Why did some dinosaurs grow so big?

Paleontologists don"t know for certain, but perhaps a large body size protected them from most predators, helped to regulate internal body temperature, or let them reach new sources of food (some probably browsed treetops, as giraffes do today). No modern animals except whales are even close in size to the largest dinosaurs; therefore, paleontologists think that the dinosaurs" world was much different from the world today and that climate and food supplies must have been favorable for reaching great size.

Did dinosaurs communicate?

Dinosaurs probably communicated both vocally and visually. The chambered headcrests on some dinosaurs such as Corythosaurus and Parasaurolophus might haved been used to amplify grunts or bellows. Defensive posturing, courtship behavior, and territory fights probably involved both vocal and visual displays. An angry Triceratops bull shaking his head at you, even silently, would have made himself very clearly understood!

How fast could dinosaurs walk or run

Estimates of dinosaur speeds vary because several different methods are used to calculate them. One recent estimate suggests that an average person might have been able to to outrun an adult Tyrannosaurus (although you probably would not volunteer to try). The two basic approaches for estimating dinosaur speed are comparing to recorded speeds of modern animals of similar body size and build, and measuring distances between fossil footprints in a trackway and using these distances to calculate estimated speed. Walking-speed estimates for medium-sized bipedal (two-legged) dinosaurs vary from 4 kph to 6 kph, and peak running-speed estimates vary from 37 kph to 88 kph. The highest figure (88.6 kph) is the same as the peak speed of the currently fastest land animals, such as the North American pronghorn "antelope" (Antilocapra americana), and very probably is too high.

Speed comparison of some ancient and modern animals

What did dinosaurs eat?

Some dinosaurs ate lizards, turtles, eggs, or early mammals. Some hunted other dinosaurs or scavenged dead animals. Most, however, ate plants (but not grass, which hadn"t evolved yet). Rocks that contains dinosaur bones also contain fossil pollen and spores that indicate hundreds to thousands of types of plants existed during the Mesozoic Era. Many of these plants had edible leaves, including evergreen conifers (pine trees, redwoods, and their relatives), ferns, mosses, horsetail rushes, cycads, ginkos, and in the latter part of the dinosaur age flowering (fruiting) plants. Although the exact time of origin for flowering plants is still uncertain, the last of the dinosaurs certainly had fruit available to eat.

How are dinosaurs named?

Dinosaurs generally are named after a characteristic body feature, after the place where they were found, or after a person involved in the discovery. Usually the name consists of two Greek or Latin words (or combinations); in order, these are the genus (plural, genera) and the species name. For example, the Greek and Latin combination (binomen) Tyrannosaurus rex means "king of the tyrant lizards." Biologists name modern animals exactly the same way. Some examples include humans (Homo sapiens), domestic dogs (Canis familiaris), golden eagles (Aquila chrysaetos), box turtles (Terrapene carolina), and rattlesnakes (Crotalus horridus).

Why did the dinosaurs die out

There are dozens of theories to explain a probable cause or causes. Throughout the Mesozoic Era, individual dinosaur species were evolving and becoming extinct for various reasons. The unusually massive extinction at the end of the Cretaceous exterminated the last of the dinosaurs, the flying reptiles, and the large swimming reptiles, as well as many other marine animals. There is now widespread evidence that a meteorite impact was at least the partial cause for this extinction. Impact craters are visible on most planets in our solar system. A spectacular example of this was witnessed in 1994, when Jupiter was struck by a series of cometary fragments. Some of these impact blasts were larger than the Earth"s diameter. Other factors such as extensive release of volcanic gases, climatic cooling (with related changes in ocean currents and weather patterns), sea-level change, low reproduction rates, poison gases from a comet, or changes in the Earth"s orbit or magnetic field may have contributed to this extinction event.