Lesson 6: Attack and Defense Flashcards
How were horns, spikes, and armor used as defense by herbivorous dinosaurs?
having horns or spikes is a common strategy used by modern animals
horns of buffalo and rhinos or the spiky quills of porcupines make them dangerous prey to attack
even if predators succeed at killing such prey, they may be seriously injured in the process
What are deterrents?
weapons like horns and spikes, beyond their usefulness in defending prey when attacked, are also deterrents
they discourage predators from choosing to attack in the first place
armor, like the shell of a turtle, can also be a deterrent because it makes the animal difficult to eat, and therefore not worth the effort
large size can be a defense entirely on its own
What deterrents did giant sauropods use to avoid predators?
giant sauropods may have lacked horns and armor, but their sheer size would have made them formidable prey
like modern elephants, giant sauropods could have trampled even their largest potential predators, and, although they were not armed with spikes and clubs, sauropods could have dealt severe blows with their massive tails
How are cursorial limbs a defense against predators?
being able to outrun and/or outmaneuver potential predators keep prey safe and avoids a physical fight altogether
based on their hind limb proportions, ornithomimids and many small ornithopods are cursorially adapted, and it is likely that these dinosaurs made use of their speed when threatened
however, predators can also make use of speed, and long limbs in a carnivore can be seen as a predatory adaptation
How do cryptic adaptations help prey to avoid predators?
cryptic adaptations allow potential prey to go a step further and avoid even being seen by predators
crypsis is the ability of an animal to avoid detection, and cryptic adaptations include camouflage color patterns, hiding behaviors, and odor-making chemicals
crypsis is difficult to judge from only fossil evidence
because cryptic adaptations are widespread among modern animals, it is reasonable to assume that cryptic adaptations were also wide spread among dinosaurs
however, relying primarily on crypsis as a predator defense is more common among small animals, which are able to hide more easily behind environmental structures, than among large animals, and it is unlikely that crypsis was the sole predator defense of any large herbivorous dinosaurs
it is difficult to demonstrate that any dinosaur species used cryptic adaptations like camouflage, because color and color patterns are not usually preserved in dinosaur fossils and “hiding” isn’t something that can be fossilized
What defenses cannot be observed through the fossil record?
like crypsis, many defenses, including chemical weapons and intimidating displays, are difficult to detect from fossil evidence
some modern animals use bright colors or false eyes to scare predators away, or to clearly label themselves as toxic or otherwise dangerous
given the diversity of dinosaurs, it is more likely that some dinosaurs, it is more likely that some dinosaurs used such defenses then that no dinosaurs did
What is finite element analysis?
a technique that has been used by paleontologist to help evaluate hypotheses about the functions of many dinosaur adaptations
finite element analyses are computer simulations that apply set material properties to a digital object and that report data on how stresses are dispersed through the object, when a force is applied at a particular point
How was finite element analysis carried out to evaluate the hypothesis that the tail cubs of ankylosaurs were used as weapons?
the reasoning behind this study was that, if ankylosaur tail cubs were used as weapons, it is likely that the tail cubs were able to withstand large impact forces without breaking, whereas, if ankylosaur tail cubs were not used as weapons, it would be very unlikely that the tail cubs were adapted in such a way as to withstand large impact forces
the tail club of the ankylosaur Euoplocephalus was digitally scanned, and this digital model was them imported into a finite element analysis program
the digital tail cub model was given material properties equivalent to that of bone
to stimulate a tail club strike, the force of a Euoplocephalus tail swing was estimated and was applied to a point on the outer surface of the digital tail club model
the results showed that the resulting stresses across the tail club were insufficient to damage the tail club
thus, the study concluded that ankylosaur tail clubs were capable of serving as weapons, and this supports the hypothesis that weapons were the function of the tail clubs
How can paleontologists determine how well a dinosaur could see, hear, and smell?
the brain cases of dinosaurs offer some clues, because the sizes of different regions of the brain relate directly to the strength of specific senses
eye size can be estimated from the size of the orbits, and the inner ear cavity of the skull offers many clues to the strength of a dinosaur’s hearing
What adaptations serve the sensory needs of prey?
herbivores, who are concerned with avoiding being snuck up on by predators, benefit from a wide field of view
for this reason, herbivores often have eyes positioned on the sides of their heads
this prevents the field of vision of one eye from redundantly overlapping with the field of vision of the other eye and maximizes how much of its surrounding an animal can see at one time
What adaptations serve the sensory needs of predators?
predators benefit from being able to maximize their perception of a single target
often, but by no means always, predators have eyes that are positioned near each other and that both face forward
this causes the field of vision of both eyes to overlap and grants the predator stereoscopic vision
What is stereoscopic vision?
allows an animal to see the same object with both eyes, and thus to see it from two slightly different angles, which improves the animal’s ability to judge depth
other animals besides predators may benefit from enhanced depth perception, and stereotypic vision is also common among animals that fly and climb
What are ambush predators?
lie in wait until prey comes within striking distance
a good example of this kind of hunting strategy is a crocodile, waiting for prey to enter the water, then lunging
What are stealthy predators?
stalk and pursue prey, and may rely on stealth to approach quietly and strike
What are pursuit predators?
still others, like wolves, may pursue prey over long distances, using their endurance to tire out and eventually overtake their prey
