9 - dinosaur eating ability

reptilian chewing

• Snakes

  • Teeth that hook backwards

  • Only used for holding not showing

  • Prey is swallowed whole

• Rattlesnakes

  • Fangs are mostly just used to inject venom

• Komodo Dragons

  • Pointy teeth angled backwards to grab and RIP flesh into smaller pieces

  • Spaced out so things don't get stuck in between

  • Not used for chewing

• Can open jaw really wide to seize, kill, dismember prey

  • Joint is at the same level as the lower tooth row

  • Does not allow the jaw to move from side to side

    • Good for holding on to prey

  • Jaw works like a scissor

    • Slices from back to front

    • But does not allow for chewing because the teeth do not all contact at once

herbivore chewing

• Skull divided into 3 parts

  • Cropping section

    • Teeth shaped like blades to bite off food

  • Diastema

    • Gap used for food manipulation

  • Cheek teeth

    • AKa molars

    • Food is ground into a paste

• Adaptations that allow for chewing

  • Coronoid process bone expands for jaw muscle attachment

  • Teeth closely packed together with flat grinding surfaces

    • Teeth occlusion

  • Inset tooth row that supports cheeks

  • jaw joint is above the tooth row

    • All of the upper and lower teeth contact at the same time

    • Less stable but allows for grinding from side to side

    • Hypothetically a jaw joint below could also function the same way

chewers v. non-chewer

• Non chewers

  • Usually carnivores

  • Rarely herbivores

• chewers

  • Herbivore's and omnivores

carnivores

• Do not chew their food

• Larger pieces of meat can easily be digested by stomach acid

• Characteristics

  • Simple, single chambered stomach

  • Short digestive tracks

  • Slim torsos that are V shaped or tapered

herbivores

• Plants are harder to digest so need to be chewed

  • Digestive enzyme in saliva that helps breakdown carbohydrates

• Large, barrel shaped guts for long digestive tracks needed to breakdown plant matter

  • Enable symbiotic relationship between herbivore and bacteria

gastroliths

• Small stones to mechanically processed food for those who do not chew

• Becomes round overtime

• Some animals retain them others passed them and need to replace them

• Also used as a weight in many aquatic animals

• ex. Birds, crocodiles, alligators, seals, sea lions

•  principle of uniformitarianism

  • found in modern world so can assume existed in dinosaurs too

chewing ability of theropods

• Spaced out teeth or areas where there's no teeth

• Tooth row is not inset

• Wide gape

• Pointy serrated teeth

• Main tooth function is tearing things apart

• Slim torso

• jaw joint is at the to throw so the jaw worked like scissors

• How do they deal with prey?

  • Some were able to hold onto their prey

    • For prey smaller than them

  • others had the slashing bite tactic

    • Biting then releasing to wait for the animal to bleed out

    • For prey larger than them

chewing ability of sauropodomorphs

• jaw joint is below the tooth row but still bad chewers

• Spaced out teeth

• Tooth row is not inset

• Tooth shape

  • Leaf, Spatula, Peg shaped

  • So few grinding surfaces

• Main tooth function is to puncture vegetation

• Barrel shaped cuts for fermentation

• Evidence for gastroliths

chewing ability of ornithischians

• Skull is similar to mammals

  • Cropping section

    • Cropping is done with the beak aka rhamphotheca

    • Made of keratin which does not preserve in fossils

  •  diastema

  •  cheek teeth

• jaw Joint is below the tooth row

• Some groups were better than others

direct evidence of what they ate

• Coprolite aka poop

  • Can see bones, plants, crab legs

• Cololites

  • Gut contents like seeds

• Rare because they're soft material that does not fossilize well

indirect evidenc eof what they ate

• Find all the fossils in an area

• Generalization

  • The carnivores probably ate the herbivores and the herbivores ate plants

• Finding teeth marks on bones

• Comparative anatomy

comparative anatomy

• Fish eaters

  • ex. Crocodiles

  • Long narrow snout

    • Can whip head from side to side to catch fish

  • Cone shaped teeth that interlock with each other

    • To trap slippery prey

  • Forward tilting teeth

    • Procumbent teeth to spear fish

  • Birds

    • Will have a sharp pointed beak the spear fish or large lower jaw to scoop them out of the water

• Plant eaters

  • ex. Koala

  • Incisors at the front of the mouth are chisel shaped

    • To grasp at trees

  • diastema between incisors and large cheek teeth (molars) that have broad grinding surfaces

    • Molars shred into smaller pieces

    • Can store food in the cheek pouch

  • Jaw joints above tooth row

    • Less sheer but allows side to side motion

  • Inset Teeth rows

• Insect eaters

  • ex. Anteaters

  • No teeth

  • Narrow long jaw

  • Long tongue with hooks

    • Shape of mouth allows it to flick in and out quickly and efficiently

    • Can reach up to two feet beyond the end of its snout

    • Covered in tiny barbs and thick sticky saliva so that it can collect as many insects as possible

  • Strong claws to break open mounds

• Carnivores

  • ex. hawk

  • No teeth

  • Hooked beak

    • To tear meat apart

  • Sharp talons

    • To kill

ex. of what diff. dinosaurs ate

• Allosaurus

  • Ancestor of T Rex

  • carnivore

• Parasaurolophus

  • Offset jaw

  • Beak and diastema

  • Probably a good chewer

• Shuvuuia

  • Long jaw

  • Probably ate insects

• Spinosaurus

  • Big separated teeth that are curved

  • Probably ate fish