Lec 11 Dinosaurs & Birds Flashcards
What are the synapomorphies of Avemetatarsalia?
(hints: 4 post-cranial, compared to crocodile)
shortened forelimbs, tibia longer than femur, mesotarsal ankle joint, no dorsal body osteoderms
What are the main clades in Avemetatarsalia?
Pterosauromorpha, Dinosauria
What are the 5 main features of Pterosaurs?
(3 post, 2 whole body)
Pteroid bone
elongated 4th finger supports wing membrane
Hollow bone with thin cortex
Pycnofibre integumentary covering
Synsacrum
What are the 3 synapomorphies of Dinosauria?
(all post-cranial)
- Deltopectoral crest on humerus
- Perforated acetabulum
- femoral head inturned and distinctly offset from the shaft
What are the two main clades of Dinosauria?
Saurischia, Ornithisichia
What are the 3 synapomorphies of Ornithischia?
(2 cranial, 1 post-cranial)
- Predentary
- ossified tendons along vertebral column
- tooth crown expanded above root
What are the characteristic of Ornithischia: Thyreophora?
(1 whole body)
extensive development of osteoderms
What are the 2 characteristics of Thyreophora: Stegosaurs?
(all post-cranial)
bony plates that ran vertically down the middle of the back; spikes on tail
What are the characteristics of Thyreophora: Ankylosauria?
Heavily armoured since osteoderms embedded in the skin
Bony tail clubs and bony eyelids
What are the 3 characteristics of Ornithischia: Ornithopoda?
- fossa-like depression on premaxilla-maxilla boundary
- paired frontals narrow and elongated
- fenestra located dorsally on surangular-dentary joint
What are 2 examples of Orithopoda?
Iguanodontia, Hadrosauridae
What are the 4 key features of Ornithischia: Orithopoda: Hadrosauridae?
(all cranial)
- dental battery w/ >=3 replacement teeth
- cranial crest formed of nasal bone
- circumnarial fossa
- lancoelate tooth crowns
What are the 5 key features of Ornithischia: Ceratopsidae?
(4 cranial, 1 post-cranial)
- rostral bone
- Horns on face
- Frills formed by parietal and squamosal
- Shearing dentition
- Syncervical bar (fused anterior neck vertebrae)
What are the uses of horns and frills in Ceratopsidae?
Socio-sexual display
What are the key features of Ornithischia: Pachycephalosauria?
(2 cranial, 1 post-cranial)
- Thickened frontoparietal dome of skull
- ornamented parietosquamosal shelf
- wide flaring pelvis
What are the 4 synapomorphies of Saurischia?
(1 cranial, 3 post-cranial)
- Lacrimal folds over posterior part of antorbital fenestra
- Hand > 40% of humerus+radius
- Twisted first phalanx in the thumb
- manual digit V lack phalanges
What are the two clades of Saurischia?
Sauropodomorpha, Theropoda
What are the synapomorphies of Saurischia: Sauropodomorpha?
(1 cranial, 2 post-cranial)
- Small skull (< 50% of femur)
- > = 10 cervical vertebrae forming elongate neck
- forelimb > 50% length of hindlimb
What are the 4 key features of Sauropodomorpha: Sauropoda?
(all post-cranial)
- > = 4 sacral vertebrae
- long forelimbs (over 2/3 the length of hindlimb)
- straight femur
- digit V of foot weight-bearing
What are the synapomorphies of Saurischia: Theropoda?
(1 cranial, 2 post-cranial)
- Anterior tympanic recess in braincase
- elongated and curved anterior wing on iliac blade
- MT 1 reduced and attached to MT II, not reach ankle joint
What is the theropod body plan?
(1 cranial, 3 post-cranial)
1, Bipedal gait
2. blade-like serrated teeth
3. s-shaped neck
4. foot with 3 main weight-bearing digits and a short hallux
What are the synapomorphies of Theropoda: Tetanurae
(1 cranial, 1 post-cranial)
maxillary fenestra in antorbital fossa
sharp ridge on tibia for close attachment of fibula
What are the synapomorphies of Theropoda: Tentanurae: Coelurosauria?
(2 cranial, 1 whole body)
- maxilla antorbital fenestra > 40% of external antorbital fenestra
- No serrations on premaxillary teeth
- simple filamentous feathers
What are the 5 common features of herbivorous Coelurosauria?
(3 jaw features)
loss of teeth
toothless beaks
downturned lower jaws
large body size
stomach stones
What are the synapomorphies of Theropoda: Tentanurae: Coelurosauria: Maniraptora?
(3 cranial, 1 whole body)
- complex, vaned feathers
- maxilla participates broadly in external naris
- fused parietals
- maxillary and dentary teeth lack serrations anteriorly
What are the synapomorphies of Theropoda: Tentanurae: Coelurosauria: Maniraptora: Paraves?
(2 post-cranial, 1 whole body)
- asymmetric vaned feathers on forelimbs
- humerus longer than scapula
- calcaneum and astragulus fused but not to tibia
What are the 2 clades of Paraves?
Deinonychosauria, Aves
What are the two clades of Paraves: Deinonychosauria?
Troodontidae, Dromaeosauridae
What are the 2 key features of Troodontidae & Dramaeosauridae?
extensive features covering, wings with shafted feathers on arms and legs
What are the synapomorphies of Aves?
(1 cranial, 1 post-cranial)
Parietals separate
Elongate forelimbs (humerus and ulna longer than femur)
What is the key feature of Pygostylia?
Reduced number and fusion of caudal vertebrae in the pygostyle
What are the 4 synapomorphies of Neornithes?
(2 cranial, 2 post-cranial)
no teeth
dentaries fused anteriorly into a beak
pneumatized coracoid and humerus
>=11 sacral vertebrae
What are the 2 hypotheses on how flight evolves?
- Trees Down Hypothesis: first in arboreal forms that glide then powered flight
- Ground Up Hypothesis: first in ground dwelling forms that used their wings to generate lift either while climbing or chasing down prey, then powered flight
(Wing assisted incline running)
Sequence of evolution of feathers
- Filamentous feathers for display, sensory, insulation
- Shafted feathers
- Asymmetrical
