Lesson 3: Eating Flashcards
How can paleontologists determine the diet of a dinosaur?
sometimes, a dinosaur skeleton includes fossils of its incompletely-digested last meal inside of its ribcage, but such fossil gut contents are rare
usually, to figure out a dinosaur’s diet, paleontologists must compare its feeding adaptations with those of modern animals whose diets can be directly observed
What are herbivores?
tend to have thin, ridged or “leaf-shaped” teeth for shearing and broad, flat teeth for grinding
modern birds lack teeth, but herbivorous birds tend to have short, triangular beaks
herbivores that browse high in trees, but cannot climb, have long legs and necks, like giraffes
What are carnivores?
tend to have sharp pointed teeth for piercing, and sharp hooked claws for holding onto struggling prey
raptorial birds have sharp and hooked beaks and claws
like modern carnivores, carnivorous dinosaurs usually have sharp teeth and hooked claws, and, like some carnivorous lizards, most also have teeth with serrated edges
What are serrations?
small sharp bumps on a tooth that are arranged in a line that usually runs from the tip to the base of the tooth
you can see serrations at work on the edge of a steak knife, and, just like the serrated knife edge, serrated tooth edges helped carnivorous dinosaur teeth to slice through flesh
What are frugivores?
eat primarily fruit
the beak of a parrot is sharp and hooked (not unlike the beak of a carnivorous bird), because it needs to rip and tear apart the peels and protective husks of large tropical fruits
What are piscivores?
specialized carnivores that primarily eat fish
tend to have tall, sharp, conical teeth that usually lack serrations
these adaptations make piscivore teeth good at spearing and holding onto slippery fish
also tend to have long jaws that are long, strait, and sharp at the tips
What are insectivores?
specialized carnivores that primarily eat insects
have sharp piercing teeth for puncturing the chitinous exoskeletons of insects
but many insects are soft bodied and can be swallowed whole, without being chewed, so many insectivores have weak jaws and reduced teeth
some have no teeth at all
have large spade-shaped claws and powerful, but short, limbs
What is durophagy?
some carnivores, like hyenas, Tasmanian devils, and alligators, have sharp teeth for puncturing and ripping flesh but also have strong rounded teeth that enable them to crack bones
durophagy also requires extremely powerful jaws
What are omnivores?
animals that eat significant amounts of both meat and plants
humans are a good example of an omnivore, as are pigs, most bears, rats, crows, and many turtles
tend to have either unspecialized beaks and teeth or a variety of teeth with different shapes (some shaped like those of herbivores and other like those of carnivores)
in your mouth, you have pointed canines, which have a shape characteristic of a carnivore, and you also have molars, which have a shape characteristic of a herbivore
What is resorption?
is the chemical process by which a dinosaur breaks down its own teeth and bones so that the minerals and nutrients that compose them can be reused
after a new tooth was ready to replace an old one, and after the old tooth’s root was reabsorbed, the top, or “crown”, of the old tooth could be shed
How did dinosaurs shed their teeth?
teeth that are ready to be shed still usually require a little help getting free from the little bit of gum that still surrounds their base
often loose teeth are shed while an animal is feeding
throughout their lives, dinosaurs were constantly in the process of replacing teeth
What can shed teeth tell us about the dinosaurs diet?
often, the skeletons of dinosaurs will be discovered with many shed teeth nearby
that tells us that the dinosaur to whom the shed teeth belong to was probably feeding on the other dinosaur’s carcass
What is a dental battery?
Dense arrangement of teeth found in the jaws of hadrosaurs and ceratopsians
two groups of dinosaurs evolved dental batteries: hadrosaurs and ceratopsians
because the individual teeth that make up dental batteries are small, and because chewing grinds teeth down quickly, dinosaurs with dental batteries replaced their teeth rapidly
in the skull, there can be over 1,000 teeth
surface is intricate, varied, and abrasive
What is cellulose?
Tough organic compound that forms plant cell walls
How do animals digest cellulose?
animals cannot digest cellulose on their own
animals need help from bacteria that live within their stomach and intestines
even with the help of bacteria, getting all the raw energy that a large animal needs to survive from plants is not easy
chewing food before sending it down to the digestive organs helps, because chewing breaks plants into smaller pieces that are easier for bacteria and digestive enzymes to envelope
What tissues were dinosaur teeth made of?
enamel: which usually covers the outside of a tooth
dentine: which is usually common on the inside of a tooth
How did hadrosaurs use their dental batteries?
the chewing surfaces formed by the dental batteries are angled downwards, but still mostly horizontal
when they chewed, they moved their jaws backwards and forwards and also from side to side
How did ceratopsians use their dental batteries?
almost vertical
teeth in their jaws would slid together like scissor blades, with the opposing lateral sides of the teeth doing most of the grinding
What do teeth that are inset in the jaw look like?
they are positioned close to the tongue
inset teeth probably helped make room for large cheeks, and cheeks are important for holding in food while an animal chews
What are the characteristics of ankylosaur and sauropod teeth?
had simple teeth that could be used to nip off vegetation but could only help break down their food a little
what these dinosaurs lacked in chewing ability, the made up for in guts
What are the characteristics of ankylosaur and sauropod digestive systems?
have huge ribcages that housed immense digestive organs
although it would take a long time for these dinosaurs to digest plant matter, they still got the energy they needed thanks to their extensive series of digestive vats and the sheer volume of food their digestive tracks were able to hold
What are gastric mills?
Muscular pouch in the digestive tract near the stomach that holds swallowed stones called gastroliths
as the muscles rub the stones against one another, food passing through the mill is ground up, performing the same function as a set of chewing teeth
they help toothless animals to “chew” their food
What are the characteristics of Dromaeosaurs?
a group of therapod dinosaurs with thin tails supported by special rod-like projections of their caudal vertebrae and chevrons
had serrated blade-like teeth and a large sickle-shaped claw on each hind foot
these special foot claws resemble the retractable claws of modern cats, and could be raised off the ground
Why are retractable claws an advantage?
keeping their claws raised would have prevented the claws from scratching the ground as dromaeosaurs walked, and this would’ve kept the claws sharp
What are the characteristics of Spinosaurs?
a group of therapods with skulls that strongly resemble those of crocodiles
are thought to be piscivores
teeth are conical, have sharp tips, and have few or no serrations
What are the characteristics of Alvarezsaurs?
a group of small theropods with short front limbs and compact hands
thought to have been insectivores
most have reduced teeth and short, but strong, front limbs
What are the characteristics of Tyrannosaurs?
a group of therapods that evolved late in the history of dinosaurs and have reduced front limbs and robust skulls
teeth have serrated edges and are well adapted for puncturing and cutting flesh
most of their teeth have blunt tips and the attachment sites for jaw muscles in their skulls indicate a capacity for a tremendous biting force
these adaptations indicate that tyrannosaurs may have been capable of durophagy
What is scavenging?
refers to the consumption of an already dead animal by a carnivore that did not play a part in killing it
Why is durophagy beneficial?
because it may allow a carnivore to access nutrients within the bones of a carcass that has already been picked over by other carnivores
however, many durophagous carnivores crush and consume the bones of animal that they themselves have killed, and many animals that are not capable of durophagy regularly scavenge
vertebrate carnivores that only scavenge are rare, as are those that never scavenge
scavenging is an opportunistic part of virtually every carnivores life
What are cololites?
fossil gut content
What are coprolites?
fossil poop
alothough it is often difficult to identify what kind of dinosaur a particular coprolite came from, coprolites can give information not only on what a dinosaur ate but how it was digested
