Pachycephalosaur
Sister Group Group Ceratopsians
Relationships Ornithiscians Genosaurs Cerapodans Marginocephalians
Location North America and Eurasia
Age Early-Late Cretaceous
General Long hind limbs, very short front limbs, short neck, long trunk, long tail, transverse processes of tail vertebrae Frill and Horn arangements
Diet Herbivores Chewing Minimal Digestion took place in very large hind gut Herbivores Chewing and Slicing Jaw closing muscles attached to frills Well-Dev Dental Batteries Selective Feeders Did not have a very large gut so they did not rely as much on chemical breakdown of food
Locomotion Suggested Bipedal But we don't know what the foot looked like Max. speeds= 2050 km/hr Slow Progression Normally Most likely Quadrapedal But argued semisprawled gait with front limbs held upright
Social Behavior Head-butt Sexual Dimorphism in the Domes
Uniting Charecteristics Ossified Tendons Elongated Sacral Ribs
Size Small to medium
Ceratopsians
Pachycephalosaurs
Ornithiscians Genosaurs Cerapodans Marginocephalians
Northern Hemisphere Continents (North America and Eurasia)
Mostly a Cretaceous Group
Horns and Frills could have been used for Defense, Male To Male combat Species Specfic (Display) Sexual Dimorphic
Rostral Bone (Beak Bone) Narrow Beak (Narrow Skull in mouth region) Flaring Skull in cheek region Frill composed of parietal bones
Small to Medium
Marginocephalians
Ornithopods
Narrow Shelf over back of skull formed by parietal and squamosal bones Reduced premaxillary contribution to palate Shortened pubis Wide-spaced hips
Ornithopods
Marginocephalians
Ornithiscians Genosaurs Cerapodans
All over the Globe Evidence for habitat
Early Jurassic till Late Cretaceous
Larger onithopods developed hoofed hands
Herbivores Not Selective Feeders Big-time
Small Forms typically bipedal, larger forms
Social Monospecific Bone Beds Multiple
Depression of mandibular condyle (Jaw Joint)
Small to Medium
partitioning
One of the Oldest Groups of Dinosaurs
Prosauropods
Sauropods
Saurischians Sauropodomorphia
Global Distribution Lived while Pangea was still intact
Late Triassic and Early Jurassic
Long neck and Tails Disproportionately small skull, bulky body, moderately long front limbs relative to the hind limbs
Sauropods
Prosauropods
Saurischians Sauropodomorphia
Global Distribution Lived while Pangea was still intact
One of the oldest living groups Late Triassic to end of Cretaceous Most abundant in Jurassic Period
Long Neck and Tail Disproportionately small skull bulky body Moderately front long limbs relative to hind limbs Lived on land
Chewers Large horny ramphotecae Developed Dental Batteries Complex Chewing Patterns Herbivores or Possibly Ornivores Not Chewers Poorly Developed Coronoid process Jaw join did not permit side to side motion Food Processed in Gut (gastroliths) Herbivores Not Chewers Despite long necks were browsers Swung neck from side to side to more than 90
were bipedal to quadrupedal Very Slow
Parallel trackways Parents Took care of young
Small = Bipedal Large = Quadrupedal May have been Facultative Bipeds (change at will
Gergarious (Herding) Based on monospecific bone beds
Vestigal Digit V (No Phalanges, Not Fully Developed)
Small to Medium
Obligate Quadrupeds Moved rather slowly but could have ran
Gregarious Monospecific Bone Beds Parrallel Trackways Site FidelityCame back to the same site year after year to lay eggs
Fully Developed Digit V Legs and Metacarpals held vertically Hind feet had a large fleshy pad Forelimb 60% or more than haind limb length compared to prosauropods whose forelimb is much smaller
Largest Animals to have ever lived Possibly 40 m Grew Rapidly
Sauropodomorpha
Theropoda
Saurischians
Theropods
Sauropodomorphia
Saurischians
Global Distribution
Longest living groups of Dinosaurs Late Triassic Today (Birds)
Arms much shorter than legs Arms designed for grasping not weight bearing Held bodies out horizontally and balanced them over the hips with their long tails Stalked Sauropods Reproduced with Eggs
Carnivores based on sharp, pointed teeth and claws on hands and feet May have feed on fish Swallowed large chunks of meat, along with bone, and processed in a two-part stomach Proventiculusenzyme producing region Gizzardmuscular region that ground food
All were Bipedal Sitting Traces have been found Most theoropods regardless of size walked slow Some ran Strong Evidence that they could Swim
Thin, Flat, Spatualte Serrated Teeth Minimum of 10 elongate cervical vertebrae (neck) Large Digit I claw on manus Large hole in pubis near acetabulum Extreme Hollowing of Vertebrae and long Bones (Arms and Legs) Enlarged Hand (primitively) Reduced Vestigal IV and V digits
Wide Range of sizes 1m 15 m long
Birds
Vertebrates Tetrapods Amniotes Diapsids Archosaurs Dinosaurs Theropods
Hand highly modified with three digitws being fued onto a single bone (Digit 1) which is very important for flight
Absence of teeth Large brain and Eyes Modified hand (carpometacarpus) Modified foot with tarsometatarsus Synsacrum Reduced tail Keeled sternum Pneumaticized Bone