Lesson 6: Attack and Defense Flashcards
Recall: What adaptations for attack/defense did tyrannosaurs, dromaeosaurs, ceratopsians, ankylosaurs and stegosaurs have?
Bone crushing jaws, sickle claws, big horns, and an array of spikes and armor.
What are deterrents?
Spikes, armor and horns act as deterrents, discouraging predators from attacking in the first place.
Based on their hind limb proportions, ornithomimids and many small ornithopods are ___ ___, and it is likely that these dinosaurs made use of their speed when threatened.
Cursorially adapted.
What are cryptic adaptations?
Crypsis is the ability of an animal to avoid detection, and cryptic adaptations include camouflage color patterns, hiding behaviors, and odor-masking chemicals. Crypsis is difficult to judge from only fossil evidence.
Finite element analysis is a technique that has been used by paleontologist to help evaluate hypotheses about the functions of many dinosaur adaptations. What is it?
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.
A recent finite element analysis carried out by University of Alberta researchers attempted to evaluate the hypothesis that the tail cubs of ankylosaurs were used as weapons. Describe the process that was used.
The tail club of the ankylosaur Euoplocephalus was digitally scanned, and this digital model was then imported into a finite element analysis program. The digital tail club model was given material properties equivalent to that of bone. To simulate 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 cub model.
What are some ways we can determine how well dino’s 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.
How do the sensory needs of predators and prey differ?
- Prey needs a wide field of vision and usually has eyes on the sides of its head.
- Predators benefit from being able to maximize their perception of a single target and usually have eyes near each other and facing forward.
What is stereoscopic vision?
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.
What are some different hunting styles among extant predators?
Some hunters are ambush predators, which 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. Other hunters stalk and pursue prey, and may rely on stealth to approach quietly and then strike (large cats, also need sprint speed). Still others, like wolves, may pursue prey over long distances, using their endurance to tire out and eventually overtake their prey (wolves).
What are social predators?
Hunters that work cooperatively to acquire prey that would be too difficult to kill on their own. The downside of this is sharing the kill.
Hunting behaviours can be diverse even among closely related animals. Give an example.
For example, tigers are solitary hunters, lions hunt cooperatively, and cheetahs sometimes hunt alone and sometimes hunt in pairs or small groups.
In Dry Island Buffalo Jump Provincial Park in Alberta, a bonebed of the tyrannosaurid theropod Albertosaurus preserves the remains of more than 20 individuals. What does this suggest?
This seems to suggest that Albertosaurus may have lived in groups rather than as solitary individuals. But there are other reasons why many individual dinosaurs may have collected in one spot. However, the geological and taphonomic evidence at Dry Island suggests that these Albertosaurus represented a single pack that met some catastrophic end. It appears that at least some theropod dinosaurs formed groups, and therefore may have been social hunters.
An incredible fossil, called the “Fighting Dinosaurs”, from Mongolia preserves a Velociraptor (a dromaeosaurid theropod) and a Protoceratops (a ceratopsian) seemingly interacting with each other. One hand of the Velociraptor is in the mouth of the Protoceratops, and the other is holding on to the frill of the Protoceratops. The Velociraptor’s sickle-shaped claw is positioned in the throat of the Protoceratops. What does this suggest?
This amazing fossil pair seems to be a snapshot of a Velociraptor in the midst of killing a Protoceratops, and provides support for the use of the sickle-shaped toe claw as a predatory adaptation. Based on this fossil, we might guess that Velociraptor was a solitary hunter. However, maybe other Velociraptor were present, but were able to escape whatever killed the Fighting Dinosaurs.
What are agonistic behaviors?
It is common for members of the same species to fight over territory, mates, food resources, and for social rank within a group. Fighting and aggressive displays between members of the same species are called agonistic behaviors.
