller than sauropods, the first tall browsing herbivores in Earth’s history

Question 7

_______: a typical prosauropod

Answer 7

Plateosaurus, bonebeds suggest herd living

Question 8

Sauropoda

Answer 8

monophyletic, shortening of the rear portion of skull, lower temporal opening situated partly beneath eye socket, 12-19 neck vertebrae and 4-7 sacral vertebrae, quadrupedal. Massive and vertical limbs and solid long bones. Broad snout with spoon shaped or pencil like teeth at the front of the jaw, loss of overbite, long tail (modified in some species to end in a small club or a very long whip)

Question 9

What did sauropoda evolve from?

Answer 9

Prosauropods in the late triassic, Increased in size and diversity in the jurassic, absent in north america in the late cretaceous but succesful until the end of the cretaceous in most of the world

Question 10

History of discovery

Answer 10

First sauropodomorph species were named from European discoveries in the 1830s and 1840s: thecodontosaurus, plateosaurus.
However, they were NOT among the reptiles included by Richard Owen in his original concept of dinosauria
Sauropods and prosauropods not formally classified together as sauropdomorpha until 1930s

Question 11

North American Discoveries

Answer 11

New chapter in sauropod research began in 1870s by cope and Marsh. Most prolific source is the Morrison formation, late jurassic, western USA. continues with new sauropods from this formation still recently being named Suuwassea (2004) , kaatedocus (2013). NO sauropod body fossils yet from Canada, but footprints recently found in BC

Question 12

Camarasaurus

Answer 12

Most common sauropod in North America, 18m long body, head high, short and powerful, teeth not restricted to front jaws

Question 13

Diplodocus

Answer 13

27m long, nostril opening far back on skull, elongate snout, pencil-like teeth at the front jaws only, long drawn out tail with 80 vertebrae acting as whip

Question 14

Neck vertebrae in _________ with Y shaped neural arches

holding a ligament called nuchal ligament

Answer 14

Diplodocus

Question 15

Seismosaurus

Answer 15

named in the early 1990s, may be a very large individual of diplodocus

Question 16

Sauropods worldwide

Answer 16

Tendaguru hills in Tanzania, Major expedition by E. Fraas and Werner Janensch, 1907 500 local workers

Question 17

size of expedition

Answer 17

225000 man days, over 100 articulated skeletons, hundreds of isolated bones, 4300 jackets to be carried to port city, 5400 walks each one four days, specimens shipped to Berlin, new late jurassic sauropods

Question 18

Giraffatitan=

Answer 18

one of the tallest sauropods, on display in Berlin from Tendaguru

Question 19

Rebbachisaurids=

Answer 19

Bizarre early late cretaceous diplocoids of South America , Africa and Europe: most are recently discovered

Question 20

Nigersaurus is specialized for

Answer 20

low feeding with dental battery at the front of the snout (not seen in typical sauropods) but skull is extremely lightly built. Highest rate of tooth replacement for dinosaurs: individual teeth lasted as short as two weeks

Question 21

Titanosauria

Answer 21

Very succesful clade, the only sauropods at the end of the late cretaceous. wide heavy bodies, more flexbile vertebral articulations, some of them had osteoderms. Huge range of body size: some titanosaurs were relatively small sauropods, others were among the largest that ever lived

Question 22

Yonginglong, a titanosaur from the early cretaceous of ______ published in early 2014, one of many recent sauropod discoveries

Answer 22

China

Question 23

Taphonomy

Answer 23

Most skeletons are incomplete: bodies too big to be rapidly buried, most skulls are missing, some late cretaceous monoglian sauropods are known only from their skulls (nemegtosaurus)

Question 24

Habitats

Answer 24

Wide geographic distribution, different habitats (fine grained floodplains, channels, eolian sandstones, lakes, rivers. Many represented in the morrison formation, jurassic of western USA

Question 25

Migration

Answer 25

western interior was seasonally dry during jurassic, sauropods responded with migration to lusher areas, trackways

Question 26

Did they live in deep water??

Answer 26

Early hypothesis: too big to live on land? body to heavy to be supported therefore needing buoyancy of water? breathing like whales? long tails used for swimming?

Question 27

Arguments against the deep water theory

Answer 27

Air pressure: animals breathe air at 1 atmosphere of pressure, in water pressure increases by 1 atmosphere every 9.8m, lungs of sauropods would have collapsed, air sacs in bones would make sauropods float like corks

Question 28

diplocidae

Answer 28

shorter forelimbs, most of weight supported by hindlimbs

Question 29

brachiosauridae

Answer 29

long forelimbs

Question 30

Blood pressure

Answer 30

Distance between heart and brain is huge, heart has to pump blood high to prevent fainting, blood pressure of humans: 120/70, brachiosaurus 8.5m long neck, blood pressure at about 620 for the high value; giraffe has about 320

Question 31

Heart Size

Answer 31

Very large muscular heart, estimated up to 400kg, other anatomical features, one way valve to prevent backflow, undirectional avian style respiration where air sacs support lungs to pump air

Question 32

Posture

Answer 32

Head up in the air requires high blood pressure, tripodal posture: lifting up forelimbs, using the tail for third leg

Question 33

Oxygen Exchange

Answer 33

Oxygen has to be transported to lungs through the wind pipe (trachea) for exchange with carbon dioxide

Question 34

Mammals

Answer 34

Mammals: not very efficiemt only 20% of air makes it to the lungs for exchange, bidirectional airflow, air remains within the trachea, birds: about 40% exchanged, unidirectional airflow

Question 35

The respiration system of birds

Answer 35

Air sacs accomodated in hollow cavities of bones, some sauropods have cavities in backbone

Question 36

Oxygen exchange in sauropods

Answer 36

Giraffes have narrow tracheas to limit dead air space, giraffes are at the limit with length of neck for mammals, sauropods surpassed them

Question 37

Food

Answer 37

Triassic: ferns, seed plants, cycads, ginkgoes
Jurassic: conifers, less ginkgoes, ferns and horsetails
cretaceous: conifers or angiosperms
Fossil plants found with sauropod remains
diversity of skull and tooth types suggests diversity of feeding strategies

Question 38

Social behavior

Answer 38

trackways and large bonebeds, gregarious, large impact on environment, migration in search of food

Question 39

Trackways

Answer 39

Found in north and south america, europe, asia and Africa, narrow & huge, horseshoe shaped with no imprint of massive claw on thumb, foot ovoid with toe claws and heel pad, rare tail drag marks

Question 40

Giving birth to live young?

Answer 40

Titanosaur nesting ground found in patagonia, a square km large with thousands of unhatched eggs, 4 layers of eggs with clusters of 15-34 eggs (eggs contained embryos, some with impression of skin). No adult bones found at nest site

Question 41

Juvenille Titanosaur- cretaceous madagascar

Answer 41

a small specimen of rapetosaurus Krausei, weighed 3.4kg, as a hatchling, death several weeks later due to starvation, at death it has a mass of 40kg, 35cm tall at the hip