discovery: Ornithischia Dinosaurs of Great Britain - Darren Naish
Ornithodira - UC-Mercedjdyeakel.github.io/slides/dinos/07_Dinosauria.pdf · Ornithodira Dinosauria...
Transcript of Ornithodira - UC-Mercedjdyeakel.github.io/slides/dinos/07_Dinosauria.pdf · Ornithodira Dinosauria...
Archosauria
Crown-clade Archosauria
OrnithodiraCrurotarsi
Ornithosuchidae
Pterosauria Dinosauria
“Rauisuchia”Crocodylomorpha
Basal archosaurs
Basal archosaur?Maybe... or it split off before archosauria
TanystropheusProlacertiform
Archosauria
prolacertiform?
Archosauromorpha
Archosauria: synapomorphies
Antorbital fenestra (in front of eye)Teeth with serrated marginsMandibular fenestra
ProterosuchusBasal Archosaur
Euparkeria (Facultative biped)Derived, Basal ArchosaurBony dermal plates down back
Faculatative biped vs. Obligate biped
Stances: sprawling <=> semi-erect <=> erect
aquatic <=> terrestrial
Rauisuchians-Pillar-Erect Posture
Locomotion(Pelvis)
Buttress-ErectOrnithodiransMammals
Archosauria
Crown-clade Archosauria
OrnithodiraCrurotarsi
Ornithosuchidae“Rauisuchia”Crocodylomorpha
Basal archosaurs
Pillar-ErectButtress-Erect
Buttress-Erect
Locomotion: Pelvic/Hind leg conditions:
Digitigradevs.Plantigrade
Barrel-like articulationConstrained ‘twisting’ motion to the plane parallel with its body
astragalus calcaneum
PM: Primitive Metatarsal
CN: Crocodyle NormalCrocodylomorphs/Rauisuchians
CR: Crocodyle ReversedOrnithosuchids
AM: Advanced MesotarsalPterosaurs, Dinosaurs
Hinge
Hinge
Rotation Rotation
Proterosuchus
The importance of a twisting ankle for animals with sprawling-erect posture
The importance of a twisting ankle for animals with sprawling-erect posture
Archosauria
Crown-clade Archosauria
OrnithodiraCrurotarsi
Ornithosuchidae“Rauisuchia”Crocodylomorpha
Basal archosaurs
Pillar-ErectRotation
Buttress-erect*Rotation
Buttress-erectRotation
Buttress-erectHinge
Sprawling/Semi-erectHinge
buttress-erect = parasagittal
CrocodylomorphaLate TriassicTerrestrisuchusSaltoposuchus
BIPEDAL!/TERRESTRIAL!
Saltoposuchus
Terrestrisuchus
Buttress-erect*Rotation
A return to aquatic environments was more recent for crocodylomorphs
Ornithodira
DinosauriaPterosauria(later)
Saurischia Ornithischia
Dinosaur expansion: multiple models
Competitive Replacement Scenario (Gradual)
Opportunistic Scenario (Abrupt)
DINOSAURS
Dinosaur synapomorphiesA) Crest on humerusB) Shelf on top surface of iliumC) Perforated acetabulumD) Tibia w/ expanded endE) Ascending astragular process on front surface of tibia
(parasagittal stance)
DINOSAURS
Herrerosaurus
Lagosuchus
Heterodontosaurus
Eoraptor
Herrerosaurus
Pisanosaurus
Basal Dinosaurs
Coelophysis
Ornithischians!
‘Cheeky’ saurs
Lesothosaurus
Heterodontosaurus
Shared, derived traits of skull
PredentaryLow jaw jointPalpebral bone: EAGLE EYE!Deep set cheek teeth
Head Tail
Hip shared, derived, trait
‘Opisthopubic pelvis’
Basal Ornithodiran condition
Heterodontosaurus
Shared, derived traits of skull
PredentaryLow jaw jointPalpebral bone: EAGLE EYE!Deep set cheek teeth
Head Tail
Hip shared, derived, trait
‘Opisthopubic pelvis’
Basal Ornithodiran condition
Other shared, derived traits
At least 5 sacral vertebraeOssified tendons above sacral regionFrontal process on illium
Lesothosaurus
How do mammals chew?Front: CroppingDiastem: Manipulation by tongueCheek teeth: Grinding (occluding)Coronoid Process ~ Muscle attachmentsInset molars for cheeks ~ keep food in mouth
How do mammals chew?Front: CroppingDiastem: Manipulation by tongueCheek teeth: Grinding (occluding)Coronoid Process ~ Muscle attachmentsInset molars for cheeks ~ keep food in mouth
How did Ornithischians chew? In very similar waysFront: Cropping: carried out by keratin RAMPHOTHECADiastem: Manipulation by tongueCheek teeth: Grinding! Dental BatteriesCoronoid Process ~ Different shape, different muscle attachmentsInset molars for cheeks ~ keep food in mouth
EdmontosaurusOrnithopod
How did Ornithischians chew? The Angle of the jaw. Scissors vs. Pliers
Traveling forceSmall area, large force
Broadly distributed force
Large area, less force
Basal Ornithischians
Pisanosaurus Lesothosaurus
Everything else in Ornithischiais in Genasauria Chewing
‘Cheeky’ saurs
Lesothosaurus
Heterodontosauridae
Heterodontosaurids: Not Primitive... unique chewing.
Three kinds of teethAnterior: Snipping/CroppingPosterior: ChewingTusks: Potentially display/courtship
Heterodontosaurids: Not Primitive... unique chewing.
Three kinds of teethAnterior: Snipping/CroppingPosterior: ChewingTusks: Potentially display/courtship
Chevrotain