Lecture 11: Ornithopoda

Question 1

Fossil record

Answer 1

Ornithopoda “bird foot”, ornithischian dinosaurs, middle jurassic to late cretaceous, extensive fossil record, worldwide distribuion

Question 2

History of discovery

Answer 2

1820-1830s, Gideon Mantell discovers Iguanodon teeth and bones in England, body form not well understood in early decades. 1850’s, Joseph leidy discovers hadrosaurs in new jersey, hadrosaurs becomes the first dinosaur mounted on display in a museum

Question 3

What discovery was made at bernissart, Belgium?

Answer 3

Over 30 skeletons of iguanodon in a coal seam, anatomy becomes completely known. continuous discoveries, over 100 ornithopod species now described.

Question 4

What are the characteristic features of an ornithopoda?

Answer 4

Cranial kinesis, lower position of the jaw joing and ventral margin of premaxilla with respect to the maxilla, and obturator process (obp) on ischium (is)

Question 5

basal ornithopoda (“hypsilophodontidae”)

Answer 5

Traditional paraphyletic grade of non-iguanodont ornithopods. Some jurassic ornithischians usually included in this group may be just outside cerapoda, and thus not true ornithopods. smalll bipedal herbivores, fleet footed. some lived in burrows

Question 6

Iguanodontia

Answer 6

Monophyletic, middle jurassic to late cretaceous.

Question 7

Characters features of iguanodontia

Answer 7

generally larger and more heavily built than basal ornithopods (up to about 15m long) expanded premaxilla lacking teeth, hoof like unguals, reduction in number of phalanges/digits

Question 8

Hadrosauridae (a very successful family within iguanodontia)

Answer 8

The duckbills, late cretaceous, north and south America, Europe, Asia, Antarctica. An example is the edmontosaurus

Question 9

Paleogeographic distribution

Answer 9

From paleoquator to polar latitudes and notable high paleoattitude discoveries
Spitsbergen, Norway: big iguanodont tracks, north slope of Alaska: edmontosaurus, bonebed , thescelosaurid teeth
Dinosaur cove, SE australia and James Ross island, Antarctica: new genera of basal ornithopods

Question 10

Paleoenvironments of hadrosauridae

Answer 10

Coastal plain deposits, Fluvial deposits, Marine deposits

Question 11

Locomotion of hadrosauridae

Answer 11

Bipedal terrestial animals, quadrupedal stance when standing still or feeding, iguanodon- quadrupedal locomotion? strong hind limbs support weight

Question 12

Iguanodon

Answer 12

Possibly capable of both bipedal and quadrupedal locomotion? strong front limbs support weight, strong hindlimbs, tail is strengthened by ossified tendons and served as counterbalance

Question 13

Speeds and brains of ignuanodon

Answer 13

15-20km/hr with max speeds estimated up to 60km/hour for smaller ornithopods, relatively large brains, intelligence helped alertness, no other means of protection (e.g., armour, tail spikes) present

Question 14

The Hands of non hadrosaurid iguanodonts

Answer 14

Some non-hadrosaurid iguanodonts (iguanodon, ouranosaurus)
first digit (thumb) was conical and sharply pointed
fifth digit opposite to thumn
three middle digits were hoofed

Question 15

Hadrosaur hands

Answer 15

Thumb spike was absent, hooves on inner fingers, digits joined in a thickened pad

Question 16

Their Feeding habits (hadrosaurs)

Answer 16

fossilized stomach content: Twigs, berries, and coarse plant matter, beak for cropping vegetation

Question 17

Teeth (hadrosaurs)

Answer 17

Block of cheek teeth, dental batteries for grinding coarse material, strong muscles, teeth deeply set indicating large fleshy cheeks

Question 18

Bilateral occlusion

Answer 18

Both teeth meet on both sides of the jaw

Pleurokinesis: lateral mobility of the upper jaws

Question 19

Pleurokinesis

Answer 19

Opposing rotation of both jaws, impossible in humans. very flexible joints of the skull bones, dental batteries chewing vegetation with large amount of fiber. A new alternative view: akinetic upper jaws, chewing with mandibular rotation only

Question 20

Behaviour and head structure

Answer 20

Hadrosaurs: Cranial features with nasal cavity, solid hollow crests, for visual and vocal display, important in mating behavior

Question 21

Lambeosaurines

Answer 21

Hollow crest on top of head, served as resonating chambers within crest

Question 22

Display features in lambeosaurines

Answer 22

Good hearing and vision, large eye sockets, preserved middle and inner ear structures, hearing of a wide range of frequencies, elaborate outer shapes of crests point towards display, species specific, less developed in juvenilles

Question 23

Difference between species (lamb.)

Answer 23

If species live at the same time in the same area: display features have to be different to avoid attracting the wrong mate, therefore different headdresses

Question 24

Saurolophinae

Answer 24

Accentuated nasal arches and stout cranial crest possibly used
for head pushing during male tomale combat. Nostrils covered by skin flaps which were blown out to impress enemy or make noise?

Question 25

Herd living (sauro.)

Answer 25

Bonebeds suggest living in herds, herds up to 10,000 individuals, complex social behavior, safety in numbers

Question 26

Use of crests (sauro.)

Answer 26

for Species recognition
for intraspecific combat
for ritualized display
Courtship
parent-offspring communication
social ranking

Question 27

Maiasaura and hypacrosaurus

Answer 27

Nests with up to 17 eggs, soft sediment, nest spacing as large as body of parent, shells are damaged from trampling, hatchling remained in nest, estimated nesting time:8-9 months, quick growth

Question 28

______ _______ well known for hadrosauridae

Answer 28

Skin impressions